diff options
Diffstat (limited to 'ext2ed')
| -rw-r--r-- | ext2ed/COPYRIGHT | 346 | ||||
| -rw-r--r-- | ext2ed/Makefile.in | 97 | ||||
| -rw-r--r-- | ext2ed/README | 160 | ||||
| -rw-r--r-- | ext2ed/blockbitmap_com.c | 266 | ||||
| -rw-r--r-- | ext2ed/dir_com.c | 678 | ||||
| -rw-r--r-- | ext2ed/disk.c | 239 | ||||
| -rw-r--r-- | ext2ed/doc/ext2ed-design.sgml | 3459 | ||||
| -rw-r--r-- | ext2ed/doc/ext2fs-overview.sgml | 1569 | ||||
| -rw-r--r-- | ext2ed/doc/user-guide.sgml | 2258 | ||||
| -rw-r--r-- | ext2ed/ext2.descriptors | 976 | ||||
| -rw-r--r-- | ext2ed/ext2_com.c | 98 | ||||
| -rw-r--r-- | ext2ed/ext2ed.8.in | 72 | ||||
| -rw-r--r-- | ext2ed/ext2ed.conf.in | 79 | ||||
| -rw-r--r-- | ext2ed/ext2ed.h | 435 | ||||
| -rw-r--r-- | ext2ed/file_com.c | 565 | ||||
| -rw-r--r-- | ext2ed/general_com.c | 907 | ||||
| -rw-r--r-- | ext2ed/group_com.c | 183 | ||||
| -rw-r--r-- | ext2ed/init.c | 633 | ||||
| -rw-r--r-- | ext2ed/inode_com.c | 437 | ||||
| -rw-r--r-- | ext2ed/inodebitmap_com.c | 215 | ||||
| -rw-r--r-- | ext2ed/main.c | 548 | ||||
| -rw-r--r-- | ext2ed/super_com.c | 156 | ||||
| -rw-r--r-- | ext2ed/win.c | 232 |
23 files changed, 14608 insertions, 0 deletions
diff --git a/ext2ed/COPYRIGHT b/ext2ed/COPYRIGHT new file mode 100644 index 0000000..5585eb6 --- /dev/null +++ b/ext2ed/COPYRIGHT @@ -0,0 +1,346 @@ +EXT2ED is hereby placed under the terms of the GNU General Public License. +Follows the GNU license. + +Gadi Oxman, August 1995 + +--------------------------------------------------------------------------- + + GNU GENERAL PUBLIC LICENSE + Version 2, June 1991 + + Copyright (C) 1989, 1991 Free Software Foundation, Inc. + 675 Mass Ave, Cambridge, MA 02139, USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The licenses for most software are designed to take away your +freedom to share and change it. By contrast, the GNU General Public +License is intended to guarantee your freedom to share and change free +software--to make sure the software is free for all its users. This +General Public License applies to most of the Free Software +Foundation's software and to any other program whose authors commit to +using it. (Some other Free Software Foundation software is covered by +the GNU Library General Public License instead.) You can apply it to +your programs, too. + + When we speak of free software, we are referring to freedom, not +price. Our General Public Licenses are designed to make sure that you +have the freedom to distribute copies of free software (and charge for +this service if you wish), that you receive source code or can get it +if you want it, that you can change the software or use pieces of it +in new free programs; and that you know you can do these things. + + To protect your rights, we need to make restrictions that forbid +anyone to deny you these rights or to ask you to surrender the rights. +These restrictions translate to certain responsibilities for you if you +distribute copies of the software, or if you modify it. + + For example, if you distribute copies of such a program, whether +gratis or for a fee, you must give the recipients all the rights that +you have. You must make sure that they, too, receive or can get the +source code. And you must show them these terms so they know their +rights. + + We protect your rights with two steps: (1) copyright the software, and +(2) offer you this license which gives you legal permission to copy, +distribute and/or modify the software. + + Also, for each author's protection and ours, we want to make certain +that everyone understands that there is no warranty for this free +software. If the software is modified by someone else and passed on, we +want its recipients to know that what they have is not the original, so +that any problems introduced by others will not reflect on the original +authors' reputations. + + Finally, any free program is threatened constantly by software +patents. We wish to avoid the danger that redistributors of a free +program will individually obtain patent licenses, in effect making the +program proprietary. To prevent this, we have made it clear that any +patent must be licensed for everyone's free use or not licensed at all. + + The precise terms and conditions for copying, distribution and +modification follow. + + GNU GENERAL PUBLIC LICENSE + TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION + + 0. This License applies to any program or other work which contains +a notice placed by the copyright holder saying it may be distributed +under the terms of this General Public License. The "Program", below, +refers to any such program or work, and a "work based on the Program" +means either the Program or any derivative work under copyright law: +that is to say, a work containing the Program or a portion of it, +either verbatim or with modifications and/or translated into another +language. (Hereinafter, translation is included without limitation in +the term "modification".) Each licensee is addressed as "you". + +Activities other than copying, distribution and modification are not +covered by this License; they are outside its scope. The act of +running the Program is not restricted, and the output from the Program +is covered only if its contents constitute a work based on the +Program (independent of having been made by running the Program). +Whether that is true depends on what the Program does. + + 1. You may copy and distribute verbatim copies of the Program's +source code as you receive it, in any medium, provided that you +conspicuously and appropriately publish on each copy an appropriate +copyright notice and disclaimer of warranty; keep intact all the +notices that refer to this License and to the absence of any warranty; +and give any other recipients of the Program a copy of this License +along with the Program. + +You may charge a fee for the physical act of transferring a copy, and +you may at your option offer warranty protection in exchange for a fee. + + 2. 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But when you +distribute the same sections as part of a whole which is a work based +on the Program, the distribution of the whole must be on the terms of +this License, whose permissions for other licensees extend to the +entire whole, and thus to each and every part regardless of who wrote it. + +Thus, it is not the intent of this section to claim rights or contest +your rights to work written entirely by you; rather, the intent is to +exercise the right to control the distribution of derivative or +collective works based on the Program. + +In addition, mere aggregation of another work not based on the Program +with the Program (or with a work based on the Program) on a volume of +a storage or distribution medium does not bring the other work under +the scope of this License. + + 3. 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IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING +WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR +REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, +INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING +OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED +TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY +YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER +PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE +POSSIBILITY OF SUCH DAMAGES. + + END OF TERMS AND CONDITIONS + + Appendix: How to Apply These Terms to Your New Programs + + If you develop a new program, and you want it to be of the greatest +possible use to the public, the best way to achieve this is to make it +free software which everyone can redistribute and change under these terms. + + To do so, attach the following notices to the program. It is safest +to attach them to the start of each source file to most effectively +convey the exclusion of warranty; and each file should have at least +the "copyright" line and a pointer to where the full notice is found. + + <one line to give the program's name and a brief idea of what it does.> + Copyright (C) 19yy <name of author> + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this +when it starts in an interactive mode: + + Gnomovision version 69, Copyright (C) 19yy name of author + Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, the commands you use may +be called something other than `show w' and `show c'; they could even be +mouse-clicks or menu items--whatever suits your program. + +You should also get your employer (if you work as a programmer) or your +school, if any, to sign a "copyright disclaimer" for the program, if +necessary. Here is a sample; alter the names: + + Yoyodyne, Inc., hereby disclaims all copyright interest in the program + `Gnomovision' (which makes passes at compilers) written by James Hacker. + + <signature of Ty Coon>, 1 April 1989 + Ty Coon, President of Vice + +This General Public License does not permit incorporating your program into +proprietary programs. If your program is a subroutine library, you may +consider it more useful to permit linking proprietary applications with the +library. If this is what you want to do, use the GNU Library General +Public License instead of this License. diff --git a/ext2ed/Makefile.in b/ext2ed/Makefile.in new file mode 100644 index 0000000..e4724ca --- /dev/null +++ b/ext2ed/Makefile.in @@ -0,0 +1,97 @@ +# +# Standard e2fsprogs prologue.... +# + +srcdir = @srcdir@ +top_srcdir = @top_srcdir@ +VPATH = @srcdir@ +top_builddir = .. +my_dir = ext2ed +INSTALL = @INSTALL@ +MKDIR_P = @MKDIR_P@ + +@MCONFIG@ + +PROGS= ext2ed +MANPAGES= ext2ed.8 + +DOC_DIR = $datadir/doc/ext2ed + +LIBS = -lncurses $(LIBEXT2FS) + +SRCS= $(srcdir)/main.c $(srcdir)/init.c $(srcdir)/general_com.c \ + $(srcdir)/inode_com.c $(srcdir)/dir_com.c $(srcdir)/super_com.c \ + $(srcdir)/disk.c $(srcdir)/win.c $(srcdir)/group_com.c \ + $(srcdir)/file_com.c $(srcdir)/blockbitmap_com.c \ + $(srcdir)/ext2_com.c $(srcdir)/inodebitmap_com.c + +OBJS= main.o init.o general_com.o inode_com.o dir_com.o super_com.o \ + disk.o win.o group_com.o file_com.o blockbitmap_com.o ext2_com.o \ + inodebitmap_com.o + +DOCS= doc/ext2ed-design.pdf doc/user-guide.pdf doc/ext2fs-overview.pdf \ + doc/ext2ed-design.html doc/user-guide.html doc/ext2fs-overview.html + +.c.o: + $(CC) -c $(ALL_CFLAGS) $< -o $@ + $(CHECK_CMD) $(ALL_CFLAGS) $< + $(CPPCHECK_CMD) $(CPPFLAGS) $< + +.SUFFIXES: .sgml .ps .pdf .html + +.sgml.ps: + mkdir -p doc + sgmltools -b ps $< + -mv `echo $< | sed -e 's/.sgml$$/.ps/'` $@ + +.sgml.pdf: + mkdir -p doc + sgmltools -b pdf $< + -mv `echo $< | sed -e 's/.sgml$$/.pdf/'` $@ + +.sgml.html: + mkdir -p doc + sgmltools -b onehtml $< + -mv `echo $< | sed -e 's/.sgml$$/.html/'` $@ + +all:: $(PROGS) $(MANPAGES) ext2ed.conf + +docs: $(DOCS) + +ext2ed: $(OBJS) + $(CC) $(ALL_LDFLAGS) -o ext2ed $(OBJS) $(LIBS) + +ext2ed.8: $(DEP_SUBSTITUTE) $(srcdir)/ext2ed.8.in + $(SUBSTITUTE_UPTIME) $(srcdir)/ext2ed.8.in ext2ed.8 + +ext2ed.conf: $(DEP_SUBSTITUTE) $(srcdir)/ext2ed.conf.in + $(SUBSTITUTE_UPTIME) $(srcdir)/ext2ed.conf.in ext2ed.conf + +clean:: + $(RM) -f ext2ed $(OBJS) $(DOCS) ext2ed.conf ext2ed.8 + -rmdir doc + +install: ext2ed + install -d $(root_sysconfdir) + install -m 755 ext2ed $(sbindir) + install -m 644 $(srcdir)/ext2.descriptors $(datadir) + install -m 644 ext2ed.conf $(root_sysconfdir) + install -m 644 ext2ed.8 $(man8dir) + +# +++ Dependency line eater +++ +# +# Makefile dependencies follow. This must be the last section in +# the Makefile.in file +# +main.o: $(srcdir)/main.c $(srcdir)/ext2ed.h +general_com.o: $(srcdir)/general_com.c $(srcdir)/ext2ed.h +inode_com.o: $(srcdir)/inode_com.c $(srcdir)/ext2ed.h +dir_com.o: $(srcdir)/dir_com.c $(srcdir)/ext2ed.h +super_com.o: $(srcdir)/super_com.c $(srcdir)/ext2ed.h +disk.o: $(srcdir)/disk.c $(srcdir)/ext2ed.h +win.o: $(srcdir)/win.c $(srcdir)/ext2ed.h +group_com.o: $(srcdir)/group_com.c $(srcdir)/ext2ed.h +file_com.o: $(srcdir)/file_com.c $(srcdir)/ext2ed.h +blockbitmap_com.o: $(srcdir)/blockbitmap_com.c $(srcdir)/ext2ed.h +ext2_com.o: $(srcdir)/ext2_com.c $(srcdir)/ext2ed.h +inodebitmap_com.o: $(srcdir)/inodebitmap_com.c $(srcdir)/ext2ed.h diff --git a/ext2ed/README b/ext2ed/README new file mode 100644 index 0000000..1f473cf --- /dev/null +++ b/ext2ed/README @@ -0,0 +1,160 @@ +ext2ed - The extended-2 filesystem editor, version e2fsprogs + + +This version of ext2ed has been modified and updated by Theodore Ts'o +for inclusion with the e2fsprogs package. It now builds with modern +ncurses and I've fixed various small bugs, particular in the redrawing +and resizing functions. + +It is currently not built by default -- the top-level e2fsprogs +Makefile doesn't recurse into this directory. This is because ext2ed +has a number of VERY SERIOUS shortcomings: + +1) It doesn't work on filesystems bigger than 2GB + +2) It assumes that all's the world an Intel, and assumes that + everything is in Intel (little-endian) byte order. + +Fixing either of these problems would be non-trivial, and so I at this +point DO NOT RECOMMEND that distributions try to include this program, +even as modified and updated in e2fsprogs. This especially goes for +Debian, where the Debian maintainer for e2fsprogs has a history of +making authorized changes to e2fsprogs to include programs that aren't +supported, and then starts bugging me with bug reports. YES I KNOW. +THIS PROGRAM HAS HORRIBLE SHORTCOMINGS. IT IS INCLUDED HERE ONLY +BECAUSE IT'S A CONVENIENT WAY FOR (FOR E2FSPROGS DEVELOPERS ON INTEL +MACHINES) TO GENERATE TEST CASES BY SELECTIVELY CORRUPTING +FILESYSTEMS. I WILL NOT SUPPORT THIS PROGRAM FOR USE BY GENERAL USERS +SO PLEASE DO NOT INCLUDE IT IN A DISTRIBUTION. + +I have currently disabled the use of GNU Readline in this program, +because readline and ncurses really don't play well together at all. +Readline assumes that it can write arbitrary text to the screen +(especially when it tries to print out a completion list), which just +doesn't work with ncurses. Fixing this so they would work together +would require wholesale changes to readline. + + Theodore Ts'o + tytso@MIT.EDU + May 12, 2001 + +---------------------------------------------------------------------------- + +ext2ed - The extended-2 filesystem editor, version 0.2 +------------------------------------------------------ + +This is version 0.2 of ext2ed - The extended-2 filesystem editor. + +Modifications on Apr 5 2001 +This is minor bug fixes to ext2ed, as of April 2001. +It supports modern ext2 version that has file type in directory structure +and fixes the misunderstanding between ncurses and +readline. + +I first applied patches from Red Hat except the one for readline that +rewrote a readline behavior. + +Globals diffs between version 0.1 and 0.2 is stored in file : + diff-ext2ed.1.2 + +Christian Bac <Christian.Bac@nt-evry.fr> + +---------------------------------------------------------------------------- + +Documentation +------------- + +ext2ed's documentation consists of three documents: + +1. The user's guide. +2. Technical overview of the ext2 filesystem. +3. The EXT2ED design and implementation document. + +Those documents are available in the doc directory, in linuxdoc-sgml and +postscript formats. + +The documentation is also available online at: + +http://tochnapc2.technion.ac.il + +under the ext2ed section. + +Installation +------------ + +ext2ed requires the kernel sources and the readline and ncurses packages. +Please edit the makefile if you are using an "old" version of ncurses (See the +details below) or if gcc can't find the various header files and libraries. + +To install, simply issue a 'make' command to compile and a 'make install' +command to install. I have also included an already compiled linux a.out +binary. + +ext2ed and ncurses +------------------ + +ext2ed uses the ncurses library for terminal output. It is very important +that ncurses will be properly installed on your system: + +1. Old versions of ncurses (around 1.8.5) need the OLD_NCURSES compile + time option in EXT2ED. + + At least from 1.9.2c, this flag should not be used. I would recommend + upgrading the ncurses library to the newer versions. + +2. ncurses uses its own terminfo database rather then the termcap file. + It is important that the terminfo database will be found by ncurses. + If this is not the case, you will see on startup some lines which + refer to /etc/termcap. This will mean that there is a problem with + the terminfo database. + +3. Newer versions of ncurses (and the 1.3 series of the kernel) describe + the linux console in the entry 'linux' and not 'console', as it was + before. If you run ext2ed in the linux console, you should either + set your TERM environment variable to 'linux' or link + l/linux to c/console in the terminfo database. + +4. The precompiled binary was linked with ncurses 1.9.4 and will search + for the terminfo database on /usr/local/lib/terminfo. If you are + using it, and your 1.9.4 compatible terminfo database is not on the + directory above, use the TERMINFO environment variable to specify + an alternate location. + +Running ext2ed +-------------- + +For those of you who don't like reading lengthy articles, here are a few +basic guidelines: + +1. Don't use ext2ed to change a mounted filesystem ! + + Using ext2ed in read-only mode on a mounted filesystem can be allowed + by using the configuration file option 'AllowMountedRead on'. However, + note that the displayed data will be unreliable. + +2. ext2ed currently can't handle filesystems bigger than 2 GB. I am + sorry for the inconvenience. This will hopefully be fixed in future + releases. + +3. Before running ext2ed, edit the configuration file + /var/lib/ext2ed/ext2ed.conf to suit your needs. The various + configuration options are documented there. + +4. Use the 'setdevice' command to open an ext2 filesystem. + e.g. 'setdevice /dev/hda1'. + +5. If the filesystem is an ext2 filesystem and ext2ed fails to + autodetect this, use the 'ForceExt2 on' configuration file option. + +6. The filesystem will always be opened in read-only mode. Feel free to + experiment, but take care with the 'enablewrite' command. + +----------------------------------------------------------------------------- + +Feel free to send me feedback with anything regarding to ext2ed. + +Enjoy, + +Gadi Oxman <tgud@tochnapc2.technion.ac.il> +Haifa, August 23 1995 + diff --git a/ext2ed/blockbitmap_com.c b/ext2ed/blockbitmap_com.c new file mode 100644 index 0000000..53e61dc --- /dev/null +++ b/ext2ed/blockbitmap_com.c @@ -0,0 +1,266 @@ +/* + +/usr/src/ext2ed/blockbitmap_com.c + +A part of the extended file system 2 disk editor. + +------------------------- +Handles the block bitmap. +------------------------- + +This file implements the commands which are specific to the blockbitmap type. + +First written on: July 5 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" + +/* + +The functions in this file use the flobal structure block_bitmap_info. This structure contains the current +position in the bitmap. + +*/ + +void type_ext2_block_bitmap___entry (char *command_line) + +/* + +This function changes the current entry in the bitmap. It just changes the entry_num variable in block_bitmap_info +and dispatches a show command to show the new entry. + +*/ + +{ + unsigned long entry_num; + char *ptr,buffer [80]; + + + + ptr=parse_word (command_line,buffer); /* Get the requested entry */ + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n"); + refresh_command_win (); return; + } + ptr=parse_word (ptr,buffer); + + entry_num=atol (buffer); + + + if (entry_num >= file_system_info.super_block.s_blocks_per_group) { /* Check if it is a valid entry number */ + + wprintw (command_win,"Error - Entry number out of bounds\n"); + refresh_command_win ();return; + } + + + + block_bitmap_info.entry_num=entry_num; /* If it is, just change entry_num and */ + strcpy (buffer,"show");dispatch (buffer); /* dispatch a show command */ +} + +void type_ext2_block_bitmap___next (char *command_line) + +/* + +This function passes to the next entry in the bitmap. We just call the above entry command. + +*/ + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",block_bitmap_info.entry_num+entry_offset); + dispatch (buffer); +} + +void type_ext2_block_bitmap___prev (char *command_line) + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",block_bitmap_info.entry_num-entry_offset); + dispatch (buffer); +} + +void type_ext2_block_bitmap___allocate (char *command_line) + +/* + +This function starts allocating block from the current position. Allocating involves setting the correct bits +in the bitmap. This function is a vector version of allocate_block below - We just run on the blocks that +we need to allocate, and call allocate_block for each one. + +*/ + +{ + long entry_num,num=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); /* Get the number of blocks to allocate */ + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + num=atol (buffer); + } + + entry_num=block_bitmap_info.entry_num; + /* Check for limits */ + if (num > file_system_info.super_block.s_blocks_per_group-entry_num) { + wprintw (command_win,"Error - There aren't that much blocks in the group\n"); + refresh_command_win ();return; + } + + while (num) { /* And call allocate_block */ + allocate_block (entry_num); /* for each block */ + num--;entry_num++; + } + + dispatch ("show"); /* Show the result */ +} + +void type_ext2_block_bitmap___deallocate (char *command_line) + +/* This is the opposite of the above function - We call deallocate_block instead of allocate_block */ + +{ + long entry_num,num=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + num=atol (buffer); + } + + entry_num=block_bitmap_info.entry_num; + if (num > file_system_info.super_block.s_blocks_per_group-entry_num) { + wprintw (command_win,"Error - There aren't that much blocks in the group\n"); + refresh_command_win ();return; + } + + while (num) { + deallocate_block (entry_num); + num--;entry_num++; + } + + dispatch ("show"); +} + + +void allocate_block (long entry_num) + +/* In this function we convert the bit number into the right byte and inner bit positions. */ + +{ + unsigned char bit_mask=1; + int byte_offset,j; + + byte_offset=entry_num/8; /* Find the correct byte - entry_num/8 */ + /* The position inside the byte is entry_num %8 */ + for (j=0;j<entry_num%8;j++) + bit_mask*=2; /* Generate the or mask - 1 at the right place */ + type_data.u.buffer [byte_offset] |= bit_mask; /* And apply it */ +} + +void deallocate_block (long entry_num) + +/* This is the opposite of allocate_block above. We use an and mask instead of an or mask. */ + +{ + unsigned char bit_mask=1; + int byte_offset,j; + + byte_offset=entry_num/8; + for (j=0;j<entry_num%8;j++) + bit_mask*=2; + bit_mask^=0xff; + + type_data.u.buffer [byte_offset] &= bit_mask; +} + +void type_ext2_block_bitmap___show (char *command_line) + +/* + +We show the bitmap as a series of bits, grouped at 8-bit intervals. We display 8 such groups on each line. +The current position (as known from block_bitmap_info.entry_num) is highlighted. + +*/ + +{ + int i,j; + unsigned char *ptr; + unsigned long block_num,entry_num; + + ptr=type_data.u.buffer; + show_pad_info.line=0;show_pad_info.max_line=-1; + + wmove (show_pad,0,0); + for (i=0,entry_num=0;i<file_system_info.super_block.s_blocks_per_group/8;i++,ptr++) { + for (j=1;j<=128;j*=2) { /* j contains the and bit mask */ + if (entry_num==block_bitmap_info.entry_num) { /* Highlight the current entry */ + wattrset (show_pad,A_REVERSE); + show_pad_info.line=show_pad_info.max_line-show_pad_info.display_lines/2; + } + + if ((*ptr) & j) /* Apply the mask */ + wprintw (show_pad,"1"); + else + wprintw (show_pad,"0"); + + if (entry_num==block_bitmap_info.entry_num) + wattrset (show_pad,A_NORMAL); + + entry_num++; /* Pass to the next entry */ + } + wprintw (show_pad," "); + if (i%8==7) { /* Display 8 groups in a row */ + wprintw (show_pad,"\n"); + show_pad_info.max_line++; + } + } + + refresh_show_pad (); + show_info (); /* Show the usual information */ + + /* Show the group number */ + wmove (show_win,1,0); + wprintw (show_win,"Block bitmap of block group %ld\n",block_bitmap_info.group_num); + /* Show the block number */ + + block_num=block_bitmap_info.entry_num+block_bitmap_info.group_num*file_system_info.super_block.s_blocks_per_group; + block_num+=file_system_info.super_block.s_first_data_block; + + wprintw (show_win,"Status of block %ld - ",block_num); /* and the allocation status */ + ptr=type_data.u.buffer+block_bitmap_info.entry_num/8; + j=1; + for (i=block_bitmap_info.entry_num % 8;i>0;i--) + j*=2; + if ((*ptr) & j) + wprintw (show_win,"Allocated\n"); + else + wprintw (show_win,"Free\n"); + refresh_show_win (); +} diff --git a/ext2ed/dir_com.c b/ext2ed/dir_com.c new file mode 100644 index 0000000..67bb4b5 --- /dev/null +++ b/ext2ed/dir_com.c @@ -0,0 +1,678 @@ +/* + +/usr/src/ext2ed/dir_com.c + +A part of the extended file system 2 disk editor. + +-------------------- +Handles directories. +-------------------- + +This file contains the codes which allows the user to handle directories. + +Most of the functions use the global variable file_info (along with the special directory fields there) to save +information and pass it between them. + +Since a directory is just a big file which is composed of directory entries, you will find that +the functions here are a superset of those in the file_com.c source. + +We assume that the user reached here using the dir command of the inode type and not by using settype dir, so +that init_dir_info is indeed called to gather the required information. + +type_data is not changed! It still contains the inode of the file - We handle the directory in our own +variables, so that settype ext2_inode will "go back" to the inode of this directory. + +First written on: April 28 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" + +char name_search [80]; +long entry_num_search; + +int init_dir_info (struct struct_file_info *info_ptr) + +/* + +This function is called by the inode of the directory when the user issues the dir command from the inode. +It is used to gather information about the inode and to reset some variables which we need in order to handle +directories. + +*/ + +{ + struct ext2_inode *ptr; + + ptr=&type_data.u.t_ext2_inode; /* type_data contains the inode */ + + info_ptr->inode_ptr=ptr; + info_ptr->inode_offset=device_offset; /* device offset contains the inode's offset */ + + /* Reset the current position to the start */ + + info_ptr->global_block_num=ptr->i_block [0]; + info_ptr->global_block_offset=ptr->i_block [0]*file_system_info.block_size; + info_ptr->block_num=0; + info_ptr->file_offset=0; + /* Set the size of the directory */ + + info_ptr->blocks_count=(ptr->i_size+file_system_info.block_size-1)/file_system_info.block_size; + info_ptr->file_length=ptr->i_size; + + info_ptr->level=0; /* We start using direct blocks */ + info_ptr->display=HEX; /* This is not actually used */ + + info_ptr->dir_entry_num=0;info_ptr->dir_entries_count=0; /* We'll start at the first directory entry */ + info_ptr->dir_entry_offset=0; + + /* Find dir_entries_count */ + + info_ptr->dir_entries_count=count_dir_entries (); /* Set the total number of entries */ + + return (1); +} + +struct struct_file_info search_dir_entries (int (*action) (struct struct_file_info *info),int *status) + +/* + This is the main function in this source file. Various actions are implemented using this basic function. + + This routine runs on all directory entries in the current directory. + For each entry, action is called. We'll act according to the return code of action: + + ABORT - Current dir entry is returned. + CONTINUE - Continue searching. + FOUND - Current dir entry is returned. + + If the last entry is reached, it is returned, along with an ABORT status. + + status is updated to the returned code of action. +*/ + +{ + struct struct_file_info info; /* Temporary variables used to */ + struct ext2_dir_entry_2 *dir_entry_ptr; /* contain the current search entries */ + int return_code, next; + + info=first_file_info; /* Start from the first entry - Read it */ + low_read (info.buffer,file_system_info.block_size,info.global_block_offset); + dir_entry_ptr=(struct ext2_dir_entry_2 *) (info.buffer+info.dir_entry_offset); + + while (info.file_offset < info.file_length) { /* While we haven't reached the end */ + + *status=return_code=action (&info); /* Call the client function to test */ + /* the current entry */ + if (return_code==ABORT || return_code==FOUND) + return (info); /* Stop, if so asked */ + + /* Pass to the next entry */ + + dir_entry_ptr=(struct ext2_dir_entry_2 *) (info.buffer+info.dir_entry_offset); + + info.dir_entry_num++; + next = dir_entry_ptr->rec_len; + if (!next) + next = file_system_info.block_size - info.dir_entry_offset; + info.dir_entry_offset += next; + info.file_offset += next; + + if (info.file_offset >= info.file_length) break; + + if (info.dir_entry_offset >= file_system_info.block_size) { /* We crossed a block boundary */ + /* Find the next block, */ + info.block_num++; + info.global_block_num=file_block_to_global_block (info.block_num,&info); + info.global_block_offset=info.global_block_num*file_system_info.block_size; + info.file_offset=info.block_num*file_system_info.block_size; + info.dir_entry_offset=0; + /* read it and update the pointer */ + + low_read (info.buffer,file_system_info.block_size,info.global_block_offset); + dir_entry_ptr=(struct ext2_dir_entry_2 *) (info.buffer+info.dir_entry_offset); + + } + + } + + *status=ABORT;return (info); /* There was no match */ +} + +long count_dir_entries (void) + +/* + +This function counts the number of entries in the directory. We just call search_dir_entries till the end. +The client function is action_count, which just tell search_dir_entries to continue. + +*/ + +{ + int status; + + return (search_dir_entries (&action_count,&status).dir_entry_num); +} + +int action_count (struct struct_file_info *info) + +/* + +Used by count_dir_entries above - This function is called by search_dir_entries, and it tells it to continue +searching, until we get to the last entry. + +*/ + +{ + return (CONTINUE); /* Just continue searching */ +} + +void type_dir___cd (char *command_line) + +/* + Changes to a directory, relative to the current directory. + + This is a complicated operation, so I would repeat here the explanation from the design and + implementation document. + +1. The path is checked that it is not an absolute path (from /). If it is, we let the general cd to do the job by + calling directly type_ext2___cd. + +2. The path is divided into the nearest path and the rest of the path. For example, cd 1/2/3/4 is divided into + 1 and into 2/3/4. + +3. It is the first part of the path that we need to search for in the current directory. We search for it using + search_dir_entries, which accepts the action_name function as the client function. + +4. search_dir_entries will scan the entire entries and will call our action_name function for each entry. + In action_name, the required name will be checked against the name of the current entry, and FOUND will be + returned when a match occurs. + +5. If the required entry is found, we dispatch a remember command to insert the current inode (remember that + type_data is still intact and contains the inode of the current directory) into the object memory. + This is required to easily support symbolic links - If we find later that the inode pointed by the entry is + actually a symbolic link, we'll need to return to this point, and the above inode doesn't have (and can't have, + because of hard links) the information necessary to "move back". + +6. We then dispatch a followinode command to reach the inode pointed by the required entry. This command will + automatically change the type to ext2_inode - We are now at an inode, and all the inode commands are available. + +7. We check the inode's type to see if it is a directory. If it is, we dispatch a dir command to "enter the directory", + and recursively call ourself (The type is dir again) by dispatching a cd command, with the rest of the path + as an argument. + +8. If the inode's type is a symbolic link (only fast symbolic link were meanwhile implemented. I guess this is + typically the case.), we note the path it is pointing at, the saved inode is recalled, we dispatch dir to + get back to the original directory, and we call ourself again with the link path/rest of the path argument. + +9. In any other case, we just stop at the resulting inode. + +*/ + +{ + int status; + char *ptr,full_dir_name [500],dir_name [500],temp [500],temp2 [500]; + struct struct_file_info info; + struct ext2_dir_entry_2 *dir_entry_ptr; + + dir_entry_ptr=(struct ext2_dir_entry_2 *) (file_info.buffer+file_info.dir_entry_offset); + + ptr=parse_word (command_line,dir_name); + + if (*ptr==0) { /* cd alone will enter the highlighted directory */ + strncpy (full_dir_name,dir_entry_ptr->name,dir_entry_ptr->name_len); + full_dir_name [dir_entry_ptr->name_len]=0; + } + else + ptr=parse_word (ptr,full_dir_name); + + ptr=strchr (full_dir_name,'/'); + + if (ptr==full_dir_name) { /* Pathname is from root - Let the general cd do the job */ + sprintf (temp,"cd %s",full_dir_name);type_ext2___cd (temp);return; + } + + if (ptr==NULL) { + strcpy (dir_name,full_dir_name); + full_dir_name [0]=0; + } + + else { + strncpy (dir_name,full_dir_name,ptr-full_dir_name); + dir_name [ptr-full_dir_name]=0; + strcpy (full_dir_name,++ptr); + } + /* dir_name contains the current entry, while */ + /* full_dir_name contains the rest */ + + strcpy (name_search,dir_name); /* name_search is used to hold the required entry name */ + + if (dir_entry_ptr->name_len != strlen (dir_name) || + strncmp (dir_name,dir_entry_ptr->name,dir_entry_ptr->name_len)!=0) + info=search_dir_entries (&action_name,&status); /* Search for the entry. Answer in info. */ + else { + status=FOUND;info=file_info; + } + + if (status==FOUND) { /* If found */ + file_info=info; /* Switch to it, by setting the global file_info */ + dispatch ("remember internal_variable"); /* Move the inode into the objects memory */ + + dispatch ("followinode"); /* Go to the inode pointed by this directory entry */ + + if (S_ISLNK (type_data.u.t_ext2_inode.i_mode)) {/* Symbolic link ? */ + + if (type_data.u.t_ext2_inode.i_size > 60) { /* I'm lazy, I guess :-) */ + wprintw (command_win,"Error - Sorry, Only fast symbolic link following is currently supported\n"); + refresh_command_win (); + return; + } + /* Get the pointed name and append the previous path */ + + strcpy (temp2,(unsigned char *) &type_data.u.t_ext2_inode.i_block); + strcat (temp2,"/"); + strcat (temp2,full_dir_name); + + dispatch ("recall internal_variable"); /* Return to the original inode */ + dispatch ("dir"); /* and to the directory */ + + sprintf (temp,"cd %s",temp2); /* And continue from there by dispatching a cd command */ + dispatch (temp); /* (which can call ourself or the general cd) */ + + return; + } + + if (S_ISDIR (type_data.u.t_ext2_inode.i_mode)) { /* Is it an inode of a directory ? */ + + dispatch ("dir"); /* Yes - Pass to the pointed directory */ + + if (full_dir_name [0] != 0) { /* And call ourself with the rest of the pathname */ + sprintf (temp,"cd %s",full_dir_name); + dispatch (temp); + } + + return; + } + + else { /* If we can't continue from here, we'll just stop */ + wprintw (command_win,"Can\'t continue - Stopping at last inode\n");refresh_command_win (); + return; + } + } + + wprintw (command_win,"Error - Directory entry %s not found.\n",dir_name); /* Hmm, an invalid path somewhere */ + refresh_command_win (); +} + +int action_name (struct struct_file_info *info) + +/* + +Compares the current search entry name (somewhere inside info) with the required name (in name_search). +Returns FOUND if found, or CONTINUE if not found. + +*/ + +{ + struct ext2_dir_entry_2 *dir_entry_ptr; + + dir_entry_ptr=(struct ext2_dir_entry_2 *) (info->buffer+info->dir_entry_offset); + + if (dir_entry_ptr->name_len != strlen (name_search)) + return (CONTINUE); + + if (strncmp (dir_entry_ptr->name,name_search,dir_entry_ptr->name_len)==0) + return (FOUND); + + return (CONTINUE); +} + +void type_dir___entry (char *command_line) + +/* + +Selects a directory entry according to its number. +search_dir_entries is used along with action_entry_num, in the same fashion as the previous usage of search_dir_entries. + +*/ + +{ + int status; + struct struct_file_info info; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - Argument_not_specified\n");wrefresh (command_win); + return; + } + ptr=parse_word (ptr,buffer); + entry_num_search=atol (buffer); + + if (entry_num_search < 0 || entry_num_search >= file_info.dir_entries_count) { + wprintw (command_win,"Error - Entry number out of range\n");wrefresh (command_win); + return; + } + + info=search_dir_entries (&action_entry_num,&status); + if (status==FOUND) { + file_info=info; + dispatch ("show"); + return; + } +#ifdef DEBUG + internal_error ("dir_com","type_dir___entry","According to our gathered data, we should have found this entry"); +#endif +} + +int action_entry_num (struct struct_file_info *info) + +/* + +Used by the above function. Just compares the current number (in info) with the required one. + +*/ + +{ + if (info->dir_entry_num == entry_num_search) + return (FOUND); + + return (CONTINUE); +} + +void type_dir___followinode (char *command_line) + +/* + +Here we pass to the inode pointed by the current entry. +It involves computing the device offset of the inode and using directly the setoffset and settype commands. + +*/ +{ + long inode_offset; + char buffer [80]; + + struct ext2_dir_entry_2 *dir_entry_ptr; + + low_read (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + dir_entry_ptr=(struct ext2_dir_entry_2 *) (file_info.buffer+file_info.dir_entry_offset); + + inode_offset=inode_num_to_inode_offset (dir_entry_ptr->inode); /* Compute the inode's offset */ + sprintf (buffer,"setoffset %ld",inode_offset);dispatch (buffer); /* Move to it */ + sprintf (buffer,"settype ext2_inode");dispatch (buffer); /* and set the type to an inode */ +} + +void type_dir___inode (char *command_line) + +/* + +Returns to the parent inode of the current directory. +This is trivial, as we type_data is still intact and contains the parent inode ! + +*/ + +{ + dispatch ("settype ext2_inode"); +} + + +void type_dir___show (char *command_line) + +/* + +We use search_dir_entries to run on all the entries. Each time, action_show will be called to show one entry. + +*/ + +{ + int status; + + wmove (show_pad,0,0); + show_pad_info.max_line=-1; + + search_dir_entries (&action_show,&status); + show_pad_info.line=file_info.dir_entry_num-show_pad_info.display_lines/2; + refresh_show_pad (); + show_dir_status (); +} + +int action_show (struct struct_file_info *info) + +/* + +Show the current search entry (info) in one line. If the entry happens to be the current edited entry, it is highlighted. + +*/ + +{ + unsigned char temp [80]; + struct ext2_dir_entry_2 *dir_entry_ptr; + + dir_entry_ptr=(struct ext2_dir_entry_2 *) (info->buffer+info->dir_entry_offset); + + if (info->dir_entry_num == file_info.dir_entry_num) /* Highlight the current entry */ + wattrset (show_pad,A_REVERSE); + + strncpy (temp,dir_entry_ptr->name,dir_entry_ptr->name_len); /* The name is not terminated */ + temp [dir_entry_ptr->name_len]=0; + if (dir_entry_ptr->name_len > (COLS - 55) && COLS > 55) + temp [COLS-55]=0; + wprintw (show_pad,"inode = %-8lu rec_len = %-4lu name_len = %-3lu name = %s\n", /* Display the various fields */ + dir_entry_ptr->inode,dir_entry_ptr->rec_len,dir_entry_ptr->name_len,temp); + + show_pad_info.max_line++; + + if (info->dir_entry_num == file_info.dir_entry_num) + wattrset (show_pad,A_NORMAL); + + return (CONTINUE); /* And pass to the next */ +} + +void type_dir___next (char *command_line) + +/* + +This function moves to the next directory entry. It just uses the current information and the entry command. + +*/ + +{ + int offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset*=atol (buffer); + } + + sprintf (buffer,"entry %ld",file_info.dir_entry_num+offset);dispatch (buffer); + +} + +void type_dir___prev (char *command_line) + +{ + int offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset*=atol (buffer); + } + + sprintf (buffer,"entry %ld",file_info.dir_entry_num-offset);dispatch (buffer); +} + +void show_dir_status (void) + +/* + +Various statistics about the directory. + +*/ + +{ + long inode_num; + + wmove (show_win,0,0); + wprintw (show_win,"Directory listing. Block %ld. ",file_info.global_block_num); + wprintw (show_win,"Directory entry %ld of %ld.\n",file_info.dir_entry_num,file_info.dir_entries_count-1); + wprintw (show_win,"Directory Offset %ld of %ld. ",file_info.file_offset,file_info.file_length-1); + + inode_num=inode_offset_to_inode_num (file_info.inode_offset); + wprintw (show_win,"File inode %ld. Indirection level %ld.\n",inode_num,file_info.level); + + refresh_show_win (); +} + +void type_dir___remember (char *command_line) + +/* + +This is overridden here because we don't remember a directory - It is too complicated. Instead, we remember the +inode of the current directory. + +*/ + +{ + int found=0; + long entry_num; + char *ptr,buffer [80]; + struct struct_descriptor *descriptor_ptr; + + ptr=parse_word (command_line,buffer); + + if (*ptr==0) { + wprintw (command_win,"Error - Argument not specified\n");wrefresh (command_win); + return; + } + + ptr=parse_word (ptr,buffer); + + entry_num=remember_lifo.entries_count++; + if (entry_num>REMEMBER_COUNT-1) { + entry_num=0; + remember_lifo.entries_count--; + } + + descriptor_ptr=first_type; + while (descriptor_ptr!=NULL && !found) { + if (strcmp (descriptor_ptr->name,"ext2_inode")==0) + found=1; + else + descriptor_ptr=descriptor_ptr->next; + } + + + remember_lifo.offset [entry_num]=device_offset; + remember_lifo.type [entry_num]=descriptor_ptr; + strcpy (remember_lifo.name [entry_num],buffer); + + wprintw (command_win,"Object %s in Offset %ld remembered as %s\n",descriptor_ptr->name,device_offset,buffer); + wrefresh (command_win); +} + +void type_dir___set (char *command_line) + +/* + +Since the dir object doesn't have variables, we provide the impression that it has here. ext2_dir_entry was not used +because it is of variable length. + +*/ + +{ + int found=0; + unsigned char *ptr,buffer [80],variable [80],value [80],temp [80]; + struct ext2_dir_entry_2 *dir_entry_ptr; + + dir_entry_ptr=(struct ext2_dir_entry_2 *) (file_info.buffer+file_info.dir_entry_offset); + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - Missing arguments\n");refresh_command_win (); + return; + } + parse_word (ptr,buffer); + ptr=strchr (buffer,'='); + if (ptr==NULL) { + wprintw (command_win,"Error - Bad syntax\n");refresh_command_win ();return; + } + strncpy (variable,buffer,ptr-buffer);variable [ptr-buffer]=0; + strcpy (value,++ptr); + + if (strcasecmp ("inode",variable)==0) { + found=1; + dir_entry_ptr->inode=atol (value); + wprintw (command_win,"Variable %s set to %lu\n",variable,dir_entry_ptr->inode);refresh_command_win (); + + } + + if (strcasecmp ("rec_len",variable)==0) { + found=1; + dir_entry_ptr->rec_len=(unsigned int) atol (value); + wprintw (command_win,"Variable %s set to %lu\n",variable,dir_entry_ptr->rec_len);refresh_command_win (); + + } + + if (strcasecmp ("name_len",variable)==0) { + found=1; + dir_entry_ptr->name_len=(unsigned int) atol (value); + wprintw (command_win,"Variable %s set to %lu\n",variable,dir_entry_ptr->name_len);refresh_command_win (); + + } + + if (strcasecmp ("name",variable)==0) { + found=1; + if (strlen (value) > dir_entry_ptr->name_len) { + wprintw (command_win,"Error - Length of name greater then name_len\n"); + refresh_command_win ();return; + } + strncpy (dir_entry_ptr->name,value,strlen (value)); + wprintw (command_win,"Variable %s set to %s\n",variable,value);refresh_command_win (); + + } + + if (found) { + wattrset (show_pad,A_REVERSE); + strncpy (temp,dir_entry_ptr->name,dir_entry_ptr->name_len); + temp [dir_entry_ptr->name_len]=0; + wmove (show_pad,file_info.dir_entry_num,0); + wprintw (show_pad,"inode = %-8lu rec_len = %-4lu name_len = %-3lu name = %s\n", + dir_entry_ptr->inode,dir_entry_ptr->rec_len,dir_entry_ptr->name_len,temp); + wattrset (show_pad,A_NORMAL); + show_pad_info.line=file_info.dir_entry_num-show_pad_info.display_lines/2; + refresh_show_pad (); + show_dir_status (); + } + + else { + wprintw (command_win,"Error - Variable %s not found\n",variable); + refresh_command_win (); + } + +} + +void type_dir___writedata (char *command_line) + +/* + +We need to override this since the data is not in type_data. Instead, we have to write the buffer which corresponds +to the current block. + +*/ + +{ + low_write (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + return; +} diff --git a/ext2ed/disk.c b/ext2ed/disk.c new file mode 100644 index 0000000..4612d00 --- /dev/null +++ b/ext2ed/disk.c @@ -0,0 +1,239 @@ +/* + +/usr/src/ext2ed/disk.c + +A part of the extended file system 2 disk editor. + +------------------------------------------------- +The filesystem's disk activity pass through here. +------------------------------------------------- + +This file is acting as a filter - Before we pass an actual read or write request to the operating system, we +double check the various permissions and possible errors here. + +The major update which needs to be done here is switching to the use of the llseek system call, so that we will +be able to support ext2 filesystems up to 4 TB. Currently, due to the standard fseek usage, we can't handle +filesystems bigger than 4 GB. The limit is actually 2 GB because I used long rather than unsigned long long at too +many places in the program. To conclude - This upgrade needs to be done carefully; There are many places to change. + +First written on: April 9 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +#include "ext2ed.h" + +int write_access; + +int low_read (unsigned char *buffer,unsigned long length,unsigned long offset) + +/* + +This function is used when we need to read something from the filesystem. + +*/ + +{ + +#ifdef DEBUG + + char temp [80]; + + if (device_handle==NULL) { /* Check that a device is indeed open */ + internal_error ("No device opened yet read requested","disk","low_read"); + return (0); + } + if (offset > file_system_info.file_system_size) { /* Check that the offset is within limits */ + sprintf (temp,"Seek offset %ld is out of range",offset); + internal_error (temp,"disk","low_read"); + return (0); + } + +#endif + + if ( (fseek (device_handle,offset,SEEK_SET))==-1) { /* Seek to the required offset */ + wprintw (command_win,"Error - Failed to seek to offset %ld in device %s\n",offset,device_name); + refresh_command_win (); + return (0); + }; + + if ( (fread (buffer,1,length,device_handle))==-1) { /* And do the actual reading */ + wprintw (command_win,"Error - Failed to read from offset %ld in device %s\n",offset,device_name); + refresh_command_win ();return (0); + }; + + return (1); +} + +int low_write (unsigned char *buffer,unsigned long length,unsigned long offset) + +/* + +This is used to change something in the filesystem. +write_access is checked to see if we are allowed to do the actual writing. +As a double safety measure, AllowChanges is rechecked here. +If logging is enabled, we log the change before writing it to the device. + +*/ +{ + char temp [80]; + + if (!write_access) { + wprintw (command_win,"Error - Write access not available (use enablewrite)\n"); + return (0); + } + +#ifdef DEBUG + + if (!AllowChanges) { + internal_error ("AllowChanges=0 yet enablewrite succeeded","disk","low_write"); + return (0); + } + + if (device_handle==NULL) { + internal_error ("No device opened yet read requested","disk","low_write"); + return (0); + } + + if (offset > file_system_info.file_system_size) { + sprintf (temp,"Seek offset %ld is out of range",offset); + internal_error (temp,"disk","low_write"); + return (0); + } + +#endif + + if (LogChanges) + if (!log_changes (buffer,length,offset)) + return (0); + + if ( (fseek (device_handle,offset,SEEK_SET))==-1) { + wprintw (command_win,"Error - Failed to seek to offset %ld in device %s\n",offset,device_name); + refresh_command_win ();return (0); + }; + + + if ( (fwrite (buffer,1,length,device_handle))==-1) { + wprintw (command_win,"Error - Failed to write to offset %ld in device %s\n",offset,device_name); + refresh_command_win ();return (0); + }; + + wprintw (command_win,"Data written");refresh_command_win (); + return (1); +} + +int log_changes (unsigned char *buffer,unsigned long length,unsigned long offset) + +/* + +Log the change in a primitive form - An hex dump of the data before the change and after the change. +The hex bytes are converted to text, so that they will be readable with a standard text editor. + +*/ + +{ + unsigned char *original; + + int i; + time_t current_time; + FILE *fp; + + if ((fp=fopen (LogFile,"a+"))==NULL) { + wprintw (command_win,"Error - Unable to open log file %s\n",LogFile); + refresh_command_win ();return (0); + }; + + current_time=time (NULL); + + fprintf (fp,"\n----- EXT2ED log begin -----\n\n"); + fprintf (fp,"Time: %s\nDevice: %s\n",ctime ((time_t *) ¤t_time),device_name); + fprintf (fp,"Offset: %lu\nLength: %lu\n",offset,length); + + original=(unsigned char *) malloc (length*sizeof (unsigned char)); + + if (original==NULL) { + wprintw (command_win,"Fatal error - Can\'t allocate %lu bytes!"); + refresh_command_win ();fclose (fp);return (0); + } + + if (!low_read (original,length,offset)) { + fclose (fp);return (0); + } + + fprintf (fp,"\nOriginal data:\n\n"); + + for (i=0;i<length;i++) { + if (i%16==0 && i!=0) fprintf (fp,"\n"); + fprintf (fp,"%02x ",original [i]); + } + + fprintf (fp,"\n\nNew data:\n\n"); + + for (i=0;i<length;i++) { + if (i%16==0 && i!=0) fprintf (fp,"\n"); + fprintf (fp,"%02x ",buffer [i]); + } + + fprintf (fp,"\n----- EXT2ED log end -----\n"); + + fclose (fp); + return (1); +} + +int load_type_data (void) + +/* + +Just read from the current position into type data. + +*/ + +{ + if (device_handle==NULL) { + printf ("Error - No device opened\n"); + return (0); + } + + if (device_offset==-1) { + printf ("Error - No offset set\n"); + return (0); + } + + if (low_read (type_data.u.buffer,EXT2_MAX_BLOCK_SIZE,device_offset)==0) + return (0); + + if (current_type!=NULL) + if (strcmp (current_type->name,"ext2_dir_entry")==0) + current_type->length=type_data.u.t_ext2_dir_entry.rec_len; + + return (1); +} + +int write_type_data (void) + +{ + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n"); + refresh_command_win (); + return (0); + } + + if (device_offset==-1) { + wprintw (command_win,"Error - No offset set\n"); + refresh_command_win (); + return (0); + } + + if (low_write (type_data.u.buffer,file_system_info.block_size,device_offset)==0) + return (0); + + return (1); +} + diff --git a/ext2ed/doc/ext2ed-design.sgml b/ext2ed/doc/ext2ed-design.sgml new file mode 100644 index 0000000..b2cab37 --- /dev/null +++ b/ext2ed/doc/ext2ed-design.sgml @@ -0,0 +1,3459 @@ +<!DOCTYPE Article PUBLIC "-//Davenport//DTD DocBook V3.0//EN"> + +<Article> + +<ArtHeader> + +<Title>EXT2ED - The Extended-2 filesystem editor - Design and implementation</Title> +<AUTHOR +> +<FirstName>Programmed by Gadi Oxman, with the guide of Avner Lottem</FirstName> +</AUTHOR +> +<PubDate>v0.1, August 3 1995</PubDate> + +</ArtHeader> + +<Sect1> +<Title>About EXT2ED documentation</Title> + +<Para> +The EXT2ED documentation consists of three parts: + +<ItemizedList> +<ListItem> + +<Para> + The ext2 filesystem overview. +</Para> +</ListItem> +<ListItem> + +<Para> + The EXT2ED user's guide. +</Para> +</ListItem> +<ListItem> + +<Para> + The EXT2ED design and implementation. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +This document is not the user's guide. If you just intend to use EXT2ED, you +may not want to read it. +</Para> + +<Para> +However, if you intend to browse and modify the source code, this document is +for you. +</Para> + +<Para> +In any case, If you intend to read this article, I strongly suggest that you +will be familiar with the material presented in the other two articles as well. +</Para> + +</Sect1> + +<Sect1> +<Title>Preface</Title> + +<Para> +In this document I will try to explain how EXT2ED is constructed. +At this time of writing, the initial version is finished and ready +for distribution; It is fully functional. However, this was not always the +case. +</Para> + +<Para> +At first, I didn't know much about Unix, much less about Unix filesystems, +and even less about Linux and the extended-2 filesystem. While working +on this project, I gradually acquired knowledge about all of the above +subjects. I can think of two ways in which I could have made my project: + +<OrderedList> +<ListItem> + +<Para> + The "Engineer" way + +Learn the subject thoroughly before I get to the programming itself. +Then, I could easily see the entire picture and select the best +course of action, taking all the factors into account. +</Para> +</ListItem> +<ListItem> + +<Para> + The "Explorer - Progressive" way. + +Jump immediately into the cold water - Start programming and +learning the material in parallel. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +<Para> +I guess that the above dilemma is typical and appears all through science and +technology. +</Para> + +<Para> +However, I didn't have the luxury of choice when I started my project - +Linux is a relatively new (and great!) operating system. The extended-2 +filesystem is even newer - Its first release lies somewhere in 1993 - Only +passed two years until I started working on my project. +</Para> + +<Para> +The situation I found myself at the beginning was that I didn't have a fully +detailed document which describes the ext2 filesystem. In fact, I didn't +have any ext2 document at all. When I asked Avner about documentation, he +suggested two references: + +<ItemizedList> +<ListItem> + +<Para> + A general Unix book - THE DESIGN OF THE UNIX OPERATING SYSTEM, by +Maurice J. Bach. +</Para> +</ListItem> +<ListItem> + +<Para> + The kernel sources. +</Para> +</ListItem> + +</ItemizedList> + +I read the relevant parts of the book before I started my project - It is a +bit old now, but the principles are still the same. However, I needed +more than just the principles. +</Para> + +<Para> +The kernel sources are a rare bonus! You don't get everyday the full +sources of the operating system. There is so much that can be learned from +them, and it is the ultimate source - The exact answer how the kernel +works is there, with all the fine details. At the first week I started to +look at random at the relevant parts of the sources. However, it is difficult +to understand the global picture from direct reading of over one hundred +page sources. Then, I started to do some programming. I didn't know +yet what I was looking for, and I started to work on the project like a kid +who starts to build a large puzzle. +</Para> + +<Para> +However, this was exactly the interesting part! It is frustrating to know +it all from advance - I think that the discovery itself, bit by bit, is the +key to a true learning and understanding. +</Para> + +<Para> +Now, in this document, I am trying to present the subject. Even though I +developed EXT2ED progressively, I now can see the entire subject much +brighter than I did before, and though I do have the option of presenting it +only in the "engineer" way. However, I will not do that. +</Para> + +<Para> +My presentation will be mixed - Sometimes I will present a subject with an +incremental perspective, and sometimes from a "top down" view. I'll leave +you to decide if my presentation choice was wise :-) +</Para> + +<Para> +In addition, you'll notice that the sections tend to get shorter as we get +closer to the end. The reason is simply that I started to feel that I was +repeating myself so I decided to present only the new ideas. +</Para> + +</Sect1> + +<Sect1> +<Title>Getting started ...</Title> + +<Para> +Getting started is almost always the most difficult task. Once you get +started, things start "running" ... +</Para> + +<Sect2> +<Title>Before the actual programming</Title> + +<Para> +From mine talking with Avner, I understood that Linux, like any other Unix +system, provides accesses to the entire disk as though it were a general +file - Accessing the device. It is surely a nice idea. Avner suggested two +ways of action: + +<ItemizedList> +<ListItem> + +<Para> + Opening the device like a regular file in the user space. +</Para> +</ListItem> +<ListItem> + +<Para> + Constructing a device driver which will run in the kernel space and +provide hooks for the user space program. The advantage is that it +will be a part of the kernel, and would be able to use the ext2 +kernel functions to do some of the work. +</Para> +</ListItem> + +</ItemizedList> + +I chose the first way. I think that the basic reason was simplicity - Learning +the ext2 filesystem was complicated enough, and adding to it the task of +learning how to program in the kernel space was too much. I still don't know +how to program a device driver, and this is perhaps the bad part, but +concerning the project in a back-perspective, I think that the first way is +superior to the second; Ironically, because of the very reason I chose it - +Simplicity. EXT2ED can now run entirely in the user space (which I think is +a point in favor, because it doesn't require the user to recompile its +kernel), and the entire hard work is mine, which fitted nicely into the +learning experience - I didn't use other code to do the job (aside from +looking at the sources, of-course). +</Para> + +</Sect2> + +<Sect2> +<Title>Jumping into the cold water</Title> + +<Para> +I didn't know almost anything of the structure of the ext2 filesystem. +Reading the sources was not enough - I needed to experiment. However, a tool +for experiments in the ext2 filesystem was exactly my project! - Kind of a +paradox. +</Para> + +<Para> +I started immediately with constructing a simple <Literal remap="tt">hex editor</Literal> - It would +open the device as a regular file, provide means of moving inside the +filesystem with a simple <Literal remap="tt">offset</Literal> method, and just show a +<Literal remap="tt"> hex dump</Literal> of the contents at this point. Programming this was trivially +simple of-course. At this point, the user-interface didn't matter to me - I +wanted a fast way to interact. As a result, I chose a simple command line +parser. Of course, there where no windows at this point. +</Para> + +<Para> +A hex editor is nice, but is not enough. It indeed enabled me to see each part +of the filesystem, but the format of the viewed data was difficult to +analyze. I wanted to see the data in a more intuitive way. +</Para> + +<Para> +At this point of time, the most helpful file in the sources was the ext2 +main include file - <Literal remap="tt">/usr/include/linux/ext2_fs.h</Literal>. Among its contents +there were various structures which I assumed they are disk images - Appear +exactly like that on the disk. +</Para> + +<Para> +I wanted a <Literal remap="tt">quick</Literal> way to get going. I didn't have the patience to learn +each of the structures use in the code. Rather, I wanted to see them in action, +so that I could explore the connections between them - Test my assumptions, +and reach other assumptions. +</Para> + +<Para> +So after the <Literal remap="tt">hex editor</Literal>, EXT2ED progressed into a tool which has some +elements of a compiler. I programmed EXT2ED to <Literal remap="tt">dynamically read the kernel +ext2 main include file in run time</Literal>, and process the information. The goal +was to <Literal remap="tt">imply a structure-definition on the current offset at the +filesystem</Literal>. EXT2ED would then display the structure as a list of its +variables names and contents, instead of a meaningless hex dump. +</Para> + +<Para> +The format of the include file is not very complicated - The structures +are mostly <Literal remap="tt">flat</Literal> - Didn't contain a lot of recursive structure; Only a +global structure definition, and some variables. There were cases of +structures inside structures, I treated them in a somewhat non-elegant way - I +made all the structures flat, and expanded the arrays. As a result, the parser +was very simple. After all, this was not an exercise in compiling, and I +wanted to quickly get some results. +</Para> + +<Para> +To handle the task, I constructed the <Literal remap="tt">struct_descriptor</Literal> structure. +Each <Literal remap="tt">struct_descriptor instance</Literal> contained information which is needed +in order to format a block of data according to the C structure contained in +the kernel source. The information contained: + +<ItemizedList> +<ListItem> + +<Para> + The descriptor name, used to reference to the structure in EXT2ED. +</Para> +</ListItem> +<ListItem> + +<Para> + The name of each variable. +</Para> +</ListItem> +<ListItem> + +<Para> + The relative offset of the each variable in the data block. +</Para> +</ListItem> +<ListItem> + +<Para> + The length, in bytes, of each variable. +</Para> +</ListItem> + +</ItemizedList> + +Since I didn't want to limit the number of structures, I chose a simple +double linked list to store the information. One variable contained the +<Literal remap="tt">current structure type</Literal> - A pointer to the relevant +<Literal remap="tt">struct_descriptor</Literal>. +</Para> + +<Para> +Now EXT2ED contained basically three command line operations: + +<ItemizedList> +<ListItem> + +<Para> + setdevice + +Used to open a device for reading only. Write access was postponed +to a very advanced state in the project, simply because I didn't +know a thing of the filesystem structure, and I believed that +making actual changes would do nothing but damage :-) +</Para> +</ListItem> +<ListItem> + +<Para> + setoffset + +Used to move in the device. +</Para> +</ListItem> +<ListItem> + +<Para> + settype + +Used to imply a structure definition on the current place. +</Para> +</ListItem> +<ListItem> + +<Para> + show + +Used to display the data. It displayed the data in a simple hex dump +if there was no type set, or in a nice formatted way - As a list of +the variable contents, if there was. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +Command line analyzing was primitive back then - A simple switch, as far as +I can remember - Nothing alike the current flow control, but it was enough +at the time. +</Para> + +<Para> +At the end, I had something to start working with. It knew to format many +structures - None of which I understood - and provided me, without too much +work, something to start with. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Starting to explore</Title> + +<Para> +With the above tool in my pocket, I started to explore the ext2 filesystem +structure. From the brief reading in Bach's book, I got familiar to some +basic concepts - The <Literal remap="tt">superblock</Literal>, for example. It seems that the +superblock is an important part of the filesystem. I decided to start +exploring with that. +</Para> + +<Para> +I realized that the superblock should be at a fixed location in the +filesystem - Probably near the beginning. There can be no other way - +The kernel should start at some place to find it. A brief looking in +the kernel sources revealed that the superblock is signed by a special +signature - A <Literal remap="tt">magic number</Literal> - EXT2_SUPER_MAGIC (0xEF53 - EF probably +stands for Extended Filesystem). I quickly found the superblock at the +fixed offset 1024 in the filesystem - The <Literal remap="tt">s_magic</Literal> variable in the +superblock was set exactly to the above value. +</Para> + +<Para> +It seems that starting with the <Literal remap="tt">superblock</Literal> was a good bet - Just from +the list of variables, one can learn a lot. I didn't understand all of them +at the time, but it seemed that the following keywords were repeating themselves +in various variables: + +<ItemizedList> +<ListItem> + +<Para> + block +</Para> +</ListItem> +<ListItem> + +<Para> + inode +</Para> +</ListItem> +<ListItem> + +<Para> + group +</Para> +</ListItem> + +</ItemizedList> + +At this point, I started to explore the block groups. I will not detail here +the technical design of the ext2 filesystem. I have written a special +article which explains just that, in the "engineering" way. Please refer to it +if you feel that you are lacking knowledge in the structure of the ext2 +filesystem. +</Para> + +<Para> +I was exploring the filesystem in this way for some time, along with reading +the sources. This lead naturally to the next step. +</Para> + +</Sect1> + +<Sect1> +<Title>Object specific commands</Title> + +<Para> +What has become clear is that the above way of exploring is not powerful +enough - I found myself doing various calculations manually in order to pass +between related structures. I needed to replace some tasks with an automated +procedure. +</Para> + +<Para> +In addition, it also became clear that (of-course) each key object in the +filesystem has its special place in regard to the overall ext2 filesystem +design, and needs a <Literal remap="tt">fine tuned handling</Literal>. It is at this point that the +structure definitions <Literal remap="tt">came to life</Literal> - They became <Literal remap="tt">object +definitions</Literal>, making EXT2ED <Literal remap="tt">object oriented</Literal>. +</Para> + +<Para> +The actual meaning of the breathtaking words above, is that each structure +now had a list of <Literal remap="tt">private commands</Literal>, which ended up in +<Literal remap="tt">calling special fine-tuned C functions</Literal>. This approach was +found to be very powerful and is <Literal remap="tt">the heart of EXT2ED even now</Literal>. +</Para> + +<Para> +In order to implement the above concepts, I added the structure +<Literal remap="tt">struct_commands</Literal>. The role of this structure is to group together a +group of commands, which can be later assigned to a specific type. Each +structure had: + +<ItemizedList> +<ListItem> + +<Para> + A list of command names. +</Para> +</ListItem> +<ListItem> + +<Para> + A list of pointers to functions, which binds each command to its +special fine-tuned C function. +</Para> +</ListItem> + +</ItemizedList> + +In order to relate a list of commands to a type definition, each +<Literal remap="tt">struct_descriptor</Literal> structure (explained earlier) was added a private +<Literal remap="tt">struct_commands</Literal> structure. +</Para> + +<Para> +Follows the current definitions of <Literal remap="tt">struct_descriptor</Literal> and of +<Literal remap="tt">struct_command</Literal>: + +<ProgramListing> +struct struct_descriptor { + unsigned long length; + unsigned char name [60]; + unsigned short fields_num; + unsigned char field_names [MAX_FIELDS][80]; + unsigned short field_lengths [MAX_FIELDS]; + unsigned short field_positions [MAX_FIELDS]; + struct struct_commands type_commands; + struct struct_descriptor *prev,*next; +}; + +typedef void (*PF) (char *); + +struct struct_commands { + int last_command; + char *names [MAX_COMMANDS_NUM]; + char *descriptions [MAX_COMMANDS_NUM]; + PF callback [MAX_COMMANDS_NUM]; +}; +</ProgramListing> + + +</Para> + +</Sect1> + +<Sect1 id="flow-control"> +<Title>Program flow control</Title> + +<Para> +Obviously the above approach lead to a major redesign of EXT2ED. The +main engine of the resulting design is basically the same even now. +</Para> + +<Para> +I redesigned the program flow control. Up to now, I analyzed the user command +line with the simple switch method. Now I used the far superior callback +method. +</Para> + +<Para> +I divided the available user commands into two groups: + +<OrderedList> +<ListItem> + +<Para> + General commands. +</Para> +</ListItem> +<ListItem> + +<Para> + Type specific commands. +</Para> +</ListItem> + +</OrderedList> + +As a result, at each point in time, the user was able to enter a +<Literal remap="tt">general command</Literal>, selectable from a list of general commands which was +always available, or a <Literal remap="tt">type specific command</Literal>, selectable from a list of +commands which <Literal remap="tt">changed in time</Literal> according to the current type that the +user was editing. The special <Literal remap="tt">type specific command</Literal> "knew" how to +handle the object in the best possible way - It was "fine tuned" for the +object's place in the ext2 filesystem design. +</Para> + +<Para> +In order to implement the above idea, I constructed a global variable of +type <Literal remap="tt">struct_commands</Literal>, which contained the <Literal remap="tt">general commands</Literal>. +The <Literal remap="tt">type specific commands</Literal> were accessible through the <Literal remap="tt">struct +descriptors</Literal>, as explained earlier. +</Para> + +<Para> +The program flow was now done according to the following algorithm: + +<OrderedList> +<ListItem> + +<Para> + Ask the user for a command line. +</Para> +</ListItem> +<ListItem> + +<Para> + Analyze the user command - Separate it into <Literal remap="tt">command</Literal> and +<Literal remap="tt">arguments</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Trace the list of known objects to match the command name to a type. +If the type is found, call the callback function, with the arguments +as a parameter. Then go back to step (1). +</Para> +</ListItem> +<ListItem> + +<Para> + If the command is not type specific, try to find it in the general +commands, and call it if found. Go back to step (1). +</Para> +</ListItem> +<ListItem> + +<Para> + If the command is not found, issue a short error message, and return +to step (1). +</Para> +</ListItem> + +</OrderedList> + +Note the <Literal remap="tt">order</Literal> of the above steps. In particular, note that a command +is first assumed to be a type-specific command and only if this fails, a +general command is searched. The "<Literal remap="tt">side-effect</Literal>" (main effect, actually) +is that when we have two commands with the <Literal remap="tt">same name</Literal> - One that is a +type specific command, and one that is a general command, the dispatching +algorithm will call the <Literal remap="tt">type specific command</Literal>. This allows +<Literal remap="tt">overriding</Literal> of a command to provide <Literal remap="tt">fine-tuned</Literal> operation. +For example, the <Literal remap="tt">show</Literal> command is overridden nearly everywhere, +to accommodate for the different ways in which different objects are displayed, +in order to provide an intuitive fine-tuned display. +</Para> + +<Para> +The above is done in the <Literal remap="tt">dispatch</Literal> function, in <Literal remap="tt">main.c</Literal>. Since +it is a very important function in EXT2ED, and it is relatively short, I will +list it entirely here. Note that a redesign was made since then - Another +level was added between the two described, but I'll elaborate more on this +later. However, the basic structure follows the explanation described above. + +<ProgramListing> +int dispatch (char *command_line) + +{ + int i,found=0; + char command [80]; + + parse_word (command_line,command); + + if (strcmp (command,"quit")==0) return (1); + + /* 1. Search for type specific commands FIRST - Allows overriding of a general command */ + + if (current_type != NULL) + for (i=0;i<=current_type->type_commands.last_command && !found;i++) { + if (strcmp (command,current_type->type_commands.names [i])==0) { + (*current_type->type_commands.callback [i]) (command_line); + found=1; + } + } + + /* 2. Now search for ext2 filesystem general commands */ + + if (!found) + for (i=0;i<=ext2_commands.last_command && !found;i++) { + if (strcmp (command,ext2_commands.names [i])==0) { + (*ext2_commands.callback [i]) (command_line); + found=1; + } + } + + + /* 3. If not found, search the general commands */ + + if (!found) + for (i=0;i<=general_commands.last_command && !found;i++) { + if (strcmp (command,general_commands.names [i])==0) { + (*general_commands.callback [i]) (command_line); + found=1; + } + } + + if (!found) { + wprintw (command_win,"Error: Unknown command\n"); + refresh_command_win (); + } + + return (0); +} +</ProgramListing> + +</Para> + +</Sect1> + +<Sect1> +<Title>Source files in EXT2ED</Title> + +<Para> +The project was getting large enough to be split into several source +files. I split the source as much as I could into self-contained +source files. The source files consist of the following blocks: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">Main include file - ext2ed.h</Literal> + +This file contains the definitions of the various structures, +variables and functions used in EXT2ED. It is included by all source +files in EXT2ED. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Main block - main.c</Literal> + +<Literal remap="tt">main.c</Literal> handles the upper level of the program flow control. +It contains the <Literal remap="tt">parser</Literal> and the <Literal remap="tt">dispatcher</Literal>. Its task is +to ask the user for a required action, and to pass control to other +lower level functions in order to do the actual job. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Initialization - init.c</Literal> + +The init source is responsible for the various initialization +actions which need to be done through the program. For example, +auto detection of an ext2 filesystem when selecting a device and +initialization of the filesystem-specific structures described +earlier. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Disk activity - disk.c</Literal> + +<Literal remap="tt">disk.c</Literal> is handles the lower level interaction with the +device. All disk activity is passed through this file - The various +functions through the source code request disk actions from the +functions in this file. In this way, for example, we can easily block +the write access to the device. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Display output activity - win.c</Literal> + +In a similar way to <Literal remap="tt">disk.c</Literal>, the user-interface functions and +most of the interaction with the <Literal remap="tt">ncurses library</Literal> are done +here. Nothing will be actually written to a specific window without +calling a function from this file. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Commands available through dispatching - *_com.c </Literal> + +The above file name is generic - Each file which ends with +<Literal remap="tt">_com.c</Literal> contains a group of related commands which can be +called through <Literal remap="tt">the dispatching function</Literal>. + +Each object typically has its own file. A separate file is also +available for the general commands. +</Para> +</ListItem> + +</ItemizedList> + +The entire list of source files available at this time is: + +<ItemizedList> +<ListItem> + +<Para> + blockbitmap_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + dir_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + disk.c +</Para> +</ListItem> +<ListItem> + +<Para> + ext2_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + file_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + general_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + group_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + init.c +</Para> +</ListItem> +<ListItem> + +<Para> + inode_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + inodebitmap_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + main.c +</Para> +</ListItem> +<ListItem> + +<Para> + super_com.c +</Para> +</ListItem> +<ListItem> + +<Para> + win.c +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect1> + +<Sect1> +<Title>User interface</Title> + +<Para> +The user interface is text-based only and is based on the following +libraries: +</Para> + +<Para> + +<ItemizedList> +<ListItem> + +<Para> + The <Literal remap="tt">ncurses</Literal> library, developed by <Literal remap="tt">Zeyd Ben-Halim</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + The <Literal remap="tt">GNU readline</Literal> library. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The user interaction is command line based - The user enters a command +line, which consists of a <Literal remap="tt">command</Literal> and of <Literal remap="tt">arguments</Literal>. This fits +nicely with the program flow control described earlier - The <Literal remap="tt">command</Literal> +is used by <Literal remap="tt">dispatch</Literal> to select the right function, and the +<Literal remap="tt">arguments</Literal> are interpreted by the function itself. +</Para> + +<Sect2> +<Title>The ncurses library</Title> + +<Para> +The <Literal remap="tt">ncurses</Literal> library enables me to divide the screen into "windows". +The main advantage is that I treat the "window" in a virtual way, asking +the ncurses library to "write to a window". However, the ncurses +library internally buffers the requests, and nothing is actually passed to the +terminal until an explicit refresh is requested. When the refresh request is +made, ncurses compares the current terminal state (as known in the last time +that a refresh was done) with the new to be shown state, and passes to the +terminal the minimal information required to update the display. As a +result, the display output is optimized behind the scenes by the +<Literal remap="tt">ncurses</Literal> library, while I can still treat it in a virtual way. +</Para> + +<Para> +There are two basic concepts in the <Literal remap="tt">ncurses</Literal> library: + +<ItemizedList> +<ListItem> + +<Para> + A window. +</Para> +</ListItem> +<ListItem> + +<Para> + A pad. +</Para> +</ListItem> + +</ItemizedList> + +A window can be no bigger than the actual terminal size. A pad, however, is +not limited in its size. +</Para> + +<Para> +The user screen is divided by EXT2ED into three windows and one pad: + +<ItemizedList> +<ListItem> + +<Para> + Title window. +</Para> +</ListItem> +<ListItem> + +<Para> + Status window. +</Para> +</ListItem> +<ListItem> + +<Para> + Main display pad. +</Para> +</ListItem> +<ListItem> + +<Para> + Command window. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The <Literal remap="tt">title window</Literal> is static - It just displays the current version +of EXT2ED. +</Para> + +<Para> +The user interaction is done in the <Literal remap="tt">command window</Literal>. The user enters a +<Literal remap="tt">command line</Literal>, feedback is usually displayed there, and then relevant +data is usually displayed in the main display and in the status window. +</Para> + +<Para> +The <Literal remap="tt">main display</Literal> is using a <Literal remap="tt">pad</Literal> instead of a window because +the amount of information which is written to it is not known in advance. +Therefor, the user treats the main display as a "window" into a bigger +display and can <Literal remap="tt">scroll vertically</Literal> using the <Literal remap="tt">pgdn</Literal> and <Literal remap="tt">pgup</Literal> +commands. Although the <Literal remap="tt">pad</Literal> mechanism enables me to use horizontal +scrolling, I have not utilized this. +</Para> + +<Para> +When I need to show something to the user, I use the ncurses <Literal remap="tt">wprintw</Literal> +command. Then an explicit refresh command is required. As explained before, +the refresh commands is piped through <Literal remap="tt">win.c</Literal>. For example, to update +the command window, <Literal remap="tt">refresh_command_win ()</Literal> is used. +</Para> + +</Sect2> + +<Sect2> +<Title>The readline library</Title> + +<Para> +Avner suggested me to integrate the GNU <Literal remap="tt">readline</Literal> library in my project. +The <Literal remap="tt">readline</Literal> library is designed specifically for programs which use +command line interface. It provides a nice package of <Literal remap="tt">command line editing +tools</Literal> - Inserting, deleting words, and the whole package of editing tools +which are normally available in the <Literal remap="tt">bash</Literal> shell (Refer to the readline +documentation for details). In addition, I utilized the <Literal remap="tt">history</Literal> +feature of the readline library - The entered commands are saved in a +<Literal remap="tt">command history</Literal>, and can be called later by whatever means that the +readline package provides. Command completion is also supported - When the +user enters a partial command name, EXT2ED will provide the readline library +with the possible completions. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Possible support of other filesystems</Title> + +<Para> +The entire ext2 layer is provided through specific objects. Given another +set of objects, support of other filesystem can be provided using the same +dispatching mechanism. In order to prepare the surface for this option, I +added yet another layer to the two-layer structure presented earlier. EXT2ED +commands now consist of three layers: + +<ItemizedList> +<ListItem> + +<Para> + The general commands. +</Para> +</ListItem> +<ListItem> + +<Para> + The ext2 general commands. +</Para> +</ListItem> +<ListItem> + +<Para> + The ext2 object specific commands. +</Para> +</ListItem> + +</ItemizedList> + +The general commands are provided by the <Literal remap="tt">general_com.c</Literal> source file, +and are always available. The two other levels are not present when EXT2ED +loads - They are dynamically added by <Literal remap="tt">init.c</Literal> when EXT2ED detects an +ext2 filesystem on the device. +</Para> + +<Para> +The abstraction levels presented above helps to extend EXT2ED to fully +support a new filesystem, with its own specific type commands. +</Para> + +<Para> +Even without any source code modification, the user is free to add structure +definitions in a separate file (specified in the configuration file), +which will be added to the list of available objects. The added objects will +consist only of variables, of-course, and will be used through the more +primitive <Literal remap="tt">setoffset</Literal> and <Literal remap="tt">settype</Literal> commands. +</Para> + +</Sect1> + +<Sect1> +<Title>On the implementation of the various commands</Title> + +<Para> +This section points out some typical programming style that I used in many +places at the code. +</Para> + +<Sect2> +<Title>The explicit use of the dispatch function</Title> + +<Para> +The various commands are reached by the user through the <Literal remap="tt">dispatch</Literal> +function. This is not surprising. The fact that can be surprising, at least in +a first look, is that <Literal remap="tt">you'll find the dispatch call in many of my +own functions!</Literal>. +</Para> + +<Para> +I am in fact using my own implemented functions to construct higher +level operations. I am heavily using the fact that the dispatching mechanism +is object oriented ant that the <Literal remap="tt">overriding</Literal> principle takes place and +selects the proper function to call when several commands with the same name +are accessible. +</Para> + +<Para> +Sometimes, however, I call the explicit command directly, without passing +through <Literal remap="tt">dispatch</Literal>. This is typically done when I want to bypass the +<Literal remap="tt">overriding</Literal> effect. +</Para> + +<Para> + +This is used, for example, in the interaction between the global cd command +and the dir object specific cd command. You will see there that in order +to implement the "entire" cd command, the type specific cd command uses both +a dispatching mechanism to call itself recursively if a relative path is +used, or a direct call of the general cd handling function if an explicit path +is used. + +</Para> + +</Sect2> + +<Sect2> +<Title>Passing information between handling functions</Title> + +<Para> +Typically, every source code file which handles one object type has a global +structure specifically designed for it which is used by most of the +functions in that file. This is used to pass information between the various +functions there, and to physically provide the link to other related +objects, typically for initialization use. +</Para> + +<Para> + +For example, in order to edit a file, information about the +inode is needed - The file command is available only when editing an +inode. When the file command is issued, the handling function (found, +according to the source division outlined above, in inode_com.c) will +store the necessary information about the inode in a specific structure +of type struct_file_info which will be available for use by the file_com.c +functions. Only then it will set the type to file. This is also the reason +that a direct asynchronous set of the object type to a file through a settype +command will fail - The above data structure will not be initialized +properly because the user never was at the inode of the file. + +</Para> + +</Sect2> + +<Sect2> +<Title>A very simplified overview of a typical command handling function</Title> + +<Para> +This is a very simplified overview. Detailed information will follow +where appropriate. +</Para> + +<Sect3> +<Title>The prototype of a typical handling function</Title> + +<Para> + +<OrderedList> +<ListItem> + +<Para> + I chose a unified <Literal remap="tt">naming convention</Literal> for the various object +specific commands. It is perhaps best showed with an example: + +The prototype of the handling function of the command <Literal remap="tt">next</Literal> of +the type <Literal remap="tt">file</Literal> is: + +<Screen> + extern void type_file___next (char *command_line); + +</Screen> + + +For other types and commands, the words <Literal remap="tt">file</Literal> and <Literal remap="tt">next</Literal> +should be replaced accordingly. + +</Para> +</ListItem> +<ListItem> + +<Para> + The ext2 general commands syntax is similar. For example, the ext2 +general command <Literal remap="tt">super</Literal> results in calling: + +<Screen> + extern void type_ext2___super (char *command_line); + +</Screen> + +Those functions are available in <Literal remap="tt">ext2_com.c</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + The general commands syntax is even simpler - The name of the +handling function is exactly the name of the commands. Those +functions are available in <Literal remap="tt">general_com.c</Literal>. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +</Sect3> + +<Sect3> +<Title>"Typical" algorithm</Title> + +<Para> +This section can't of-course provide meaningful information - Each +command is handled differently, but the following frame is typical: + +<OrderedList> +<ListItem> + +<Para> + Parse command line arguments and analyze them. Return with an error +message if the syntax is wrong. +</Para> +</ListItem> +<ListItem> + +<Para> + "Act accordingly", perhaps making use of the global variable available +to this type. +</Para> +</ListItem> +<ListItem> + +<Para> + Use some <Literal remap="tt">dispatch / direct </Literal> calls in order to pass control to +other lower-level user commands. +</Para> +</ListItem> +<ListItem> + +<Para> + Sometimes <Literal remap="tt">dispatch</Literal> to the object's <Literal remap="tt">show</Literal> command to +display the resulting data to the user. +</Para> +</ListItem> + +</OrderedList> + +I told you it is meaningless :-) +</Para> + +</Sect3> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Initialization overview</Title> + +<Para> +In this section I will discuss some aspects of the various initialization +routines available in the source file <Literal remap="tt">init.c</Literal>. +</Para> + +<Sect2> +<Title>Upon startup</Title> + +<Para> +Follows the function <Literal remap="tt">main</Literal>, appearing of-course in <Literal remap="tt">main.c</Literal>: + + +<ProgramListing> +int main (void) + +{ + if (!init ()) return (0); /* Perform some initial initialization */ + /* Quit if failed */ + + parser (); /* Get and parse user commands */ + + prepare_to_close (); /* Do some cleanup */ + printf ("Quitting ...\n"); + return (1); /* And quit */ +} +</ProgramListing> + +</Para> + +<Para> +The two initialization functions, which are called by <Literal remap="tt">main</Literal>, are: + +<ItemizedList> +<ListItem> + +<Para> + init +</Para> +</ListItem> +<ListItem> + +<Para> + prepare_to_close +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Sect3> +<Title>The init function</Title> + +<Para> +<Literal remap="tt">init</Literal> is called from <Literal remap="tt">main</Literal> upon startup. It initializes the +following tasks / subsystems: + +<OrderedList> +<ListItem> + +<Para> + Processing of the <Literal remap="tt">user configuration file</Literal>, by using the +<Literal remap="tt">process_configuration_file</Literal> function. Failing to complete the +configuration file processing is considered a <Literal remap="tt">fatal error</Literal>, +and EXT2ED is aborted. I did it this way because the configuration +file has some sensitive user options like write access behavior, and +I wanted to be sure that the user is aware of them. +</Para> +</ListItem> +<ListItem> + +<Para> + Registration of the <Literal remap="tt">general commands</Literal> through the use of +the <Literal remap="tt">add_general_commands</Literal> function. +</Para> +</ListItem> +<ListItem> + +<Para> + Reset of the object memory rotating lifo structure. +</Para> +</ListItem> +<ListItem> + +<Para> + Reset of the device parameters and of the current type. +</Para> +</ListItem> +<ListItem> + +<Para> + Initialization of the windows subsystem - The interface between the +ncurses library and EXT2ED, through the use of the <Literal remap="tt">init_windows</Literal> +function, available in <Literal remap="tt">win.c</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Initialization of the interface between the readline library and +EXT2ED, through <Literal remap="tt">init_readline</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Initialization of the <Literal remap="tt">signals</Literal> subsystem, through +<Literal remap="tt">init_signals</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Disabling write access. Write access needs to be explicitly enabled +using a user command, to prevent accidental user mistakes. +</Para> +</ListItem> + +</OrderedList> + +When <Literal remap="tt">init</Literal> is finished, it dispatches the <Literal remap="tt">help</Literal> command in order +to show the available commands to the user. Note that the ext2 layer is still +not added; It will be added if and when EXT2ED will detect an ext2 +filesystem on a device. +</Para> + +</Sect3> + +<Sect3> +<Title>The prepare_to_close function</Title> + +<Para> +The <Literal remap="tt">prepare_to_close</Literal> function reverses some of the actions done +earlier in EXT2ED and freeing the dynamically allocated memory. +Specifically, it: + +<OrderedList> +<ListItem> + +<Para> + Closes the open device, if any. +</Para> +</ListItem> +<ListItem> + +<Para> + Removes the first level - Removing the general commands, through +the use of <Literal remap="tt">free_user_commands</Literal>, with a pointer to the +general_commands structure as a parameter. +</Para> +</ListItem> +<ListItem> + +<Para> + Removes of the second level - Removing the ext2 ext2 general +commands, in much the same way. +</Para> +</ListItem> +<ListItem> + +<Para> + Removes of the third level - Removing the objects and the object +specific commands, by using <Literal remap="tt">free_struct_descriptors</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Closes the window subsystem, and detaches EXT2ED from the ncurses +library, through the use of the <Literal remap="tt">close_windows</Literal> function, +available in <Literal remap="tt">win.c</Literal>. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +</Sect3> + +</Sect2> + +<Sect2> +<Title>Registration of commands</Title> + +<Para> +Addition of a user command is done through the <Literal remap="tt">add_user_command</Literal> +function. The prototype is: + +<Screen> +void add_user_command (struct struct_commands *ptr,char *name,char +*description,PF callback); +</Screen> + +The function receives a pointer to a structure of type +<Literal remap="tt">struct_commands</Literal>, a desired name for the command which will be used by +the user to identify the command, a short description which is utilized by the +<Literal remap="tt">help</Literal> subsystem, and a pointer to a C function which will be called if +<Literal remap="tt">dispatch</Literal> decides that this command was requested. +</Para> + +<Para> +The <Literal remap="tt">add_user_command</Literal> is a <Literal remap="tt">low level function</Literal> used in the three +levels to add user commands. For example, addition of the <Literal remap="tt">ext2 +general commands is done by:</Literal> + +<ProgramListing> +void add_ext2_general_commands (void) + +{ + add_user_command (&ext2_commands,"super","Moves to the superblock of the filesystem",type_ext2___super); + add_user_command (&ext2_commands,"group","Moves to the first group descriptor",type_ext2___group); + add_user_command (&ext2_commands,"cd","Moves to the directory specified",type_ext2___cd); +} +</ProgramListing> + +</Para> + +</Sect2> + +<Sect2> +<Title>Registration of objects</Title> + +<Para> +Registration of objects is based, as explained earlier, on the "compilation" +of an external user file, which has a syntax similar to the C language +<Literal remap="tt">struct</Literal> keyword. The primitive parser I have implemented detects the +definition of structures, and calls some lower level functions to actually +register the new detected object. The parser's prototype is: + +<Screen> +int set_struct_descriptors (char *file_name) +</Screen> + +It opens the given file name, and calls, when appropriate: + +<ItemizedList> +<ListItem> + +<Para> + add_new_descriptor +</Para> +</ListItem> +<ListItem> + +<Para> + add_new_variable +</Para> +</ListItem> + +</ItemizedList> + +<Literal remap="tt">add_new_descriptor</Literal> is a low level function which adds a new descriptor +to the doubly linked list of the available objects. It will then call +<Literal remap="tt">fill_type_commands</Literal>, which will add specific commands to the object, +if the object is known. +</Para> + +<Para> +<Literal remap="tt">add_new_variable</Literal> will add a new variable of the requested length to the +specified descriptor. +</Para> + +</Sect2> + +<Sect2> +<Title>Initialization upon specification of a device</Title> + +<Para> +When the general command <Literal remap="tt">setdevice</Literal> is used to open a device, some +initialization sequence takes place, which is intended to determine two +factors: + +<ItemizedList> +<ListItem> + +<Para> + Are we dealing with an ext2 filesystem ? +</Para> +</ListItem> +<ListItem> + +<Para> + What are the basic filesystem parameters, such as its total size and +its block size ? +</Para> +</ListItem> + +</ItemizedList> + +This questions are answered by the <Literal remap="tt">set_file_system_info</Literal>, possibly +using some <Literal remap="tt">help from the user</Literal>, through the configuration file. +The answers are placed in the <Literal remap="tt">file_system_info</Literal> structure, which is of +type <Literal remap="tt">struct_file_system_info</Literal>: + +<ProgramListing> +struct struct_file_system_info { + unsigned long file_system_size; + unsigned long super_block_offset; + unsigned long first_group_desc_offset; + unsigned long groups_count; + unsigned long inodes_per_block; + unsigned long blocks_per_group; /* The name is misleading; beware */ + unsigned long no_blocks_in_group; + unsigned short block_size; + struct ext2_super_block super_block; +}; +</ProgramListing> + +</Para> + +<Para> +Autodetection of an ext2 filesystem is usually recommended. However, on a damaged +filesystem I can't assure a success. That's were the user comes in - He can +<Literal remap="tt">override</Literal> the auto detection procedure and force an ext2 filesystem, by +selecting the proper options in the configuration file. +</Para> + +<Para> +If auto detection succeeds, the second question above is automatically +answered - I get all the information I need from the filesystem itself. In +any case, default parameters can be supplied in the configuration file and +the user can select the required behavior. +</Para> + +<Para> +If we decide to treat the filesystem as an ext2 filesystem, <Literal remap="tt">registration of +the ext2 specific objects</Literal> is done at this point, by calling the +<Literal remap="tt">set_struct_descriptors</Literal> outlined earlier, with the name of the file +which describes the ext2 objects, and is basically based on the ext2 sources +main include file. At this point, EXT2ED can be fully used by the user. +</Para> + +<Para> +If we do not register the ext2 specific objects, the user can still provide +object definitions in a separate file, and will be able to use EXT2ED in a +<Literal remap="tt">limited form</Literal>, but more sophisticated than a simple hex editor. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>main.c</Title> + +<Para> +As described earlier, <Literal remap="tt">main.c</Literal> is used as a front-head to the entire +program. <Literal remap="tt">main.c</Literal> contains the following elements: +</Para> + +<Sect2> +<Title>The main routine</Title> + +<Para> +The <Literal remap="tt">main</Literal> routine was displayed above. Its task is to pass control to +the initialization routines and to the parser. +</Para> + +</Sect2> + +<Sect2> +<Title>The parser</Title> + +<Para> +The parser consists of the following functions: + +<ItemizedList> +<ListItem> + +<Para> + The <Literal remap="tt">parser</Literal> function, which reads the command line from the +user and saves it in readline's history buffer and in the internal +last-command buffer. +</Para> +</ListItem> +<ListItem> + +<Para> + The <Literal remap="tt">parse_word</Literal> function, which receives a string and parses +the first word from it, ignoring whitespaces, and returns a pointer +to the rest of the string. +</Para> +</ListItem> +<ListItem> + +<Para> + The <Literal remap="tt">complete_command</Literal> function, which is used by the readline +library for command completion. It scans the available commands at +this point and determines the possible completions. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>The dispatcher</Title> + +<Para> +The dispatcher was already explained in the flow control section - section +<XRef LinkEnd="flow-control">. Its task is to pass control to the proper command +handling function, based on the command line's command. +</Para> + +</Sect2> + +<Sect2> +<Title>The self-sanity control</Title> + +<Para> +This is not fully implemented. +</Para> + +<Para> +The general idea was to provide a control system which will supervise the +internal work of EXT2ED. Since I am pretty sure that bugs exist, I have +double checked myself in a few instances, and issued an <Literal remap="tt">internal +error</Literal> warning if I reached the conclusion that something is not logical. +The internal error is reported by the function <Literal remap="tt">internal_error</Literal>, +available in <Literal remap="tt">main.c</Literal>. +</Para> + +<Para> +The self sanity check is compiled only if the compile time option +<Literal remap="tt">DEBUG</Literal> is selected. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The windows interface</Title> + +<Para> +Screen handling and interfacing to the <Literal remap="tt">ncurses</Literal> library is done in +<Literal remap="tt">win.c</Literal>. +</Para> + +<Sect2> +<Title>Initialization</Title> + +<Para> +Opening of the windows is done in <Literal remap="tt">init_windows</Literal>. In +<Literal remap="tt">close_windows</Literal>, we just close our windows. The various window lengths +with an exception to the <Literal remap="tt">show pad</Literal> are defined in the main header file. +The rest of the display will be used by the <Literal remap="tt">show pad</Literal>. +</Para> + +</Sect2> + +<Sect2> +<Title>Display output</Title> + +<Para> +Each actual refreshing of the terminal monitor is done by using the +appropriate refresh function from this file: <Literal remap="tt">refresh_title_win</Literal>, +<Literal remap="tt">refresh_show_win</Literal>, <Literal remap="tt">refresh_show_pad</Literal> and +<Literal remap="tt">refresh_command_win</Literal>. +</Para> + +<Para> +With the exception of the <Literal remap="tt">show pad</Literal>, each function simply calls the +<Literal remap="tt">ncurses refresh command</Literal>. In order to provide to <Literal remap="tt">scrolling</Literal> in +the <Literal remap="tt">show pad</Literal>, some information about its status is constantly updated +by the various functions which display output in it. <Literal remap="tt">refresh_show_pad</Literal> +passes this information to <Literal remap="tt">ncurses</Literal> so that the correct part of the pad +is actually copied to the display. +</Para> + +<Para> +The above information is saved in a global variable of type <Literal remap="tt">struct +struct_pad_info</Literal>: +</Para> + +<Para> + +<ProgramListing> +struct struct_pad_info { + int display_lines,display_cols; + int line,col; + int max_line,max_col; + int disable_output; +}; +</ProgramListing> + +</Para> + +</Sect2> + +<Sect2> +<Title>Screen redraw</Title> + +<Para> +The <Literal remap="tt">redraw_all</Literal> function will just reopen the windows. This action is +necessary if the display gets garbled from some reason. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The disk interface</Title> + +<Para> +All the disk activity with regard to the filesystem passes through the file +<Literal remap="tt">disk.c</Literal>. This is done that way to provide additional levels of safety +concerning the disk access. This way, global decisions considering the disk +can be easily accomplished. The benefits of this isolation will become even +clearer in the next sections. +</Para> + +<Sect2> +<Title>Low level functions</Title> + +<Para> +Read requests are ultimately handled by <Literal remap="tt">low_read</Literal> and write requests +are handled by <Literal remap="tt">low_write</Literal>. They just receive the length of the data +block, the offset in the filesystem and a pointer to the buffer and pass the +request to the <Literal remap="tt">fread</Literal> or <Literal remap="tt">fwrite</Literal> standard library functions. +</Para> + +</Sect2> + +<Sect2> +<Title>Mounted filesystems</Title> + +<Para> +EXT2ED design assumes that the edited filesystem is not mounted. Even if +a <Literal remap="tt">reasonably simple</Literal> way to handle mounted filesystems exists, it is +probably <Literal remap="tt">too complicated</Literal> :-) +</Para> + +<Para> +Write access to a mounted filesystem will be denied. Read access can be +allowed by using a configuration file option. The mount status is determined +by reading the file /etc/mtab. +</Para> + +</Sect2> + +<Sect2> +<Title>Write access</Title> + +<Para> +Write access is the most sensitive part in the program. This program is +intended for <Literal remap="tt">editing filesystems</Literal>. It is obvious that a small mistake +in this regard can make the filesystem not usable anymore. +</Para> + +<Para> +The following safety measures are added, of-course, to the general Unix +permission protection - The user can always disable write access on the +device file itself. +</Para> + +<Para> +Considering the user, the following safety measures were taken: + +<OrderedList> +<ListItem> + +<Para> + The filesystem is <Literal remap="tt">never</Literal> opened with write-access enables. +Rather, the user must explicitly request to enable write-access. +</Para> +</ListItem> +<ListItem> + +<Para> + The user can <Literal remap="tt">disable</Literal> write access entirely by using a +<Literal remap="tt">configuration file option</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Changes are never done automatically - Whenever the user makes +changes, they are done in memory. An explicit <Literal remap="tt">writedata</Literal> +command should be issued to make the changes active in the disk. +</Para> +</ListItem> + +</OrderedList> + +Considering myself, I tried to protect against my bugs by: + +<ItemizedList> +<ListItem> + +<Para> + Opening the device in read-only mode until a write request is +issued by the user. +</Para> +</ListItem> +<ListItem> + +<Para> + Limiting <Literal remap="tt">actual</Literal> filesystem access to two functions only - +<Literal remap="tt">low_read</Literal> for reading, and <Literal remap="tt">low_write</Literal> for writing. Those +functions were programmed carefully, and I added the self +sanity checks there. In addition, this is the only place in which I +need to check the user options described above - There can be no +place in which I can "forget" to check them. + +Note that The disabling of write-access through the configuration file +is double checked here only as a <Literal remap="tt">self-sanity</Literal> check - If +<Literal remap="tt">DEBUG</Literal> is selected, since write enable should have been refused +and write-access is always disabled at startup, hence finding +<Literal remap="tt">here</Literal> that the user has write access disabled through the +configuration file clearly indicates that I have a bug somewhere. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The following safety measure can provide protection against <Literal remap="tt">both</Literal> user +mistakes and my own bugs: + +<ItemizedList> +<ListItem> + +<Para> + I added a <Literal remap="tt">logging option</Literal>, which logs every actual write +access to the disk in the lowest level - In <Literal remap="tt">low_write</Literal> itself. + +The logging has nothing to do with the current type and the various +other higher level operations of EXT2ED - It is simply a hex dump of +the contents which will be overwritten; Both the original contents +and the new written data. + +In that case, even if the user makes a mistake, the original data +can be retrieved. + +Even If I have a bug somewhere which causes incorrect data to be +written to the disk, the logging option will still log exactly the +original contents at the place were data was incorrectly overwritten. +(This assumes, of-course, that <Literal remap="tt">low-write</Literal> and the <Literal remap="tt">logging +itself</Literal> work correctly. I have done my best to verify that this is +indeed the case). + +The <Literal remap="tt">logging</Literal> option is implemented in the <Literal remap="tt">log_changes</Literal> +function. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>Reading / Writing objects</Title> + +<Para> +Usually <Literal remap="tt">(not always)</Literal>, the current object data is available in the +global variable <Literal remap="tt">type_data</Literal>, which is of the type: + +<ProgramListing> +struct struct_type_data { + long offset_in_block; + + union union_type_data { + char buffer [EXT2_MAX_BLOCK_SIZE]; + struct ext2_acl_header t_ext2_acl_header; + struct ext2_acl_entry t_ext2_acl_entry; + struct ext2_old_group_desc t_ext2_old_group_desc; + struct ext2_group_desc t_ext2_group_desc; + struct ext2_inode t_ext2_inode; + struct ext2_super_block t_ext2_super_block; + struct ext2_dir_entry t_ext2_dir_entry; + } u; +}; +</ProgramListing> + +The above union enables me, in the program, to treat the data as raw data or +as a meaningful filesystem object. +</Para> + +<Para> +The reading and writing, if done to this global variable, are done through +the functions <Literal remap="tt">load_type_data</Literal> and <Literal remap="tt">write_type_data</Literal>, available in +<Literal remap="tt">disk.c</Literal>. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The general commands</Title> + +<Para> +The <Literal remap="tt">general commands</Literal> are handled in the file <Literal remap="tt">general_com.c</Literal>. +</Para> + +<Sect2> +<Title>The help system</Title> + +<Para> +The help command is handled by the function <Literal remap="tt">help</Literal>. The algorithm is as +follows: +</Para> + +<Para> + +<OrderedList> +<ListItem> + +<Para> + Check the command line arguments. If there is an argument, pass +control to the <Literal remap="tt">detailed_help</Literal> function, in order to provide +help on the specific command. +</Para> +</ListItem> +<ListItem> + +<Para> + If general help was requested, display a list of the available +commands at this point. The three levels are displayed in reverse +order - First the commands which are specific to the current type +(If a current type is defined), then the ext2 general commands (If +we decided that the filesystem should be treated like an ext2 +filesystem), then the general commands. +</Para> +</ListItem> +<ListItem> + +<Para> + Display information about EXT2ED - Current version, general +information about the project, etc. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>The setdevice command</Title> + +<Para> +The <Literal remap="tt">setdevice</Literal> commands result in calling the <Literal remap="tt">set_device</Literal> +function. The algorithm is: +</Para> + +<Para> + +<OrderedList> +<ListItem> + +<Para> + Parse the command line argument. If it isn't available report the +error and return. +</Para> +</ListItem> +<ListItem> + +<Para> + Close the current open device, if there is one. +</Para> +</ListItem> +<ListItem> + +<Para> + Open the new device in read-only mode. Update the global variables +<Literal remap="tt">device_name</Literal> and <Literal remap="tt">device_handle</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Disable write access. +</Para> +</ListItem> +<ListItem> + +<Para> + Empty the object memory. +</Para> +</ListItem> +<ListItem> + +<Para> + Unregister the ext2 general commands, using +<Literal remap="tt">free_user_commands</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Unregister the current objects, using <Literal remap="tt">free_struct_descriptors</Literal> +</Para> +</ListItem> +<ListItem> + +<Para> + Call <Literal remap="tt">set_file_system_info</Literal> to auto-detect an ext2 filesystem +and set the basic filesystem values. +</Para> +</ListItem> +<ListItem> + +<Para> + Add the <Literal remap="tt">alternate descriptors</Literal>, supplied by the user. +</Para> +</ListItem> +<ListItem> + +<Para> + Set the device offset to the filesystem start by dispatching +<Literal remap="tt">setoffset 0</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + Show the new available commands by dispatching the <Literal remap="tt">help</Literal> +command. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>Basic maneuvering</Title> + +<Para> +Basic maneuvering is done using the <Literal remap="tt">setoffset</Literal> and the <Literal remap="tt">settype</Literal> +user commands. +</Para> + +<Para> +<Literal remap="tt">set_offset</Literal> accepts some alternative forms of specifying the new +offset. They all ultimately lead to changing the <Literal remap="tt">device_offset</Literal> +global variable and seeking to the new position. <Literal remap="tt">set_offset</Literal> also +calls <Literal remap="tt">load_type_data</Literal> to read a block ahead of the new position into +the <Literal remap="tt">type_data</Literal> global variable. +</Para> + +<Para> +<Literal remap="tt">set_type</Literal> will point the global variable <Literal remap="tt">current_type</Literal> to the +correct entry in the double linked list of the known objects. If the +requested type is <Literal remap="tt">hex</Literal> or <Literal remap="tt">none</Literal>, <Literal remap="tt">current_type</Literal> will be +initialized to <Literal remap="tt">NULL</Literal>. <Literal remap="tt">set_type</Literal> will also dispatch <Literal remap="tt">show</Literal>, +so that the object data will be re-formatted in the new format. +</Para> + +<Para> +When editing an ext2 filesystem, it is not intended that those commands will +be used directly, and it is usually not required. My implementation of the +ext2 layer, on the other hand, uses this lower level commands on countless +occasions. +</Para> + +</Sect2> + +<Sect2> +<Title>The display functions</Title> + +<Para> +The general command version of <Literal remap="tt">show</Literal> is handled by the <Literal remap="tt">show</Literal> +function. This command is overridden by various objects to provide a display +which is better suited to the object. +</Para> + +<Para> +The general show command will format the data in <Literal remap="tt">type_data</Literal> according +to the structure definition of the current type and show it on the <Literal remap="tt">show +pad</Literal>. If there is no current type, the data will be shown as a simple hex +dump; Otherwise, the list of variables, along with their values will be shown. +</Para> + +<Para> +A call to <Literal remap="tt">show_info</Literal> is also made - <Literal remap="tt">show_info</Literal> will provide +<Literal remap="tt">general statistics</Literal> on the <Literal remap="tt">show_window</Literal>, such as the current +block, current type, current offset and current page. +</Para> + +<Para> +The <Literal remap="tt">pgup</Literal> and <Literal remap="tt">pgdn</Literal> general commands just update the +<Literal remap="tt">show_pad_info</Literal> global variable - We just increment +<Literal remap="tt">show_pad_info.line</Literal> with the number of lines in the screen - +<Literal remap="tt">show_pad_info.display_lines</Literal>, which was initialized in +<Literal remap="tt">init_windows</Literal>. +</Para> + +</Sect2> + +<Sect2> +<Title>Changing data</Title> + +<Para> +Data change is done in memory only. An update to the disk if followed by an +explicit <Literal remap="tt">writedata</Literal> command to the disk. The <Literal remap="tt">write_data</Literal> +function simple calls the <Literal remap="tt">write_type_data</Literal> function, outlined earlier. +</Para> + +<Para> +The <Literal remap="tt">set</Literal> command is used for changing the data. +</Para> + +<Para> +If there is no current type, control is passed to the <Literal remap="tt">hex_set</Literal> function, +which treats the data as a block of bytes and uses the +<Literal remap="tt">type_data.offset_in_block</Literal> variable to write the new text or hex string +to the correct place in the block. +</Para> + +<Para> +If a current type is defined, the requested variable is searched in the +current object, and the desired new valued is entered. +</Para> + +<Para> +The <Literal remap="tt">enablewrite</Literal> commands just sets the global variable +<Literal remap="tt">write_access</Literal> to <Literal remap="tt">1</Literal> and re-opens the filesystem in read-write +mode, if possible. +</Para> + +<Para> +If the current type is NULL, a hex-mode is assumed - The <Literal remap="tt">next</Literal> and +<Literal remap="tt">prev</Literal> commands will just update <Literal remap="tt">type_data.offset_in_block</Literal>. +</Para> + +<Para> +If the current type is not NULL, the The <Literal remap="tt">next</Literal> and <Literal remap="tt">prev</Literal> command +are usually overridden anyway. If they are not overridden, it will be assumed +that the user is editing an array of such objects, and they will just pass +to the next / prev element by dispatching to <Literal remap="tt">setoffset</Literal> using the +<Literal remap="tt">setoffset type + / - X</Literal> syntax. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The ext2 general commands</Title> + +<Para> +The ext2 general commands are contained in the <Literal remap="tt">ext2_general_commands</Literal> +global variable (which is of type <Literal remap="tt">struct struct_commands</Literal>). +</Para> + +<Para> +The handling functions are implemented in the source file <Literal remap="tt">ext2_com.c</Literal>. +I will include the entire source code since it is relatively short. +</Para> + +<Sect2> +<Title>The super command</Title> + +<Para> +The super command just "brings the user" to the main superblock and set the +type to ext2_super_block. The implementation is trivial: +</Para> + +<Para> + +<ProgramListing> +void type_ext2___super (char *command_line) + +{ + char buffer [80]; + + super_info.copy_num=0; + sprintf (buffer,"setoffset %ld",file_system_info.super_block_offset);dispatch (buffer); + sprintf (buffer,"settype ext2_super_block");dispatch (buffer); +} +</ProgramListing> + +It involves only setting the <Literal remap="tt">copy_num</Literal> variable to indicate the main +copy, dispatching a <Literal remap="tt">setoffset</Literal> command to reach the superblock, and +dispatching a <Literal remap="tt">settype</Literal> to enable the superblock specific commands. +This last command will also call the <Literal remap="tt">show</Literal> command of the +<Literal remap="tt">ext2_super_block</Literal> type, through dispatching at the general command +<Literal remap="tt">settype</Literal>. +</Para> + +</Sect2> + +<Sect2> +<Title>The group command</Title> + +<Para> +The group command will bring the user to the specified group descriptor in +the main copy of the group descriptors. The type will be set to +<Literal remap="tt">ext2_group_desc</Literal>: + +<ProgramListing> +void type_ext2___group (char *command_line) + +{ + long group_num=0; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + group_num=atol (buffer); + } + + group_info.copy_num=0;group_info.group_num=0; + sprintf (buffer,"setoffset %ld",file_system_info.first_group_desc_offset);dispatch (buffer); + sprintf (buffer,"settype ext2_group_desc");dispatch (buffer); + sprintf (buffer,"entry %ld",group_num);dispatch (buffer); +} +</ProgramListing> + +The implementation is as trivial as the <Literal remap="tt">super</Literal> implementation. Note +the use of the <Literal remap="tt">entry</Literal> command, which is a command of the +<Literal remap="tt">ext2_group_desc</Literal> object, to pass to the correct group descriptor. +</Para> + +</Sect2> + +<Sect2> +<Title>The cd command</Title> + +<Para> +The <Literal remap="tt">cd</Literal> command performs the usual cd function. The path to the global +cd command is a path from <Literal remap="tt">/</Literal>. +</Para> + +<Para> +<Literal remap="tt">This is one of the best examples of the power of the object oriented +design and of the dispatching mechanism. The operation is complicated, yet the +implementation is surprisingly short!</Literal> +</Para> + +<Para> + +<ProgramListing> +void type_ext2___cd (char *command_line) + +{ + char temp [80],buffer [80],*ptr; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n"); + refresh_command_win ();return; + } + ptr=parse_word (ptr,buffer); + + if (buffer [0] != '/') { + wprintw (command_win,"Error - Use a full pathname (begin with '/')\n"); + refresh_command_win ();return; + } + + dispatch ("super");dispatch ("group");dispatch ("inode"); + dispatch ("next");dispatch ("dir"); + if (buffer [1] != 0) { + sprintf (temp,"cd %s",buffer+1);dispatch (temp); + } +} +</ProgramListing> + +</Para> + +<Para> +Note the number of the dispatch calls! +</Para> + +<Para> +<Literal remap="tt">super</Literal> is used to get to the superblock. <Literal remap="tt">group</Literal> to get to the +first group descriptor. <Literal remap="tt">inode</Literal> brings us to the first inode - The bad +blocks inode. A <Literal remap="tt">next</Literal> is command to pass to the root directory inode, +a <Literal remap="tt">dir</Literal> command "enters" the directory, and then we let the <Literal remap="tt">object +specific cd command</Literal> to take us from there (The object is <Literal remap="tt">dir</Literal>, so +that <Literal remap="tt">dispatch</Literal> will call the <Literal remap="tt">cd</Literal> command of the <Literal remap="tt">dir</Literal> type). +Note that a symbolic link following could bring us back to the root directory, +thus the innocent calls above treats nicely such a recursive case! +</Para> + +<Para> +I feel that the above is <Literal remap="tt">intuitive</Literal> - I was expressing myself "in the +language" of the ext2 filesystem - (Go to the inode, etc), and the code was +written exactly in this spirit! +</Para> + +<Para> +I can write more at this point, but I guess I am already a bit carried +away with the self compliments :-) +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The superblock</Title> + +<Para> +This section details the handling of the superblock. +</Para> + +<Sect2> +<Title>The superblock variables</Title> + +<Para> +The superblock object is <Literal remap="tt">ext2_super_block</Literal>. The definition is just +taken from the kernel ext2 main include file - /usr/include/linux/ext2_fs.h. +<FOOTNOTE> + +<Para> +Those lines of source are copyrighted by <Literal remap="tt">Remy Card</Literal> - The author of the +ext2 filesystem, and by <Literal remap="tt">Linus Torvalds</Literal> - The first author of the Linux +operating system. Please cross reference the section Acknowledgments for the +full copyright. +</Para> + +</FOOTNOTE> + + + +<ProgramListing> +struct ext2_super_block { + __u32 s_inodes_count; /* Inodes count */ + __u32 s_blocks_count; /* Blocks count */ + __u32 s_r_blocks_count; /* Reserved blocks count */ + __u32 s_free_blocks_count; /* Free blocks count */ + __u32 s_free_inodes_count; /* Free inodes count */ + __u32 s_first_data_block; /* First Data Block */ + __u32 s_log_block_size; /* Block size */ + __s32 s_log_frag_size; /* Fragment size */ + __u32 s_blocks_per_group; /* # Blocks per group */ + __u32 s_frags_per_group; /* # Fragments per group */ + __u32 s_inodes_per_group; /* # Inodes per group */ + __u32 s_mtime; /* Mount time */ + __u32 s_wtime; /* Write time */ + __u16 s_mnt_count; /* Mount count */ + __s16 s_max_mnt_count; /* Maximal mount count */ + __u16 s_magic; /* Magic signature */ + __u16 s_state; /* File system state */ + __u16 s_errors; /* Behavior when detecting errors */ + __u16 s_pad; + __u32 s_lastcheck; /* time of last check */ + __u32 s_checkinterval; /* max. time between checks */ + __u32 s_creator_os; /* OS */ + __u32 s_rev_level; /* Revision level */ + __u16 s_def_resuid; /* Default uid for reserved blocks */ + __u16 s_def_resgid; /* Default gid for reserved blocks */ + __u32 s_reserved[0]; /* Padding to the end of the block */ + __u32 s_reserved[1]; /* Padding to the end of the block */ + . + . + . + __u32 s_reserved[234]; /* Padding to the end of the block */ +}; +</ProgramListing> + +</Para> + +<Para> +Note that I <Literal remap="tt">expanded</Literal> the array due to my primitive parser +implementation. The various fields are described in the <Literal remap="tt">technical +document</Literal>. +</Para> + +</Sect2> + +<Sect2> +<Title>The superblock commands</Title> + +<Para> +This section explains the commands available in the <Literal remap="tt">ext2_super_block</Literal> +type. They all appear in <Literal remap="tt">super_com.c</Literal> +</Para> + +<Sect3> +<Title>The show command</Title> + +<Para> +The <Literal remap="tt">show</Literal> command is overridden here in order to provide more +information than just the list of variables. A <Literal remap="tt">show</Literal> command will end +up in calling <Literal remap="tt">type_super_block___show</Literal>. +</Para> + +<Para> +The first thing that we do is calling the <Literal remap="tt">general show command</Literal> in +order to display the list of variables. +</Para> + +<Para> +We then add some interpretation to the various lines to make the data +somewhat more intuitive (Expansion of the time variables and the creator +operating system code, for example). +</Para> + +<Para> +We also display the <Literal remap="tt">backup copy number</Literal> of the superblock in the status +window. This copy number is saved in the <Literal remap="tt">super_info</Literal> global variable - +<Literal remap="tt">super_info.copy_num</Literal>. Currently, this is the only variable there ... +but this type of internal variable saving is typical through my +implementation. +</Para> + +</Sect3> + +<Sect3> +<Title>The backup copies handling commands</Title> + +<Para> +The <Literal remap="tt">current copy number</Literal> is available in <Literal remap="tt">super_info.copy_num</Literal>. It +was initialized in the ext2 command <Literal remap="tt">super</Literal>, and is used by the various +superblock routines. +</Para> + +<Para> +The <Literal remap="tt">gocopy</Literal> routine will pass to another copy of the superblock. The +new device offset will be computed with the aid of the variables in the +<Literal remap="tt">file_system_info</Literal> structure. Then the routine will <Literal remap="tt">dispatch</Literal> to +the <Literal remap="tt">setoffset</Literal> and the <Literal remap="tt">show</Literal> routines. +</Para> + +<Para> +The <Literal remap="tt">setactivecopy</Literal> routine will just save the current superblock data +in a temporary variable of type <Literal remap="tt">ext2_super_block</Literal>, and will dispatch +<Literal remap="tt">gocopy 0</Literal> to pass to the main superblock. Then it will place the saved +data in place of the actual data. +</Para> + +<Para> +The above two commands can be used if the main superblock is corrupted. +</Para> + +</Sect3> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The group descriptors</Title> + +<Para> +The group descriptors handling mechanism allows the user to take a tour in +the group descriptors table, stopping at each point, and examining the +relevant inode table, block allocation map or inode allocation map through +dispatching to the relevant objects. +</Para> + +<Para> +Some information about the group descriptors is available in the global +variable <Literal remap="tt">group_info</Literal>, which is of type <Literal remap="tt">struct_group_info</Literal>: +</Para> + +<Para> + +<ProgramListing> +struct struct_group_info { + unsigned long copy_num; + unsigned long group_num; +}; +</ProgramListing> + +</Para> + +<Para> +<Literal remap="tt">group_num</Literal> is the index of the current descriptor in the table. +</Para> + +<Para> +<Literal remap="tt">copy_num</Literal> is the number of the current backup copy. +</Para> + +<Sect2> +<Title>The group descriptor's variables</Title> + +<Para> + +<ProgramListing> +struct ext2_group_desc +{ + __u32 bg_block_bitmap; /* Blocks bitmap block */ + __u32 bg_inode_bitmap; /* Inodes bitmap block */ + __u32 bg_inode_table; /* Inodes table block */ + __u16 bg_free_blocks_count; /* Free blocks count */ + __u16 bg_free_inodes_count; /* Free inodes count */ + __u16 bg_used_dirs_count; /* Directories count */ + __u16 bg_pad; + __u32 bg_reserved[3]; +}; +</ProgramListing> + +</Para> + +<Para> +The first three variables are used to provide the links to the +<Literal remap="tt">blockbitmap, inodebitmap and inode</Literal> objects. +</Para> + +</Sect2> + +<Sect2> +<Title>Movement in the table</Title> + +<Para> +Movement in the group descriptors table is done using the <Literal remap="tt">next, prev and +entry</Literal> commands. Note that the first two commands <Literal remap="tt">override</Literal> the +general commands of the same name. The <Literal remap="tt">next and prev</Literal> command are just +calling the <Literal remap="tt">entry</Literal> function to do the job. I will show <Literal remap="tt">next</Literal>, +for example: +</Para> + +<Para> + +<ProgramListing> +void type_ext2_group_desc___next (char *command_line) + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",group_info.group_num+entry_offset); + dispatch (buffer); +} +</ProgramListing> + +The <Literal remap="tt">entry</Literal> function is also simple - It just calculates the offset +using the information in <Literal remap="tt">group_info</Literal> and in <Literal remap="tt">file_system_info</Literal>, +and uses the usual <Literal remap="tt">setoffset / show</Literal> pair. +</Para> + +</Sect2> + +<Sect2> +<Title>The show command</Title> + +<Para> +As usual, the <Literal remap="tt">show</Literal> command is overridden. The implementation is +similar to the superblock's show implementation - We just call the general +show command, and add some information in the status window - The contents of +the <Literal remap="tt">group_info</Literal> structure. +</Para> + +</Sect2> + +<Sect2> +<Title>Moving between backup copies</Title> + +<Para> +This is done exactly like the superblock case. Please refer to explanation +there. +</Para> + +</Sect2> + +<Sect2> +<Title>Links to the available friends</Title> + +<Para> +From a group descriptor, one typically wants to reach an <Literal remap="tt">inode</Literal>, or +one of the <Literal remap="tt">allocation bitmaps</Literal>. This is done using the <Literal remap="tt">inode, +blockbitmap or inodebitmap</Literal> commands. The implementation is again trivial +- Get the necessary information from the group descriptor, initialize the +structures of the next type, and issue the <Literal remap="tt">setoffset / settype</Literal> pair. +</Para> + +<Para> +For example, here is the implementation of the <Literal remap="tt">blockbitmap</Literal> command: +</Para> + +<Para> + +<ProgramListing> +void type_ext2_group_desc___blockbitmap (char *command_line) + +{ + long block_bitmap_offset; + char buffer [80]; + + block_bitmap_info.entry_num=0; + block_bitmap_info.group_num=group_info.group_num; + + block_bitmap_offset=type_data.u.t_ext2_group_desc.bg_block_bitmap; + sprintf (buffer,"setoffset block %ld",block_bitmap_offset);dispatch (buffer); + sprintf (buffer,"settype block_bitmap");dispatch (buffer); +} +</ProgramListing> + +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The inode table</Title> + +<Para> +The inode handling enables the user to move in the inode table, edit the +various attributes of the inode, and follow to the next stage - A file or a +directory. +</Para> + +<Sect2> +<Title>The inode variables</Title> + +<Para> + +<ProgramListing> +struct ext2_inode { + __u16 i_mode; /* File mode */ + __u16 i_uid; /* Owner Uid */ + __u32 i_size; /* Size in bytes */ + __u32 i_atime; /* Access time */ + __u32 i_ctime; /* Creation time */ + __u32 i_mtime; /* Modification time */ + __u32 i_dtime; /* Deletion Time */ + __u16 i_gid; /* Group Id */ + __u16 i_links_count; /* Links count */ + __u32 i_blocks; /* Blocks count */ + __u32 i_flags; /* File flags */ + union { + struct { + __u32 l_i_reserved1; + } linux1; + struct { + __u32 h_i_translator; + } hurd1; + } osd1; /* OS dependent 1 */ + __u32 i_block[EXT2_N_BLOCKS]; /* Pointers to blocks */ + __u32 i_version; /* File version (for NFS) */ + __u32 i_file_acl; /* File ACL */ + __u32 i_size_high; /* High 32bits of size */ + __u32 i_faddr; /* Fragment address */ + union { + struct { + __u8 l_i_frag; /* Fragment number */ + __u8 l_i_fsize; /* Fragment size */ + __u16 i_pad1; + __u32 l_i_reserved2[2]; + } linux2; + struct { + __u8 h_i_frag; /* Fragment number */ + __u8 h_i_fsize; /* Fragment size */ + __u16 h_i_mode_high; + __u16 h_i_uid_high; + __u16 h_i_gid_high; + __u32 h_i_author; + } hurd2; + } osd2; /* OS dependent 2 */ +}; +</ProgramListing> + +</Para> + +<Para> +The above is the original source code definition. We can see that the inode +supports <Literal remap="tt">Operating systems specific structures</Literal>. In addition to the +expansion of the arrays, I have <Literal remap="tt">"flattened</Literal> the inode to support only +the <Literal remap="tt">Linux</Literal> declaration. It seemed that this one occasion of multiple +variable aliases didn't justify the complication of generally supporting +aliases. In any case, the above system specific variables are not used +internally by EXT2ED, and the user is free to change the definition in +<Literal remap="tt">ext2.descriptors</Literal> to accommodate for his needs. +</Para> + +</Sect2> + +<Sect2> +<Title>The handling functions</Title> + +<Para> +The user interface to <Literal remap="tt">movement</Literal> is the usual <Literal remap="tt">next / prev / +entry</Literal> interface. There is really nothing special in those functions - The +size of the inode is fixed, the total number of inodes is known from the +superblock information, and the current entry can be figured up from the +device offset and the inode table start offset, which is known from the +corresponding group descriptor. Those functions are a bit older then some +other implementations of <Literal remap="tt">next</Literal> and <Literal remap="tt">prev</Literal>, and they do not save +information in a special structure. Rather, they recompute it when +necessary. +</Para> + +<Para> +The <Literal remap="tt">show</Literal> command is overridden here, and provides a lot of additional +information about the inode - Its type, interpretation of the permissions, +special ext2 attributes (Immutable file, for example), and a lot more. +Again, the <Literal remap="tt">general show</Literal> is called first, and then the additional +information is written. +</Para> + +</Sect2> + +<Sect2> +<Title>Accessing files and directories</Title> + +<Para> +From the inode, a <Literal remap="tt">file</Literal> or a <Literal remap="tt">directory</Literal> can typically be reached. +In order to treat a file, for example, its inode needs to be constantly +accessed. To satisfy that need, when editing a file or a directory, the +inode is still saved in memory - <Literal remap="tt">type_data</Literal> is not overwritten. +Rather, the following takes place: + +<ItemizedList> +<ListItem> + +<Para> + An internal global structure which is used by the types <Literal remap="tt">file</Literal> +and <Literal remap="tt">dir</Literal> handling functions is initialized by calling the +appropriate function. +</Para> +</ListItem> +<ListItem> + +<Para> + The type is changed accordingly. +</Para> +</ListItem> + +</ItemizedList> + +The result is that a <Literal remap="tt">settype ext2_inode</Literal> is the only action necessary +to return to the inode - We actually never left it. +</Para> + +<Para> +Follows the implementation of the inode's <Literal remap="tt">file</Literal> command: +</Para> + +<Para> + +<ProgramListing> +void type_ext2_inode___file (char *command_line) + +{ + char buffer [80]; + + if (!S_ISREG (type_data.u.t_ext2_inode.i_mode)) { + wprintw (command_win,"Error - Inode type is not file\n"); + refresh_command_win (); return; + } + + if (!init_file_info ()) { + wprintw (command_win,"Error - Unable to show file\n"); + refresh_command_win ();return; + } + + sprintf (buffer,"settype file");dispatch (buffer); +} +</ProgramListing> + +</Para> + +<Para> +As we can see - We just call <Literal remap="tt">init_file_info</Literal> to get the necessary +information from the inode, and set the type to <Literal remap="tt">file</Literal>. The next call +to <Literal remap="tt">show</Literal>, will dispatch to the <Literal remap="tt">file's show</Literal> implementation. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Viewing a file</Title> + +<Para> +There isn't an ext2 kernel structure which corresponds to a file - A file is +just a series of blocks which are determined by its inode. As explained in +the last section, the inode is never actually left - The type is changed to +<Literal remap="tt">file</Literal> - A type which contains no variables, and a special structure is +initialized: +</Para> + +<Para> + +<ProgramListing> +struct struct_file_info { + + struct ext2_inodes *inode_ptr; + + long inode_offset; + long global_block_num,global_block_offset; + long block_num,blocks_count; + long file_offset,file_length; + long level; + unsigned char buffer [EXT2_MAX_BLOCK_SIZE]; + long offset_in_block; + + int display; + /* The following is used if the file is a directory */ + + long dir_entry_num,dir_entries_count; + long dir_entry_offset; +}; +</ProgramListing> + +</Para> + +<Para> +The <Literal remap="tt">inode_ptr</Literal> will just point to the inode in <Literal remap="tt">type_data</Literal>, which +is not overwritten while the user is editing the file, as the +<Literal remap="tt">setoffset</Literal> command is not internally used. The <Literal remap="tt">buffer</Literal> +will contain the current viewed block of the file. The other variables +contain information about the current place in the file. For example, +<Literal remap="tt">global_block_num</Literal> just contains the current block number. +</Para> + +<Para> +The general idea is that the above data structure will provide the file +handling functions all the accurate information which is needed to accomplish +their task. +</Para> + +<Para> +The global structure of the above type, <Literal remap="tt">file_info</Literal>, is initialized by +<Literal remap="tt">init_file_info</Literal> in <Literal remap="tt">file_com.c</Literal>, which is called by the +<Literal remap="tt">type_ext2_inode___file</Literal> function when the user requests to watch the +file. <Literal remap="tt">It is updated as necessary to provide accurate information as long as +the file is edited.</Literal> +</Para> + +<Sect2> +<Title>Returning to the file's inode</Title> + +<Para> +Concerning the method I used to handle files, the above task is trivial: + +<ProgramListing> +void type_file___inode (char *command_line) + +{ + dispatch ("settype ext2_inode"); +} +</ProgramListing> + +</Para> + +</Sect2> + +<Sect2> +<Title>File movement</Title> + +<Para> +EXT2ED keeps track of the current position in the file. Movement inside the +current block is done using <Literal remap="tt">next, prev and offset</Literal> - They just change +<Literal remap="tt">file_info.offset_in_block</Literal>. +</Para> + +<Para> +Movement between blocks is done using <Literal remap="tt">nextblock, prevblock and block</Literal>. +To accomplish this, the direct blocks, indirect blocks, etc, need to be +traced. This is done by <Literal remap="tt">file_block_to_global_block</Literal>, which accepts a +file's internal block number, and converts it to the actual filesystem block +number. +</Para> + +<Para> + +<ProgramListing> +long file_block_to_global_block (long file_block,struct struct_file_info *file_info_ptr) + +{ + long last_direct,last_indirect,last_dindirect; + long f_indirect,s_indirect; + + last_direct=EXT2_NDIR_BLOCKS-1; + last_indirect=last_direct+file_system_info.block_size/4; + last_dindirect=last_indirect+(file_system_info.block_size/4) \ + *(file_system_info.block_size/4); + + if (file_block <= last_direct) { + file_info_ptr->level=0; + return (file_info_ptr->inode_ptr->i_block [file_block]); + } + + if (file_block <= last_indirect) { + file_info_ptr->level=1; + file_block=file_block-last_direct-1; + return (return_indirect (file_info_ptr->inode_ptr-> \ + i_block [EXT2_IND_BLOCK],file_block)); + } + + if (file_block <= last_dindirect) { + file_info_ptr->level=2; + file_block=file_block-last_indirect-1; + return (return_dindirect (file_info_ptr->inode_ptr-> \ + i_block [EXT2_DIND_BLOCK],file_block)); + } + + file_info_ptr->level=3; + file_block=file_block-last_dindirect-1; + return (return_tindirect (file_info_ptr->inode_ptr-> \ + i_block [EXT2_TIND_BLOCK],file_block)); +} +</ProgramListing> + +<Literal remap="tt">last_direct, last_indirect, etc</Literal>, contain the last internal block number +which is accessed by this method - If the requested block is smaller then +<Literal remap="tt">last_direct</Literal>, for example, it is a direct block. +</Para> + +<Para> +If the block is a direct block, its number is just taken from the inode. +A non-direct block is handled by <Literal remap="tt">return_indirect, return_dindirect and +return_tindirect</Literal>, which correspond to indirect, double-indirect and +triple-indirect. Each of the above functions is constructed using the lower +level functions. For example, <Literal remap="tt">return_dindirect</Literal> is constructed as +follows: +</Para> + +<Para> + +<ProgramListing> +long return_dindirect (long table_block,long block_num) + +{ + long f_indirect; + + f_indirect=block_num/(file_system_info.block_size/4); + f_indirect=return_indirect (table_block,f_indirect); + return (return_indirect (f_indirect,block_num%(file_system_info.block_size/4))); +} +</ProgramListing> + +</Para> + +</Sect2> + +<Sect2> +<Title>Object memory</Title> + +<Para> +The <Literal remap="tt">remember</Literal> command is overridden here and in the <Literal remap="tt">dir</Literal> type - +We just remember the inode of the file. It is just simpler to implement, and +doesn't seem like a big limitation. +</Para> + +</Sect2> + +<Sect2> +<Title>Changing data</Title> + +<Para> +The <Literal remap="tt">set</Literal> command is overridden, and provides the same functionality +like the usage of the <Literal remap="tt">general set</Literal> command with no type declared. The +<Literal remap="tt">writedata</Literal> is overridden so that we'll write the edited block +(file_info.buffer) and not <Literal remap="tt">type_data</Literal> (Which contains the inode). +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Directories</Title> + +<Para> +A directory is just a file which is formatted according to a special format. +As such, EXT2ED handles directories and files quite alike. Specifically, the +same variable of type <Literal remap="tt">struct_file_info</Literal> which is used in the +<Literal remap="tt">file</Literal>, is used here. +</Para> + +<Para> +The <Literal remap="tt">dir</Literal> type uses all the variables in the above structure, as +opposed to the <Literal remap="tt">file</Literal> type, which didn't use the last ones. +</Para> + +<Sect2> +<Title>The search_dir_entries function</Title> + +<Para> +The entire situation is similar to that which was described in the +<Literal remap="tt">file</Literal> type, with one main change: +</Para> + +<Para> +The main function in <Literal remap="tt">dir_com.c</Literal> is <Literal remap="tt">search_dir_entries</Literal>. This +function will <Literal remap="tt">"run"</Literal> on the entire entries in the directory, and will +call a client's function each time. The client's function is supplied as an +argument, and will check the current entry for a match, based on its own +criterion. It will then signal <Literal remap="tt">search_dir_entries</Literal> whether to +<Literal remap="tt">ABORT</Literal> the search, whether it <Literal remap="tt">FOUND</Literal> the entry it was looking +for, or that the entry is still not found, and we should <Literal remap="tt">CONTINUE</Literal> +searching. Follows the declaration: + +<ProgramListing> +struct struct_file_info search_dir_entries \ + (int (*action) (struct struct_file_info *info),int *status) + +/* + This routine runs on all directory entries in the current directory. + For each entry, action is called. The return code of action is one of + the following: + + ABORT - Current dir entry is returned. + CONTINUE - Continue searching. + FOUND - Current dir entry is returned. + + If the last entry is reached, it is returned, along with an ABORT status. + + status is updated to the returned code of action. +*/ +</ProgramListing> + +</Para> + +<Para> +With the above tool in hand, many operations are simple to perform - Here is +the way I counted the entries in the current directory: +</Para> + +<Para> + +<ProgramListing> +long count_dir_entries (void) + +{ + int status; + + return (search_dir_entries (&action_count,&status).dir_entry_num); +} + +int action_count (struct struct_file_info *info) + +{ + return (CONTINUE); +} +</ProgramListing> + +It will just <Literal remap="tt">CONTINUE</Literal> until the last entry. The returned structure +(of type <Literal remap="tt">struct_file_info</Literal>) will have its number in the +<Literal remap="tt">dir_entry_num</Literal> field, and this is exactly the required number! +</Para> + +</Sect2> + +<Sect2> +<Title>The cd command</Title> + +<Para> +The <Literal remap="tt">cd</Literal> command accepts a relative path, and moves there ... +The implementation is of-course a bit more complicated: + +<OrderedList> +<ListItem> + +<Para> + The path is checked that it is not an absolute path (from <Literal remap="tt">/</Literal>). +If it is, we let the <Literal remap="tt">general cd</Literal> to do the job by calling +directly <Literal remap="tt">type_ext2___cd</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + The path is divided into the nearest path and the rest of the path. +For example, cd 1/2/3/4 is divided into <Literal remap="tt">1</Literal> and into +<Literal remap="tt">2/3/4</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + It is the first part of the path that we need to search for in the +current directory. We search for it using <Literal remap="tt">search_dir_entries</Literal>, +which accepts the <Literal remap="tt">action_name</Literal> function as the user defined +function. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">search_dir_entries</Literal> will scan the entire entries and will call +our <Literal remap="tt">action_name</Literal> function for each entry. In +<Literal remap="tt">action_name</Literal>, the required name will be checked against the +name of the current entry, and <Literal remap="tt">FOUND</Literal> will be returned when a +match occurs. +</Para> +</ListItem> +<ListItem> + +<Para> + If the required entry is found, we dispatch a <Literal remap="tt">remember</Literal> +command to insert the current <Literal remap="tt">inode</Literal> into the object memory. +This is required to easily support <Literal remap="tt">symbolic links</Literal> - If we +find later that the inode pointed by the entry is actually a +symbolic link, we'll need to return to this point, and the above +inode doesn't have (and can't have, because of <Literal remap="tt">hard links</Literal>) the +information necessary to "move back". +</Para> +</ListItem> +<ListItem> + +<Para> + We then dispatch a <Literal remap="tt">followinode</Literal> command to reach the inode +pointed by the required entry. This command will automatically +change the type to <Literal remap="tt">ext2_inode</Literal> - We are now at an inode, and +all the inode commands are available. +</Para> +</ListItem> +<ListItem> + +<Para> + We check the inode's type to see if it is a directory. If it is, we +dispatch a <Literal remap="tt">dir</Literal> command to "enter the directory", and +recursively call ourself (The type is <Literal remap="tt">dir</Literal> again) by +dispatching a <Literal remap="tt">cd</Literal> command, with the rest of the path as an +argument. +</Para> +</ListItem> +<ListItem> + +<Para> + If the inode's type is a symbolic link (only fast symbolic link were +meanwhile implemented. I guess this is typically the case.), we note +the path it is pointing at, the saved inode is recalled, we dispatch +<Literal remap="tt">dir</Literal> to get back to the original directory, and we call +ourself again with the <Literal remap="tt">link path/rest of the path</Literal> argument. +</Para> +</ListItem> +<ListItem> + +<Para> + In any other case, we just stop at the resulting inode. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The block and inode allocation bitmaps</Title> + +<Para> +The block allocation bitmap is reached by the corresponding group descriptor. +The group descriptor handling functions will save the necessary information +into a structure of the <Literal remap="tt">struct_block_bitmap_info</Literal> type: +</Para> + +<Para> + +<ProgramListing> +struct struct_block_bitmap_info { + unsigned long entry_num; + unsigned long group_num; +}; +</ProgramListing> + +</Para> + +<Para> +The <Literal remap="tt">show</Literal> command is overridden, and will show the block as a series of +bits, each bit corresponding to a block. The main variable is the +<Literal remap="tt">entry_num</Literal> variable, declared above, which is just the current block +number in this block group. The current entry is highlighted, and the +<Literal remap="tt">next, prev and entry</Literal> commands just change the above variable. +</Para> + +<Para> +The <Literal remap="tt">allocate and deallocate</Literal> change the specified bits. Nothing +special about them - They just contain code which converts between bit and +byte locations. +</Para> + +<Para> +The <Literal remap="tt">inode allocation bitmap</Literal> is treated in much the same fashion, with +the same commands available. +</Para> + +</Sect1> + +<Sect1> +<Title>Filesystem size limitation</Title> + +<Para> +While an ext2 filesystem has a size limit of <Literal remap="tt">4 TB</Literal>, EXT2ED currently +<Literal remap="tt">can't</Literal> handle filesystems which are <Literal remap="tt">bigger than 2 GB</Literal>. +</Para> + +<Para> +This limitation results from my usage of <Literal remap="tt">32 bit long variables</Literal> and +of the <Literal remap="tt">fseek</Literal> filesystem call, which can't seek up to 4 TB. +</Para> + +<Para> +By looking in the <Literal remap="tt">ext2 library</Literal> source code by <Literal remap="tt">Theodore Ts'o</Literal>, +I discovered the <Literal remap="tt">llseek</Literal> system call which can seek to a +<Literal remap="tt">64 bit unsigned long long</Literal> offset. Correcting the situation is not +difficult in concept - I need to change long into unsigned long long where +appropriate and modify <Literal remap="tt">disk.c</Literal> to use the llseek system call. +</Para> + +<Para> +However, fixing the above limitation involves making changes in many places +in the code and will obviously make the entire code less stable. For that +reason, I chose to release EXT2ED as it is now and to postpone the above fix +to the next release. +</Para> + +</Sect1> + +<Sect1> +<Title>Conclusion</Title> + +<Para> +Had I known in advance the structure of the ext2 filesystem, I feel that +the resulting design would have been quite different from the presented +design above. +</Para> + +<Para> +EXT2ED has now two levels of abstraction - A <Literal remap="tt">general</Literal> filesystem, and an +<Literal remap="tt">ext2</Literal> filesystem, and the surface is more or less prepared for additions +of other filesystems. Had I approached the design in the "engineering" way, +I guess that the first level above would not have existed. +</Para> + +</Sect1> + +<Sect1> +<Title>Copyright</Title> + +<Para> +EXT2ED is Copyright (C) 1995 Gadi Oxman. +</Para> + +<Para> +EXT2ED is hereby placed under the GPL - Gnu Public License. You are free and +welcome to copy, view and modify the sources. My only wish is that my +copyright presented above will be left and that a list of the bug fixes, +added features, etc, will be provided. +</Para> + +<Para> +The entire EXT2ED project is based, of-course, on the kernel sources. The +<Literal remap="tt">ext2.descriptors</Literal> distributed with EXT2ED is a slightly modified +version of the main ext2 include file, /usr/include/linux/ext2_fs.h. Follows +the original copyright: +</Para> + +<Para> + +<ProgramListing> +/* + * linux/include/linux/ext2_fs.h + * + * Copyright (C) 1992, 1993, 1994, 1995 + * Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * from + * + * linux/include/linux/minix_fs.h + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +</ProgramListing> + +</Para> + +</Sect1> + +<Sect1> +<Title>Acknowledgments</Title> + +<Para> +EXT2ED was constructed as a student project in the software +laboratory of the faculty of electrical-engineering in the +<Literal remap="tt">Technion - Israel's institute of technology</Literal>. +</Para> + +<Para> +At first, I would like to thank <Literal remap="tt">Avner Lottem</Literal> and <Literal remap="tt">Doctor Ilana +David</Literal> for their interest and assistance in this project. +</Para> + +<Para> +I would also like to thank the following people, who were involved in the +design and implementation of the ext2 filesystem kernel code and support +utilities: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">Remy Card</Literal> + +Who designed, implemented and maintains the ext2 filesystem kernel +code, and some of the ext2 utilities. <Literal remap="tt">Remy Card</Literal> is also the +author of several helpful slides concerning the ext2 filesystem. +Specifically, he is the author of <Literal remap="tt">File Management in the Linux +Kernel</Literal> and of <Literal remap="tt">The Second Extended File System - Current +State, Future Development</Literal>. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Wayne Davison</Literal> + +Who designed the ext2 filesystem. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Stephen Tweedie</Literal> + +Who helped designing the ext2 filesystem kernel code and wrote the +slides <Literal remap="tt">Optimizations in File Systems</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Theodore Ts'o</Literal> + +Who is the author of several ext2 utilities and of the ext2 library +<Literal remap="tt">libext2fs</Literal> (which I didn't use, simply because I didn't know +it exists when I started to work on my project). +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +Lastly, I would like to thank, of-course, <Literal remap="tt">Linus Torvalds</Literal> and the +<Literal remap="tt">Linux community</Literal> for providing all of us with such a great operating +system. +</Para> + +<Para> +Please contact me in a case of bug report, suggestions, or just about +anything concerning EXT2ED. +</Para> + +<Para> +Enjoy, +</Para> + +<Para> +Gadi Oxman <tgud@tochnapc2.technion.ac.il> +</Para> + +<Para> +Haifa, August 95 +</Para> + +</Sect1> + +</Article> diff --git a/ext2ed/doc/ext2fs-overview.sgml b/ext2ed/doc/ext2fs-overview.sgml new file mode 100644 index 0000000..0d54f07 --- /dev/null +++ b/ext2ed/doc/ext2fs-overview.sgml @@ -0,0 +1,1569 @@ +<!DOCTYPE Article PUBLIC "-//Davenport//DTD DocBook V3.0//EN"> + +<Article> + +<ArtHeader> + +<Title>The extended-2 filesystem overview</Title> +<AUTHOR +> +<FirstName>Gadi Oxman, tgud@tochnapc2.technion.ac.il</FirstName> +</AUTHOR +> +<PubDate>v0.1, August 3 1995</PubDate> + +</ArtHeader> + +<Sect1> +<Title>Preface</Title> + +<Para> +This document attempts to present an overview of the internal structure of +the ext2 filesystem. It was written in summer 95, while I was working on the +<Literal remap="tt">ext2 filesystem editor project (EXT2ED)</Literal>. +</Para> + +<Para> +In the process of constructing EXT2ED, I acquired knowledge of the various +design aspects of the the ext2 filesystem. This document is a result of an +effort to document this knowledge. +</Para> + +<Para> +This is only the initial version of this document. It is obviously neither +error-prone nor complete, but at least it provides a starting point. +</Para> + +<Para> +In the process of learning the subject, I have used the following sources / +tools: + +<ItemizedList> +<ListItem> + +<Para> + Experimenting with EXT2ED, as it was developed. +</Para> +</ListItem> +<ListItem> + +<Para> + The ext2 kernel sources: + +<ItemizedList> +<ListItem> + +<Para> + The main ext2 include file, +<FILENAME>/usr/include/linux/ext2_fs.h</FILENAME> +</Para> +</ListItem> +<ListItem> + +<Para> + The contents of the directory <FILENAME>/usr/src/linux/fs/ext2</FILENAME>. +</Para> +</ListItem> +<ListItem> + +<Para> + The VFS layer sources (only a bit). +</Para> +</ListItem> + +</ItemizedList> + +</Para> +</ListItem> +<ListItem> + +<Para> + The slides: The Second Extended File System, Current State, Future +Development, by <personname><firstname>Remy</firstname> <surname>Card</surname></personname>. +</Para> +</ListItem> +<ListItem> + +<Para> + The slides: Optimisation in File Systems, by <personname><firstname>Stephen</firstname> <surname>Tweedie</surname></personname>. +</Para> +</ListItem> +<ListItem> + +<Para> + The various ext2 utilities. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect1> + +<Sect1> +<Title>Introduction</Title> + +<Para> +The <Literal remap="tt">Second Extended File System (Ext2fs)</Literal> is very popular among Linux +users. If you use Linux, chances are that you are using the ext2 filesystem. +</Para> + +<Para> +Ext2fs was designed by <personname><firstname>Remy</firstname> <surname>Card</surname></personname> and <personname><firstname>Wayne</firstname> <surname>Davison</surname></personname>. It was +implemented by <personname><firstname>Remy</firstname> <surname>Card</surname></personname> and was further enhanced by <personname><firstname>Stephen</firstname> +<surname>Tweedie</surname></personname> and <personname><firstname>Theodore</firstname> <surname>Ts'o</surname></personname>. +</Para> + +<Para> +The ext2 filesystem is still under development. I will document here +version 0.5a, which is distributed along with Linux 1.2.x. At this time of +writing, the most recent version of Linux is 1.3.13, and the version of the +ext2 kernel source is 0.5b. A lot of fancy enhancements are planned for the +ext2 filesystem in Linux 1.3, so stay tuned. +</Para> + +</Sect1> + +<Sect1> +<Title>A filesystem - Why do we need it?</Title> + +<Para> +I thought that before we dive into the various small details, I'll reserve a +few minutes for the discussion of filesystems from a general point of view. +</Para> + +<Para> +A <Literal remap="tt">filesystem</Literal> consists of two word - <Literal remap="tt">file</Literal> and <Literal remap="tt">system</Literal>. +</Para> + +<Para> +Everyone knows the meaning of the word <Literal remap="tt">file</Literal> - A bunch of data put +somewhere. where? This is an important question. I, for example, usually +throw almost everything into a single drawer, and have difficulties finding +something later. +</Para> + +<Para> +This is where the <Literal remap="tt">system</Literal> comes in - Instead of just throwing the data +to the device, we generalize and construct a <Literal remap="tt">system</Literal> which will +virtualize for us a nice and ordered structure in which we could arrange our +data in much the same way as books are arranged in a library. The purpose of +the filesystem, as I understand it, is to make it easy for us to update and +maintain our data. +</Para> + +<Para> +Normally, by <Literal remap="tt">mounting</Literal> filesystems, we just use the nice and logical +virtual structure. However, the disk knows nothing about that - The device +driver views the disk as a large continuous paper in which we can write notes +wherever we wish. It is the task of the filesystem management code to store +bookkeeping information which will serve the kernel for showing us the nice +and ordered virtual structure. +</Para> + +<Para> +In this document, we consider one particular administrative structure - The +Second Extended Filesystem. +</Para> + +</Sect1> + +<Sect1> +<Title>The Linux VFS layer</Title> + +<Para> +When Linux was first developed, it supported only one filesystem - The +<Literal remap="tt">Minix</Literal> filesystem. Today, Linux has the ability to support several +filesystems concurrently. This was done by the introduction of another layer +between the kernel and the filesystem code - The Virtual File System (VFS). +</Para> + +<Para> +The kernel "speaks" with the VFS layer. The VFS layer passes the kernel's +request to the proper filesystem management code. I haven't learned much of +the VFS layer as I didn't need it for the construction of EXT2ED so that I +can't elaborate on it. Just be aware that it exists. +</Para> + +</Sect1> + +<Sect1> +<Title>About blocks and block groups</Title> + +<Para> +In order to ease management, the ext2 filesystem logically divides the disk +into small units called <Literal remap="tt">blocks</Literal>. A block is the smallest unit which +can be allocated. Each block in the filesystem can be <Literal remap="tt">allocated</Literal> or +<Literal remap="tt">free</Literal>. +<FOOTNOTE> + +<Para> +The Ext2fs source code refers to the concept of <Literal remap="tt">fragments</Literal>, which I +believe are supposed to be sub-block allocations. As far as I know, +fragments are currently unsupported in Ext2fs. +</Para> + +</FOOTNOTE> + +The block size can be selected to be 1024, 2048 or 4096 bytes when creating +the filesystem. +</Para> + +<Para> +Ext2fs groups together a fixed number of sequential blocks into a <Literal remap="tt">group +block</Literal>. The resulting situation is that the filesystem is managed as a +series of group blocks. This is done in order to keep related information +physically close on the disk and to ease the management task. As a result, +much of the filesystem management reduces to management of a single blocks +group. +</Para> + +</Sect1> + +<Sect1> +<Title>The view of inodes from the point of view of a blocks group</Title> + +<Para> +Each file in the filesystem is reserved a special <Literal remap="tt">inode</Literal>. I don't want +to explain inodes now. Rather, I would like to treat it as another resource, +much like a <Literal remap="tt">block</Literal> - Each blocks group contains a limited number of +inode, while any specific inode can be <Literal remap="tt">allocated</Literal> or +<Literal remap="tt">unallocated</Literal>. +</Para> + +</Sect1> + +<Sect1> +<Title>The group descriptors</Title> + +<Para> +Each blocks group is accompanied by a <Literal remap="tt">group descriptor</Literal>. The group +descriptor summarizes some necessary information about the specific group +block. Follows the definition of the group descriptor, as defined in +<FILENAME>/usr/include/linux/ext2_fs.h</FILENAME>: +</Para> + +<Para> + +<ProgramListing> +struct ext2_group_desc +{ + __u32 bg_block_bitmap; /* Blocks bitmap block */ + __u32 bg_inode_bitmap; /* Inodes bitmap block */ + __u32 bg_inode_table; /* Inodes table block */ + __u16 bg_free_blocks_count; /* Free blocks count */ + __u16 bg_free_inodes_count; /* Free inodes count */ + __u16 bg_used_dirs_count; /* Directories count */ + __u16 bg_pad; + __u32 bg_reserved[3]; +}; +</ProgramListing> + +</Para> + +<Para> +The last three variables: <Literal remap="tt">bg_free_blocks_count, bg_free_inodes_count and bg_used_dirs_count</Literal> provide statistics about the use of the three +resources in a blocks group - The <Literal remap="tt">blocks</Literal>, the <Literal remap="tt">inodes</Literal> and the +<Literal remap="tt">directories</Literal>. I believe that they are used by the kernel for balancing +the load between the various blocks groups. +</Para> + +<Para> +<Literal remap="tt">bg_block_bitmap</Literal> contains the block number of the <Literal remap="tt">block allocation +bitmap block</Literal>. This is used to allocate / deallocate each block in the +specific blocks group. +</Para> + +<Para> +<Literal remap="tt">bg_inode_bitmap</Literal> is fully analogous to the previous variable - It +contains the block number of the <Literal remap="tt">inode allocation bitmap block</Literal>, which +is used to allocate / deallocate each specific inode in the filesystem. +</Para> + +<Para> +<Literal remap="tt">bg_inode_table</Literal> contains the block number of the start of the +<Literal remap="tt">inode table of the current blocks group</Literal>. The <Literal remap="tt">inode table</Literal> is +just the actual inodes which are reserved for the current block. +</Para> + +<Para> +The block bitmap block, inode bitmap block and the inode table are created +when the filesystem is created. +</Para> + +<Para> +The group descriptors are placed one after the other. Together they make the +<Literal remap="tt">group descriptors table</Literal>. +</Para> + +<Para> +Each blocks group contains the entire table of group descriptors in its +second block, right after the superblock. However, only the first copy (in +group 0) is actually used by the kernel. The other copies are there for +backup purposes and can be of use if the main copy gets corrupted. +</Para> + +</Sect1> + +<Sect1> +<Title>The block bitmap allocation block</Title> + +<Para> +Each blocks group contains one special block which is actually a map of the +entire blocks in the group, with respect to their allocation status. Each +<Literal remap="tt">bit</Literal> in the block bitmap indicated whether a specific block in the +group is used or free. +</Para> + +<Para> +The format is actually quite simple - Just view the entire block as a series +of bits. For example, +</Para> + +<Para> +Suppose the block size is 1024 bytes. As such, there is a place for +1024*8=8192 blocks in a group block. This number is one of the fields in the +filesystem's <Literal remap="tt">superblock</Literal>, which will be explained later. +</Para> + +<Para> + +<ItemizedList> +<ListItem> + +<Para> + Block 0 in the blocks group is managed by bit 0 of byte 0 in the bitmap +block. +</Para> +</ListItem> +<ListItem> + +<Para> + Block 7 in the blocks group is managed by bit 7 of byte 0 in the bitmap +block. +</Para> +</ListItem> +<ListItem> + +<Para> + Block 8 in the blocks group is managed by bit 0 of byte 1 in the bitmap +block. +</Para> +</ListItem> +<ListItem> + +<Para> + Block 8191 in the blocks group is managed by bit 7 of byte 1023 in the +bitmap block. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +A value of "<Literal remap="tt">1</Literal>" in the appropriate bit signals that the block is +allocated, while a value of "<Literal remap="tt">0</Literal>" signals that the block is +unallocated. +</Para> + +<Para> +You will probably notice that typically, all the bits in a byte contain the +same value, making the byte's value <Literal remap="tt">0</Literal> or <Literal remap="tt">0ffh</Literal>. This is done by +the kernel on purpose in order to group related data in physically close +blocks, since the physical device is usually optimized to handle such a close +relationship. +</Para> + +</Sect1> + +<Sect1> +<Title>The inode allocation bitmap</Title> + +<Para> +The format of the inode allocation bitmap block is exactly like the format of +the block allocation bitmap block. The explanation above is valid here, with +the work <Literal remap="tt">block</Literal> replaced by <Literal remap="tt">inode</Literal>. Typically, there are much less +inodes then blocks in a blocks group and thus only part of the inode bitmap +block is used. The number of inodes in a blocks group is another variable +which is listed in the <Literal remap="tt">superblock</Literal>. +</Para> + +</Sect1> + +<Sect1> +<Title>On the inode and the inode tables</Title> + +<Para> +An inode is a main resource in the ext2 filesystem. It is used for various +purposes, but the main two are: + +<ItemizedList> +<ListItem> + +<Para> + Support of files +</Para> +</ListItem> +<ListItem> + +<Para> + Support of directories +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +Each file, for example, will allocate one inode from the filesystem +resources. +</Para> + +<Para> +An ext2 filesystem has a total number of available inodes which is determined +while creating the filesystem. When all the inodes are used, for example, you +will not be able to create an additional file even though there will still +be free blocks on the filesystem. +</Para> + +<Para> +Each inode takes up 128 bytes in the filesystem. By default, <Literal remap="tt">mke2fs</Literal> +reserves an inode for each 4096 bytes of the filesystem space. +</Para> + +<Para> +The inodes are placed in several tables, each of which contains the same +number of inodes and is placed at a different blocks group. The goal is to +place inodes and their related files in the same blocks group because of +locality arguments. +</Para> + +<Para> +The number of inodes in a blocks group is available in the superblock variable +<Literal remap="tt">s_inodes_per_group</Literal>. For example, if there are 2000 inodes per group, +group 0 will contain the inodes 1-2000, group 2 will contain the inodes +2001-4000, and so on. +</Para> + +<Para> +Each inode table is accessed from the group descriptor of the specific +blocks group which contains the table. +</Para> + +<Para> +Follows the structure of an inode in Ext2fs: +</Para> + +<Para> + +<ProgramListing> +struct ext2_inode { + __u16 i_mode; /* File mode */ + __u16 i_uid; /* Owner Uid */ + __u32 i_size; /* Size in bytes */ + __u32 i_atime; /* Access time */ + __u32 i_ctime; /* Creation time */ + __u32 i_mtime; /* Modification time */ + __u32 i_dtime; /* Deletion Time */ + __u16 i_gid; /* Group Id */ + __u16 i_links_count; /* Links count */ + __u32 i_blocks; /* Blocks count */ + __u32 i_flags; /* File flags */ + union { + struct { + __u32 l_i_reserved1; + } linux1; + struct { + __u32 h_i_translator; + } hurd1; + struct { + __u32 m_i_reserved1; + } masix1; + } osd1; /* OS dependent 1 */ + __u32 i_block[EXT2_N_BLOCKS];/* Pointers to blocks */ + __u32 i_version; /* File version (for NFS) */ + __u32 i_file_acl; /* File ACL */ + __u32 i_size_high; /* High 32bits of size */ + __u32 i_faddr; /* Fragment address */ + union { + struct { + __u8 l_i_frag; /* Fragment number */ + __u8 l_i_fsize; /* Fragment size */ + __u16 i_pad1; + __u32 l_i_reserved2[2]; + } linux2; + struct { + __u8 h_i_frag; /* Fragment number */ + __u8 h_i_fsize; /* Fragment size */ + __u16 h_i_mode_high; + __u16 h_i_uid_high; + __u16 h_i_gid_high; + __u32 h_i_author; + } hurd2; + struct { + __u8 m_i_frag; /* Fragment number */ + __u8 m_i_fsize; /* Fragment size */ + __u16 m_pad1; + __u32 m_i_reserved2[2]; + } masix2; + } osd2; /* OS dependent 2 */ +}; +</ProgramListing> + +</Para> + +<Sect2> +<Title>The allocated blocks</Title> + +<Para> +The basic functionality of an inode is to group together a series of +allocated blocks. There is no limitation on the allocated blocks - Each +block can be allocated to each inode. Nevertheless, block allocation will +usually be done in series to take advantage of the locality principle. +</Para> + +<Para> +The inode is not always used in that way. I will now explain the allocation +of blocks, assuming that the current inode type indeed refers to a list of +allocated blocks. +</Para> + +<Para> +It was found experimentally that many of the files in the filesystem are +actually quite small. To take advantage of this effect, the kernel provides +storage of up to 12 block numbers in the inode itself. Those blocks are +called <Literal remap="tt">direct blocks</Literal>. The advantage is that once the kernel has the +inode, it can directly access the file's blocks, without an additional disk +access. Those 12 blocks are directly specified in the variables +<Literal remap="tt">i_block[0] to i_block[11]</Literal>. +</Para> + +<Para> +<Literal remap="tt">i_block[12]</Literal> is the <Literal remap="tt">indirect block</Literal> - The block pointed by +i_block[12] will <Literal remap="tt">not</Literal> be a data block. Rather, it will just contain a +list of direct blocks. For example, if the block size is 1024 bytes, since +each block number is 4 bytes long, there will be place for 256 indirect +blocks. That is, block 13 till block 268 in the file will be accessed by the +<Literal remap="tt">indirect block</Literal> method. The penalty in this case, compared to the +direct blocks case, is that an additional access to the device is needed - +We need <Literal remap="tt">two</Literal> accesses to reach the required data block. +</Para> + +<Para> +In much the same way, <Literal remap="tt">i_block[13]</Literal> is the <Literal remap="tt">double indirect block</Literal> +and <Literal remap="tt">i_block[14]</Literal> is the <Literal remap="tt">triple indirect block</Literal>. +</Para> + +<Para> +<Literal remap="tt">i_block[13]</Literal> points to a block which contains pointers to indirect +blocks. Each one of them is handled in the way described above. +</Para> + +<Para> +In much the same way, the triple indirect block is just an additional level +of indirection - It will point to a list of double indirect blocks. +</Para> + +</Sect2> + +<Sect2> +<Title>The i_mode variable</Title> + +<Para> +The i_mode variable is used to determine the <Literal remap="tt">inode type</Literal> and the +associated <Literal remap="tt">permissions</Literal>. It is best described by representing it as an +octal number. Since it is a 16 bit variable, there will be 6 octal digits. +Those are divided into two parts - The rightmost 4 digits and the leftmost 2 +digits. +</Para> + +<Sect3> +<Title>The rightmost 4 octal digits</Title> + +<Para> +The rightmost 4 digits are <Literal remap="tt">bit options</Literal> - Each bit has its own +purpose. +</Para> + +<Para> +The last 3 digits (Octal digits 0,1 and 2) are just the usual permissions, +in the known form <Literal remap="tt">rwxrwxrwx</Literal>. Digit 2 refers to the user, digit 1 to +the group and digit 2 to everyone else. They are used by the kernel to grant +or deny access to the object presented by this inode. +<FOOTNOTE> + +<Para> +A <Literal remap="tt">smarter</Literal> permissions control is one of the enhancements planned for +Linux 1.3 - The ACL (Access Control Lists). Actually, from browsing of the +kernel source, some of the ACL handling is already done. +</Para> + +</FOOTNOTE> + +</Para> + +<Para> +Bit number 9 signals that the file (I'll refer to the object presented by +the inode as file even though it can be a special device, for example) is +<Literal remap="tt">set VTX</Literal>. I still don't know what is the meaning of "VTX". +</Para> + +<Para> +Bit number 10 signals that the file is <Literal remap="tt">set group id</Literal> - I don't know +exactly the meaning of the above either. +</Para> + +<Para> +Bit number 11 signals that the file is <Literal remap="tt">set user id</Literal>, which means that +the file will run with an effective user id root. +</Para> + +</Sect3> + +<Sect3> +<Title>The leftmost two octal digits</Title> + +<Para> +Note the the leftmost octal digit can only be 0 or 1, since the total number +of bits is 16. +</Para> + +<Para> +Those digits, as opposed to the rightmost 4 digits, are not bit mapped +options. They determine the type of the "file" to which the inode belongs: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">01</Literal> - The file is a <Literal remap="tt">FIFO</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">02</Literal> - The file is a <Literal remap="tt">character device</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">04</Literal> - The file is a <Literal remap="tt">directory</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">06</Literal> - The file is a <Literal remap="tt">block device</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">10</Literal> - The file is a <Literal remap="tt">regular file</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">12</Literal> - The file is a <Literal remap="tt">symbolic link</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">14</Literal> - The file is a <Literal remap="tt">socket</Literal>. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect3> + +</Sect2> + +<Sect2> +<Title>Time and date</Title> + +<Para> +Linux records the last time in which various operations occurred with the +file. The time and date are saved in the standard C library format - The +number of seconds which passed since 00:00:00 GMT, January 1, 1970. The +following times are recorded: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">i_ctime</Literal> - The time in which the inode was last allocated. In +other words, the time in which the file was created. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">i_mtime</Literal> - The time in which the file was last modified. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">i_atime</Literal> - The time in which the file was last accessed. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">i_dtime</Literal> - The time in which the inode was deallocated. In +other words, the time in which the file was deleted. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>i_size</Title> + +<Para> +<Literal remap="tt">i_size</Literal> contains information about the size of the object presented by +the inode. If the inode corresponds to a regular file, this is just the size +of the file in bytes. In other cases, the interpretation of the variable is +different. +</Para> + +</Sect2> + +<Sect2> +<Title>User and group id</Title> + +<Para> +The user and group id of the file are just saved in the variables +<Literal remap="tt">i_uid</Literal> and <Literal remap="tt">i_gid</Literal>. +</Para> + +</Sect2> + +<Sect2> +<Title>Hard links</Title> + +<Para> +Later, when we'll discuss the implementation of directories, it will be +explained that each <Literal remap="tt">directory entry</Literal> points to an inode. It is quite +possible that a <Literal remap="tt">single inode</Literal> will be pointed to from <Literal remap="tt">several</Literal> +directories. In that case, we say that there exist <Literal remap="tt">hard links</Literal> to the +file - The file can be accessed from each of the directories. +</Para> + +<Para> +The kernel keeps track of the number of hard links in the variable +<Literal remap="tt">i_links_count</Literal>. The variable is set to "1" when first allocating the +inode, and is incremented with each additional link. Deletion of a file will +delete the current directory entry and will decrement the number of links. +Only when this number reaches zero, the inode will be actually deallocated. +</Para> + +<Para> +The name <Literal remap="tt">hard link</Literal> is used to distinguish between the alias method +described above, to another alias method called <Literal remap="tt">symbolic linking</Literal>, +which will be described later. +</Para> + +</Sect2> + +<Sect2> +<Title>The Ext2fs extended flags</Title> + +<Para> +The ext2 filesystem associates additional flags with an inode. The extended +attributes are stored in the variable <Literal remap="tt">i_flags</Literal>. <Literal remap="tt">i_flags</Literal> is a 32 +bit variable. Only the 7 rightmost bits are defined. Of them, only 5 bits +are used in version 0.5a of the filesystem. Specifically, the +<Literal remap="tt">undelete</Literal> and the <Literal remap="tt">compress</Literal> features are not implemented, and +are to be introduced in Linux 1.3 development. +</Para> + +<Para> +The currently available flags are: + +<ItemizedList> +<ListItem> + +<Para> + bit 0 - Secure deletion. + +When this bit is on, the file's blocks are zeroed when the file is +deleted. With this bit off, they will just be left with their +original data when the inode is deallocated. +</Para> +</ListItem> +<ListItem> + +<Para> + bit 1 - Undelete. + +This bit is not supported yet. It will be used to provide an +<Literal remap="tt">undelete</Literal> feature in future Ext2fs developments. +</Para> +</ListItem> +<ListItem> + +<Para> + bit 2 - Compress file. + +This bit is also not supported. The plan is to offer "compression on +the fly" in future releases. +</Para> +</ListItem> +<ListItem> + +<Para> + bit 3 - Synchronous updates. + +With this bit on, the meta-data will be written synchronously to the +disk, as if the filesystem was mounted with the "sync" mount option. +</Para> +</ListItem> +<ListItem> + +<Para> + bit 4 - Immutable file. + +When this bit is on, the file will stay as it is - Can not be +changed, deleted, renamed, no hard links, etc, before the bit is +cleared. +</Para> +</ListItem> +<ListItem> + +<Para> + bit 5 - Append only file. + +With this option active, data will only be appended to the file. +</Para> +</ListItem> +<ListItem> + +<Para> + bit 6 - Do not dump this file. + +I think that this bit is used by the port of dump to linux (ported by +<Literal remap="tt">Remy Card</Literal>) to check if the file should not be dumped. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>Symbolic links</Title> + +<Para> +The <Literal remap="tt">hard links</Literal> presented above are just another pointers to the same +inode. The important aspect is that the inode number is <Literal remap="tt">fixed</Literal> when +the link is created. This means that the implementation details of the +filesystem are visible to the user - In a pure abstract usage of the +filesystem, the user should not care about inodes. +</Para> + +<Para> +The above causes several limitations: + +<ItemizedList> +<ListItem> + +<Para> + Hard links can be done only in the same filesystem. This is obvious, +since a hard link is just an inode number in some directory entry, +and the above elements are filesystem specific. +</Para> +</ListItem> +<ListItem> + +<Para> + You can not "replace" the file which is pointed to by the hard link +after the link creation. "Replacing" the file in one directory will +still leave the original file in the other directory - The +"replacement" will not deallocate the original inode, but rather +allocate another inode for the new version, and the directory entry +at the other place will just point to the old inode number. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +<Literal remap="tt">Symbolic link</Literal>, on the other hand, is analyzed at <Literal remap="tt">run time</Literal>. A +symbolic link is just a <Literal remap="tt">pathname</Literal> which is accessible from an inode. +As such, it "speaks" in the language of the abstract filesystem. When the +kernel reaches a symbolic link, it will <Literal remap="tt">follow it in run time</Literal> using +its normal way of reaching directories. +</Para> + +<Para> +As such, symbolic link can be made <Literal remap="tt">across different filesystems</Literal> and a +replacement of a file with a new version will automatically be active on all +its symbolic links. +</Para> + +<Para> +The disadvantage is that hard link doesn't consume space except to a small +directory entry. Symbolic link, on the other hand, consumes at least an +inode, and can also consume one block. +</Para> + +<Para> +When the inode is identified as a symbolic link, the kernel needs to find +the path to which it points. +</Para> + +<Sect3> +<Title>Fast symbolic links</Title> + +<Para> +When the pathname contains up to 64 bytes, it can be saved directly in the +inode, on the <Literal remap="tt">i_block[0] - i_block[15]</Literal> variables, since those are not +needed in that case. This is called <Literal remap="tt">fast</Literal> symbolic link. It is fast +because the pathname resolution can be done using the inode itself, without +accessing additional blocks. It is also economical, since it allocates only +an inode. The length of the pathname is stored in the <Literal remap="tt">i_size</Literal> +variable. +</Para> + +</Sect3> + +<Sect3> +<Title>Slow symbolic links</Title> + +<Para> +Starting from 65 bytes, additional block is allocated (by the use of +<Literal remap="tt">i_block[0]</Literal>) and the pathname is stored in it. It is called slow +because the kernel needs to read additional block to resolve the pathname. +The length is again saved in <Literal remap="tt">i_size</Literal>. +</Para> + +</Sect3> + +</Sect2> + +<Sect2> +<Title>i_version</Title> + +<Para> +<Literal remap="tt">i_version</Literal> is used with regard to Network File System. I don't know +its exact use. +</Para> + +</Sect2> + +<Sect2> +<Title>Reserved variables</Title> + +<Para> +As far as I know, the variables which are connected to ACL and fragments +are not currently used. They will be supported in future versions. +</Para> + +<Para> +Ext2fs is being ported to other operating systems. As far as I know, +at least in linux, the os dependent variables are also not used. +</Para> + +</Sect2> + +<Sect2> +<Title>Special reserved inodes</Title> + +<Para> +The first ten inodes on the filesystem are special inodes: + +<ItemizedList> +<ListItem> + +<Para> + Inode 1 is the <Literal remap="tt">bad blocks inode</Literal> - I believe that its data +blocks contain a list of the bad blocks in the filesystem, which +should not be allocated. +</Para> +</ListItem> +<ListItem> + +<Para> + Inode 2 is the <Literal remap="tt">root inode</Literal> - The inode of the root directory. +It is the starting point for reaching a known path in the filesystem. +</Para> +</ListItem> +<ListItem> + +<Para> + Inode 3 is the <Literal remap="tt">acl index inode</Literal>. Access control lists are +currently not supported by the ext2 filesystem, so I believe this +inode is not used. +</Para> +</ListItem> +<ListItem> + +<Para> + Inode 4 is the <Literal remap="tt">acl data inode</Literal>. Of course, the above applies +here too. +</Para> +</ListItem> +<ListItem> + +<Para> + Inode 5 is the <Literal remap="tt">boot loader inode</Literal>. I don't know its +usage. +</Para> +</ListItem> +<ListItem> + +<Para> + Inode 6 is the <Literal remap="tt">undelete directory inode</Literal>. It is also a +foundation for future enhancements, and is currently not used. +</Para> +</ListItem> +<ListItem> + +<Para> + Inodes 7-10 are <Literal remap="tt">reserved</Literal> and currently not used. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Directories</Title> + +<Para> +A directory is implemented in the same way as files are implemented (with +the direct blocks, indirect blocks, etc) - It is just a file which is +formatted with a special format - A list of directory entries. +</Para> + +<Para> +Follows the definition of a directory entry: +</Para> + +<Para> + +<ProgramListing> +struct ext2_dir_entry { + __u32 inode; /* Inode number */ + __u16 rec_len; /* Directory entry length */ + __u16 name_len; /* Name length */ + char name[EXT2_NAME_LEN]; /* File name */ +}; +</ProgramListing> + +</Para> + +<Para> +Ext2fs supports file names of varying lengths, up to 255 bytes. The +<Literal remap="tt">name</Literal> field above just contains the file name. Note that it is +<Literal remap="tt">not zero terminated</Literal>; Instead, the variable <Literal remap="tt">name_len</Literal> contains +the length of the file name. +</Para> + +<Para> +The variable <Literal remap="tt">rec_len</Literal> is provided because the directory entries are +padded with zeroes so that the next entry will be in an offset which is +a multiplication of 4. The resulting directory entry size is stored in +<Literal remap="tt">rec_len</Literal>. If the directory entry is the last in the block, it is +padded with zeroes till the end of the block, and rec_len is updated +accordingly. +</Para> + +<Para> +The <Literal remap="tt">inode</Literal> variable points to the inode of the above file. +</Para> + +<Para> +Deletion of directory entries is done by appending of the deleted entry +space to the previous (or next, I am not sure) entry. +</Para> + +</Sect1> + +<Sect1> +<Title>The superblock</Title> + +<Para> +The <Literal remap="tt">superblock</Literal> is a block which contains information which describes +the state of the internal filesystem. +</Para> + +<Para> +The superblock is located at the <Literal remap="tt">fixed offset 1024</Literal> in the device. Its +length is 1024 bytes also. +</Para> + +<Para> +The superblock, like the group descriptors, is copied on each blocks group +boundary for backup purposes. However, only the main copy is used by the +kernel. +</Para> + +<Para> +The superblock contain three types of information: + +<ItemizedList> +<ListItem> + +<Para> + Filesystem parameters which are fixed and which were determined when +this specific filesystem was created. Some of those parameters can +be different in different installations of the ext2 filesystem, but +can not be changed once the filesystem was created. +</Para> +</ListItem> +<ListItem> + +<Para> + Filesystem parameters which are tunable - Can always be changed. +</Para> +</ListItem> +<ListItem> + +<Para> + Information about the current filesystem state. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +Follows the superblock definition: +</Para> + +<Para> + +<ProgramListing> +struct ext2_super_block { + __u32 s_inodes_count; /* Inodes count */ + __u32 s_blocks_count; /* Blocks count */ + __u32 s_r_blocks_count; /* Reserved blocks count */ + __u32 s_free_blocks_count; /* Free blocks count */ + __u32 s_free_inodes_count; /* Free inodes count */ + __u32 s_first_data_block; /* First Data Block */ + __u32 s_log_block_size; /* Block size */ + __s32 s_log_frag_size; /* Fragment size */ + __u32 s_blocks_per_group; /* # Blocks per group */ + __u32 s_frags_per_group; /* # Fragments per group */ + __u32 s_inodes_per_group; /* # Inodes per group */ + __u32 s_mtime; /* Mount time */ + __u32 s_wtime; /* Write time */ + __u16 s_mnt_count; /* Mount count */ + __s16 s_max_mnt_count; /* Maximal mount count */ + __u16 s_magic; /* Magic signature */ + __u16 s_state; /* File system state */ + __u16 s_errors; /* Behaviour when detecting errors */ + __u16 s_pad; + __u32 s_lastcheck; /* time of last check */ + __u32 s_checkinterval; /* max. time between checks */ + __u32 s_creator_os; /* OS */ + __u32 s_rev_level; /* Revision level */ + __u16 s_def_resuid; /* Default uid for reserved blocks */ + __u16 s_def_resgid; /* Default gid for reserved blocks */ + __u32 s_reserved[235]; /* Padding to the end of the block */ +}; +</ProgramListing> + +</Para> + +<Sect2> +<Title>superblock identification</Title> + +<Para> +The ext2 filesystem's superblock is identified by the <Literal remap="tt">s_magic</Literal> field. +The current ext2 magic number is 0xEF53. I presume that "EF" means "Extended +Filesystem". In versions of the ext2 filesystem prior to 0.2B, the magic +number was 0xEF51. Those filesystems are not compatible with the current +versions; Specifically, the group descriptors definition is different. I +doubt if there still exists such a installation. +</Para> + +</Sect2> + +<Sect2> +<Title>Filesystem fixed parameters</Title> + +<Para> +By using the word <Literal remap="tt">fixed</Literal>, I mean fixed with respect to a particular +installation. Those variables are usually not fixed with respect to +different installations. +</Para> + +<Para> +The <Literal remap="tt">block size</Literal> is determined by using the <Literal remap="tt">s_log_block_size</Literal> +variable. The block size is 1024*pow (2,s_log_block_size) and should be +between 1024 and 4096. The available options are 1024, 2048 and 4096. +</Para> + +<Para> +<Literal remap="tt">s_inodes_count</Literal> contains the total number of available inodes. +</Para> + +<Para> +<Literal remap="tt">s_blocks_count</Literal> contains the total number of available blocks. +</Para> + +<Para> +<Literal remap="tt">s_first_data_block</Literal> specifies in which of the <Literal remap="tt">device block</Literal> the +<Literal remap="tt">superblock</Literal> is present. The superblock is always present at the fixed +offset 1024, but the device block numbering can differ. For example, if the +block size is 1024, the superblock will be at <Literal remap="tt">block 1</Literal> with respect to +the device. However, if the block size is 4096, offset 1024 is included in +<Literal remap="tt">block 0</Literal> of the device, and in that case <Literal remap="tt">s_first_data_block</Literal> +will contain 0. At least this is how I understood this variable. +</Para> + +<Para> +<Literal remap="tt">s_blocks_per_group</Literal> contains the number of blocks which are grouped +together as a blocks group. +</Para> + +<Para> +<Literal remap="tt">s_inodes_per_group</Literal> contains the number of inodes available in a group +block. I think that this is always the total number of inodes divided by the +number of blocks groups. +</Para> + +<Para> +<Literal remap="tt">s_creator_os</Literal> contains a code number which specifies the operating +system which created this specific filesystem: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">Linux</Literal> :-) is specified by the value <Literal remap="tt">0</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Hurd</Literal> is specified by the value <Literal remap="tt">1</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Masix</Literal> is specified by the value <Literal remap="tt">2</Literal>. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +<Literal remap="tt">s_rev_level</Literal> contains the major version of the ext2 filesystem. +Currently this is always <Literal remap="tt">0</Literal>, as the most recent version is 0.5B. It +will probably take some time until we reach version 1.0. +</Para> + +<Para> +As far as I know, fragments (sub-block allocations) are currently not +supported and hence a block is equal to a fragment. As a result, +<Literal remap="tt">s_log_frag_size</Literal> and <Literal remap="tt">s_frags_per_group</Literal> are always equal to +<Literal remap="tt">s_log_block_size</Literal> and <Literal remap="tt">s_blocks_per_group</Literal>, respectively. +</Para> + +</Sect2> + +<Sect2> +<Title>Ext2fs error handling</Title> + +<Para> +The ext2 filesystem error handling is based on the following philosophy: + +<OrderedList> +<ListItem> + +<Para> + Identification of problems is done by the kernel code. +</Para> +</ListItem> +<ListItem> + +<Para> + The correction task is left to an external utility, such as +<Literal remap="tt">e2fsck by Theodore Ts'o</Literal> for <Literal remap="tt">automatic</Literal> analysis and +correction, or perhaps <Literal remap="tt">debugfs by Theodore Ts'o</Literal> and +<Literal remap="tt">EXT2ED by myself</Literal>, for <Literal remap="tt">hand</Literal> analysis and correction. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +<Para> +The <Literal remap="tt">s_state</Literal> variable is used by the kernel to pass the identification +result to third party utilities: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">bit 0</Literal> of s_state is reset when the partition is mounted and +set when the partition is unmounted. Thus, a value of 0 on an +unmounted filesystem means that the filesystem was not unmounted +properly - The filesystem is not "clean" and probably contains +errors. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">bit 1</Literal> of s_state is set by the kernel when it detects an +error in the filesystem. A value of 0 doesn't mean that there isn't +an error in the filesystem, just that the kernel didn't find any. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The kernel behavior when an error is found is determined by the user tunable +parameter <Literal remap="tt">s_errors</Literal>: + +<ItemizedList> +<ListItem> + +<Para> + The kernel will ignore the error and continue if <Literal remap="tt">s_errors=1</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + The kernel will remount the filesystem in read-only mode if +<Literal remap="tt">s_errors=2</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + A kernel panic will be issued if <Literal remap="tt">s_errors=3</Literal>. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The default behavior is to ignore the error. +</Para> + +</Sect2> + +<Sect2> +<Title>Additional parameters used by e2fsck</Title> + +<Para> +Of-course, <Literal remap="tt">e2fsck</Literal> will check the filesystem if errors were detected +or if the filesystem is not clean. +</Para> + +<Para> +In addition, each time the filesystem is mounted, <Literal remap="tt">s_mnt_count</Literal> is +incremented. When s_mnt_count reaches <Literal remap="tt">s_max_mnt_count</Literal>, <Literal remap="tt">e2fsck</Literal> +will force a check on the filesystem even though it may be clean. It will +then zero s_mnt_count. <Literal remap="tt">s_max_mnt_count</Literal> is a tunable parameter. +</Para> + +<Para> +E2fsck also records the last time in which the file system was checked in +the <Literal remap="tt">s_lastcheck</Literal> variable. The user tunable parameter +<Literal remap="tt">s_checkinterval</Literal> will contain the number of seconds which are allowed +to pass since <Literal remap="tt">s_lastcheck</Literal> until a check is forced. A value of +<Literal remap="tt">0</Literal> disables time-based check. +</Para> + +</Sect2> + +<Sect2> +<Title>Additional user tunable parameters</Title> + +<Para> +<Literal remap="tt">s_r_blocks_count</Literal> contains the number of disk blocks which are +reserved for root, the user whose id number is <Literal remap="tt">s_def_resuid</Literal> and the +group whose id number is <Literal remap="tt">s_deg_resgid</Literal>. The kernel will refuse to +allocate those last <Literal remap="tt">s_r_blocks_count</Literal> if the user is not one of the +above. This is done so that the filesystem will usually not be 100% full, +since 100% full filesystems can affect various aspects of operation. +</Para> + +<Para> +<Literal remap="tt">s_def_resuid</Literal> and <Literal remap="tt">s_def_resgid</Literal> contain the id of the user and +of the group who can use the reserved blocks in addition to root. +</Para> + +</Sect2> + +<Sect2> +<Title>Filesystem current state</Title> + +<Para> +<Literal remap="tt">s_free_blocks_count</Literal> contains the current number of free blocks +in the filesystem. +</Para> + +<Para> +<Literal remap="tt">s_free_inodes_count</Literal> contains the current number of free inodes in the +filesystem. +</Para> + +<Para> +<Literal remap="tt">s_mtime</Literal> contains the time at which the system was last mounted. +</Para> + +<Para> +<Literal remap="tt">s_wtime</Literal> contains the last time at which something was changed in the +filesystem. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Copyright</Title> + +<Para> +This document contains source code which was taken from the Linux ext2 +kernel source code, mainly from <FILENAME>/usr/include/linux/ext2_fs.h</FILENAME>. Follows +the original copyright: +</Para> + +<Para> + +<ProgramListing> +/* + * linux/include/linux/ext2_fs.h + * + * Copyright (C) 1992, 1993, 1994, 1995 + * Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * from + * + * linux/include/linux/minix_fs.h + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +</ProgramListing> + +</Para> + +</Sect1> + +<Sect1> +<Title>Acknowledgments</Title> + +<Para> +I would like to thank the following people, who were involved in the +design and implementation of the ext2 filesystem kernel code and support +utilities: + +<ItemizedList> +<ListItem> + +<Para> + <Literal remap="tt">Remy Card</Literal> + +Who designed, implemented and maintains the ext2 filesystem kernel +code, and some of the ext2 utilities. <Literal remap="tt">Remy Card</Literal> is also the +author of several helpful slides concerning the ext2 filesystem. +Specifically, he is the author of <Literal remap="tt">File Management in the Linux +Kernel</Literal> and of <Literal remap="tt">The Second Extended File System - Current +State, Future Development</Literal>. + +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Wayne Davison</Literal> + +Who designed the ext2 filesystem. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Stephen Tweedie</Literal> + +Who helped designing the ext2 filesystem kernel code and wrote the +slides <Literal remap="tt">Optimizations in File Systems</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> + <Literal remap="tt">Theodore Ts'o</Literal> + +Who is the author of several ext2 utilities and of the ext2 library +<Literal remap="tt">libext2fs</Literal> (which I didn't use, simply because I didn't know +it exists when I started to work on my project). +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +Lastly, I would like to thank, of-course, <Literal remap="tt">Linus Torvalds</Literal> and the +<Literal remap="tt">Linux community</Literal> for providing all of us with such a great operating +system. +</Para> + +<Para> +Please contact me in a case of an error report, suggestions, or just about +anything concerning this document. +</Para> + +<Para> +Enjoy, +</Para> + +<Para> +Gadi Oxman <tgud@tochnapc2.technion.ac.il> +</Para> + +<Para> +Haifa, August 95 +</Para> + +</Sect1> + +</Article> diff --git a/ext2ed/doc/user-guide.sgml b/ext2ed/doc/user-guide.sgml new file mode 100644 index 0000000..1e8f3cd --- /dev/null +++ b/ext2ed/doc/user-guide.sgml @@ -0,0 +1,2258 @@ +<!DOCTYPE Article PUBLIC "-//OASIS//DTD DocBook V4.1//EN"> + +<Article> + +<ArticleInfo> + +<Title>EXT2ED - The Extended-2 filesystem editor - User's guide</Title> +<AUTHOR> +<FirstName>Gadi Oxman, tgud@tochnapc2.technion.ac.il</FirstName> +</AUTHOR> +<PubDate>v0.1, August 3 1995</PubDate> + +<Abstract> + +<Para> +This is only the initial version of this document. It may be unclear at +some places. Please send me feedback with anything regarding to it. +</Para> + +</Abstract> + +</ArticleInfo> + +<Sect1> +<Title>About EXT2ED documentation</Title> + +<Para> +The EXT2ED documentation consists of three parts: + +<ItemizedList> +<ListItem> + +<Para> + The ext2 filesystem overview. +</Para> +</ListItem> +<ListItem> + +<Para> + The EXT2ED user's guide. +</Para> +</ListItem> +<ListItem> + +<Para> + The EXT2ED design and implementation. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +If you intend to used EXT2ED, I strongly suggest that you would be familiar +with the material presented in the <Literal remap="tt">ext2 filesystem overview</Literal> as well. +</Para> + +<Para> +If you also intend to browse and modify the source code, I suggest that you +will also read the article <Literal remap="tt">The EXT2ED design and implementation</Literal>, as it +provides a general overview of the structure of my source code. +</Para> + +</Sect1> + +<Sect1> +<Title>Introduction</Title> + +<Para> +EXT2ED is a "disk editor" for the ext2 filesystem. Its purpose is to show +you the internal structures of the ext2 filesystem in an rather intuitive +and logical way, so that it will be easier to "travel" between the various +internal filesystem structures. +</Para> + +</Sect1> + +<Sect1> +<Title>Basic concepts in EXT2ED</Title> + +<Para> +Two basic concepts in EXT2ED are <Literal remap="tt">commands</Literal> and <Literal remap="tt">types</Literal>. +</Para> + +<Para> +EXT2ED is object-oriented in the sense that it defines objects in the +filesystem, like a <Literal remap="tt">super-block</Literal> or a <Literal remap="tt">directory</Literal>. An object is +something which "knows" how to handle some aspect of the filesystem. +</Para> + +<Para> +Your interaction with EXT2ED is done through <Literal remap="tt">commands</Literal> which EXT2ED +accepts. There are three levels of commands: + +<ItemizedList> +<ListItem> + +<Para> + General Commands +</Para> +</ListItem> +<ListItem> + +<Para> + Extended-2 Filesystem general commands +</Para> +</ListItem> +<ListItem> + +<Para> + Type specific commands +</Para> +</ListItem> + +</ItemizedList> + +The General commands are always available. +</Para> + +<Para> +The ext2 general commands are available only when editing an ext2 filesystem. +</Para> + +<Para> +The Type specific commands are available when editing a specific object in the +filesystem. Each object typically comes with its own set of internal +variables, and its own set of commands, which are fine tuned handle the +corresponding structure in the filesystem. +</Para> + +</Sect1> + +<Sect1> +<Title>Running EXT2ED</Title> + +<Para> +Running EXT2ED is as simple as typing <Literal remap="tt">ext2ed</Literal> from the shell prompt. +There are no command line switches. +</Para> + +<Para> +When first run, EXT2ED parses its configuration file, <Literal remap="tt">ext2ed.conf</Literal>. +This file must exist. +</Para> + +<Para> +When the configuration file processing is done, EXT2ED screen should appear +on the screen, with the command prompt <Literal remap="tt">ext2ed></Literal> displayed. +</Para> + +</Sect1> + +<Sect1> +<Title>EXT2ED user interface</Title> + +<Para> +EXT2ED uses the <Emphasis>ncurses</Emphasis> library for screen management. Your screen +will be divided into four parts, from top to bottom: + +<ItemizedList> +<ListItem> + +<Para> + Title window +</Para> +</ListItem> +<ListItem> + +<Para> + Status window +</Para> +</ListItem> +<ListItem> + +<Para> + Main editing window +</Para> +</ListItem> +<ListItem> + +<Para> + Command window +</Para> +</ListItem> + +</ItemizedList> + +The title window just displays the current version of EXT2ED. +</Para> + +<Para> +The status window will display various information regarding the state of +the editing at this point. +</Para> + +<Para> +The main editing window is the place at which the actual data will be shown. +Almost every command will cause some display at this window. This window, as +opposed to the three others, is of variable length - You always look at one +page of it. The current page and the total numbers of pages at this moment +is displayed at the status window. Moving between pages is done by the use +of the <Command>pgdn</Command> and <Command>pgup</Command> commands. +</Para> + +<Para> +The command window is at the bottom of the screen. It always displays a +command prompt <Literal remap="tt">ext2ed></Literal> and allows you to type a command. Feedback +about the commands entered is displayed to this window also. +</Para> + +<Para> +EXT2ED uses the <Emphasis>readline</Emphasis> library while processing a command line. All +the usual editing keys are available. Each entered command is placed into a +history of commands, and can be recalled later. Command Completion is also +supported - Just start to type a command, and press the completion key. +</Para> + +<Para> +Pressing <Literal remap="tt">enter</Literal> at the command window, without entering a command, +recalls the last command. This is useful when moving between close entries, +in the <Command>next</Command> command, for example. +</Para> + +</Sect1> + +<Sect1> +<Title>Getting started</Title> + +<Sect2> +<Title>A few precautions</Title> + +<Para> +EXT2ED is a tool for filesystem <Literal remap="tt">editing</Literal>. As such, it can be +<Literal remap="tt">dangerous</Literal>. The summary to the subsections below is that +<Literal remap="tt">You must know what you are doing</Literal>. +</Para> + +<Sect3 id="mounted-ref"> +<Title>A mounted filesystem</Title> + +<Para> +EXT2ED is not designed to work on a mounted filesystem - It is complicated +enough as it is; I didn't even try to think of handling the various race +conditions. As such, please respect the following advice: +</Para> + +<Para> +<Literal remap="tt">Do not use EXT2ED on a mounted filesystem !</Literal> +</Para> + +<Para> +EXT2ED will not allow write access to a mounted filesystem. Although it is +fairly easy to change EXT2ED so that it will be allowed, I hereby request +again- EXT2ED is not designed for that action, and will most likely corrupt +data if used that way. Please don't do that. +</Para> + +<Para> +Concerning read access, I chose to leave the decision for the user through +the configuration file option <Literal remap="tt">AllowMountedRead</Literal>. Although read access +on a mounted partition will not do any damage to the filesystem, the data +displayed to you will not be reliable, and showing you incorrect information +may be as bad as corrupting the filesystem. However, you may still wish to +do that. +</Para> + +</Sect3> + +<Sect3> +<Title>Write access</Title> + +<Para> +Considering the obvious sensitivity of the subject, I took the following +actions: +</Para> + +<Para> + +<OrderedList> +<ListItem> + +<Para> + EXT2ED will always start with a read-only access. Write access mode +needs to be specifically entered by the <Command>enablewrite</Command> command. +Until this is done, no write will be allowed. Write access can be +disabled at any time with <Command>disablewrite</Command>. When +<Command>enablewrite</Command> is issued, the device is reopened in read-write +mode. Needless to say, the device permissions should allow that. +</Para> +</ListItem> +<ListItem> + +<Para> + As a second level of protection, you can disallow write access in +the configuration file by using the <Literal remap="tt">AllowChanges off</Literal> +configuration option. In this case, the <Command>enablewrite</Command> command +will be refused. +</Para> +</ListItem> +<ListItem> + +<Para> + When write access is enabled, the data will never change +immediately. Rather, a specific <Command>writedata</Command> command is needed +to update the object in the disk with the changed object in memory. +</Para> +</ListItem> +<ListItem> + +<Para> + In addition, A logging option is provided through the configuration +file options <Literal remap="tt">LogChanges</Literal> and <Literal remap="tt">LogFile</Literal>. With logging +enabled, each change to the disk will be logged at a very primitive +level - A hex dump of the original data and of the new written data. +The log file will be a text file which is easily readable, and you +can make use of it to undo any changes which you made (EXT2ED doesn't +make use of the log file for that purpose, it just logs the changes). +</Para> +</ListItem> + +</OrderedList> + +Please remember that this is only the initial release of EXT2ED, and it is +not very much tested - It is reasonable to assume that <Literal remap="tt">there are +bugs</Literal>. +However, the logging option above can offer protection even from this +unfortunate case. Therefor, I highly recommend that at least when first +working with EXT2ED, the logging option will be enabled, despite the disk +space which it consumes. +</Para> + +</Sect3> + +</Sect2> + +<Sect2 id="help-ref"> +<Title>The help command</Title> + +<Para> +When loaded, EXT2ED will show a short help screen. This help screen can +always be retrieved by the command <Command>help</Command>. The help screen displays a +list of all the commands which are available at this point. At startup, only +the <Literal remap="tt">General commands</Literal> are available. +This will change with time, since each object has its own commands. Thus, +commands which are available now may not be available later. +Using <Command>help</Command> <Emphasis>command</Emphasis> will display additional information about +the specific command <Emphasis>command</Emphasis>. +</Para> + +</Sect2> + +<Sect2 id="setdevice-ref"> +<Title>The setdevice command</Title> + +<Para> +The first command that is usually entered to EXT2ED is the <Command>setdevice</Command> +command. This command simply tells EXT2ED on which device the filesystem is +present. For example, suppose my ext2 filesystem is on the first partition +of my ide disk. The command will be: + +<Screen> +setdevice /dev/hda1 +</Screen> + +The following actions will take place in the following order: + +<OrderedList> +<ListItem> + +<Para> + EXT2ED will check if the partition is mounted. +If the partition is mounted (<Literal remap="tt">highly not recommended</Literal>), +the accept/reject behavior will be decided by the configuration +file. Cross reference section <XRef LinkEnd="mounted-ref">. +</Para> +</ListItem> +<ListItem> + +<Para> + The specified device will be opened in read-only mode. The +permissions of the device should be set in a way that allows +you to open the device for read access. +</Para> +</ListItem> +<ListItem> + +<Para> + Autodetection of an ext2 filesystem will be made by searching for +the ext2 magic number in the main superblock. +</Para> +</ListItem> +<ListItem> + +<Para> + In the case of a successful recognition of an ext2 filesystem, the +ext2 filesystem specific commands and the ext2 specific object +definitions will be registered. The object definitions will be read +at run time from a file specified by the configuration file. + +In case of a corrupted ext2 filesystem, it is quite possible that +the main superblock is damaged and autodetection will fail. In that +case, use the configuration option <Literal remap="tt">ForceExt2 on</Literal>. This is not +the default case since EXT2ED can be used at a lower level to edit a +non-ext2 filesystem. +</Para> +</ListItem> +<ListItem> + +<Para> + In a case of a successful autodetection, essential information about +the filesystem such as the block size will be read from the +superblock, unless the used overrides this behavior with an +configuration option (not recommended). In that case, the parameters +will be read from the configuration file. + +In a case of an autodetection failure, the essential parameters +will be read from the configuration file. +</Para> +</ListItem> + +</OrderedList> + +Assuming that you are editing an ext2 filesystem and that everything goes +well, you will notice that additional commands are now available in the help +screen, under the section <Literal remap="tt">ext2 filesystem general commands</Literal>. In +addition, EXT2ED now recognizes a few objects which are essential to the +editing of an ext2 filesystem. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Two levels of usage</Title> + +<Sect2> +<Title>Low level usage</Title> + +<Para> +This section explains what EXT2ED provides even when not editing an ext2 +filesystem. +</Para> + +<Para> +Even at this level, EXT2ED is more than just a hex editor. It still allows +definition of objects and variables in run time through a user file, +although of-course the objects will not have special fine tuned functions +connected to them. EXT2ED will allow you to move in the filesystem using +<Command>setoffset</Command>, and to apply an object definition on a specific place +using <Command>settype</Command> <Emphasis>type</Emphasis>. From this point and on, the object will +be shown <Literal remap="tt">in its native form</Literal> - You will see a list of the +variables rather than just a hex dump, and you will be able to change each +variable in the intuitive form <Command>set variable=value</Command>. +</Para> + +<Para> +To define objects, use the configuration option <Literal remap="tt">AlternateDescriptors</Literal>. +</Para> + +<Para> +There are now two forms of editing: + +<ItemizedList> +<ListItem> + +<Para> + Editing without a type. In this case, the disk block will be shown +as a text+hex dump, and you will be able to move along and change it. +</Para> +</ListItem> +<ListItem> + +<Para> + Editing with a type. In this case, the object's variables will be +shown, and you will be able to change each variable in its native form. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>High level usage</Title> + +<Para> +EXT2ED was designed for the editing of the ext2 filesystem. As such, it +"understands" the filesystem structure to some extent. Each object now has +special fine tuned 'C' functions connected to it, which knows how to display +it in an intuitive form, and how the object fits in the general design of +the ext2 filesystem. It is of-course much easier to use this type of +editing. For example: + +<Screen> +Issue <Emphasis>group 2</Emphasis> to look at the main copy of the third group block +descriptor. With <Emphasis>gocopy 1</Emphasis> you can move to its first backup copy, +and with <Emphasis>inode</Emphasis> you can start editing the inode table of the above +group block. From here, if the inode corresponds to a file, you can +use <Emphasis>file</Emphasis> to edit the file in a "continuous" way, using +<Emphasis>nextblock</Emphasis> to pass to its next block, letting EXT2ED following by +itself the direct blocks, indirect blocks, ..., while still preserving the +actual view of the exact block usage of the file. +</Screen> + +The point is that the "tour" of the filesystem will now be synchronous rather +than asynchronous - Each object has the "links" to pass between connected +logical structures, and special fine-tuned functions to deal with it. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>General commands</Title> + +<Para> +I will now start with a systematic explanation of the general commands. +Please feel free to experiment, but take care when using the +<Literal remap="tt">enablewrite</Literal> command. +</Para> + +<Para> +Whenever a command syntax is specified, arguments which are optional are +enclosed with square brackets. +</Para> + +<Para> +Please note that in EXT2ED, each command can be overridden by a specific +object to provide special fine-tuned functionality. In general, I was +attempting to preserve the similarity between those functions, which are +accessible by the same name. +</Para> + +<Sect2 id="disablewrite-ref"> +<Title>disablewrite</Title> + +<Para> + +<Screen> +Syntax: disablewrite +</Screen> + +<Command>disablewrite</Command> is used to reopen the device with read-only access. When +first running EXT2ED, the device is opened in read-only mode, and an +explicit <Command>enablewrite</Command> is required for write access. When finishing +with changing, a <Command>disablewrite</Command> is recommended for safety. Cross +reference section <XRef LinkEnd="disablewrite-ref">. +</Para> + +</Sect2> + +<Sect2 id="enablewrite-ref"> +<Title>enablewrite</Title> + +<Para> + +<Screen> +Syntax: enablewrite +</Screen> + +<Command>enablewrite</Command> is used to reopen the device with read-write access. +When first running EXT2ED, the device is opened in read-only mode, and an +explicit <Command>enablewrite</Command> is required for write access. +<Command>enablewrite</Command> will fail if write access is disabled from the +configuration file by the <Literal remap="tt">AllowChanges off</Literal> configuration option. +Even after <Command>enablewrite</Command>, an explicit <Command>writedata</Command> +is required to actually write the new data to the disk. +When finishing with changing, a <Command>disablewrite</Command> is recommended for safety. +Cross reference section <XRef LinkEnd="enablewrite-ref">. +</Para> + +</Sect2> + +<Sect2> +<Title>help</Title> + +<Para> + +<Screen> +Syntax: help [command] +</Screen> + +The <Command>help</Command> command is described at section <XRef LinkEnd="help-ref">. +</Para> + +</Sect2> + +<Sect2 id="next-ref"> +<Title>next</Title> + +<Para> + +<Screen> +Syntax: next [number] +</Screen> + +This section describes the <Emphasis>general command</Emphasis> <Command>next</Command>. <Command>next</Command> +is overridden by several types in EXT2ED, to provide fine-tuned +functionality. +</Para> + +<Para> +The <Literal remap="tt">next general command</Literal> behavior is depended on whether you are editing a +specific object, or none. +</Para> + +<Para> + +<ItemizedList> +<ListItem> + +<Para> + In the case where Type is <Literal remap="tt">none</Literal> (The current type is showed +on the status window by the <Command>show</Command> command), <Literal remap="tt">next</Literal> +passes to the next <Emphasis>number</Emphasis> bytes in the current edited block. +If <Emphasis>number</Emphasis> is not specified, <Emphasis>number=1</Emphasis> is assumed. +</Para> +</ListItem> +<ListItem> + +<Para> + In the case where Type is defined, the <Command>next</Command> commands assumes +that you are editing an array of objects of that type, and the +<Command>next</Command> command will just pass to the next entry in the array. +If <Emphasis>number</Emphasis> is defined, it will pass <Emphasis>number</Emphasis> entries +ahead. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2 id="pgdn-ref"> +<Title>pgdn</Title> + +<Para> + +<Screen> +Syntax: pgdn +</Screen> + +Usually the edited data doesn't fit into the visible main window. In this +case, the status window will indicate that there is more to see "below" by +the message <Literal remap="tt">Page x of y</Literal>. This means that there are <Emphasis>y</Emphasis> pages +total, and you are currently viewing the <Emphasis>x</Emphasis> page. With the <Command>pgdn</Command> +command, you can pass to the next available page. +</Para> + +</Sect2> + +<Sect2> +<Title>pgup</Title> + +<Para> + +<Screen> +Syntax: pgup +</Screen> + +</Para> + +<Para> +<Command>pgup</Command> is the opposite of <Command>pgdn</Command> - It will pass to the previous +page. Cross reference section <XRef LinkEnd="pgdn-ref">. +</Para> + +</Sect2> + +<Sect2> +<Title>prev</Title> + +<Para> + +<Screen> +Syntax: prev [number] +</Screen> + +</Para> + +<Para> +<Command>prev</Command> is the opposite of <Command>next</Command>. Cross reference section +<XRef LinkEnd="next-ref">. +</Para> + +</Sect2> + +<Sect2 id="recall-ref"> +<Title>recall</Title> + +<Para> + +<Screen> +Syntax: recall object +</Screen> + +<Command>recall</Command> is the opposite of <Command>remember</Command>. It will place you at the +place you where when saving the object position and type information. Cross +reference section <XRef LinkEnd="remember-ref">. +</Para> + +</Sect2> + +<Sect2> +<Title>redraw</Title> + +<Para> + +<Screen> +Syntax: redraw +</Screen> + +Sometimes the screen display gets corrupted. I still have problems with +this. The <Command>redraw</Command> command simply redraws the entire display screen. +</Para> + +</Sect2> + +<Sect2 id="remember-ref"> +<Title>remember</Title> + +<Para> + +<Screen> +Syntax: remember object +</Screen> + +EXT2ED provides you <Literal remap="tt">memory</Literal> of objects; While editing, you may reach an +object which you will like to return to later. The <Command>remember</Command> command +will store in memory the current place and type of the object. You can +return to the object by using the <Command>recall</Command> command. Cross reference +section <XRef LinkEnd="recall-ref">. +</Para> + +<Para> +<Literal remap="tt">Note:</Literal> + +<ItemizedList> +<ListItem> + +<Para> + When remembering a <Literal remap="tt">file</Literal> or a <Literal remap="tt">directory</Literal>, the +corresponding inode will be saved in memory. The basic reason is that +the inode is essential for finding the blocks of the file or the +directory. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>set</Title> + +<Para> + +<Screen> +Syntax: set [text || hex] arg1 [arg2 arg3 ...] + +or + +Syntax: set variable=value +</Screen> + +The <Command>set</Command> command is used to modify the current data. +The <Command>set general command</Command> behavior is depended on whether you are editing a +specific object, or none. +</Para> + +<Para> + +<ItemizedList> +<ListItem> + +<Para> + In the case where Type is <Command>none</Command>, the first syntax should be +used. The set command affects the data starting at the current +highlighted position in the edited block. + +<ItemizedList> +<ListItem> + +<Para> + When using the <Command>set hex</Command> command, a list of +hexadecimal bytes should follow. +</Para> +</ListItem> +<ListItem> + +<Para> + When using the <Command>set text</Command> command, it should be followed +by a text string. +</Para> +</ListItem> + +</ItemizedList> + +Examples: + +<Screen> + set hex 09 0a 0b 0c 0d 0e 0f + set text Linux is just great ! + +</Screen> + +</Para> +</ListItem> +<ListItem> + +<Para> + In the case where Type is defined, the second syntax should be used. +The set commands just sets the variable <Emphasis>variable</Emphasis> with the +value <Emphasis>value</Emphasis>. +</Para> +</ListItem> + +</ItemizedList> + +In any case, the data is only changed in memory. For an actual update to the +disk, use the <Command>writedata</Command> command. +</Para> + +</Sect2> + +<Sect2> +<Title>setdevice</Title> + +<Para> + +<Screen> +Syntax: setdevice device +</Screen> + +The <Command>setdevice</Command> command is described at section <XRef LinkEnd="setdevice-ref">. +</Para> + +</Sect2> + +<Sect2> +<Title>setoffset</Title> + +<Para> + +<Screen> +Syntax: setoffset [block || type] [+|-]offset +</Screen> + +The <Command>setoffset</Command> command is used to move asynchronously inside the file +system. It is considered a low level command, and usually should not be used +when editing an ext2 filesystem, simply because movement is better +utilized through the specific ext2 commands. +</Para> + +<Para> +The <Command>offset</Command> is in bytes, and meanwhile should be positive and smaller +than 2GB. +</Para> + +<Para> +Use of the <Command>block</Command> modifier changes the counting unit to block. +</Para> + +<Para> +Use of the <Literal remap="tt">+ or -</Literal> modifiers signals that the offset is relative to +the current position. +</Para> + +<Para> +use of the <Literal remap="tt">type</Literal> modifier is allowed only with relative offset. This +modifier will multiply the offset by the size of the current type. +</Para> + +</Sect2> + +<Sect2> +<Title>settype</Title> + +<Para> + +<Screen> +Syntax: settype type || [none | hex] +</Screen> + +The <Command>settype</Command> command is used to move apply the object definitions of +the type <Emphasis>type</Emphasis> on the current position. It is considered a low level +command and usually should not be used when editing an ext2 filesystem since +EXT2ED provides better tools. It is of-course very useful when editing a +non-ext2 filesystem and using user-defined objects. +</Para> + +<Para> +When <Emphasis>type</Emphasis> is <Emphasis>hex</Emphasis> or <Emphasis>none</Emphasis>, the data will be displayed as +a hex and text dump. +</Para> + +</Sect2> + +<Sect2> +<Title>show</Title> + +<Para> + +<Screen> +Syntax: show +</Screen> + +The <Command>show</Command> command will show the data of the current object at the +current position on the main display window. It will also update the status +window with type specific information. It may be necessary to use +<Command>pgdn</Command> and <Command>pgup</Command> to view the entire data. +</Para> + +</Sect2> + +<Sect2> +<Title>writedata</Title> + +<Para> + +<Screen> +Syntax: writedata +</Screen> + +The <Command>writedata</Command> command will update the disk with the object data that +is currently in memory. This is the point at which actual change is made to +the filesystem. Without this command, the edited data will not have any +effect. Write access should be allowed for a successful update. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>Editing an ext2 filesystem</Title> + +<Para> +In order to edit an ext2 filesystem, you should, of course, know the structure +of the ext2 filesystem. If you feel that you lack some knowledge in this +area, I suggest that you do some of the following: + +<ItemizedList> +<ListItem> + +<Para> + Read the supplied ext2 technical information. I tried to summarize +the basic information which is needed to get you started. +</Para> +</ListItem> +<ListItem> + +<Para> + Get the slides that Remy Card (The author of the ext2 filesystem) +prepared concerning the ext2 filesystem. +</Para> +</ListItem> +<ListItem> + +<Para> + Read the kernel sources. +</Para> +</ListItem> + +</ItemizedList> + +At this point, you should be familiar with the following terms: +<Literal remap="tt">block, inode, superblock, block groups, block allocation bitmap, inode +allocation bitmap, group descriptors, file, directory.</Literal>Most of the above +are objects in EXT2ED. +</Para> + +<Para> +When editing an ext2 filesystem it is recommended that you use the ext2 +specific commands, rather then the general commands <Command>setoffset</Command> and +<Command>settype</Command>, mainly because: + +<OrderedList> +<ListItem> + +<Para> + In most cases it will be unreliable, and will display incorrect +information. + +Sometimes in order to edit an object, EXT2ED needs the information +of some other related objects. For example, when editing a +directory, EXT2ED needs access to the inode of the edited directory. +Simply setting the type to a directory <Literal remap="tt">will be unreliable</Literal>, +since the object assumes that you passed through its inode to reach +it, and expects this information, which isn't initialized if you +directly set the type to a directory. +</Para> +</ListItem> +<ListItem> + +<Para> + EXT2ED offers far better tools for handling the ext2 filesystem +using the ext2 specific commands. +</Para> +</ListItem> + +</OrderedList> + +</Para> + +</Sect1> + +<Sect1> +<Title>ext2 general commands</Title> + +<Para> +The <Literal remap="tt">ext2 general commands</Literal> are available only when you are editing an +ext2 filesystem. They are <Literal remap="tt">general</Literal> in the sense that they are not +specific to some object, and can be invoked anytime. +</Para> + +<Sect2 id="general-superblock"> +<Title>super</Title> + +<Para> + +<Screen> +Syntax: super +</Screen> + +The <Command>super</Command> command will "bring you" to the main superblock copy. It +will automatically set the object type to <Literal remap="tt">ext2_super_block</Literal>. Then you +will be able to view and edit the superblock. When you are in the +superblock, other commands will be available. +</Para> + +</Sect2> + +<Sect2> +<Title>group</Title> + +<Para> + +<Screen> +Syntax: group [number] +</Screen> + +The <Command>group</Command> command will "bring you" to the main copy of the +<Emphasis>number</Emphasis> group descriptor. It will automatically set the object type to +<Literal remap="tt">ext2_group_desc</Literal>. Then you will be able to view and edit the group +descriptor entry. When you are there, other commands will be available. +</Para> + +</Sect2> + +<Sect2> +<Title>cd</Title> + +<Para> + +<Screen> +Syntax: cd path +</Screen> + +The <Command>cd</Command> command will let you travel in the filesystem in the nice way +that the mounted filesystem would have let you. +</Para> + +<Para> +The <Command>cd</Command> command is a complicated command. Although it may sound +simple at first, an implementation of a typical cd requires passing through +the group descriptors, inodes, directory entries, etc. For example: +</Para> + +<Para> +The innocent cd /usr command can be done by using more primitive +EXT2ED commands in the following way (It is implemented exactly this way): + +<OrderedList> +<ListItem> + +<Para> + Using <Command>group 0</Command> to go to the first group descriptor. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>inode</Command> to get to the Bad blocks inode. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>next</Command> to pass to the root directory inode. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>dir</Command> to see the directory. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>next</Command> until we find the directory usr. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>followinode</Command> to pass to the inode corresponding to usr. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>dir</Command> to see the directory of /usr. +</Para> +</ListItem> + +</OrderedList> + +And those commands aren't that primitive; For example, the tracing of the +blocks which belong to the root directory is done automatically by the dir +command behind the scenes, and the followinode command will automatically +"run" to the correct group descriptor in order to find the required inode. +</Para> + +<Para> +The path to the <Command>general cd</Command> command needs to be a full pathname - +Starting from <Filename>/</Filename>. The <Command>cd</Command> command stops at the last reachable +point, which can be a directory entry, in which case the type will be set to +<Literal remap="tt">dir</Literal>, or an inode, in which case the type will be set to +<Literal remap="tt">ext2_inode</Literal>. Symbolic links (Only fast symbolic links, meanwhile) are +automatically followed (if they are not across filesystems, of-course). If +the type is set to <Literal remap="tt">dir</Literal>, you can use a path relative to the +"current directory". +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The superblock</Title> + +<Para> +The superblock can always be reached by the ext2 general command +<Command>super</Command>. Cross reference section <XRef LinkEnd="general-superblock">. +</Para> + +<Para> +The status window will show you which copy of the superblock copies you are +currently editing. +</Para> + +<Para> +The main data window will show you the values of the various superblock +variables, along with some interpretation of the values. +</Para> + +<Para> +Data can be changed with the <Command>set</Command> and <Command>writedata</Command> commands. + +<Screen> +For example, set s_r_blocks_count=1400 will reserve 1400 blocks for root. +</Screen> + +</Para> + +<Sect2> +<Title>gocopy</Title> + +<Para> + +<Screen> +Syntax: gocopy number +</Screen> + +The <Command>gocopy</Command> command will "bring you" to the backup copy <Emphasis>number</Emphasis> +of the superblock copies. <Command>gocopy 0</Command>, for example, will bring you to +the main copy. +</Para> + +</Sect2> + +<Sect2> +<Title>setactivecopy</Title> + +<Para> + +<Screen> +Syntax: setactivecopy +</Screen> + +The <Command>setactivecopy</Command> command will copy the contents of the current +superblock copy onto the contents of the main copy. It will also switch to +editing of the main copy. No actual data is written to disk, of-course, +until you issue the <Command>writedata</Command> command. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The group descriptors</Title> + +<Para> +The group descriptors can be edited by the <Command>group</Command> command. +</Para> + +<Para> +The status window will indicate the current group descriptor, the total +number of group descriptors (and hence of group blocks), and the backup copy +number. +</Para> + +<Para> +The main data window will just show you the values of the various variables. +</Para> + +<Para> +Basically, you can use the <Command>next</Command> and <Command>prev</Command> commands, along with the +<Command>set</Command> command, to modify the group descriptors. +</Para> + +<Para> +The group descriptors object is a junction, from which you can reach: + +<ItemizedList> +<ListItem> + +<Para> + The inode table of the corresponding block group (the <Literal remap="tt">inode</Literal> +command) +</Para> +</ListItem> +<ListItem> + +<Para> + The block allocation bitmap (the <Literal remap="tt">blockbitmap</Literal> command) +</Para> +</ListItem> +<ListItem> + +<Para> + The inode allocation bitmap (the <Literal remap="tt">inodebitmap</Literal> command) +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Sect2> +<Title>blockbitmap</Title> + +<Para> + +<Screen> +Syntax: blockbitmap +</Screen> + +The <Command>blockbitmap</Command> command will let you edit the block bitmap allocation +block of the current group block. +</Para> + +</Sect2> + +<Sect2> +<Title>entry</Title> + +<Para> + +<Screen> +Syntax: entry number +</Screen> + +The <Command>entry</Command> command will move you to the <Emphasis>number</Emphasis> group descriptor in the +group descriptors table. +</Para> + +</Sect2> + +<Sect2> +<Title>inode</Title> + +<Para> + +<Screen> +Syntax: inode +</Screen> + +The <Command>inode</Command> command will pass you to the first inode in the current +group block. +</Para> + +</Sect2> + +<Sect2> +<Title>inodebitmap</Title> + +<Para> + +<Screen> +Syntax: inodebitmap +</Screen> + +The <Command>inodebitmap</Command> command will let you edit the inode bitmap allocation +block of the current group block. +</Para> + +</Sect2> + +<Sect2> +<Title>next</Title> + +<Para> + +<Screen> +Syntax: next [number] +</Screen> + +The <Command>next</Command> command will pass to the next <Emphasis>number</Emphasis> group +descriptor. If <Emphasis>number</Emphasis> is omitted, <Emphasis>number=1</Emphasis> is assumed. +</Para> + +</Sect2> + +<Sect2> +<Title>prev</Title> + +<Para> + +<Screen> +Syntax: prev [number] +</Screen> + +The <Command>prev</Command> command will pass to the previous <Emphasis>number</Emphasis> group +descriptor. If <Emphasis>number</Emphasis> is omitted, <Emphasis>number=1</Emphasis> is assumed. +</Para> + +</Sect2> + +<Sect2> +<Title>setactivecopy</Title> + +<Para> + +<Screen> +Syntax: setactivecopy +</Screen> + +The <Command>setactivecopy</Command> command copies the contents of the current group +descriptor, to its main copy. The updated main copy will then be shown. No +actual change is made to the disk until you issue the <Command>writedata</Command> +command. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The inode</Title> + +<Para> +An inode can be reached by the following two ways: + +<ItemizedList> +<ListItem> + +<Para> + Using <Command>inode</Command> from the corresponding group descriptor. +</Para> +</ListItem> +<ListItem> + +<Para> + Using <Command>followinode</Command> from a directory entry. +</Para> +</ListItem> +<ListItem> + +<Para> + Using the <Command>cd</Command> command with the pathname to the file. + +For example, <Command>cd /usr/src/ext2ed/ext2ed.h</Command> +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The status window will indicate: + +<ItemizedList> +<ListItem> + +<Para> + The current global inode number. +</Para> +</ListItem> +<ListItem> + +<Para> + The total total number of inodes. +</Para> +</ListItem> +<ListItem> + +<Para> + On which block group the inode is allocated. +</Para> +</ListItem> +<ListItem> + +<Para> + The total number of inodes in this group block. +</Para> +</ListItem> +<ListItem> + +<Para> + The index of the current inode in the current group block. +</Para> +</ListItem> +<ListItem> + +<Para> + The type of the inode (file, directory, special, etc). +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The main data window, in addition to the list of variables, will contain +some interpretations on the right side. +</Para> + +<Para> +If the inode corresponds to a file, you can use the <Command>file</Command> command to +edit the file. +</Para> + +<Para> +If the inode is an inode of a directory, you can use the <Command>dir</Command> command +to edit the directory. +</Para> + +<Sect2> +<Title>dir</Title> + +<Para> + +<Screen> +Syntax: dir +</Screen> + +If the inode mode corresponds to a directory (shown on the status window), +you can enter directory mode editing by using <Literal remap="tt">dir</Literal>. +</Para> + +</Sect2> + +<Sect2> +<Title>entry</Title> + +<Para> + +<Screen> +Syntax: entry number +</Screen> + +The <Command>entry</Command> command will move you to the <Emphasis>number</Emphasis> inode in the +current inode table. +</Para> + +</Sect2> + +<Sect2> +<Title>file</Title> + +<Para> + +<Screen> +Syntax: file +</Screen> + +If the inode mode corresponds to a file (shown on the status window), +you can enter file mode editing by using <Command>file</Command>. +</Para> + +</Sect2> + +<Sect2> +<Title>group</Title> + +<Para> + +<Screen> +Syntax: group +</Screen> + +The <Command>group</Command> command is used to go to the group descriptor of the +current group block. +</Para> + +</Sect2> + +<Sect2> +<Title>next</Title> + +<Para> + +<Screen> +Syntax: next [number] +</Screen> + +The <Command>next</Command> command will pass to the next <Emphasis>number</Emphasis> inode. +If <Emphasis>number</Emphasis> is omitted, <Emphasis>number=1</Emphasis> is assumed. +</Para> + +</Sect2> + +<Sect2> +<Title>prev</Title> + +<Para> + +<Screen> +Syntax: prev [number] +</Screen> + +The <Command>prev</Command> command will pass to the previous <Emphasis>number</Emphasis> inode. +If <Emphasis>number</Emphasis> is omitted, <Emphasis>number=1</Emphasis> is assumed. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The file</Title> + +<Para> +When editing a file, EXT2ED offers you a both a continuous and a true +fragmented view of the file - The file is still shown block by block with +the true block number at each stage and EXT2ED offers you commands which +allow you to move between the <Literal remap="tt">file blocks</Literal>, while finding the +allocated blocks by using the inode information behind the scenes. +</Para> + +<Para> +Aside from this, the editing is just a <Literal remap="tt">hex editing</Literal> - You move the +cursor in the current block of the file by using <Command>next</Command> and +<Command>prev</Command>, move between blocks by <Command>nextblock</Command> and <Command>prevblock</Command>, +and make changes by the <Command>set</Command> command. Note that the set command is +overridden here - There are no variables. The <Command>writedata</Command> command will +update the current block to the disk. +</Para> + +<Para> +Reaching a file can be done by using the <Command>file</Command> command from its inode. +The inode can be reached by any other means, for example, by the +<Command>cd</Command> command, if you know the file name. +</Para> + +<Para> +The status window will indicate: + +<ItemizedList> +<ListItem> + +<Para> + The global block number. +</Para> +</ListItem> +<ListItem> + +<Para> + The internal file block number. +</Para> +</ListItem> +<ListItem> + +<Para> + The file offset. +</Para> +</ListItem> +<ListItem> + +<Para> + The file size. +</Para> +</ListItem> +<ListItem> + +<Para> + The file inode number. +</Para> +</ListItem> +<ListItem> + +<Para> + The indirection level - Whether it is a direct block (0), indirect +(1), etc. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +The main data window will display the file either in hex mode or in text +mode, select-able by the <Command>display</Command> command. +</Para> + +<Para> +In hex mode, EXT2ED will display offsets in the current block, along with a +text and hex dump of the current block. +</Para> + +<Para> +In either case the <Literal remap="tt">current place</Literal> will be highlighted. In the hex mode +it will be always highlighted, while in the text mode it will be highlighted +if the character is display-able. +</Para> + +<Sect2> +<Title>block</Title> + +<Para> + +<Screen> +Syntax: block block_num +</Screen> + +The <Command>block</Command> command is used to move inside the file. The +<Emphasis>block_num</Emphasis> argument is the requested internal file block number. A +value of 0 will reach the beginning of the file. +</Para> + +</Sect2> + +<Sect2> +<Title>display</Title> + +<Para> + +<Screen> +Syntax: display [text || hex] +</Screen> + +The <Command>display</Command> command changes the display mode of the file. +<Command>display +hex</Command> will switch to <Command>hex mode</Command>, while <Command>display text</Command> will switch +to text mode. The default mode when no <Command>display</Command> command is issued is +<Command>hex mode</Command>. +</Para> + +</Sect2> + +<Sect2> +<Title>inode</Title> + +<Para> + +<Screen> +Syntax: inode +</Screen> + +The <Command>inode</Command> command will return to the inode of the current file. +</Para> + +</Sect2> + +<Sect2> +<Title>next</Title> + +<Para> + +<Screen> +Syntax: next [num] +</Screen> + +The <Command>next</Command> command will pass to the next byte in the file. If +<Emphasis>num</Emphasis> is supplied, it will pass to the next <Emphasis>num</Emphasis> bytes. +</Para> + +</Sect2> + +<Sect2> +<Title>nextblock</Title> + +<Para> + +<Screen> +Syntax: nextblock [num] +</Screen> + +The <Command>nextblock</Command> command will pass to the next block in the file. If +<Emphasis>num</Emphasis> is supplied, it will pass to the next <Emphasis>num</Emphasis> blocks. +</Para> + +</Sect2> + +<Sect2> +<Title>prev</Title> + +<Para> + +<Screen> +Syntax: prev [num] +</Screen> + +The <Command>prev</Command> command will pass to the previous byte in the file. If +<Emphasis>num</Emphasis> is supplied, it will pass to the previous <Emphasis>num</Emphasis> bytes. +</Para> + +</Sect2> + +<Sect2> +<Title>prevblock</Title> + +<Para> + +<Screen> +Syntax: prevblock [num] +</Screen> + +The <Command>nextblock</Command> command will pass to the previous block in the file. If +<Emphasis>num</Emphasis> is supplied, it will pass to the previous <Emphasis>num</Emphasis> blocks. +</Para> + +</Sect2> + +<Sect2> +<Title>offset</Title> + +<Para> + +<Screen> +Syntax: offset file_offset +</Screen> + +The <Command>offset</Command> command will move to the specified offset in the file. +</Para> + +</Sect2> + +<Sect2> +<Title>set</Title> + +<Para> + +<Screen> +Syntax: set [text || hex] arg1 [arg2 arg3 ...] +</Screen> + +The <Command>file set</Command> command is working like the <Literal remap="tt">general set command</Literal>, +with <Literal remap="tt">type=none</Literal>. There are no variables. +</Para> + +</Sect2> + +<Sect2> +<Title>writedata</Title> + +<Para> + +<Screen> +Syntax: writedata +</Screen> + +The <Command>writedata</Command> command will update the current file block in the disk. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The directory</Title> + +<Para> +When editing a file, EXT2ED analyzes for you both the allocation blocks of +the directory entries, and the directory entries. +</Para> + +<Para> +Each directory entry is displayed on one row. You can move the highlighted +entry with the usual <Command>next</Command> and <Command>prev</Command> commands, and "dive in" +with the <Command>followinode</Command> command. +</Para> + +<Para> +The status window will indicate: + +<ItemizedList> +<ListItem> + +<Para> + The directory entry number. +</Para> +</ListItem> +<ListItem> + +<Para> + The total number of directory entries in this directory. +</Para> +</ListItem> +<ListItem> + +<Para> + The current global block number. +</Para> +</ListItem> +<ListItem> + +<Para> + The current offset in the entire directory - When viewing the +directory as a continuous file. +</Para> +</ListItem> +<ListItem> + +<Para> + The inode number of the directory itself. +</Para> +</ListItem> +<ListItem> + +<Para> + The indirection level - Whether it is a direct block (0), indirect +(1), etc. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Sect2> +<Title>cd</Title> + +<Para> + +<Screen> +Syntax: cd [path] +</Screen> + +The <Command>cd</Command> command is used in the usual meaning, like the global cd +command. + +<ItemizedList> +<ListItem> + +<Para> + If <Emphasis>path</Emphasis> is not specified, the current directory entry is +followed. +</Para> +</ListItem> +<ListItem> + +<Para> + <Emphasis>path</Emphasis> can be relative to the current directory. +</Para> +</ListItem> +<ListItem> + +<Para> + <Emphasis>path</Emphasis> can also end up in a file, in which case the file inode +will be reached. +</Para> +</ListItem> +<ListItem> + +<Para> + Symbolic link (fast only, meanwhile) is automatically followed. +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +</Sect2> + +<Sect2> +<Title>entry</Title> + +<Para> + +<Screen> +Syntax: entry [entry_num] +</Screen> + +The <Command>entry</Command> command sets <Emphasis>entry_num</Emphasis> as the current directory +entry. +</Para> + +</Sect2> + +<Sect2> +<Title>followinode</Title> + +<Para> + +<Screen> +Syntax: followinode +</Screen> + +The <Command>followinode</Command> command will move you to the inode pointed by the +current directory entry. +</Para> + +</Sect2> + +<Sect2> +<Title>inode</Title> + +<Para> + +<Screen> +Syntax: inode +</Screen> + +The <Command>inode</Command> command will return you to the parent inode of the whole +directory listing. +</Para> + +</Sect2> + +<Sect2> +<Title>next</Title> + +<Para> + +<Screen> +Syntax: next [num] +</Screen> + +The <Command>next</Command> command will pass to the next directory entry. +If <Emphasis>num</Emphasis> is supplied, it will pass to the next <Emphasis>num</Emphasis> entries. +</Para> + +</Sect2> + +<Sect2> +<Title>prev</Title> + +<Para> + +<Screen> +Syntax: prev [num] +</Screen> + +The <Command>prev</Command> command will pass to the previous directory entry. +If <Emphasis>num</Emphasis> is supplied, it will pass to the previous <Emphasis>num</Emphasis> entries. +</Para> + +</Sect2> + +<Sect2> +<Title>writedata</Title> + +<Para> + +<Screen> +Syntax: writedata +</Screen> + +The <Command>writedata</Command> command will write the current directory entry to the +disk. +</Para> + +</Sect2> + +</Sect1> + +<Sect1 id="block-bitmap"> +<Title>The block allocation bitmap</Title> + +<Para> +The <Literal remap="tt">block allocation bitmap</Literal> of any block group can be reached from +the corresponding group descriptor. +</Para> + +<Para> +You will be offered a bit listing of the entire blocks in the group. The +current block will be highlighted and its number will be displayed in the +status window. +</Para> + +<Para> +A value of "1" means that the block is allocated, while a value of "0" +signals that it is free. The value is also interpreted in the status +window. You can use the usual <Command>next/prev</Command> commands, along with the +<Command>allocate/deallocate</Command> commands. +</Para> + +<Sect2> +<Title>allocate</Title> + +<Para> + +<Screen> +Syntax: allocate [num] +</Screen> + +The <Command>allocate</Command> command allocates <Emphasis>num</Emphasis> blocks, starting from the +highlighted position. If <Emphasis>num</Emphasis> is not specified, <Emphasis>num=1</Emphasis> is assumed. +Of-course, no actual change is made until you issue a <Command>writedata</Command> command. +</Para> + +</Sect2> + +<Sect2> +<Title>deallocate</Title> + +<Para> + +<Screen> +Syntax: deallocate [num] +</Screen> + +The <Command>deallocate</Command> command deallocates <Emphasis>num</Emphasis> blocks, starting from the +highlighted position. If <Emphasis>num</Emphasis> is not specified, <Emphasis>num=1</Emphasis> is assumed. +Of-course, no actual change is made until you issue a <Command>writedata</Command> command. +</Para> + +</Sect2> + +<Sect2> +<Title>entry</Title> + +<Para> + +<Screen> +Syntax: entry [entry_num] +</Screen> + +The <Command>entry</Command> command sets the current highlighted block to +<Emphasis>entry_num</Emphasis>. +</Para> + +</Sect2> + +<Sect2> +<Title>next</Title> + +<Para> + +<Screen> +Syntax: next [num] +</Screen> + +The <Command>next</Command> command will pass to the next bit, which corresponds to the +next block. If <Emphasis>num</Emphasis> is supplied, it will pass to the next <Emphasis>num</Emphasis> +bits. +</Para> + +</Sect2> + +<Sect2> +<Title>prev</Title> + +<Para> + +<Screen> +Syntax: prev [num] +</Screen> + +The <Command>prev</Command> command will pass to the previous bit, which corresponds to the +previous block. If <Emphasis>num</Emphasis> is supplied, it will pass to the previous +<Emphasis>num</Emphasis> bits. +</Para> + +</Sect2> + +</Sect1> + +<Sect1> +<Title>The inode allocation bitmap</Title> + +<Para> +The <Literal remap="tt">inode allocation bitmap</Literal> is very similar to the block allocation +bitmap explained above. It is also reached from the corresponding group +descriptor. Please refer to section <XRef LinkEnd="block-bitmap">. +</Para> + +</Sect1> + +<Sect1> +<Title>Filesystem size limitation</Title> + +<Para> +While an ext2 filesystem has a size limit of <Literal remap="tt">4 TB</Literal>, EXT2ED currently +<Literal remap="tt">can't</Literal> handle filesystems which are <Literal remap="tt">bigger than 2 GB</Literal>. +</Para> + +<Para> +I am sorry for the inconvenience. This will hopefully be fixed in future +releases. +</Para> + +</Sect1> + +<Sect1> +<Title>Copyright</Title> + +<Para> +EXT2ED is Copyright (C) 1995 Gadi Oxman. +</Para> + +<Para> +EXT2ED is hereby placed under the GPL - Gnu Public License. You are free and +welcome to copy, view and modify the sources. My only wish is that my +copyright presented above will be left and that a list of the bug fixes, +added features, etc, will be provided. +</Para> + +<Para> +The entire EXT2ED project is based, of-course, on the kernel sources. The +<Literal remap="tt">ext2.descriptors</Literal> distributed with EXT2ED is a slightly modified +version of the main ext2 include file, /usr/include/linux/ext2_fs.h. Follows +the original copyright: +</Para> + +<Para> + +<Screen> +/* + * linux/include/linux/ext2_fs.h + * + * Copyright (C) 1992, 1993, 1994, 1995 + * Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * from + * + * linux/include/linux/minix_fs.h + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +</Screen> + +</Para> + +</Sect1> + +<Sect1> +<Title>Acknowledgments</Title> + +<Para> +EXT2ED was constructed as a student project in the software +laboratory of the faculty of electrical-engineering in the +<Literal remap="tt">Technion - Israel's institute of technology</Literal>. +</Para> + +<Para> +At first, I would like to thank <PersonName><FirstName>Avner</FirstName> <SurName>Lottem</SurName></PersonName> and <PersonName><Honorific>Doctor</Honorific> <FirstName>Ilana</FirstName> <SurName>David</Surname></PersonName> for their interest and assistance in this project. +</Para> + +<Para> +I would also like to thank the following people, who were involved in the +design and implementation of the ext2 filesystem kernel code and support +utilities: + +<ItemizedList> +<ListItem> + +<Para> +<PersonName><FirstName>Remy</FirstName> <SurName>Card</SurName></PersonName> + +Who designed, implemented and maintains the ext2 filesystem kernel +code, and some of the ext2 utilities. Remy Card is also the author +of several helpful slides concerning the ext2 filesystem. +Specifically, he is the author of <Literal remap="tt">File Management in the Linux +Kernel</Literal> and of <Literal remap="tt">The Second Extended File System - Current State, +Future Development</Literal>. + +</Para> +</ListItem> +<ListItem> + +<Para> +<PersonName><FirstName>Wayne</FirstName> <SurName>Davison</SurName></PersonName> + +Who designed the ext2 filesystem. +</Para> +</ListItem> +<ListItem> + +<Para> +<PersonName><FirstName>Stephen</FirstName> <Surname>Tweedie</SurName></PersonName> + +Who helped designing the ext2 filesystem kernel code and wrote the +slides <Literal remap="tt">Optimizations in File Systems</Literal>. +</Para> +</ListItem> +<ListItem> + +<Para> +<PersonName><FirstName>Theodore</FirstName> <SurName>Ts'o</SurName></PersonName> + +Who is the author of several ext2 utilities and of the ext2 library +<Literal remap="tt">libext2fs</Literal> (which I didn't use, simply because I didn't know +it exists when I started to work on my project). +</Para> +</ListItem> + +</ItemizedList> + +</Para> + +<Para> +Lastly, I would like to thank, of-course, <PersonName><FirstName>Linus</FirstName> <SurName>Torvalds</SurName></PersonName> and the +Linux community for providing all of us with such a great operating +system. +</Para> + +<Para> +Please contact me in a case of bug report, suggestions, or just about +anything concerning EXT2ED. +</Para> + +<Para> +Enjoy, +</Para> + +<Para> +Gadi Oxman <tgud@tochnapc2.technion.ac.il> +</Para> + +<Para> +Haifa, August 95 +</Para> + +</Sect1> + +</Article> diff --git a/ext2ed/ext2.descriptors b/ext2ed/ext2.descriptors new file mode 100644 index 0000000..e356f4c --- /dev/null +++ b/ext2ed/ext2.descriptors @@ -0,0 +1,976 @@ +Extended 2 filesystem structure definitions for ext2ed. + +Most of this file is just copied from the ext2 main include file. + +My parser is very primitive - It only searches for the struct keywords, +and uses the variables in there. The rest of the file is just ignored. + +You will find at the end a few additional types which are not available in +the original include file, such as the types "file" and "dir". They have +no variables, but are necessary due to the way ext2ed binds C commands +to specific types. + +Gadi Oxman, 7/95 + +Here is the original copyright: + +/* + * linux/include/linux/ext2_fs.h + * + * Copyright (C) 1992, 1993, 1994 Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * from + * + * linux/include/linux/minix_fs.h + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + + +/* + * ACL structures + */ +struct ext2_acl_header /* Header of Access Control Lists */ +{ + unsigned long aclh_size; + unsigned long aclh_file_count; + unsigned long aclh_acle_count; + unsigned long aclh_first_acle; +}; + +struct ext2_acl_entry /* Access Control List Entry */ +{ + unsigned long acle_size; + unsigned short acle_perms; /* Access permissions */ + unsigned short acle_type; /* Type of entry */ + unsigned short acle_tag; /* User or group identity */ + unsigned short acle_pad1; + unsigned long acle_next; /* Pointer on next entry for the */ + /* same inode or on next free entry */ +}; + +/* + * Structure of a blocks group descriptor + */ + +struct ext2_group_desc +{ + __u32 bg_block_bitmap; /* Blocks bitmap block */ + __u32 bg_inode_bitmap; /* Inodes bitmap block */ + __u32 bg_inode_table; /* Inodes table block */ + __u16 bg_free_blocks_count; /* Free blocks count */ + __u16 bg_free_inodes_count; /* Free inodes count */ + __u16 bg_used_dirs_count; /* Directories count */ + __u16 bg_pad; + __u32 bg_reserved[0]; + __u32 bg_reserved[1]; + __u32 bg_reserved[2]; +}; + +/* + * Structure of an inode on the disk + */ +struct ext2_inode { + __u16 i_mode; /* File mode */ + __u16 i_uid; /* Owner Uid */ + __u32 i_size; /* Size in bytes */ + __u32 i_atime; /* Access time */ + __u32 i_ctime; /* Creation time */ + __u32 i_mtime; /* Modification time */ + __u32 i_dtime; /* Deletion Time */ + __u16 i_gid; /* Group Id */ + __u16 i_links_count; /* Links count */ + __u32 i_blocks; /* Blocks count */ + __u32 i_flags; /* File flags */ + __u32 l_i_reserved1; + __u32 i_block[0]; /* Pointers to blocks */ + __u32 i_block[1]; /* Pointers to blocks */ + __u32 i_block[2]; /* Pointers to blocks */ + __u32 i_block[3]; /* Pointers to blocks */ + __u32 i_block[4]; /* Pointers to blocks */ + __u32 i_block[5]; /* Pointers to blocks */ + __u32 i_block[6]; /* Pointers to blocks */ + __u32 i_block[7]; /* Pointers to blocks */ + __u32 i_block[8]; /* Pointers to blocks */ + __u32 i_block[9]; /* Pointers to blocks */ + __u32 i_block[10]; /* Pointers to blocks */ + __u32 i_block[11]; /* Pointers to blocks */ + __u32 i_block[12]; /* Pointers to blocks */ + __u32 i_block[13]; /* Pointers to blocks */ + __u32 i_block[14]; /* Pointers to blocks */ + __u32 i_version; /* File version (for NFS) */ + __u32 i_file_acl; /* File ACL */ + __u32 i_size_high; /* High 32bits of size */ + __u32 i_faddr; /* Fragment address */ + __u8 l_i_frag; /* Fragment number */ + __u8 l_i_fsize; /* Fragment size */ + __u16 i_pad1; + __u16 l_i_uid_high; /* these 2 fields */ + __u16 l_i_gid_high; /* were reserved2[0] */ + __u32 l_i_reserved2; +}; + +/* + * Structure of the super block + */ +struct ext2_super_block { + __u32 s_inodes_count; /* Inodes count */ + __u32 s_blocks_count; /* Blocks count */ + __u32 s_r_blocks_count; /* Reserved blocks count */ + __u32 s_free_blocks_count; /* Free blocks count */ + __u32 s_free_inodes_count; /* Free inodes count */ + __u32 s_first_data_block; /* First Data Block */ + __u32 s_log_block_size; /* Block size */ + __s32 s_log_frag_size; /* Fragment size */ + __u32 s_blocks_per_group; /* # Blocks per group */ + __u32 s_frags_per_group; /* # Fragments per group */ + __u32 s_inodes_per_group; /* # Inodes per group */ + __u32 s_mtime; /* Mount time */ + __u32 s_wtime; /* Write time */ + __u16 s_mnt_count; /* Mount count */ + __s16 s_max_mnt_count; /* Maximal mount count */ + __u16 s_magic; /* Magic signature */ + __u16 s_state; /* File system state */ + __u16 s_errors; /* Behaviour when detecting errors */ + __u16 s_minor_rev_level; /* minor revision level */ + __u32 s_lastcheck; /* time of last check */ + __u32 s_checkinterval; /* max. time between checks */ + __u32 s_creator_os; /* OS */ + __u32 s_rev_level; /* Revision level */ + __u16 s_def_resuid; /* Default uid for reserved blocks */ + __u16 s_def_resgid; /* Default gid for reserved blocks */ + __u32 s_first_ino; /* First non-reserved inode */ + __u16 s_inode_size; /* size of inode structure */ + __u16 s_block_group_nr; /* block group # of this superblock */ + __u32 s_feature_compat; /* compatible feature set */ + __u32 s_feature_incompat; /* incompatible feature set */ + __u32 s_feature_ro_compat; /* readonly-compatible feature set */ + char[16] s_uuid; /* 128-bit uuid for volume */ + char[16] s_volume_name; /* volume name */ + char[64] s_last_mounted; /* directory where last mounted */ + __u32 s_algorithm_usage_bitmap; /* For compression */ + /* + * Performance hints. Directory preallocation should only + * happen if the EXT2_FEATURE_COMPAT_DIR_PREALLOC flag is on. + */ + __u8 s_prealloc_blocks; /* Nr of blocks to try to preallocate*/ + __u8 s_prealloc_dir_blocks; /* Nr to preallocate for dirs */ + __u16 s_padding1; + /* + * Journaling support valid if EXT2_FEATURE_COMPAT_HAS_JOURNAL set. + */ + char[16] s_journal_uuid; /* uuid of journal superblock */ + __u32 s_journal_inum; /* inode number of journal file */ + __u32 s_journal_dev; /* device number of journal file */ + __u32 s_last_orphan; /* start of list of inodes to delete */ + + + __u32 s_reserved[0]; /* Padding to the end of the block */ + __u32 s_reserved[1]; + __u32 s_reserved[2]; + __u32 s_reserved[3]; + __u32 s_reserved[4]; + __u32 s_reserved[5]; + __u32 s_reserved[6]; + __u32 s_reserved[7]; + __u32 s_reserved[8]; + __u32 s_reserved[9]; + __u32 s_reserved[10]; + __u32 s_reserved[11]; + __u32 s_reserved[12]; + __u32 s_reserved[13]; + __u32 s_reserved[14]; + __u32 s_reserved[15]; + __u32 s_reserved[16]; 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+ __u32 s_reserved[181]; + __u32 s_reserved[182]; + __u32 s_reserved[183]; + __u32 s_reserved[184]; + __u32 s_reserved[185]; + __u32 s_reserved[186]; + __u32 s_reserved[187]; + __u32 s_reserved[188]; + __u32 s_reserved[189]; + __u32 s_reserved[190]; + __u32 s_reserved[191]; + __u32 s_reserved[192]; + __u32 s_reserved[193]; + __u32 s_reserved[194]; + __u32 s_reserved[195]; + __u32 s_reserved[196]; +}; + +The following is actually not used, due to the variable length of the +name field. EXT2ED handles directories through the type "dir" below. + +/* + * Structure of a directory entry + */ + +/* struct ext2_dir_entry { */ +/* + __u32 inode; /* Inode number */ + __u16 rec_len; /* Directory entry length */ + __u16 name_len; /* Name length */ + char name[EXT2_NAME_LEN]; /* File name */ +}; +*/ + +struct file { +}; + +struct dir { +}; + +struct block_bitmap { +}; + +struct inode_bitmap { +}; + +struct ext2_dx_root_node { + __u32 dot_inode; + __u16 dot_rec_len; + __u8 dot_name_len; + __u8 dot_file_type; + char[4] dot_name; + __u32 dot_dot_inode; + __u16 dot_dot_rec_len; + __u8 dot_dot_name_len; + __u8 dot_dot_file_type; + char[4] dot_dot_name; + __u32 reserved_zero; + __u8 hash_version; /* 0 now, 1 at release */ + __u8 info_length; /* 8 */ + __u8 indirect_levels; + __u8 unused_flags; + __u16 limit; + __u16 count; + __u32 block[0]; + __u32 hash[1]; + __u32 block[1]; + __u32 hash[2]; + __u32 block[2]; + __u32 hash[3]; + __u32 block[3]; + __u32 hash[4]; + __u32 block[4]; + __u32 hash[5]; + __u32 block[5]; + __u32 hash[6]; + __u32 block[6]; + __u32 hash[7]; + __u32 block[7]; + __u32 hash[8]; + __u32 block[8]; + __u32 hash[9]; + __u32 block[9]; + __u32 hash[10]; + __u32 block[10]; + __u32 hash[11]; + __u32 block[11]; + __u32 hash[12]; + __u32 block[12]; + __u32 hash[13]; + __u32 block[13]; + __u32 hash[14]; + __u32 block[14]; + __u32 hash[15]; + __u32 block[15]; + __u32 hash[16]; + __u32 block[16]; + __u32 hash[17]; + __u32 block[17]; + __u32 hash[18]; + __u32 block[18]; + __u32 hash[19]; + __u32 block[19]; + __u32 hash[20]; + __u32 block[20]; + __u32 hash[21]; + __u32 block[21]; + __u32 hash[22]; + __u32 block[22]; + __u32 hash[23]; + __u32 block[23]; + __u32 hash[24]; + __u32 block[24]; + __u32 hash[25]; + __u32 block[25]; + __u32 hash[26]; + __u32 block[26]; + __u32 hash[27]; + __u32 block[27]; + __u32 hash[28]; + __u32 block[28]; + __u32 hash[29]; + __u32 block[29]; + __u32 hash[30]; + __u32 block[30]; + __u32 hash[31]; + __u32 block[31]; + __u32 hash[32]; + __u32 block[32]; + __u32 hash[33]; + __u32 block[33]; + __u32 hash[34]; + __u32 block[34]; + __u32 hash[35]; + __u32 block[35]; + __u32 hash[36]; + __u32 block[36]; + __u32 hash[37]; + __u32 block[37]; + __u32 hash[38]; + __u32 block[38]; + __u32 hash[39]; + __u32 block[39]; + __u32 hash[40]; + __u32 block[40]; + __u32 hash[41]; + __u32 block[41]; + __u32 hash[42]; + __u32 block[42]; + __u32 hash[43]; + __u32 block[43]; + __u32 hash[44]; + __u32 block[44]; + __u32 hash[45]; + __u32 block[45]; + __u32 hash[46]; + __u32 block[46]; + __u32 hash[47]; + __u32 block[47]; + __u32 hash[48]; + __u32 block[48]; + __u32 hash[49]; + __u32 block[49]; + __u32 hash[50]; + __u32 block[50]; + __u32 hash[51]; + __u32 block[51]; + __u32 hash[52]; + __u32 block[52]; + __u32 hash[53]; + __u32 block[53]; + __u32 hash[54]; + __u32 block[54]; + __u32 hash[55]; + __u32 block[55]; + __u32 hash[56]; + __u32 block[56]; + __u32 hash[57]; + __u32 block[57]; + __u32 hash[58]; + __u32 block[58]; + __u32 hash[59]; + __u32 block[59]; + __u32 hash[60]; + __u32 block[60]; + __u32 hash[61]; + __u32 block[61]; + __u32 hash[62]; + __u32 block[62]; + __u32 hash[63]; + __u32 block[63]; + __u32 hash[64]; + __u32 block[64]; + __u32 hash[65]; + __u32 block[65]; + __u32 hash[66]; + __u32 block[66]; + __u32 hash[67]; + __u32 block[67]; + __u32 hash[68]; + __u32 block[68]; + __u32 hash[69]; + __u32 block[69]; + __u32 hash[70]; + __u32 block[70]; + __u32 hash[71]; + __u32 block[71]; + __u32 hash[72]; + __u32 block[72]; + __u32 hash[73]; + __u32 block[73]; + __u32 hash[74]; + __u32 block[74]; + __u32 hash[75]; + __u32 block[75]; + __u32 hash[76]; + __u32 block[76]; + __u32 hash[77]; + __u32 block[77]; + __u32 hash[78]; + __u32 block[78]; + __u32 hash[79]; + __u32 block[79]; + __u32 hash[80]; + __u32 block[80]; + __u32 hash[81]; + __u32 block[81]; + __u32 hash[82]; + __u32 block[82]; + __u32 hash[83]; + __u32 block[83]; + __u32 hash[84]; + __u32 block[84]; + __u32 hash[85]; + __u32 block[85]; + __u32 hash[86]; + __u32 block[86]; + __u32 hash[87]; + __u32 block[87]; + __u32 hash[88]; + __u32 block[88]; + __u32 hash[89]; + __u32 block[89]; + __u32 hash[80]; + __u32 block[80]; + __u32 hash[81]; + __u32 block[81]; + __u32 hash[82]; + __u32 block[82]; + __u32 hash[83]; + __u32 block[83]; + __u32 hash[84]; + __u32 block[84]; + __u32 hash[85]; + __u32 block[85]; + __u32 hash[86]; + __u32 block[86]; + __u32 hash[87]; + __u32 block[87]; + __u32 hash[88]; + __u32 block[88]; + __u32 hash[89]; + __u32 block[89]; + __u32 hash[90]; + __u32 block[90]; + __u32 hash[91]; + __u32 block[91]; + __u32 hash[92]; + __u32 block[92]; + __u32 hash[93]; + __u32 block[93]; + __u32 hash[94]; + __u32 block[94]; + __u32 hash[95]; + __u32 block[95]; + __u32 hash[96]; + __u32 block[96]; + __u32 hash[97]; + __u32 block[97]; + __u32 hash[98]; + __u32 block[98]; + __u32 hash[99]; + __u32 block[99]; + __u32 hash[100]; + __u32 block[100]; + __u32 hash[101]; + __u32 block[101]; + __u32 hash[102]; + __u32 block[102]; + __u32 hash[103]; + __u32 block[103]; + __u32 hash[104]; + __u32 block[104]; + __u32 hash[105]; + __u32 block[105]; + __u32 hash[106]; + __u32 block[106]; + __u32 hash[107]; + __u32 block[107]; + __u32 hash[108]; + __u32 block[108]; + __u32 hash[109]; + __u32 block[109]; + __u32 hash[110]; + __u32 block[110]; + __u32 hash[111]; + __u32 block[111]; + __u32 hash[112]; + __u32 block[112]; + __u32 hash[113]; + __u32 block[113]; + __u32 hash[114]; + __u32 block[114]; + __u32 hash[115]; + __u32 block[115]; + __u32 hash[116]; + __u32 block[116]; + __u32 hash[117]; + __u32 block[117]; + __u32 hash[118]; + __u32 block[118]; + __u32 hash[119]; + __u32 block[119]; + __u32 hash[120]; + __u32 block[120]; + __u32 hash[121]; + __u32 block[121]; + __u32 hash[122]; + __u32 block[122]; + __u32 hash[123]; + __u32 block[123]; + __u32 hash[124]; + __u32 block[124]; + __u32 hash[125]; + __u32 block[125]; + __u32 hash[126]; + __u32 block[126]; + __u32 hash[127]; + __u32 block[127]; +}; + +struct ext2_dx_int_node { + __u32 fake_inode; + __u16 fake_rec_len; + __u8 fake_name_len; + __u8 fake_file_type; + __u16 limit; + __u16 count; + __u32 block[0]; + __u32 hash[1]; + __u32 block[1]; + __u32 hash[2]; + __u32 block[2]; + __u32 hash[3]; + __u32 block[3]; + __u32 hash[4]; + __u32 block[4]; + __u32 hash[5]; + __u32 block[5]; + __u32 hash[6]; + __u32 block[6]; + __u32 hash[7]; + __u32 block[7]; + __u32 hash[8]; + __u32 block[8]; + __u32 hash[9]; + __u32 block[9]; + __u32 hash[10]; + __u32 block[10]; + __u32 hash[11]; + __u32 block[11]; + __u32 hash[12]; + __u32 block[12]; + __u32 hash[13]; + __u32 block[13]; + __u32 hash[14]; + __u32 block[14]; + __u32 hash[15]; + __u32 block[15]; + __u32 hash[16]; + __u32 block[16]; + __u32 hash[17]; + __u32 block[17]; + __u32 hash[18]; + __u32 block[18]; + __u32 hash[19]; + __u32 block[19]; + __u32 hash[20]; + __u32 block[20]; + __u32 hash[21]; + __u32 block[21]; + __u32 hash[22]; + __u32 block[22]; + __u32 hash[23]; + __u32 block[23]; + __u32 hash[24]; + __u32 block[24]; + __u32 hash[25]; + __u32 block[25]; + __u32 hash[26]; + __u32 block[26]; + __u32 hash[27]; + __u32 block[27]; + __u32 hash[28]; + __u32 block[28]; + __u32 hash[29]; + __u32 block[29]; + __u32 hash[30]; + __u32 block[30]; + __u32 hash[31]; + __u32 block[31]; + __u32 hash[32]; + __u32 block[32]; + __u32 hash[33]; + __u32 block[33]; + __u32 hash[34]; + __u32 block[34]; + __u32 hash[35]; + __u32 block[35]; + __u32 hash[36]; + __u32 block[36]; + __u32 hash[37]; + __u32 block[37]; + __u32 hash[38]; + __u32 block[38]; + __u32 hash[39]; + __u32 block[39]; + __u32 hash[40]; + __u32 block[40]; + __u32 hash[41]; + __u32 block[41]; + __u32 hash[42]; + __u32 block[42]; + __u32 hash[43]; + __u32 block[43]; + __u32 hash[44]; + __u32 block[44]; + __u32 hash[45]; + __u32 block[45]; + __u32 hash[46]; + __u32 block[46]; + __u32 hash[47]; + __u32 block[47]; + __u32 hash[48]; + __u32 block[48]; + __u32 hash[49]; + __u32 block[49]; + __u32 hash[50]; + __u32 block[50]; + __u32 hash[51]; + __u32 block[51]; + __u32 hash[52]; + __u32 block[52]; + __u32 hash[53]; + __u32 block[53]; + __u32 hash[54]; + __u32 block[54]; + __u32 hash[55]; + __u32 block[55]; + __u32 hash[56]; + __u32 block[56]; + __u32 hash[57]; + __u32 block[57]; + __u32 hash[58]; + __u32 block[58]; + __u32 hash[59]; + __u32 block[59]; + __u32 hash[60]; + __u32 block[60]; + __u32 hash[61]; + __u32 block[61]; + __u32 hash[62]; + __u32 block[62]; + __u32 hash[63]; + __u32 block[63]; + __u32 hash[64]; + __u32 block[64]; + __u32 hash[65]; + __u32 block[65]; + __u32 hash[66]; + __u32 block[66]; + __u32 hash[67]; + __u32 block[67]; + __u32 hash[68]; + __u32 block[68]; + __u32 hash[69]; + __u32 block[69]; + __u32 hash[70]; + __u32 block[70]; + __u32 hash[71]; + __u32 block[71]; + __u32 hash[72]; + __u32 block[72]; + __u32 hash[73]; + __u32 block[73]; + __u32 hash[74]; + __u32 block[74]; + __u32 hash[75]; + __u32 block[75]; + __u32 hash[76]; + __u32 block[76]; + __u32 hash[77]; + __u32 block[77]; + __u32 hash[78]; + __u32 block[78]; + __u32 hash[79]; + __u32 block[79]; + __u32 hash[80]; + __u32 block[80]; + __u32 hash[81]; + __u32 block[81]; + __u32 hash[82]; + __u32 block[82]; + __u32 hash[83]; + __u32 block[83]; + __u32 hash[84]; + __u32 block[84]; + __u32 hash[85]; + __u32 block[85]; + __u32 hash[86]; + __u32 block[86]; + __u32 hash[87]; + __u32 block[87]; + __u32 hash[88]; + __u32 block[88]; + __u32 hash[89]; + __u32 block[89]; + __u32 hash[80]; + __u32 block[80]; + __u32 hash[81]; + __u32 block[81]; + __u32 hash[82]; + __u32 block[82]; + __u32 hash[83]; + __u32 block[83]; + __u32 hash[84]; + __u32 block[84]; + __u32 hash[85]; + __u32 block[85]; + __u32 hash[86]; + __u32 block[86]; + __u32 hash[87]; + __u32 block[87]; + __u32 hash[88]; + __u32 block[88]; + __u32 hash[89]; + __u32 block[89]; + __u32 hash[90]; + __u32 block[90]; + __u32 hash[91]; + __u32 block[91]; + __u32 hash[92]; + __u32 block[92]; + __u32 hash[93]; + __u32 block[93]; + __u32 hash[94]; + __u32 block[94]; + __u32 hash[95]; + __u32 block[95]; + __u32 hash[96]; + __u32 block[96]; + __u32 hash[97]; + __u32 block[97]; + __u32 hash[98]; + __u32 block[98]; + __u32 hash[99]; + __u32 block[99]; + __u32 hash[100]; + __u32 block[100]; + __u32 hash[101]; + __u32 block[101]; + __u32 hash[102]; + __u32 block[102]; + __u32 hash[103]; + __u32 block[103]; + __u32 hash[104]; + __u32 block[104]; + __u32 hash[105]; + __u32 block[105]; + __u32 hash[106]; + __u32 block[106]; + __u32 hash[107]; + __u32 block[107]; + __u32 hash[108]; + __u32 block[108]; + __u32 hash[109]; + __u32 block[109]; + __u32 hash[110]; + __u32 block[110]; + __u32 hash[111]; + __u32 block[111]; + __u32 hash[112]; + __u32 block[112]; + __u32 hash[113]; + __u32 block[113]; + __u32 hash[114]; + __u32 block[114]; + __u32 hash[115]; + __u32 block[115]; + __u32 hash[116]; + __u32 block[116]; + __u32 hash[117]; + __u32 block[117]; + __u32 hash[118]; + __u32 block[118]; + __u32 hash[119]; + __u32 block[119]; + __u32 hash[120]; + __u32 block[120]; + __u32 hash[121]; + __u32 block[121]; + __u32 hash[122]; + __u32 block[122]; + __u32 hash[123]; + __u32 block[123]; + __u32 hash[124]; + __u32 block[124]; + __u32 hash[125]; + __u32 block[125]; + __u32 hash[126]; + __u32 block[126]; + __u32 hash[127]; + __u32 block[127]; +}; + + diff --git a/ext2ed/ext2_com.c b/ext2ed/ext2_com.c new file mode 100644 index 0000000..ed004f2 --- /dev/null +++ b/ext2ed/ext2_com.c @@ -0,0 +1,98 @@ +/* + +/usr/src/ext2ed/ext2_com.c + +A part of the extended file system 2 disk editor. + +-------------------------------------- +Extended-2 filesystem General commands +-------------------------------------- + +The commands here will be registered when we are editing an ext2 filesystem + +First written on: July 28 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" + +void type_ext2___super (char *command_line) + +/* + +We are moving to the superblock - Just use setoffset and settype. The offset was gathered in the +initialization phase (but is constant - 1024). + +*/ + +{ + char buffer [80]; + + super_info.copy_num=0; + sprintf (buffer,"setoffset %ld",file_system_info.super_block_offset);dispatch (buffer); + sprintf (buffer,"settype ext2_super_block");dispatch (buffer); +} + +void type_ext2___cd (char *command_line) + +/* + +A global cd command - The path should start with /. + +We implement it through dispatching to our primitive functions. + +*/ + +{ + char temp [80],buffer [80],*ptr; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n");refresh_command_win ();return; + } + ptr=parse_word (ptr,buffer); + + if (buffer [0] != '/') { + wprintw (command_win,"Error - Use a full pathname (begin with '/')\n");refresh_command_win ();return; + } + + /* Note the various dispatches below - They should be intuitive if you know the ext2 filesystem structure */ + + dispatch ("super");dispatch ("group");dispatch ("inode");dispatch ("next");dispatch ("dir"); + if (buffer [1] != 0) { + sprintf (temp,"cd %s",buffer+1);dispatch (temp); + } +} + +void type_ext2___group (char *command_line) + +/* + +We go to the group descriptors. +First, we go to the first group descriptor in the main copy. +Then, we use the group's entry command to pass to another group. + +*/ + +{ + long group_num=0; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + group_num=atol (buffer); + } + + group_info.copy_num=0;group_info.group_num=0; + sprintf (buffer,"setoffset %ld",file_system_info.first_group_desc_offset);dispatch (buffer); + sprintf (buffer,"settype ext2_group_desc");dispatch (buffer); + sprintf (buffer,"entry %ld",group_num);dispatch (buffer); +} diff --git a/ext2ed/ext2ed.8.in b/ext2ed/ext2ed.8.in new file mode 100644 index 0000000..e827277 --- /dev/null +++ b/ext2ed/ext2ed.8.in @@ -0,0 +1,72 @@ +.\" -*- nroff -*- +.TH EXT2ED 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@" +.SH NAME +ext2ed \- ext2 file system editor +.SH SYNOPSIS +.B ext2ed +.SH DESCRIPTION +.B ext2ed +in an +.B editor +for the +.B second extended file system. +Its aim is to show you the various internal file system structures in an +intuitive form so that you would be able to easily understand and modify +them. +.SH DOCUMENTATION +The documentation is not available in man page format. Instead, I have +written three articles which are related to ext2ed: + +The first article is +.B The user's guide. +This article explains how to use ext2ed. + +The second article is +.B The Ext2fs overview. +This article gives an overview of internal structure of the ext2 file system. +You need to understand the internal layout in order to effectively edit +your file system. + +The third article is +.B EXT2ED - Design and implementation. +This article explains how I constructed ext2ed. You may want to have a look +in it if you plan to view or modify the source code. + +.SH WARNING + +.B +Do not use ext2ed on a mounted file system. + +.SH FILES +.TP +.I /usr/bin/ext2ed +The program itself. +.TP +.I @root_sysconfdir@/ext2ed.conf +ext2ed's configuration file. +.TP +.I @datadir@/ext2.descriptors +Definition of the various objects for the ext2 file system. +.TP +.I /var/log/ext2ed.log +Log file of actual changes made to the file system. +.TP +.I /usr/man/man8/ext2ed.8 +The manual page. +.TP +.I @datadir@/doc/ext2ed/user-guide-0.1.ps +The user's guide. +.TP +.I @datadir@/doc/ext2ed/Ext2fs-overview-0.1.ps +Technical overview of the ext2 file system. +.TP +.I @datadir@/doc/ext2ed/ext2ed-design-0.1.ps +EXT2ED design notes. + +.SH BUGS +File Systems bigger than 2 GB aren't yet supported. +.SH AUTHOR +Gadi Oxman <tgud@tochnapc2.technion.ac.il> +.SH SEE ALSO +.BR e2fsck (8), +.BR debugfs (8) diff --git a/ext2ed/ext2ed.conf.in b/ext2ed/ext2ed.conf.in new file mode 100644 index 0000000..c079623 --- /dev/null +++ b/ext2ed/ext2ed.conf.in @@ -0,0 +1,79 @@ +############################################################################## +# ext2ed.conf # +# # +# Configuration file for the extended 2 file system disk editor. # +############################################################################## + +# Ext2Descriptors is the location of the ext2 filesystem structure +# definitions. + + +Ext2Descriptors @datadir@/ext2.descriptors + + +# Using AlternateDescriptors you can declare additional structures. Those +# structures can contain only variables. Linking functions to the objects is +# possible only through source code additions. + + +AlternateDescriptors + + +# LogFile is the location of the log file. Actual changes to the filesystem +# are logged there. See also LogChanges. + + +LogFile /var/log/ext2ed.log + + +# The following selects the default behavior when changes are made to the +# filesystem. When on, each change will be logged - Both the previous data +# and the new written data. + + +LogChanges on + + +# AllowChanges off will not allow ext2ed to do any changes to the +# filesystem - The "enablewrite" command will not work. When on, enablewrite +# will still have to be issued to allow write access. + + +AllowChanges on + + +# With this option you can choose whether ext2ed will allow read-only mode on +# a mounted filesystem. Read-Write mode is never allowed on a mounted +# filesystem. + + +AllowMountedRead on + + +# When ForceExt2 is set to on, the filesystem is assumed to be ext2 +# filesystem, despite the possibly corrupt superblock magic number reading. +# All the ext2 specific commands will be available despite the possible +# autodetection failure. + +ForceExt2 off + + +# Normally, the various filesystem parameters such as the block size and the +# total number of blocks are gathered from the ext2 filesystem itself. +# However, on a corrupt filesystem, ext2ed is unable to get the right +# parameters. In this case, they will be taken from here. See also +# ForceDefault. + + +DefaultBlockSize 1024 +DefaultTotalBlocks 2097151 # ~2 GB total size +DefaultBlocksInGroup 8192 + +# With ForceDefault on, you can force the use of the default parameters +# above. This is not recommended, as ext2ed will fallback by default to those +# parameters if it can't figure up the parameters from the filesystem itself. + + +ForceDefault off + + diff --git a/ext2ed/ext2ed.h b/ext2ed/ext2ed.h new file mode 100644 index 0000000..0ac77b7 --- /dev/null +++ b/ext2ed/ext2ed.h @@ -0,0 +1,435 @@ + +/* + +/usr/src/ext2ed/ext2ed.h + +A part of the extended file system 2 disk editor. + +-------------------------------------- +Include file for the ext2 disk editor. +-------------------------------------- + +This file contains declarations which are needed by all the files in ext2ed. + +First written on: April 9 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#ifndef EXT2ED_EDITOR_H +#define EXT2ED_EDITOR_H + +/* + +----------------------- + User definable options +----------------------- + +*/ + +#define DEBUG /* Activate self-sanity checks */ + +#include <ext2fs/ext2_fs.h> /* Main kernel ext2 include file */ +#include <sys/stat.h> + +#include <ncurses.h> + +#define MAX_FIELDS 400 + +#define MAX_COMMAND_LINE 81 +#define MAX_COMMANDS_NUM 30 /* Maximum number of commands of one type */ +#define REMEMBER_COUNT 30 /* Object memory size */ + +/* + The user screen consists of four parts: + + 1. Title window (title_win). + 2. Show (status) window (show_win). + 3. Main show pad (show_pad). + 4. Command window (command_win). + +*/ + +/* + + The show pad is mapped to the space left between the other three windows. + + If you wondered why ext2ed grabs so memory, the answer is probably below - I wanted to treat + the virtual display as infinite. Decrease the following for more realistic memory consumption. + +*/ + +#define SHOW_PAD_LINES 3000 +#define SHOW_PAD_COLS (COLS > 140 ? COLS : 140) + +#define COMMAND_WIN_LINES 6 /* Change this to your preferences */ +#define TITLE_WIN_LINES 3 +#define SHOW_WIN_LINES 3 + +#define HEX 1 +#define TEXT 2 + +#ifndef EXT2_PRE_02B_MAGIC + #define EXT2_PRE_02B_MAGIC 0xEF51 +#endif + + +typedef void (*PF) (char *); /* Used to point to the dispatched functions */ + +struct struct_commands { /* Holds commands of an object */ + int last_command; + char *names [MAX_COMMANDS_NUM]; + char *descriptions [MAX_COMMANDS_NUM]; + PF callback [MAX_COMMANDS_NUM]; +}; + +struct struct_descriptor { /* Describes an object */ + unsigned long length; + unsigned char name [60]; + unsigned short fields_num; + unsigned char field_names [MAX_FIELDS][80]; + unsigned char field_types [MAX_FIELDS]; + unsigned short field_lengths [MAX_FIELDS]; + unsigned short field_positions [MAX_FIELDS]; + struct struct_commands type_commands; + struct struct_descriptor *prev,*next; +}; + +#define FIELD_TYPE_INT 1 +#define FIELD_TYPE_UINT 2 +#define FIELD_TYPE_CHAR 3 + +struct struct_type_data { /* The object's data is usually here */ + long offset_in_block; + + union union_type_data { /* Format it in various ways */ + char buffer [EXT2_MAX_BLOCK_SIZE]; + struct ext2_acl_header t_ext2_acl_header; + struct ext2_acl_entry t_ext2_acl_entry; + struct ext2_group_desc t_ext2_group_desc; + struct ext2_inode t_ext2_inode; + struct ext2_super_block t_ext2_super_block; + struct ext2_dir_entry t_ext2_dir_entry; + } u; +}; + +struct struct_file_system_info { /* Important information about the filesystem */ + unsigned long long file_system_size; + unsigned long super_block_offset; + unsigned long first_group_desc_offset; + unsigned long groups_count; + unsigned long inodes_per_block; + unsigned long blocks_per_group; /* The name is misleading; beware */ + unsigned long no_blocks_in_group; + unsigned short block_size; + struct ext2_super_block super_block; +}; + +struct struct_file_info { /* Used to handle files and directories */ + + struct ext2_inode *inode_ptr; + + long inode_offset; + long global_block_num,global_block_offset; + long block_num,blocks_count; + long file_offset,file_length; + long level; + unsigned char buffer [EXT2_MAX_BLOCK_SIZE]; + long offset_in_block; + + int display; + /* The following is used if the file is a directory */ + + long dir_entry_num,dir_entries_count; + long dir_entry_offset; +}; + +struct struct_super_info { /* Used to handle the superblock */ + unsigned long copy_num; +}; + +struct struct_group_info { /* Used to handle the group descriptors */ + unsigned long copy_num; + unsigned long group_num; +}; + +struct struct_block_bitmap_info { /* Used in blockbitmap_com.c */ + unsigned long entry_num; + unsigned long group_num; +}; + +struct struct_inode_bitmap_info { /* Used in inodebitmap_com.c */ + unsigned long entry_num; + unsigned long group_num; +}; + +struct struct_remember_lifo { /* Implements the objects circular memory */ + long entries_count; + + long offset [REMEMBER_COUNT]; + struct struct_descriptor *type [REMEMBER_COUNT]; + char name [REMEMBER_COUNT][80]; +}; + +struct struct_pad_info { /* Used to zoom into the pad window */ + int display_lines,display_cols; + int line,col; + int max_line,max_col; + int disable_output; +}; + +/* Global variables (defined mostly in main.c) */ + +/* Configurable variables (Through configuration file) */ + +extern char AlternateDescriptors [200]; +extern char Ext2Descriptors [200]; +extern char LogFile [200]; +extern int LogChanges; +extern int AllowChanges; +extern int AllowMountedRead; +extern int ForceExt2; +extern int DefaultBlockSize; +extern unsigned long DefaultTotalBlocks; +extern unsigned long DefaultBlocksInGroup; +extern int ForceDefault; + +extern char device_name [80]; +extern char last_command_line [80]; +extern FILE *device_handle; +extern long device_offset; +extern int mounted; + +extern short block_size; +extern struct struct_commands general_commands; +extern struct struct_commands ext2_commands; +extern struct struct_descriptor *first_type; +extern struct struct_descriptor *last_type; +extern struct struct_descriptor *current_type; +extern struct struct_type_data type_data; +extern struct struct_file_system_info file_system_info; +extern struct struct_file_info file_info,first_file_info; +extern struct struct_group_info group_info; +extern struct struct_super_info super_info; +extern struct struct_block_bitmap_info block_bitmap_info; +extern struct struct_inode_bitmap_info inode_bitmap_info; +extern struct struct_remember_lifo remember_lifo; +extern struct struct_pad_info show_pad_info; +extern int write_access; + +extern int redraw_request; +extern char lines_s [80]; +extern char cols_s [80]; + + +/* init.c */ + +extern int init (void); +extern void prepare_to_close (void); +extern int set_struct_descriptors (char *file_name); +extern void free_struct_descriptors (void); +extern struct struct_descriptor *add_new_descriptor (char *name); +extern void add_new_variable (struct struct_descriptor *descriptor,char *v_type,char *v_name); +extern void fill_type_commands (struct struct_descriptor *ptr); +extern void add_user_command (struct struct_commands *ptr,char *name,char *description,PF callback); +extern void free_user_commands (struct struct_commands *ptr); +extern int set_file_system_info (void); +extern int process_configuration_file (void); +extern void add_general_commands (void); +extern void add_ext2_general_commands (void); +extern void check_mounted (char *name); + +int get_next_option (FILE *fp,char *option,char *value); +void init_readline (void); +void init_signals (void); +void signal_SIGWINCH_handler (int sig_num); +void signal_SIGTERM_handler (int sig_num); +void signal_SIGSEGV_handler (int sig_num); + +/* general_com.c */ + +/* General commands which are available always */ + +extern void help (char *command_line); +extern void set (char *command_line); +extern void set_device (char *command_line); +extern void set_offset (char *command_line); +extern void set_type (char *command_line); +extern void show (char *command_line); +extern void pgup (char *command_line); +extern void pgdn (char *command_line); +extern void redraw (char *command_line); +extern void remember (char *command_line); +extern void recall (char *command_line); +extern void cd (char *command_line); +extern void enable_write (char *command_line); +extern void disable_write (char *command_line); +extern void write_data (char *command_line); +extern void next (char *command_line); +extern void prev (char *command_line); + +void hex_set (char *command_line); +void detailed_help (char *text); + + +/* ext2_com.c */ + +/* Extended2 filesystem general commands - Available only when editing an + ext2 filesystem */ + +extern void type_ext2___super (char *command_line); +extern void type_ext2___group (char *command_line); +extern void type_ext2___cd (char *command_line); + + +/* main.c */ + +extern int version_major,version_minor; +extern char revision_date [80]; +extern char email_address [80]; + +#ifdef DEBUG +extern void internal_error (char *description,char *source_name,char *function_name); +#endif + +void parser (void); +extern int dispatch (char *command_line); +char *parse_word (char *source,char *dest); +char *complete_command (char *text,int state); +char *dupstr (char *src); + + + +/* disk.c */ + +extern int load_type_data (void); +extern int write_type_data (void); +extern int low_read (unsigned char *buffer,unsigned long length,unsigned long offset); +extern int low_write (unsigned char *buffer,unsigned long length,unsigned long offset); +extern int log_changes (unsigned char *buffer,unsigned long length,unsigned long offset); + +/* file_com.c */ + +extern int init_file_info (void); +extern void type_file___show (char *command_line); +extern void type_file___inode (char *command_line); +extern void type_file___display (char *command_line); +extern void type_file___prev (char *command_line); +extern void type_file___next (char *command_line); +extern void type_file___offset (char *command_line); +extern void type_file___prevblock (char *command_line); +extern void type_file___nextblock (char *command_line); +extern void type_file___block (char *command_line); +extern void type_file___remember (char *command_line); +extern void type_file___set (char *command_line); +extern void type_file___writedata (char *command_line); + +extern long file_block_to_global_block (long file_block,struct struct_file_info *file_info_ptr); +extern long return_indirect (long table_block,long block_num); +extern long return_dindirect (long table_block,long block_num); +extern long return_tindirect (long table_block,long block_num); + +void file_show_hex (void); +void file_show_text (void); +void show_status (void); + +/* inode_com.c */ + +extern void type_ext2_inode___next (char *command_line); +extern void type_ext2_inode___prev (char *command_line); +extern void type_ext2_inode___show (char *command_line); +extern void type_ext2_inode___group (char *command_line); +extern void type_ext2_inode___entry (char *command_line); +extern void type_ext2_inode___file (char *command_line); +extern void type_ext2_inode___dir (char *command_line); + +extern long inode_offset_to_group_num (long inode_offset); +extern long int inode_offset_to_inode_num (long inode_offset); +extern long int inode_num_to_inode_offset (long inode_num); + +/* dir_com.c */ + +extern int init_dir_info (struct struct_file_info *info); +extern void type_dir___show (char *command_line); +extern void type_dir___inode (char *command_line); +extern void type_dir___pgdn (char *command_line); +extern void type_dir___pgup (char *command_line); +extern void type_dir___prev (char *command_line); +extern void type_dir___next (char *command_line); +extern void type_dir___followinode (char *command_line); +extern void type_dir___remember (char *command_line); +extern void type_dir___cd (char *command_line); +extern void type_dir___entry (char *command_line); +extern void type_dir___writedata (char *command_line); +extern void type_dir___set (char *command_line); + +#define HEX 1 +#define TEXT 2 + +#define ABORT 0 +#define CONTINUE 1 +#define FOUND 2 + +struct struct_file_info search_dir_entries (int (*action) (struct struct_file_info *info),int *status); +int action_count (struct struct_file_info *info); +void show_dir_status (void); +long count_dir_entries (void); +int action_name (struct struct_file_info *info); +int action_entry_num (struct struct_file_info *info); +int action_show (struct struct_file_info *info); + +/* super_com.c */ + +extern void type_ext2_super_block___show (char *command_line); +extern void type_ext2_super_block___gocopy (char *command_line); +extern void type_ext2_super_block___setactivecopy (char *command_line); + +/* group_com.c */ + +extern void type_ext2_group_desc___next (char *command_line); +extern void type_ext2_group_desc___prev (char *command_line); +extern void type_ext2_group_desc___entry (char *command_line); +extern void type_ext2_group_desc___show (char *command_line); +extern void type_ext2_group_desc___inode (char *command_line); +extern void type_ext2_group_desc___gocopy (char *command_line); +extern void type_ext2_group_desc___blockbitmap (char *command_line); +extern void type_ext2_group_desc___inodebitmap (char *command_line); +extern void type_ext2_group_desc___setactivecopy (char *command_line); + +/* blockbitmap_com.c */ + +extern void type_ext2_block_bitmap___show (char *command_line); +extern void type_ext2_block_bitmap___entry (char *command_line); +extern void type_ext2_block_bitmap___next (char *command_line); +extern void type_ext2_block_bitmap___prev (char *command_line); +extern void type_ext2_block_bitmap___allocate (char *command_line); +extern void type_ext2_block_bitmap___deallocate (char *command_line); +void allocate_block (long entry_num); +void deallocate_block (long entry_num); + +/* inodebitmap_bom.c */ + +extern void type_ext2_inode_bitmap___show (char *command_line); +extern void type_ext2_inode_bitmap___entry (char *command_line); +extern void type_ext2_inode_bitmap___next (char *command_line); +extern void type_ext2_inode_bitmap___prev (char *command_line); +extern void type_ext2_inode_bitmap___allocate (char *command_line); +extern void type_ext2_inode_bitmap___deallocate (char *command_line); +void allocate_inode (long entry_num); +void deallocate_inode (long entry_num); + +/* win.c */ + +extern WINDOW *title_win,*show_win,*command_win,*show_pad; + +extern void init_windows (void); +extern void refresh_title_win (void); +extern void refresh_show_win (void); +extern void refresh_show_pad (void); +extern void refresh_command_win (void); +extern void show_info (void); +extern void redraw_all (void); +extern void close_windows (void); + +#endif /* EXT2ED_EDITOR_H */ diff --git a/ext2ed/file_com.c b/ext2ed/file_com.c new file mode 100644 index 0000000..d667959 --- /dev/null +++ b/ext2ed/file_com.c @@ -0,0 +1,565 @@ +/* + +/usr/src/ext2ed/file_com.c + +A part of the extended file system 2 disk editor. + +---------------------------- +Commands which handle a file +---------------------------- + +First written on: April 18 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" + +int init_file_info (void) + +{ + struct ext2_inode *ptr; + + ptr=&type_data.u.t_ext2_inode; + + file_info.inode_ptr=ptr; + file_info.inode_offset=device_offset; + + file_info.global_block_num=ptr->i_block [0]; + file_info.global_block_offset=ptr->i_block [0]*file_system_info.block_size; + file_info.block_num=0; + file_info.blocks_count=(ptr->i_size+file_system_info.block_size-1)/file_system_info.block_size; + file_info.file_offset=0; + file_info.file_length=ptr->i_size; + file_info.level=0; + file_info.offset_in_block=0; + + file_info.display=HEX; + + low_read (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + + return (1); +} + + +void type_file___inode (char *command_line) + +{ + dispatch ("settype ext2_inode"); +} + +void type_file___show (char *command_line) + +{ + if (file_info.display==HEX) + file_show_hex (); + if (file_info.display==TEXT) + file_show_text (); +} + +void type_file___nextblock (char *command_line) + +{ + long block_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + block_offset*=atol (buffer); + } + + if (file_info.block_num+block_offset >= file_info.blocks_count) { + wprintw (command_win,"Error - Block offset out of range\n");wrefresh (command_win); + return; + } + + file_info.block_num+=block_offset; + file_info.global_block_num=file_block_to_global_block (file_info.block_num,&file_info); + file_info.global_block_offset=file_info.global_block_num*file_system_info.block_size; + file_info.file_offset=file_info.block_num*file_system_info.block_size; + + low_read (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + + strcpy (buffer,"show");dispatch (buffer); +} + +void type_file___next (char *command_line) + +{ + int offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset*=atol (buffer); + } + + if (file_info.offset_in_block+offset < file_system_info.block_size) { + file_info.offset_in_block+=offset; + sprintf (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Offset out of block\n");refresh_command_win (); + } +} + +void type_file___offset (char *command_line) + +{ + unsigned long offset; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset=atol (buffer); + } + else { + wprintw (command_win,"Error - Argument not specified\n");refresh_command_win (); + return; + } + + if (offset < file_system_info.block_size) { + file_info.offset_in_block=offset; + sprintf (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Offset out of block\n");refresh_command_win (); + } +} + +void type_file___prev (char *command_line) + +{ + int offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset*=atol (buffer); + } + + if (file_info.offset_in_block-offset >= 0) { + file_info.offset_in_block-=offset; + sprintf (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Offset out of block\n");refresh_command_win (); + } +} + +void type_file___prevblock (char *command_line) + +{ + long block_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + block_offset*=atol (buffer); + } + + if (file_info.block_num-block_offset < 0) { + wprintw (command_win,"Error - Block offset out of range\n");wrefresh (command_win); + return; + } + + file_info.block_num-=block_offset; + file_info.global_block_num=file_block_to_global_block (file_info.block_num,&file_info); + file_info.global_block_offset=file_info.global_block_num*file_system_info.block_size; + file_info.file_offset=file_info.block_num*file_system_info.block_size; + + low_read (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + + strcpy (buffer,"show");dispatch (buffer); +} + +void type_file___block (char *command_line) + +{ + long block_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr==0) { + wprintw (command_win,"Error - Invalid arguments\n");wrefresh (command_win); + return; + } + + ptr=parse_word (ptr,buffer); + block_offset=atol (buffer); + + if (block_offset < 0 || block_offset >= file_info.blocks_count) { + wprintw (command_win,"Error - Block offset out of range\n");wrefresh (command_win); + return; + } + + file_info.block_num=block_offset; + file_info.global_block_num=file_block_to_global_block (file_info.block_num,&file_info); + file_info.global_block_offset=file_info.global_block_num*file_system_info.block_size; + file_info.file_offset=file_info.block_num*file_system_info.block_size; + + low_read (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + + strcpy (buffer,"show");dispatch (buffer); +} + +void type_file___display (char *command_line) + +{ + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) + strcpy (buffer,"hex"); + else + ptr=parse_word (ptr,buffer); + + if (strcasecmp (buffer,"hex")==0) { + wprintw (command_win,"Display set to hex\n");wrefresh (command_win); + file_info.display=HEX; + sprintf (buffer,"show");dispatch (buffer); + } + + else if (strcasecmp (buffer,"text")==0) { + wprintw (command_win,"Display set to text\n");wrefresh (command_win); + file_info.display=TEXT; + sprintf (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Invalid arguments\n");wrefresh (command_win); + } +} + +void file_show_hex (void) + +{ + long offset=0,l,i; + unsigned char *ch_ptr; + + /* device_offset and type_data points to the inode */ + + show_pad_info.line=0; + + wmove (show_pad,0,0); + ch_ptr=file_info.buffer; + for (l=0;l<file_system_info.block_size/16;l++) { + if (file_info.file_offset+offset>file_info.file_length-1) break; + wprintw (show_pad,"%08ld : ",offset); + for (i=0;i<16;i++) { + + if (file_info.file_offset+offset+i>file_info.file_length-1) { + wprintw (show_pad," "); + } + + else { + if (file_info.offset_in_block==offset+i) + wattrset (show_pad,A_REVERSE); + + if (ch_ptr [i]>=' ' && ch_ptr [i]<='z') + wprintw (show_pad,"%c",ch_ptr [i]); + else + wprintw (show_pad,"."); + + if (file_info.offset_in_block==offset+i) + wattrset (show_pad,A_NORMAL); + } + } + + wprintw (show_pad," "); + for (i=0;i<16;i++) { + if (file_info.file_offset+offset+i>file_info.file_length-1) break; + if (file_info.offset_in_block==offset+i) + wattrset (show_pad,A_REVERSE); + + wprintw (show_pad,"%02x",ch_ptr [i]); + + if (file_info.offset_in_block==offset+i) { + wattrset (show_pad,A_NORMAL); + show_pad_info.line=l-l % show_pad_info.display_lines; + } + + wprintw (show_pad," "); + + } + + wprintw (show_pad,"\n"); + offset+=i; + ch_ptr+=i; + } + + show_pad_info.max_line=l-1; + + refresh_show_pad (); + + show_status (); +} + +void file_show_text (void) + +{ + long offset=0,last_offset,l=0,cols=0; + unsigned char *ch_ptr; + + /* device_offset and type_data points to the inode */ + + show_pad_info.line=0; + wmove (show_pad,0,0); + ch_ptr=file_info.buffer; + + last_offset=file_system_info.block_size-1; + + if (file_info.file_offset+last_offset > file_info.file_length-1) + last_offset=file_info.file_length-1-file_info.file_offset; + + while ( (offset <= last_offset) && l<SHOW_PAD_LINES) { + + if (cols==SHOW_PAD_COLS-1) { + wprintw (show_pad,"\n"); + l++;cols=0; + } + + + if (file_info.offset_in_block==offset) + wattrset (show_pad,A_REVERSE); + + if (*ch_ptr >= ' ' && *ch_ptr <= 'z') + wprintw (show_pad,"%c",*ch_ptr); + + + else { + if (*ch_ptr == 0xa) { + wprintw (show_pad,"\n"); + l++;cols=0; + } + + else if (*ch_ptr == 0x9) + wprintw (show_pad," "); + + else + wprintw (show_pad,"."); + } + + if (file_info.offset_in_block==offset) { + wattrset (show_pad,A_NORMAL); + show_pad_info.line=l-l % show_pad_info.display_lines; + } + + + offset++;cols++;ch_ptr++; + } + + wprintw (show_pad,"\n"); + show_pad_info.max_line=l; + + refresh_show_pad (); + + show_status (); +} + +void show_status (void) + +{ + long inode_num; + + werase (show_win);wmove (show_win,0,0); + wprintw (show_win,"File contents. Block %ld. ",file_info.global_block_num); + wprintw (show_win,"File block %ld of %ld. ",file_info.block_num,file_info.blocks_count-1); + wprintw (show_win,"File Offset %ld of %ld.",file_info.file_offset,file_info.file_length-1); + + wmove (show_win,1,0); + inode_num=inode_offset_to_inode_num (file_info.inode_offset); + wprintw (show_win,"File inode %ld. Indirection level %ld.",inode_num,file_info.level); + + refresh_show_win (); +} + +void type_file___remember (char *command_line) + +{ + int found=0; + long entry_num; + char *ptr,buffer [80]; + struct struct_descriptor *descriptor_ptr; + + ptr=parse_word (command_line,buffer); + + if (*ptr==0) { + wprintw (command_win,"Error - Argument not specified\n");wrefresh (command_win); + return; + } + + ptr=parse_word (ptr,buffer); + + entry_num=remember_lifo.entries_count++; + if (entry_num>REMEMBER_COUNT-1) { + entry_num=0; + remember_lifo.entries_count--; + } + + descriptor_ptr=first_type; + while (descriptor_ptr!=NULL && !found) { + if (strcmp (descriptor_ptr->name,"ext2_inode")==0) + found=1; + else + descriptor_ptr=descriptor_ptr->next; + } + + + remember_lifo.offset [entry_num]=device_offset; + remember_lifo.type [entry_num]=descriptor_ptr; + strcpy (remember_lifo.name [entry_num],buffer); + + wprintw (command_win,"Object %s in Offset %ld remembered as %s\n",descriptor_ptr->name,device_offset,buffer); + wrefresh (command_win); +} + +void type_file___set (char *command_line) + +{ + unsigned char tmp; + char *ptr,buffer [80],*ch_ptr; + int mode=HEX; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - Argument not specified\n");refresh_command_win ();return; + } + + ptr=parse_word (ptr,buffer); + + if (strcasecmp (buffer,"text")==0) { + mode=TEXT; + strcpy (buffer,ptr); + } + + else if (strcasecmp (buffer,"hex")==0) { + mode=HEX; + ptr=parse_word (ptr,buffer); + } + + if (*buffer==0) { + wprintw (command_win,"Error - Data not specified\n");refresh_command_win ();return; + } + + if (mode==HEX) { + do { + tmp=(unsigned char) strtol (buffer,NULL,16); + file_info.buffer [file_info.offset_in_block]=tmp; + file_info.offset_in_block++; + ptr=parse_word (ptr,buffer); + if (file_info.offset_in_block==file_system_info.block_size) { + if (*ptr) { + wprintw (command_win,"Error - Ending offset outside block, only partial string changed\n"); + refresh_command_win (); + } + file_info.offset_in_block--; + } + } while (*buffer) ; + } + + else { + ch_ptr=buffer; + while (*ch_ptr) { + tmp=(unsigned char) *ch_ptr++; + file_info.buffer [file_info.offset_in_block]=tmp; + file_info.offset_in_block++; + if (file_info.offset_in_block==file_system_info.block_size) { + if (*ch_ptr) { + wprintw (command_win,"Error - Ending offset outside block, only partial string changed\n"); + refresh_command_win (); + } + file_info.offset_in_block--; + } + } + } + + strcpy (buffer,"show");dispatch (buffer); +} + +void type_file___writedata (char *command_line) + +{ + low_write (file_info.buffer,file_system_info.block_size,file_info.global_block_offset); + return; +} + +long file_block_to_global_block (long file_block,struct struct_file_info *file_info_ptr) + +{ + long last_direct,last_indirect,last_dindirect; + + last_direct=EXT2_NDIR_BLOCKS-1; + last_indirect=last_direct+file_system_info.block_size/4; + last_dindirect=last_indirect+(file_system_info.block_size/4)*(file_system_info.block_size/4); + + if (file_block <= last_direct) { + file_info_ptr->level=0; + return (file_info_ptr->inode_ptr->i_block [file_block]); + } + + if (file_block <= last_indirect) { + file_info_ptr->level=1; + file_block=file_block-last_direct-1; + return (return_indirect (file_info_ptr->inode_ptr->i_block [EXT2_IND_BLOCK],file_block)); + } + + if (file_block <= last_dindirect) { + file_info_ptr->level=2; + file_block=file_block-last_indirect-1; + return (return_dindirect (file_info_ptr->inode_ptr->i_block [EXT2_DIND_BLOCK],file_block)); + } + + file_info_ptr->level=3; + file_block=file_block-last_dindirect-1; + return (return_tindirect (file_info_ptr->inode_ptr->i_block [EXT2_TIND_BLOCK],file_block)); +} + +long return_indirect (long table_block,long block_num) + +{ + long block_table [EXT2_MAX_BLOCK_SIZE/4]; + + low_read ((char *) block_table,file_system_info.block_size,table_block*file_system_info.block_size); + return (block_table [block_num]); +} + +long return_dindirect (long table_block,long block_num) + +{ + long f_indirect; + + f_indirect=block_num/(file_system_info.block_size/4); + f_indirect=return_indirect (table_block,f_indirect); + return (return_indirect (f_indirect,block_num%(file_system_info.block_size/4))); +} + +long return_tindirect (long table_block,long block_num) + +{ + long s_indirect; + + s_indirect=block_num/((file_system_info.block_size/4)*(file_system_info.block_size/4)); + s_indirect=return_indirect (table_block,s_indirect); + return (return_dindirect (s_indirect,block_num%((file_system_info.block_size/4)*(file_system_info.block_size/4)))); +} diff --git a/ext2ed/general_com.c b/ext2ed/general_com.c new file mode 100644 index 0000000..aa274e3 --- /dev/null +++ b/ext2ed/general_com.c @@ -0,0 +1,907 @@ +/* + +/usr/src/ext2ed/general_com.c + +A part of the extended file system 2 disk editor. + +--------------------- +General user commands +--------------------- + +First written on: April 9 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" +#include "../version.h" + +void help (char *command_line) + +{ + int i,max_line=0; + char argument [80],*ptr; + + werase (show_pad);wmove (show_pad,0,0); + + ptr=parse_word (command_line,argument); + + if (*ptr!=0) { + ptr=parse_word (ptr,argument); + if (*argument!=0) { + detailed_help (argument); + return; + } + } + + if (current_type!=NULL) { + + wprintw (show_pad,"Type %s specific commands:\n",current_type->name);max_line++; + + if (current_type->type_commands.last_command==-1) { + wprintw (show_pad,"\nnone\n");max_line+=2; + } + else + for (i=0;i<=current_type->type_commands.last_command;i++) { + if (i%5==0) { + wprintw (show_pad,"\n");max_line++; + } + wprintw (show_pad,"%-13s",current_type->type_commands.names [i]); + if (i%5!=4) + wprintw (show_pad,"; "); + } + + wprintw (show_pad,"\n\n");max_line+=2; + } + + if (ext2_commands.last_command != -1) { + wprintw (show_pad,"ext2 filesystem general commands: \n");max_line++; + for (i=0;i<=ext2_commands.last_command;i++) { + if (i%5==0) { + wprintw (show_pad,"\n");max_line++; + } + wprintw (show_pad,"%-13s",ext2_commands.names [i]); + if (i%5!=4) + wprintw (show_pad,"; "); + + } + wprintw (show_pad,"\n\n");max_line+=2; + } + + wprintw (show_pad,"General commands: \n"); + + for (i=0;i<=general_commands.last_command;i++) { + if (i%5==0) { + wprintw (show_pad,"\n");max_line++; + } + wprintw (show_pad,"%-13s",general_commands.names [i]); + if (i%5!=4) + wprintw (show_pad,"; "); + } + + wprintw (show_pad,"\n\n");max_line+=2; + + wprintw (show_pad,"EXT2ED ver %s (%s)\n",E2FSPROGS_VERSION, E2FSPROGS_DATE); + wprintw (show_pad,"Copyright (C) 1995 Gadi Oxman\n"); + wprintw (show_pad,"Reviewed 2001 Christian Bac\n"); + wprintw (show_pad,"Modified and enhanced by Theodore Ts'o, 2002\n"); + wprintw (show_pad,"EXT2ED is hereby placed under the terms of the GNU General Public License.\n\n"); + wprintw (show_pad,"EXT2ED was programmed as a student project in the software laboratory\n"); + wprintw (show_pad,"of the faculty of electrical engineering in the\n"); + wprintw (show_pad,"Technion - Israel Institute of Technology\n"); + wprintw (show_pad,"with the guide of Avner Lottem and Dr. Ilana David.\n"); + + max_line+=10; + + show_pad_info.line=0;show_pad_info.max_line=max_line; + + werase (show_win);wmove (show_win,0,0); + wprintw (show_win,"EXT2ED help"); + + refresh_show_win (); + refresh_show_pad (); +} + +void detailed_help (char *text) + +{ + int i; + + if (current_type != NULL) + for (i=0;i<=current_type->type_commands.last_command;i++) { + if (strcmp (current_type->type_commands.names [i],text)==0) { + wprintw (show_pad,"%s - %s\n",text,current_type->type_commands.descriptions [i]); + refresh_show_pad ();return; + } + } + + for (i=0;i<=ext2_commands.last_command;i++) { + if (strcmp (ext2_commands.names [i],text)==0) { + wprintw (show_pad,"%s - %s\n",text,ext2_commands.descriptions [i]); + refresh_show_pad ();return; + } + } + + for (i=0;i<=general_commands.last_command;i++) { + if (strcmp (general_commands.names [i],text)==0) { + wprintw (show_pad,"%s - %s\n",text,general_commands.descriptions [i]); + refresh_show_pad ();return; + } + } + + if (strcmp ("quit",text)==0) { + wprintw (show_pad,"quit - Exists EXT2ED"); + refresh_show_pad ();return; + } + + wprintw (show_pad,"Error - Command %s not available now\n",text); + refresh_show_pad ();return; +} + + + +void set_device (char *command_line) + +{ + char *ptr,new_device [80]; + + ptr=parse_word (command_line,new_device); + if (*ptr==0) { + wprintw (command_win,"Error - Device name not specified\n"); + refresh_command_win ();return; + } + parse_word (ptr,new_device); + check_mounted (new_device); + if (mounted && !AllowMountedRead) { + wprintw (command_win,"Error - Filesystem is mounted, aborting\n"); + wprintw (command_win,"You may wish to use the AllowMountedRead on configuration option\n"); + refresh_command_win ();return; + } + + if (mounted && AllowMountedRead) { + wprintw (command_win,"Warning - Filesystem is mounted. Displayed data may be unreliable.\n"); + refresh_command_win (); + } + + if (device_handle!=NULL) + fclose (device_handle); + + if ( (device_handle=fopen (new_device,"rb"))==NULL) { + wprintw (command_win,"Error - Can not open device %s\n",new_device);refresh_command_win (); + return; + } + else { + strcpy (device_name,new_device); + write_access=0; /* Write access disabled */ + current_type=NULL; /* There is no type now */ + remember_lifo.entries_count=0; /* Empty Object memory */ + free_user_commands (&ext2_commands); /* Free filesystem specific objects */ + free_struct_descriptors (); + if (!set_file_system_info ()) { /* Error while getting info --> abort */ + free_user_commands (&ext2_commands); + free_struct_descriptors (); + fclose (device_handle); + device_handle=NULL; /* Notice that our device is still not set up */ + device_offset=-1; + return; + } + if (*AlternateDescriptors) /* Check if user defined objects exist */ + set_struct_descriptors (AlternateDescriptors); + dispatch ("setoffset 0"); + dispatch ("help"); /* Show help screen */ + wprintw (command_win,"Device changed to %s",device_name);refresh_command_win (); + } +} + +void set_offset (char *command_line) + +{ + long mult=1; + long new_offset; + char *ptr,new_offset_buffer [80]; + + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n");refresh_command_win (); + return; + } + + ptr=parse_word (command_line,new_offset_buffer); + + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n");refresh_command_win (); + return; + } + + ptr=parse_word (ptr,new_offset_buffer); + + if (strcmp (new_offset_buffer,"block")==0) { + mult=file_system_info.block_size; + ptr=parse_word (ptr,new_offset_buffer); + } + + if (strcmp (new_offset_buffer,"type")==0) { + if (current_type==NULL) { + wprintw (command_win,"Error - No type set\n");refresh_command_win (); + return; + } + + mult=current_type->length; + ptr=parse_word (ptr,new_offset_buffer); + } + + if (*new_offset_buffer==0) { + wprintw (command_win,"Error - No offset specified\n");refresh_command_win (); + return; + } + + if (new_offset_buffer [0]=='+') { + if (device_offset==-1) { + wprintw (command_win,"Error - Select a fixed offset first\n");refresh_command_win (); + return; + } + new_offset=device_offset+atol (new_offset_buffer+1)*mult; + } + + else if (new_offset_buffer [0]=='-') { + if (device_offset==-1) { + wprintw (command_win,"Error - Select a fixed offset first\n");refresh_command_win (); + return; + } + new_offset=device_offset-atol (new_offset_buffer+1)*mult; + if (new_offset<0) new_offset=0; + } + + else + new_offset=atol (new_offset_buffer)*mult; + + if ( (fseek (device_handle,new_offset,SEEK_SET))==-1) { + wprintw (command_win,"Error - Failed to seek to offset %ld in device %s\n",new_offset,device_name); + refresh_command_win (); + return; + }; + device_offset=new_offset; + wprintw (command_win,"Device offset changed to %ld\n",device_offset);refresh_command_win (); + load_type_data (); + type_data.offset_in_block=0; +} + +void set_int(short len, void *ptr, char *name, char *value) +{ + char *char_ptr; + short *short_ptr; + long *long_ptr; + long v; + char *tmp; + + v = strtol(value, &tmp, 0); + if (*tmp) { + wprintw( command_win, "Bad value - %s\n", value); + return; + } + switch (len) { + case 1: + char_ptr = (char *) ptr; + *char_ptr = v; + break; + case 2: + short_ptr = (short *) ptr; + *short_ptr = v; + break; + case 4: + long_ptr = (long *) ptr; + *long_ptr = v; + break; + default: + wprintw (command_win, + "set_int: unsupported length: %d\n", len); + return; + } + wprintw (command_win, "Variable %s set to %s\n", + name, value); +} + +void set_uint(short len, void *ptr, char *name, char *value) +{ + unsigned char *char_ptr; + unsigned short *short_ptr; + unsigned long *long_ptr; + unsigned long v; + char *tmp; + + v = strtoul(value, &tmp, 0); + if (*tmp) { + wprintw( command_win, "Bad value - %s\n", value); + return; + } + switch (len) { + case 1: + char_ptr = (unsigned char *) ptr; + *char_ptr = v; + break; + case 2: + short_ptr = (unsigned short *) ptr; + *short_ptr = v; + break; + case 4: + long_ptr = (unsigned long *) ptr; + *long_ptr = v; + break; + default: + wprintw (command_win, + "set_uint: unsupported length: %d\n", len); + return; + } + wprintw (command_win, "Variable %s set to %s\n", + name, value); +} + +void set_char(short len, void *ptr, char *name, char *value) +{ + if (strlen(value)+1 > len) { + wprintw( command_win, "Value %s too big for field\n", + name, len); + return; + } + memset(ptr, 0, len); + strcpy((char *) ptr, value); + wprintw (command_win, "Variable %s set to %s\n", + name, value); +} + + +void set (char *command_line) + +{ + unsigned short *int_ptr; + unsigned char *char_ptr; + unsigned long *long_ptr,offset=0; + int i,len, found=0; + char *ptr,buffer [80],variable [80],value [80]; + + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n");refresh_command_win (); + return; + } + + if (current_type==NULL) { + hex_set (command_line); + return; + } + + ptr=parse_word (command_line,buffer); + if (ptr==NULL || *ptr==0) { + wprintw (command_win,"Error - Missing arguments\n");refresh_command_win (); + return; + } + parse_word (ptr,buffer); + ptr=strchr (buffer,'='); + if (ptr==NULL) { + wprintw (command_win,"Error - Bad syntax\n");refresh_command_win ();return; + } + strncpy (variable,buffer,ptr-buffer);variable [ptr-buffer]=0; + strcpy (value,++ptr); + + if (current_type==NULL) { + wprintw (command_win,"Sorry, not yet supported\n");refresh_command_win ();return; + } + + for (i=0;i<current_type->fields_num && !found;i++) { + if (strcmp (current_type->field_names [i],variable)==0) { + found=1; + ptr=type_data.u.buffer+offset; + len = current_type->field_lengths [i]; + switch (current_type->field_types [i]) { + case FIELD_TYPE_INT: + set_int(len, ptr, variable, value); + break; + case FIELD_TYPE_UINT: + set_uint(len, ptr, variable, value); + break; + case FIELD_TYPE_CHAR: + set_char(len, ptr, variable, value); + break; + default: + wprintw (command_win, + "set: unhandled type %d\n", + current_type->field_types [i]); + break; + } + refresh_command_win (); + } + offset+=current_type->field_lengths [i]; + } + if (found) + dispatch ("show"); + else { + wprintw (command_win,"Error - Variable %s not found\n",variable); + refresh_command_win (); + } +} + +void hex_set (char *command_line) + +{ + unsigned char tmp; + char *ptr,buffer [80],*ch_ptr; + int mode=HEX; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - Argument not specified\n");refresh_command_win ();return; + } + + ptr=parse_word (ptr,buffer); + + if (strcasecmp (buffer,"text")==0) { + mode=TEXT; + strcpy (buffer,ptr); + } + + else if (strcasecmp (buffer,"hex")==0) { + mode=HEX; + ptr=parse_word (ptr,buffer); + } + + if (*buffer==0) { + wprintw (command_win,"Error - Data not specified\n");refresh_command_win ();return; + } + + if (mode==HEX) { + do { + tmp=(unsigned char) strtol (buffer,NULL,16); + type_data.u.buffer [type_data.offset_in_block]=tmp; + type_data.offset_in_block++; + ptr=parse_word (ptr,buffer); + if (type_data.offset_in_block==file_system_info.block_size) { + if (*ptr) { + wprintw (command_win,"Error - Ending offset outside block, only partial string changed\n"); + refresh_command_win (); + } + type_data.offset_in_block--; + } + } while (*buffer) ; + } + + else { + ch_ptr=buffer; + while (*ch_ptr) { + tmp=(unsigned char) *ch_ptr++; + type_data.u.buffer [type_data.offset_in_block]=tmp; + type_data.offset_in_block++; + if (type_data.offset_in_block==file_system_info.block_size) { + if (*ch_ptr) { + wprintw (command_win,"Error - Ending offset outside block, only partial string changed\n"); + refresh_command_win (); + } + type_data.offset_in_block--; + } + } + } + + strcpy (buffer,"show");dispatch (buffer); +} + + + +void set_type (char *command_line) + +{ + struct struct_descriptor *descriptor_ptr; + char *ptr,buffer [80],tmp_buffer [80]; + short found=0; + + if (!load_type_data ()) + return; + + ptr=parse_word (command_line,buffer); + parse_word (ptr,buffer); + + if (strcmp (buffer,"none")==0 || strcmp (buffer,"hex")==0) { + wprintw (command_win,"Data will be shown as hex dump\n");refresh_command_win (); + current_type=NULL; + sprintf (tmp_buffer,"show");dispatch (tmp_buffer); + return; + } + + descriptor_ptr=first_type; + while (descriptor_ptr!=NULL && !found) { + if (strcmp (descriptor_ptr->name,buffer)==0) + found=1; + else + descriptor_ptr=descriptor_ptr->next; + } + if (found) { + wprintw (command_win,"Structure type set to %s\n",buffer);refresh_command_win (); + current_type=descriptor_ptr; + sprintf (tmp_buffer,"show");dispatch (tmp_buffer); + } + else { + wprintw (command_win,"Error - %s is not a valid type\n",buffer);refresh_command_win (); + } +} + +void show_int(short len, void *ptr) +{ + long temp; + char *format; + + switch (len) { + case 1: + temp = *((char *) ptr); + format = "%3d (0x%02x)\n"; + break; + case 2: + temp = *((short *) ptr); + format = "%d (0x%x)\n"; + break; + case 4: + temp = *((long *) ptr); + format = "%d\n"; + break; + default: + wprintw (show_pad, "unimplemented\n"); + return; + } + wprintw(show_pad, format, temp, temp); +} + +void show_uint(short len, void *ptr) +{ + unsigned long temp; + char *format; + + switch (len) { + case 1: + temp = *((unsigned char *) ptr); + temp = temp & 0xFF; + format = "%3u (0x%02x)\n"; + break; + case 2: + temp = *((unsigned short *) ptr); + temp = temp & 0xFFFF; + format = "%u (0x%x)\n"; + break; + case 4: + temp = (unsigned long) *((unsigned long *) ptr); + format = "%u\n"; + break; + default: + wprintw (show_pad, "unimplemented\n"); + return; + } + wprintw(show_pad, format, temp, temp); +} + +void show_char(short len, void *ptr) +{ + unsigned char *cp = (unsigned char *) ptr; + unsigned char ch; + int i,j; + + wprintw(show_pad, "\""); + + for (i=0; i < len; i++) { + ch = *cp++; + if (ch == 0) { + for (j=i+1; j < len; j++) + if (cp[j-i]) + break; + if (j == len) + break; + } + if (ch > 128) { + wprintw(show_pad, "M-"); + ch -= 128; + } + if ((ch < 32) || (ch == 0x7f)) { + wprintw(show_pad, "^"); + ch ^= 0x40; /* ^@, ^A, ^B; ^? for DEL */ + } + wprintw(show_pad, "%c", ch); + } + + wprintw(show_pad, "\"\n"); +} + + + +void show (char *command_line) + +{ + unsigned int i,l,len,temp_int; + unsigned long offset=0,temp_long; + unsigned char temp_char,*ch_ptr; + void *ptr; + + if (device_handle==NULL) + return; + + show_pad_info.line=0; + + if (current_type==NULL) { + wmove (show_pad,0,0); + ch_ptr=type_data.u.buffer; + for (l=0;l<file_system_info.block_size/16;l++) { + wprintw (show_pad,"%08ld : ",offset); + for (i=0;i<16;i++) { + if (type_data.offset_in_block==offset+i) + wattrset (show_pad,A_REVERSE); + + if (ch_ptr [i]>=' ' && ch_ptr [i]<='z') + wprintw (show_pad,"%c",ch_ptr [i]); + else + wprintw (show_pad,"."); + if (type_data.offset_in_block==offset+i) + wattrset (show_pad,A_NORMAL); + } + wprintw (show_pad," "); + for (i=0;i<16;i++) { + if (type_data.offset_in_block==offset+i) + wattrset (show_pad,A_REVERSE); + + wprintw (show_pad,"%02x",ch_ptr [i]); + + if (type_data.offset_in_block==offset+i) { + wattrset (show_pad,A_NORMAL); + show_pad_info.line=l-l % show_pad_info.display_lines; + } + + wprintw (show_pad," "); + } + wprintw (show_pad,"\n"); + offset+=16; + ch_ptr+=16; + } + show_pad_info.max_line=l-1;show_pad_info.max_col=COLS-1; + refresh_show_pad ();show_info (); + } + else { + wmove (show_pad,0,0);l=0; + for (i=0;i<current_type->fields_num;i++) { + wprintw (show_pad,"%-20s = ",current_type->field_names [i]); + ptr=type_data.u.buffer+offset; + len = current_type->field_lengths[i]; + switch (current_type->field_types[i]) { + case FIELD_TYPE_INT: + show_int(len, ptr); + break; + case FIELD_TYPE_UINT: + show_uint(len, ptr); + break; + case FIELD_TYPE_CHAR: + show_char(len, ptr); + break; + default: + wprintw (show_pad, "unimplemented\n"); + break; + } + offset+=len; + l++; + } + current_type->length=offset; + show_pad_info.max_line=l-1; + refresh_show_pad ();show_info (); + } +} + +void next (char *command_line) + +{ + long offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset*=atol (buffer); + } + + if (current_type!=NULL) { + sprintf (buffer,"setoffset type +%ld",offset); + dispatch (buffer); + return; + } + + if (type_data.offset_in_block+offset < file_system_info.block_size) { + type_data.offset_in_block+=offset; + sprintf (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Offset out of block\n");refresh_command_win (); + } +} + +void prev (char *command_line) + +{ + long offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + offset*=atol (buffer); + } + + if (current_type!=NULL) { + sprintf (buffer,"setoffset type -%ld",offset); + dispatch (buffer); + return; + } + + if (type_data.offset_in_block-offset >= 0) { + type_data.offset_in_block-=offset; + sprintf (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Offset out of block\n");refresh_command_win (); + } +} + +void pgdn (char *commnad_line) + +{ + show_pad_info.line+=show_pad_info.display_lines; + refresh_show_pad ();refresh_show_win (); +} + +void pgup (char *command_line) + +{ + show_pad_info.line-=show_pad_info.display_lines; + refresh_show_pad ();refresh_show_win (); +} + +void redraw (char *command_line) + +{ + redraw_all (); + dispatch ("show"); +} + +void remember (char *command_line) + +{ + long entry_num; + char *ptr,buffer [80]; + + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n");refresh_command_win (); + return; + } + + ptr=parse_word (command_line,buffer); + + if (*ptr==0) { + wprintw (command_win,"Error - Argument not specified\n");refresh_command_win (); + return; + } + + ptr=parse_word (ptr,buffer); + + entry_num=remember_lifo.entries_count++; + if (entry_num>REMEMBER_COUNT-1) { + entry_num=0; + remember_lifo.entries_count--; + } + + remember_lifo.offset [entry_num]=device_offset; + remember_lifo.type [entry_num]=current_type; + strcpy (remember_lifo.name [entry_num],buffer); + + if (current_type!=NULL) + wprintw (command_win,"Object %s in Offset %ld remembered as %s\n",current_type->name,device_offset,buffer); + else + wprintw (command_win,"Offset %ld remembered as %s\n",device_offset,buffer); + + refresh_command_win (); +} + +void recall (char *command_line) + +{ + char *ptr,buffer [80]; + long entry_num; + + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n");refresh_command_win (); + return; + } + + ptr=parse_word (command_line,buffer); + + if (*ptr==0) { + wprintw (command_win,"Error - Argument not specified\n");refresh_command_win (); + return; + } + + ptr=parse_word (ptr,buffer); + + + for (entry_num=remember_lifo.entries_count-1;entry_num>=0;entry_num--) { + if (strcmp (remember_lifo.name [entry_num],buffer)==0) + break; + } + + if (entry_num==-1) { + wprintw (command_win,"Error - Can not recall %s\n",buffer);refresh_command_win (); + return; + } + + sprintf (buffer,"setoffset %ld",remember_lifo.offset [entry_num]);dispatch (buffer); + if (remember_lifo.type [entry_num] != NULL) { + sprintf (buffer,"settype %s",remember_lifo.type [entry_num]->name);dispatch (buffer); + } + + else { + sprintf (buffer,"settype none");dispatch (buffer); + } + + wprintw (command_win,"Object %s in Offset %ld recalled\n",current_type->name,device_offset); + refresh_command_win (); +} + +void enable_write (char *command_line) + +{ + FILE *fp; + + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n");refresh_command_win (); + return; + } + + if (!AllowChanges) { + wprintw (command_win,"Sorry, write access is not allowed\n"); + return; + } + + if (mounted) { + wprintw (command_win,"Error - Filesystem is mounted\n"); + return; + } + + if ( (fp=fopen (device_name,"r+b"))==NULL) { + wprintw (command_win,"Error - Can not open device %s for reading and writing\n",device_name);refresh_command_win (); + return; + } + fclose (device_handle); + device_handle=fp;write_access=1; + wprintw (command_win,"Write access enabled - Be careful\n");refresh_command_win (); +} + +void disable_write (char *command_line) + +{ + FILE *fp; + + if (device_handle==NULL) { + wprintw (command_win,"Error - No device opened\n");refresh_command_win (); + return; + } + + if ( (fp=fopen (device_name,"rb"))==NULL) { + wprintw (command_win,"Error - Can not open device %s\n",device_name);refresh_command_win (); + return; + } + + fclose (device_handle); + device_handle=fp;write_access=0; + wprintw (command_win,"Write access disabled\n");refresh_command_win (); +} + +void write_data (char *command_line) + +{ + write_type_data (); +} diff --git a/ext2ed/group_com.c b/ext2ed/group_com.c new file mode 100644 index 0000000..aaed16e --- /dev/null +++ b/ext2ed/group_com.c @@ -0,0 +1,183 @@ +/* + +/usr/src/ext2ed/group_com.c + +A part of the extended file system 2 disk editor. + +General user commands + +First written on: April 17 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" + +void type_ext2_group_desc___next (char *command_line) + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",group_info.group_num+entry_offset); + dispatch (buffer); +} + +void type_ext2_group_desc___prev (char *command_line) + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",group_info.group_num-entry_offset); + dispatch (buffer); +} + +void type_ext2_group_desc___entry (char *command_line) + +{ + long group_num; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n");refresh_command_win ();return; + } + ptr=parse_word (ptr,buffer); + + group_num=atol (buffer); + + if (group_num < 0 || group_num >= file_system_info.groups_count) { + wprintw (command_win,"Error - Entry number out of bounds\n");refresh_command_win ();return; + } + + device_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + sprintf (buffer,"setoffset %ld",device_offset);dispatch (buffer); + strcpy (buffer,"show");dispatch (buffer); + group_info.group_num=group_num; +} + + +void type_ext2_group_desc___gocopy (char *command_line) + +{ + unsigned long copy_num,offset; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n");refresh_command_win ();return; + } + ptr=parse_word (ptr,buffer); + + copy_num=atol (buffer); + + offset=file_system_info.first_group_desc_offset+copy_num*file_system_info.super_block.s_blocks_per_group*file_system_info.block_size; + + if (offset > file_system_info.file_system_size) { + wprintw (command_win,"Error - Copy number out of bounds\n");refresh_command_win ();return; + } + + group_info.copy_num=copy_num; + device_offset=offset+group_info.group_num*sizeof (struct ext2_group_desc); + + sprintf (buffer,"setoffset %ld",device_offset);dispatch (buffer); + strcpy (buffer,"show");dispatch (buffer); +} + + +void type_ext2_group_desc___show (char *command_line) + +{ + long group_num,temp; + + temp=(device_offset-file_system_info.first_group_desc_offset) % (file_system_info.super_block.s_blocks_per_group*file_system_info.block_size); + group_num=temp/sizeof (struct ext2_group_desc); + + show (command_line); + + wmove (show_win,1,0);wprintw (show_win,"\n");wmove (show_win,2,0); + wprintw (show_win,"Group %ld of %ld ",group_num,file_system_info.groups_count-1); + wprintw (show_win,"in copy %ld ",group_info.copy_num); + if (group_info.copy_num==0) wprintw (show_win,"(Main copy)"); + wprintw (show_win,"\n");refresh_show_win (); + + if (group_num==0) { + wprintw (command_win,"Reached first group descriptor\n"); + wrefresh (command_win); + } + + if (group_num==file_system_info.groups_count-1) { + wprintw (command_win,"Reached last group descriptor\n"); + wrefresh (command_win); + } +} + +void type_ext2_group_desc___inode (char *command_line) + +{ + long inode_offset; + char buffer [80]; + + inode_offset=type_data.u.t_ext2_group_desc.bg_inode_table; + sprintf (buffer,"setoffset block %ld",inode_offset);dispatch (buffer); + sprintf (buffer,"settype ext2_inode");dispatch (buffer); +} + +void type_ext2_group_desc___blockbitmap (char *command_line) + +{ + long block_bitmap_offset; + char buffer [80]; + + block_bitmap_info.entry_num=0; + block_bitmap_info.group_num=group_info.group_num; + + block_bitmap_offset=type_data.u.t_ext2_group_desc.bg_block_bitmap; + sprintf (buffer,"setoffset block %ld",block_bitmap_offset);dispatch (buffer); + sprintf (buffer,"settype block_bitmap");dispatch (buffer); +} + +void type_ext2_group_desc___inodebitmap (char *command_line) + +{ + long inode_bitmap_offset; + char buffer [80]; + + inode_bitmap_info.entry_num=0; + inode_bitmap_info.group_num=group_info.group_num; + + inode_bitmap_offset=type_data.u.t_ext2_group_desc.bg_inode_bitmap; + sprintf (buffer,"setoffset block %ld",inode_bitmap_offset);dispatch (buffer); + sprintf (buffer,"settype inode_bitmap");dispatch (buffer); +} + +void type_ext2_group_desc___setactivecopy (char *command_line) + +{ + struct ext2_group_desc gd; + + gd=type_data.u.t_ext2_group_desc; + dispatch ("gocopy 0"); + type_data.u.t_ext2_group_desc=gd; + dispatch ("show"); +} diff --git a/ext2ed/init.c b/ext2ed/init.c new file mode 100644 index 0000000..4e58431 --- /dev/null +++ b/ext2ed/init.c @@ -0,0 +1,633 @@ +/* + +/usr/src/ext2ed/init.c + +A part of the extended file system 2 disk editor. + +-------------------------------- +Various initialization routines. +-------------------------------- + +First written on: April 9 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#ifdef HAVE_READLINE +#include <readline.h> +#endif +#include <signal.h> +#include <unistd.h> + +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> + +#include "ext2ed.h" + +char lines_s [80],cols_s [80]; + +void signal_handler (void); + +void prepare_to_close (void) + +{ + close_windows (); + if (device_handle!=NULL) + fclose (device_handle); + free_user_commands (&general_commands); + free_user_commands (&ext2_commands); + free_struct_descriptors (); +} + +int init (void) + +{ + printf ("Initializing ...\n"); + + if (!process_configuration_file ()) { + fprintf (stderr,"Error - Unable to complete configuration. Quitting.\n"); + return (0); + }; + + general_commands.last_command=-1; /* No commands whatsoever meanwhile */ + ext2_commands.last_command=-1; + add_general_commands (); /* Add the general commands, available always */ + device_handle=NULL; /* Notice that our device is still not set up */ + device_offset=-1; + current_type=NULL; /* No filesystem specific types yet */ + + remember_lifo.entries_count=0; /* Object memory is empty */ + + init_windows (); /* Initialize the NCURSES interface */ + init_readline (); /* Initialize the READLINE interface */ + init_signals (); /* Initialize the signal handlers */ + write_access=0; /* Write access disabled */ + + strcpy (last_command_line,"help"); /* Show the help screen to the user */ + dispatch ("help"); + return (1); /* Success */ +} + +void add_general_commands (void) + +{ + add_user_command (&general_commands,"help","EXT2ED help system",help); + add_user_command (&general_commands,"set","Changes a variable in the current object",set); + add_user_command (&general_commands,"setdevice","Selects the filesystem block device (e.g. /dev/hda1)",set_device); + add_user_command (&general_commands,"setoffset","Moves asynchronously in the filesystem",set_offset); + add_user_command (&general_commands,"settype","Tells EXT2ED how to interpret the current object",set_type); + add_user_command (&general_commands,"show","Displays the current object",show); + add_user_command (&general_commands,"pgup","Scrolls data one page up",pgup); + add_user_command (&general_commands,"pgdn","Scrolls data one page down",pgdn); + add_user_command (&general_commands,"redraw","Redisplay the screen",redraw); + add_user_command (&general_commands,"remember","Saves the current position and data information",remember); + add_user_command (&general_commands,"recall","Gets back to the saved object position",recall); + add_user_command (&general_commands,"enablewrite","Enters Read/Write mode - Allows changing the filesystem",enable_write); + add_user_command (&general_commands,"disablewrite","Enters read only mode",disable_write); + add_user_command (&general_commands,"writedata","Write data back to disk",write_data); + add_user_command (&general_commands,"next","Moves to the next byte in hex mode",next); + add_user_command (&general_commands,"prev","Moves to the previous byte in hex mode",prev); +} + +void add_ext2_general_commands (void) + +{ + add_user_command (&ext2_commands,"super","Moves to the superblock of the filesystem",type_ext2___super); + add_user_command (&ext2_commands,"group","Moves to the first group descriptor",type_ext2___group); + add_user_command (&ext2_commands,"cd","Moves to the directory specified",type_ext2___cd); +} + +int set_struct_descriptors (char *file_name) + +{ + FILE *fp; + char current_line [500],current_word [50],*ch; + char variable_name [50],variable_type [20]; + struct struct_descriptor *current_descriptor; + + if ( (fp=fopen (file_name,"rt"))==NULL) { + wprintw (command_win,"Error - Failed to open descriptors file %s\n",file_name); + refresh_command_win (); return (0); + }; + + while (!feof (fp)) { + fgets (current_line,500,fp); + if (feof (fp)) break; + ch=parse_word (current_line,current_word); + if (strcmp (current_word,"struct")==0) { + ch=parse_word (ch,current_word); + current_descriptor=add_new_descriptor (current_word); + + while (strchr (current_line,'{')==NULL) { + fgets (current_line,500,fp); + if (feof (fp)) break; + }; + if (feof (fp)) break; + + fgets (current_line,500,fp); + + while (strchr (current_line,'}')==NULL) { + while (strchr (current_line,';')==NULL) { + fgets (current_line,500,fp); + if (strchr (current_line,'}')!=NULL) break; + }; + if (strchr (current_line,'}') !=NULL) break; + ch=parse_word (current_line,variable_type); + ch=parse_word (ch,variable_name); + while (variable_name [strlen (variable_name)-1]!=';') { + strcpy (variable_type,variable_name); + ch=parse_word (ch,variable_name); + }; + variable_name [strlen (variable_name)-1]=0; + add_new_variable (current_descriptor,variable_type,variable_name); + fgets (current_line,500,fp); + }; + }; + }; + + fclose (fp); + return (1); +} + +void free_struct_descriptors (void) + +{ + struct struct_descriptor *ptr,*next; + + ptr=first_type; + while (ptr!=NULL) { + next=ptr->next; + free_user_commands (&ptr->type_commands); + free (ptr); + ptr=next; + } + first_type=last_type=current_type=NULL; +} + +void free_user_commands (struct struct_commands *ptr) + +{ + int i; + + for (i=0;i<=ptr->last_command;i++) { + free (ptr->names [i]); + free (ptr->descriptions [i]); + } + + ptr->last_command=-1; +} + +struct struct_descriptor *add_new_descriptor (char *name) + +{ + struct struct_descriptor *ptr; + + ptr = malloc (sizeof (struct struct_descriptor)); + if (ptr == NULL) { + printf ("Error - Can not allocate memory - Quitting\n"); + exit (1); + } + memset(ptr, 0, sizeof(struct struct_descriptor)); + ptr->prev = ptr->next = NULL; + strcpy (ptr->name,name); + ptr->length=0; + ptr->fields_num=0; + if (first_type==NULL) { + first_type = last_type = ptr; + } else { + ptr->prev = last_type; last_type->next = ptr; last_type=ptr; + } + ptr->type_commands.last_command=-1; + fill_type_commands (ptr); + return (ptr); +} + +struct type_table { + char *name; + int field_type; + int len; +}; + +struct type_table type_table[] = { + { "long", FIELD_TYPE_INT, 4 }, + { "short", FIELD_TYPE_INT, 2 }, + { "char", FIELD_TYPE_CHAR, 1 }, + { "__u32", FIELD_TYPE_UINT, 4 }, + { "__s32", FIELD_TYPE_INT, 4 }, + { "__u16", FIELD_TYPE_UINT, 2 }, + { "__s16", FIELD_TYPE_INT, 2 }, + { "__u8", FIELD_TYPE_UINT, 1 }, + { "__s8", FIELD_TYPE_INT, 1 }, + { 0, 0, 0 } +}; + +void add_new_variable (struct struct_descriptor *ptr,char *v_type,char *v_name) + +{ + short len=1; + char field_type=FIELD_TYPE_INT; + struct type_table *p; + + strcpy (ptr->field_names [ptr->fields_num],v_name); + ptr->field_positions [ptr->fields_num]=ptr->length; + + for (p = type_table; p->name; p++) { + if (strcmp(v_type, p->name) == 0) { + len = p->len; + field_type = p->field_type; + break; + } + } + if (p->name == 0) { + if (strncmp(v_type, "char[", 5) == 0) { + len = atoi(v_type+5); + field_type = FIELD_TYPE_CHAR; + } else { + printf("Unknown type %s for field %s\n", v_type, v_name); + exit(1); + } + } + + ptr->field_lengths [ptr->fields_num] = len; + ptr->field_types [ptr->fields_num] = field_type; + + ptr->length+=len; + ptr->fields_num++; +} + +void fill_type_commands (struct struct_descriptor *ptr) + +/* + +Set specific type user commands. + +*/ + +{ + + if (strcmp ((ptr->name),"file")==0) { + add_user_command (&ptr->type_commands,"show","Shows file data",type_file___show); + add_user_command (&ptr->type_commands,"inode","Returns to the inode of the current file",type_file___inode); + add_user_command (&ptr->type_commands,"display","Specifies data format - text or hex",type_file___display); + add_user_command (&ptr->type_commands,"next","Pass to next byte",type_file___next); + add_user_command (&ptr->type_commands,"prev","Pass to the previous byte",type_file___prev); + add_user_command (&ptr->type_commands,"offset","Pass to a specified byte in the current block",type_file___offset); + add_user_command (&ptr->type_commands,"nextblock","Pass to next file block",type_file___nextblock); + add_user_command (&ptr->type_commands,"prevblock","Pass to the previous file block",type_file___prevblock); + add_user_command (&ptr->type_commands,"block","Specify which file block to edit",type_file___block); + add_user_command (&ptr->type_commands,"remember","Saves the file\'s inode position for later reference",type_file___remember); + add_user_command (&ptr->type_commands,"set","Sets the current byte",type_file___set); + add_user_command (&ptr->type_commands,"writedata","Writes the current block to the disk",type_file___writedata); + } + + if (strcmp ((ptr->name),"ext2_inode")==0) { + add_user_command (&ptr->type_commands,"show","Shows inode data",type_ext2_inode___show); + add_user_command (&ptr->type_commands,"next","Move to next inode in current block group",type_ext2_inode___next); + add_user_command (&ptr->type_commands,"prev","Move to next inode in current block group",type_ext2_inode___prev); + add_user_command (&ptr->type_commands,"group","Move to the group descriptors of the current inode table",type_ext2_inode___group); + add_user_command (&ptr->type_commands,"entry","Move to a specified entry in the current inode table",type_ext2_inode___entry); + add_user_command (&ptr->type_commands,"file","Display file data of the current inode",type_ext2_inode___file); + add_user_command (&ptr->type_commands,"dir","Display directory data of the current inode",type_ext2_inode___dir); + } + + if (strcmp ((ptr->name),"dir")==0) { + add_user_command (&ptr->type_commands,"show","Shows current directory data",type_dir___show); + add_user_command (&ptr->type_commands,"inode","Returns to the inode of the current directory",type_dir___inode); + add_user_command (&ptr->type_commands,"next","Pass to the next directory entry",type_dir___next); + add_user_command (&ptr->type_commands,"prev","Pass to the previous directory entry",type_dir___prev); + add_user_command (&ptr->type_commands,"followinode","Follows the inode specified in this directory entry",type_dir___followinode); + add_user_command (&ptr->type_commands,"remember","Remember the inode of the current directory entry",type_dir___remember); + add_user_command (&ptr->type_commands,"cd","Changes directory relative to the current directory",type_dir___cd); + add_user_command (&ptr->type_commands,"entry","Moves to a specified entry in the current directory",type_dir___entry); + add_user_command (&ptr->type_commands,"writedata","Writes the current entry to the disk",type_dir___writedata); + add_user_command (&ptr->type_commands,"set","Changes a variable in the current directory entry",type_dir___set); + } + + if (strcmp ((ptr->name),"ext2_super_block")==0) { + add_user_command (&ptr->type_commands,"show","Displays the super block data",type_ext2_super_block___show); + add_user_command (&ptr->type_commands,"gocopy","Move to another backup copy of the superblock",type_ext2_super_block___gocopy); + add_user_command (&ptr->type_commands,"setactivecopy","Copies the current superblock to the main superblock",type_ext2_super_block___setactivecopy); + } + + if (strcmp ((ptr->name),"ext2_group_desc")==0) { + add_user_command (&ptr->type_commands,"next","Pass to the next block group descriptor",type_ext2_group_desc___next); + add_user_command (&ptr->type_commands,"prev","Pass to the previous group descriptor",type_ext2_group_desc___prev); + add_user_command (&ptr->type_commands,"entry","Pass to a specific group descriptor",type_ext2_group_desc___entry); + add_user_command (&ptr->type_commands,"show","Shows the current group descriptor",type_ext2_group_desc___show); + add_user_command (&ptr->type_commands,"inode","Pass to the inode table of the current group block",type_ext2_group_desc___inode); + add_user_command (&ptr->type_commands,"gocopy","Move to another backup copy of the group descriptor",type_ext2_group_desc___gocopy); + add_user_command (&ptr->type_commands,"blockbitmap","Show the block allocation bitmap of the current group block",type_ext2_group_desc___blockbitmap); + add_user_command (&ptr->type_commands,"inodebitmap","Show the inode allocation bitmap of the current group block",type_ext2_group_desc___inodebitmap); + add_user_command (&ptr->type_commands,"setactivecopy","Copies the current group descriptor to the main table",type_ext2_super_block___setactivecopy); + } + + if (strcmp ((ptr->name),"block_bitmap")==0) { + add_user_command (&ptr->type_commands,"show","Displays the block allocation bitmap",type_ext2_block_bitmap___show); + add_user_command (&ptr->type_commands,"entry","Moves to a specific bit",type_ext2_block_bitmap___entry); + add_user_command (&ptr->type_commands,"next","Moves to the next bit",type_ext2_block_bitmap___next); + add_user_command (&ptr->type_commands,"prev","Moves to the previous bit",type_ext2_block_bitmap___prev); + add_user_command (&ptr->type_commands,"allocate","Allocates the current block",type_ext2_block_bitmap___allocate); + add_user_command (&ptr->type_commands,"deallocate","Deallocates the current block",type_ext2_block_bitmap___deallocate); + } + + if (strcmp ((ptr->name),"inode_bitmap")==0) { + add_user_command (&ptr->type_commands,"show","Displays the inode allocation bitmap",type_ext2_inode_bitmap___show); + add_user_command (&ptr->type_commands,"entry","Moves to a specific bit",type_ext2_inode_bitmap___entry); + add_user_command (&ptr->type_commands,"next","Moves to the next bit",type_ext2_inode_bitmap___next); + add_user_command (&ptr->type_commands,"prev","Moves to the previous bit",type_ext2_inode_bitmap___prev); + add_user_command (&ptr->type_commands,"allocate","Allocates the current inode",type_ext2_inode_bitmap___allocate); + add_user_command (&ptr->type_commands,"deallocate","Deallocates the current inode",type_ext2_inode_bitmap___deallocate); + } + +} + +void add_user_command (struct struct_commands *ptr,char *name,char *description,PF callback) + +{ + int num; + + num=ptr->last_command; + if (num+1==MAX_COMMANDS_NUM) { + printf ("Internal Error - Can't add command %s\n",name); + return; + } + + ptr->last_command=++num; + + ptr->names [num]=(char *) malloc (strlen (name)+1); + strcpy (ptr->names [num],name); + + if (*description!=0) { + ptr->descriptions [num]=(char *) malloc (strlen (description)+1); + strcpy (ptr->descriptions [num],description); + } + + ptr->callback [num]=callback; +} + +int set_file_system_info (void) + +{ + int ext2_detected=0; + struct ext2_super_block *sb; + + file_system_info.super_block_offset=1024; + file_system_info.file_system_size=DefaultTotalBlocks*DefaultBlockSize; + + low_read ((char *) &file_system_info.super_block,sizeof (struct ext2_super_block),file_system_info.super_block_offset); + + sb=&file_system_info.super_block; + + if (sb->s_magic == EXT2_SUPER_MAGIC) + ext2_detected=1; + + if (ext2_detected) + wprintw (command_win,"Detected extended 2 file system on device %s\n",device_name); + else + wprintw (command_win,"Warning - Extended 2 filesystem not detected on device %s\n",device_name); + + if (!ext2_detected && !ForceExt2) + wprintw (command_win,"You may wish to use the configuration option ForceExt2 on\n"); + + if (ForceExt2 && !ext2_detected) + wprintw (command_win,"Forcing extended 2 filesystem\n"); + + if (ForceDefault || !ext2_detected) + wprintw (command_win,"Forcing default parameters\n"); + + refresh_command_win (); + + if (ext2_detected || ForceExt2) { + add_ext2_general_commands (); + if (!set_struct_descriptors (Ext2Descriptors)) + return (0); + } + + if (!ForceDefault && ext2_detected) { + + file_system_info.block_size=EXT2_MIN_BLOCK_SIZE << sb->s_log_block_size; + if (file_system_info.block_size == EXT2_MIN_BLOCK_SIZE) + file_system_info.first_group_desc_offset=2*EXT2_MIN_BLOCK_SIZE; + else + file_system_info.first_group_desc_offset=file_system_info.block_size; + file_system_info.groups_count = ext2fs_div64_ceil(ext2fs_blocks_count(sb), + sb->s_blocks_per_group); + + file_system_info.inodes_per_block=file_system_info.block_size/sizeof (struct ext2_inode); + file_system_info.blocks_per_group=sb->s_inodes_per_group/file_system_info.inodes_per_block; + file_system_info.no_blocks_in_group=sb->s_blocks_per_group; + file_system_info.file_system_size=(ext2fs_blocks_count(sb)-1)*file_system_info.block_size; + } + + else { + file_system_info.file_system_size=DefaultTotalBlocks*DefaultBlockSize; + file_system_info.block_size=DefaultBlockSize; + file_system_info.no_blocks_in_group=DefaultBlocksInGroup; + } + + if (file_system_info.file_system_size > 2147483647) { + wprintw (command_win,"Sorry, filesystems bigger than 2 GB are currently not supported\n"); + return (0); + } + return (1); +} + +void init_readline (void) + +{ +#ifdef HAVE_READLINE + rl_completion_entry_function=(Function *) complete_command; +#endif +} + +void init_signals (void) + +{ + signal (SIGWINCH, signal_SIGWINCH_handler); /* Catch SIGWINCH */ + signal (SIGTERM, signal_SIGTERM_handler); + signal (SIGSEGV, signal_SIGSEGV_handler); + +} + +void signal_SIGWINCH_handler (int sig_num) + +{ + redraw_request=1; /* We will handle it in main.c */ + + /* Reset signal handler */ + signal (SIGWINCH, signal_SIGWINCH_handler); + +} + +void signal_SIGTERM_handler (int sig_num) + +{ + prepare_to_close (); + printf ("Terminated due to signal %d\n",sig_num); + exit (1); +} + +void signal_SIGSEGV_handler (int sig_num) + +{ + prepare_to_close (); + printf ("Killed by signal %d!\n",sig_num); + exit (1); +} + +int process_configuration_file (void) + +{ + char buffer [300]; + char option [80],value [80]; + FILE *fp; + + strcpy (buffer, ROOT_SYSCONFDIR); + strcat (buffer,"/ext2ed.conf"); + + if ((fp=fopen (buffer,"rt"))==NULL) { + fprintf (stderr,"Error - Unable to open configuration file %s\n",buffer); + return (0); + } + + while (get_next_option (fp,option,value)) { + if (strcasecmp (option,"Ext2Descriptors")==0) { + strcpy (Ext2Descriptors,value); + } + + else if (strcasecmp (option,"AlternateDescriptors")==0) { + strcpy (AlternateDescriptors,value); + } + + else if (strcasecmp (option,"LogFile")==0) { + strcpy (LogFile,value); + } + + else if (strcasecmp (option,"LogChanges")==0) { + if (strcasecmp (value,"on")==0) + LogChanges = 1; + else if (strcasecmp (value,"off")==0) + LogChanges = 0; + else { + fprintf (stderr,"Error - Illegal value: %s %s\n",option,value); + fclose (fp);return (0); + } + } + + else if (strcasecmp (option,"AllowChanges")==0) { + if (strcasecmp (value,"on")==0) + AllowChanges = 1; + else if (strcasecmp (value,"off")==0) + AllowChanges = 0; + else { + fprintf (stderr,"Error - Illegal value: %s %s\n",option,value); + fclose (fp);return (0); + } + } + + else if (strcasecmp (option,"AllowMountedRead")==0) { + if (strcasecmp (value,"on")==0) + AllowMountedRead = 1; + else if (strcasecmp (value,"off")==0) + AllowMountedRead = 0; + else { + fprintf (stderr,"Error - Illegal value: %s %s\n",option,value); + fclose (fp);return (0); + } + } + + else if (strcasecmp (option,"ForceExt2")==0) { + if (strcasecmp (value,"on")==0) + ForceExt2 = 1; + else if (strcasecmp (value,"off")==0) + ForceExt2 = 0; + else { + fprintf (stderr,"Error - Illegal value: %s %s\n",option,value); + fclose (fp);return (0); + } + } + + else if (strcasecmp (option,"DefaultBlockSize")==0) { + DefaultBlockSize = atoi (value); + } + + else if (strcasecmp (option,"DefaultTotalBlocks")==0) { + DefaultTotalBlocks = strtoul (value,NULL,10); + } + + else if (strcasecmp (option,"DefaultBlocksInGroup")==0) { + DefaultBlocksInGroup = strtoul (value,NULL,10); + } + + else if (strcasecmp (option,"ForceDefault")==0) { + if (strcasecmp (value,"on")==0) + ForceDefault = 1; + else if (strcasecmp (value,"off")==0) + ForceDefault = 0; + else { + fprintf (stderr,"Error - Illegal value: %s %s\n",option,value); + fclose (fp);return (0); + } + } + + else { + fprintf (stderr,"Error - Unknown option: %s\n",option); + fclose (fp);return (0); + } + } + + printf ("Configuration completed\n"); + fclose (fp); + return (1); +} + +int get_next_option (FILE *fp,char *option,char *value) + +{ + char *ptr; + char buffer [600]; + + if (feof (fp)) return (0); + do{ + if (feof (fp)) return (0); + fgets (buffer,500,fp); + } while (buffer [0]=='#' || buffer [0]=='\n'); + + ptr=parse_word (buffer,option); + ptr=parse_word (ptr,value); + return (1); +} + +void check_mounted (char *name) + +{ + FILE *fp; + char *ptr; + char current_line [500],current_word [200]; + + mounted=0; + + if ( (fp=fopen ("/etc/mtab","rt"))==NULL) { + wprintw (command_win,"Error - Failed to open /etc/mtab. Assuming filesystem is mounted.\n"); + refresh_command_win ();mounted=1;return; + }; + + while (!feof (fp)) { + fgets (current_line,500,fp); + if (feof (fp)) break; + ptr=parse_word (current_line,current_word); + if (strcasecmp (current_word,name)==0) { + mounted=1;fclose (fp);return; + } + }; + + fclose (fp); + + return; +} diff --git a/ext2ed/inode_com.c b/ext2ed/inode_com.c new file mode 100644 index 0000000..2d3dd6d --- /dev/null +++ b/ext2ed/inode_com.c @@ -0,0 +1,437 @@ +/* + +/usr/src/ext2ed/inode_com.c + +A part of the extended file system 2 disk editor. + +Commands relevant to ext2_inode type. + +First written on: April 9 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +#include "ext2ed.h" + +void type_ext2_inode___prev (char *command_line) + +{ + + char *ptr,buffer [80]; + + long group_num,group_offset,entry_num,block_num,first_entry,last_entry; + long inode_num,mult=1; + struct ext2_group_desc desc; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + mult=atol (buffer); + } + + block_num=device_offset/file_system_info.block_size; + + group_num=inode_offset_to_group_num (device_offset); + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + + entry_num=(device_offset-desc.bg_inode_table*file_system_info.block_size)/sizeof (struct ext2_inode); + + first_entry=0;last_entry=file_system_info.super_block.s_inodes_per_group-1; + inode_num=0; + + if (entry_num-mult+1>0) { + device_offset-=sizeof (struct ext2_inode)*mult; + entry_num-=mult; + + sprintf (buffer,"setoffset %ld",device_offset);dispatch (buffer); + strcpy (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Entry out of limits\n");refresh_command_win (); + } + + if (entry_num==0) { + wprintw (command_win,"Reached first inode in current group descriptor\n"); + refresh_command_win (); + } +} + +void type_ext2_inode___next (char *command_line) + +{ + + char *ptr,buffer [80]; + + long group_num,group_offset,entry_num,block_num,first_entry,last_entry; + long inode_num,mult=1; + struct ext2_group_desc desc; + + ptr=parse_word (command_line,buffer); + + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + mult=atol (buffer); + } + + + block_num=device_offset/file_system_info.block_size; + + group_num=inode_offset_to_group_num (device_offset); + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + + entry_num=(device_offset-desc.bg_inode_table*file_system_info.block_size)/sizeof (struct ext2_inode); + + first_entry=0;last_entry=file_system_info.super_block.s_inodes_per_group-1; + inode_num=0; + + if (entry_num+mult-1<last_entry) { + device_offset+=sizeof (struct ext2_inode)*mult; + entry_num+=mult; + + sprintf (buffer,"setoffset %ld",device_offset);dispatch (buffer); + strcpy (buffer,"show");dispatch (buffer); + } + + else { + wprintw (command_win,"Error - Entry out of limits\n");refresh_command_win (); + } + + if (entry_num==last_entry) { + wprintw (command_win,"Reached last inode in current group descriptor\n"); + refresh_command_win (); + } +} + + +void type_ext2_inode___show (char *command_line) + +{ + struct ext2_inode *inode_ptr; + + unsigned short temp; + int i; + + long group_num,group_offset,entry_num,block_num,first_entry,last_entry,inode_num; + struct ext2_group_desc desc; + + block_num=device_offset/file_system_info.block_size; + + group_num=inode_offset_to_group_num (device_offset); + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + + entry_num=(device_offset-desc.bg_inode_table*file_system_info.block_size)/sizeof (struct ext2_inode); + first_entry=0;last_entry=file_system_info.super_block.s_inodes_per_group-1; + inode_num=group_num*file_system_info.super_block.s_inodes_per_group+1; + inode_num+=entry_num; + + inode_ptr=&type_data.u.t_ext2_inode; + + show (command_line); + + wmove (show_pad,0,40);wprintw (show_pad,"octal = %06o ",inode_ptr->i_mode); + for (i=6;i>=0;i-=3) { + temp=inode_ptr->i_mode & 0x1ff; + temp=temp >> i; + if (temp & 4) + wprintw (show_pad,"r"); + else + wprintw (show_pad,"-"); + + if (temp & 2) + wprintw (show_pad,"w"); + else + wprintw (show_pad,"-"); + + if (temp & 1) + wprintw (show_pad,"x"); + else + wprintw (show_pad,"-"); + } + wmove (show_pad,3,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_inode.i_atime)); + wmove (show_pad,4,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_inode.i_ctime)); + wmove (show_pad,5,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_inode.i_mtime)); + wmove (show_pad,6,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_inode.i_dtime)); + + wmove (show_pad,10,40); + temp=inode_ptr->i_flags; + + if (temp & EXT2_SECRM_FL) + wprintw (show_pad,"s"); + else + wprintw (show_pad,"-"); + + + if (temp & EXT2_UNRM_FL) + wprintw (show_pad,"u"); + else + wprintw (show_pad,"-"); + + if (temp & EXT2_COMPR_FL) + wprintw (show_pad,"c"); + else + wprintw (show_pad,"-"); + + if (temp & EXT2_SYNC_FL) + wprintw (show_pad,"S"); + else + wprintw (show_pad,"-"); + + if (temp & EXT2_IMMUTABLE_FL) + wprintw (show_pad,"i"); + else + wprintw (show_pad,"-"); + + if (temp & EXT2_APPEND_FL) + wprintw (show_pad,"a"); + else + wprintw (show_pad,"-"); + + if (temp & EXT2_NODUMP_FL) + wprintw (show_pad,"d"); + else + wprintw (show_pad,"-"); + + refresh_show_pad (); + + wmove (show_win,1,0); + + wprintw (show_win,"Inode %ld of %ld. Entry %ld of %ld in group descriptor %ld.\n" + ,inode_num,file_system_info.super_block.s_inodes_count,entry_num,last_entry,group_num); + + wprintw (show_win,"Inode type: "); + + if (inode_num < EXT2_GOOD_OLD_FIRST_INO) { + switch (inode_num) { + case EXT2_BAD_INO: + wprintw (show_win,"Bad blocks inode - "); + break; + case EXT2_ROOT_INO: + wprintw (show_win,"Root inode - "); + break; + case EXT4_USR_QUOTA_INO: + wprintw (show_win,"User quota inode - "); + break; + case EXT4_GRP_QUOTA_INO: + wprintw (show_win,"Group quota inode - "); + break; + case EXT2_BOOT_LOADER_INO: + wprintw (show_win,"Boot loader inode - "); + break; + case EXT2_UNDEL_DIR_INO: + wprintw (show_win,"Undelete directory inode - "); + break; + default: + wprintw (show_win,"Reserved inode - "); + break; + } + } + if (type_data.u.t_ext2_inode.i_mode==0) + wprintw (show_win,"Free. "); + + if (S_ISREG (type_data.u.t_ext2_inode.i_mode)) + wprintw (show_win,"File. "); + + if (S_ISDIR (type_data.u.t_ext2_inode.i_mode)) + wprintw (show_win,"Directory. "); + + if (S_ISLNK (type_data.u.t_ext2_inode.i_mode)) { + wprintw (show_win,"Symbolic link. "); + wmove (show_pad,12,40); + + if (inode_ptr->i_size <= 60) + wprintw (show_pad,"-> %s",(char *) &type_data.u.t_ext2_inode.i_block [0]); + else + wprintw (show_pad,"Slow symbolic link\n"); + refresh_show_pad (); + } + + if (S_ISCHR (type_data.u.t_ext2_inode.i_mode)) + wprintw (show_win,"Character device."); + + if (S_ISBLK (type_data.u.t_ext2_inode.i_mode)) + wprintw (show_win,"Block device. "); + + wprintw (show_win,"\n");refresh_show_win (); + + if (entry_num==last_entry) { + wprintw (command_win,"Reached last inode in current group descriptor\n"); + refresh_command_win (); + } + + if (entry_num==first_entry) { + wprintw (command_win,"Reached first inode in current group descriptor\n"); + refresh_command_win (); + } + +} + +void type_ext2_inode___entry (char *command_line) + +{ + char *ptr,buffer [80]; + + long group_num,group_offset,entry_num,block_num,wanted_entry; + struct ext2_group_desc desc; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) return; + ptr=parse_word (ptr,buffer); + wanted_entry=atol (buffer); + + block_num=device_offset/file_system_info.block_size; + + group_num=inode_offset_to_group_num (device_offset); + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + + entry_num=(device_offset-desc.bg_inode_table*file_system_info.block_size)/sizeof (struct ext2_inode); + + if (wanted_entry > entry_num) { + sprintf (buffer,"next %ld",wanted_entry-entry_num); + dispatch (buffer); + } + + else if (wanted_entry < entry_num) { + sprintf (buffer,"prev %ld",entry_num-wanted_entry); + dispatch (buffer); + } +} + +void type_ext2_inode___group (char *command_line) + +{ + char buffer [80]; + + long group_num,group_offset; + + group_num=inode_offset_to_group_num (device_offset); + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + sprintf (buffer,"setoffset %ld",group_offset);dispatch (buffer); + sprintf (buffer,"settype ext2_group_desc");dispatch (buffer); +} + +void type_ext2_inode___file (char *command_line) + +{ + char buffer [80]; + + if (!S_ISREG (type_data.u.t_ext2_inode.i_mode)) { + wprintw (command_win,"Error - Inode type is not file\n");refresh_command_win (); + return; + } + + if (!init_file_info ()) { + wprintw (command_win,"Error - Unable to show file\n");refresh_command_win (); + return; + } + + sprintf (buffer,"settype file");dispatch (buffer); +} + +void type_ext2_inode___dir (char *command_line) + +{ + char buffer [80]; + + if (!S_ISDIR (type_data.u.t_ext2_inode.i_mode)) { + wprintw (command_win,"Error - Inode type is not directory\n");refresh_command_win (); + return; + } + +/* It is very important to init first_file_info first, as search_dir_entries relies on it */ + + if (!init_dir_info (&first_file_info)) { + wprintw (command_win,"Error - Unable to show directory\n");refresh_command_win (); + return; + } + + file_info=first_file_info; + + sprintf (buffer,"settype dir");dispatch (buffer); +} + +long inode_offset_to_group_num (long inode_offset) + +{ + int found=0; + struct ext2_group_desc desc; + + long block_num,group_offset,group_num; + + block_num=inode_offset/file_system_info.block_size; + + group_offset=file_system_info.first_group_desc_offset; + group_num=(group_offset-file_system_info.first_group_desc_offset)/sizeof (struct ext2_group_desc); + + while (!found && group_num>=0 && group_num<file_system_info.groups_count) { + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + if (block_num>=desc.bg_inode_table && block_num<desc.bg_inode_table+file_system_info.blocks_per_group) + found=1; + else + group_offset+=sizeof (struct ext2_group_desc); + group_num=(group_offset-file_system_info.first_group_desc_offset)/sizeof (struct ext2_group_desc); + } + + if (!found) + return (-1); + + return (group_num); +} + + + +long int inode_offset_to_inode_num (long inode_offset) + +{ + long group_num,group_offset,entry_num,block_num,first_entry,last_entry,inode_num; + struct ext2_group_desc desc; + + block_num=inode_offset/file_system_info.block_size; + + group_num=inode_offset_to_group_num (inode_offset); + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + + entry_num=(inode_offset-desc.bg_inode_table*file_system_info.block_size)/sizeof (struct ext2_inode); + first_entry=0;last_entry=file_system_info.super_block.s_inodes_per_group-1; + inode_num=group_num*file_system_info.super_block.s_inodes_per_group+1; + inode_num+=entry_num; + + return (inode_num); +} + +long int inode_num_to_inode_offset (long inode_num) + +{ + long group_num,group_offset,inode_offset,inode_entry; + struct ext2_group_desc desc; + + inode_num--; + + group_num=inode_num/file_system_info.super_block.s_inodes_per_group; + inode_entry=inode_num%file_system_info.super_block.s_inodes_per_group; + group_offset=file_system_info.first_group_desc_offset+group_num*sizeof (struct ext2_group_desc); + low_read ((char *) &desc,sizeof (struct ext2_group_desc),group_offset); + + inode_offset=desc.bg_inode_table*file_system_info.block_size+inode_entry*sizeof (struct ext2_inode); + + return (inode_offset); +} diff --git a/ext2ed/inodebitmap_com.c b/ext2ed/inodebitmap_com.c new file mode 100644 index 0000000..157807a --- /dev/null +++ b/ext2ed/inodebitmap_com.c @@ -0,0 +1,215 @@ +/* + +/usr/src/ext2ed/inodebitmap_com.c + +A part of the extended file system 2 disk editor. + +------------------------- +Handles the inode bitmap. +------------------------- + +Please refer to the documentation in blockbitmap_com.c - Those two files are almost equal. + +First written on: July 25 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "ext2ed.h" + + +void type_ext2_inode_bitmap___entry (char *command_line) + +{ + unsigned long entry_num; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n");refresh_command_win ();return; + } + ptr=parse_word (ptr,buffer); + + entry_num=atol (buffer); + + if (entry_num >= file_system_info.super_block.s_inodes_per_group) { + wprintw (command_win,"Error - Entry number out of bounds\n");refresh_command_win ();return; + } + + inode_bitmap_info.entry_num=entry_num; + strcpy (buffer,"show");dispatch (buffer); +} + +void type_ext2_inode_bitmap___next (char *command_line) + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",inode_bitmap_info.entry_num+entry_offset); + dispatch (buffer); +} + +void type_ext2_inode_bitmap___prev (char *command_line) + +{ + long entry_offset=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + entry_offset=atol (buffer); + } + + sprintf (buffer,"entry %ld",inode_bitmap_info.entry_num-entry_offset); + dispatch (buffer); +} + +void type_ext2_inode_bitmap___allocate (char *command_line) + +{ + long entry_num,num=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + num=atol (buffer); + } + + entry_num=inode_bitmap_info.entry_num; + if (num > file_system_info.super_block.s_inodes_per_group-entry_num) { + wprintw (command_win,"Error - There aren't that much inodes in the group\n"); + refresh_command_win ();return; + } + + while (num) { + allocate_inode (entry_num); + num--;entry_num++; + } + + dispatch ("show"); +} + +void type_ext2_inode_bitmap___deallocate (char *command_line) + +{ + long entry_num,num=1; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr!=0) { + ptr=parse_word (ptr,buffer); + num=atol (buffer); + } + + entry_num=inode_bitmap_info.entry_num; + if (num > file_system_info.super_block.s_inodes_per_group-entry_num) { + wprintw (command_win,"Error - There aren't that much inodes in the group\n"); + refresh_command_win ();return; + } + + while (num) { + deallocate_inode (entry_num); + num--;entry_num++; + } + + dispatch ("show"); +} + + +void allocate_inode (long entry_num) + +{ + unsigned char bit_mask=1; + int byte_offset,j; + + byte_offset=entry_num/8; + for (j=0;j<entry_num%8;j++) + bit_mask*=2; + type_data.u.buffer [byte_offset] |= bit_mask; +} + +void deallocate_inode (long entry_num) + +{ + unsigned char bit_mask=1; + int byte_offset,j; + + byte_offset=entry_num/8; + for (j=0;j<entry_num%8;j++) + bit_mask*=2; + bit_mask^=0xff; + + type_data.u.buffer [byte_offset] &= bit_mask; +} + +void type_ext2_inode_bitmap___show (char *command_line) + +{ + int i,j; + unsigned char *ptr; + unsigned long inode_num,entry_num; + + ptr=type_data.u.buffer; + show_pad_info.line=0;show_pad_info.max_line=-1; + + wmove (show_pad,0,0); + for (i=0,entry_num=0;i<file_system_info.super_block.s_inodes_per_group/8;i++,ptr++) { + for (j=1;j<=128;j*=2) { + if (entry_num==inode_bitmap_info.entry_num) { + wattrset (show_pad,A_REVERSE); + show_pad_info.line=show_pad_info.max_line-show_pad_info.display_lines/2; + } + + if ((*ptr) & j) + wprintw (show_pad,"1"); + else + wprintw (show_pad,"0"); + + if (entry_num==inode_bitmap_info.entry_num) + wattrset (show_pad,A_NORMAL); + + entry_num++; + } + wprintw (show_pad," "); + if (i%8==7) { + wprintw (show_pad,"\n"); + show_pad_info.max_line++; + } + } + + if (i%8!=7) { + wprintw (show_pad,"\n"); + show_pad_info.max_line++; + } + + refresh_show_pad (); + show_info (); + wmove (show_win,1,0);wprintw (show_win,"Inode bitmap of block group %ld\n",inode_bitmap_info.group_num); + + inode_num=1+inode_bitmap_info.entry_num+inode_bitmap_info.group_num*file_system_info.super_block.s_inodes_per_group; + wprintw (show_win,"Status of inode %ld - ",inode_num); + ptr=type_data.u.buffer+inode_bitmap_info.entry_num/8; + j=1; + for (i=inode_bitmap_info.entry_num % 8;i>0;i--) + j*=2; + if ((*ptr) & j) + wprintw (show_win,"Allocated\n"); + else + wprintw (show_win,"Free\n"); + refresh_show_win (); +} diff --git a/ext2ed/main.c b/ext2ed/main.c new file mode 100644 index 0000000..9d33a8e --- /dev/null +++ b/ext2ed/main.c @@ -0,0 +1,548 @@ +/* + +/usr/src/ext2ed/main.c + +A part of the extended file system 2 disk editor. + +------------ +Main program +------------ + +This file mostly contains: + +1. A list of global variables used through the entire program. +2. The parser, which asks the command line from the user. +3. The dispatcher, which analyzes the command line and calls the appropriate handler function. +4. A command pattern matcher which is used along with the readline completion feature. +5. A function which tells the user that an internal error has occurred. + +First written on: March 30 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <signal.h> + +#ifdef HAVE_READLINE +#include <readline.h> +#include <history.h> +#endif + +#ifdef HAVE_GETOPT_H +#include <getopt.h> +#else +extern int optind; +extern char *optarg; +#endif + +#include "ext2ed.h" + +/* Global variables */ + +/* + +Configuration file options + +The following variables will be set by init.c to the values selected in the user configuration file. +They are initialized below to some logical defaults. + +*/ + + +char Ext2Descriptors [200]="ext2.descriptors"; /* The location of the ext2 filesystem object definition */ +char AlternateDescriptors [200]=""; /* We allow the user to define additional structures */ +char LogFile [200]="ext2ed.log"; /* The location of the log file - Each write will be logged there */ +int LogChanges=1; /* 1 enables logging, 0 disables logging */ +int AllowChanges=0; /* When set, the enablewrite command will fail */ +int AllowMountedRead=0; /* Behavior when trying to open a mounted filesystem read-only */ +int ForceExt2=0; /* When set, ext2 autodetection is overridden */ +int DefaultBlockSize=1024; +unsigned long DefaultTotalBlocks=2097151; +unsigned long DefaultBlocksInGroup=8192; /* The default values are used when an ext2 filesystem is not */ +int ForceDefault=0; /* detected, or ForceDefault is set */ + +char last_command_line [80]; /* A simple one command cache, in addition to the readline history */ + +char device_name [80]; /* The location of the filesystem */ +FILE *device_handle=NULL; /* This is passed to the fopen / fread ... commands */ +long device_offset; /* The current position in the filesystem */ + /* Note that we have a 2 GB limitation */ + +int mounted=0; /* This is set when we find that the filesystem is mounted */ + +struct struct_commands general_commands,ext2_commands; /* Used to define the general and ext2 commands */ +struct struct_descriptor *first_type,*last_type,*current_type; /* Used to access the double linked list */ +struct struct_type_data type_data; /* The current data is sometimes stored here */ +struct struct_file_system_info file_system_info; /* Essential information on the filesystem */ +struct struct_file_info file_info,first_file_info; /* Used by file_com.c to access files */ +struct struct_group_info group_info; /* Used by group_com.c */ +struct struct_super_info super_info; /* Used by super_com.c */ +struct struct_remember_lifo remember_lifo; /* A circular memory of objects */ +struct struct_block_bitmap_info block_bitmap_info; /* Used by blockbitmap_com.c */ +struct struct_inode_bitmap_info inode_bitmap_info; /* Used by inodebitmap_com.c */ + +int redraw_request=0; /* Is set by a signal handler to handle terminal */ + /* screen size change. */ + + +/* + * We just call the parser to get commands from the user. We quit when + * parser returns. + */ +int main (int argc, char **argv) +{ + int write_priv = 0; + int c; + char *buf; + + if (!init ()) + return (1); + while ((c = getopt (argc, argv, "w")) != EOF) { + switch (c) { + case 'w': + write_priv++; + break; + } + } + if (optind < argc) { + buf = malloc(strlen(argv[optind]) + 32); + if (!buf) { + fprintf(stderr, "Couldn't allocate filename buffer\n"); + exit(1); + } + strcpy(buf, "set_device "); + strcat(buf, argv[optind]); + set_device(buf); + free(buf); + if (write_priv) { + wprintw (command_win,"\n"); + enable_write("enable_write"); + } + } + parser (); /* Get and parse user commands */ + prepare_to_close(); /* Do some cleanup */ + printf("Quitting ...\n"); + return(0); +} + + +/* + * Read a character from the command window + */ +int command_read_key() +{ + int key = 0; + + while (!key) { + if (redraw_request) { + redraw_all(); + redraw_request=0; + } + key = wgetch(command_win); + switch (key) { + case 0x1A: + key = 0; + kill(getpid(), SIGTSTP); + break; + + case KEY_NPAGE: + pgdn(""); + refresh_command_win (); + break; + + case KEY_PPAGE: + pgup(""); + refresh_command_win (); + break; + case ERR: + key = 0; + break; + + case KEY_BACKSPACE: + key = '\b'; + } + if ((key < 32 && key != '\b' && key != '\n') || + (key > 127)) + key = 0; + } + return key; +} + +#ifdef HAVE_READLINE +int rl_getc_replacement(FILE *f) +{ + int key = command_read_key(); + + if (key == '\b') { + if (rl_point > 0) + wprintw(command_win, "\b \b"); + } else + wprintw(command_win, "%c", key); + return key; +} + +/* + * This function asks the user for a command and calls the dispatcher + * function, dispatch, to analyze it. We use the readline library + * function readline to read the command, hence all the usual readline + * keys are available. The new command is saved both in the + * readline's history and in our tiny one-command cache, so that only + * the enter key is needed to retype it. + */ +void parser (void) +{ + char *ptr,command_line [80]; + int quit=0; + +#if 0 + noecho(); + cbreak(); + keypad(command_win, 1); + wtimeout(command_win, 100); + + rl_getc_function = rl_getc_replacement; +#endif + + while (!quit) { + /* Terminal screen size has changed */ + if (redraw_request) { + redraw_all(); + redraw_request=0; + } + + wmove (command_win,0,0); + wclrtoeol (command_win); + wprintw (command_win,"ext2ed > "); + refresh_command_win (); + + /* + * The ncurses library optimizes cursor movement by + * keeping track of the cursor position. However, by + * using the readline library I'm breaking its + * assumptions. The double -1 arguments tell ncurses + * to disable cursor movement optimization this + * time. + */ + mvcur (-1,-1,LINES-COMMAND_WIN_LINES,0); + + /* echo (); */ + ptr=readline ("ext2ed > "); + /* noecho (); */ + + /* + * Readline allocated the buffer - Copy the string + * and free the allocated buffer + * XXX WHY??? + */ + strcpy (command_line,ptr); + free (ptr); + + if (*command_line != 0) + add_history (command_line); + + /* If only enter was pressed, recall the last command */ + if (*command_line==0) + strcpy (command_line,last_command_line); + + /* Emulate readline's actions for ncurses */ + mvcur (-1,-1,LINES-COMMAND_WIN_LINES,0); + werase (command_win); + wprintw (command_win,"ext2ed > "); + wprintw (command_win,command_line); + wprintw (command_win,"\n"); + refresh_command_win (); + + /* Save this command in our tiny cache */ + strcpy (last_command_line,command_line); + + /* And call dispatch to do the actual job */ + quit=dispatch (command_line); + } +} +#else +void read_line(char * foo) { + char * chptr = foo; + int ch; + int done = 0; + + while (!done && (ch = command_read_key())) { + switch (ch) { + case '\n': + done = 1; + break; + + case '\b': + if (chptr > foo) { + wprintw(command_win, "\b \b"); + chptr--; + } + break; + + default: + if (ch > 256) + break; + if (ch == '\n') break; + *chptr++ = ch; + wprintw(command_win, "%c", ch); + break; + } + } + *chptr = '\0'; +} + +void parser (void) +{ + char command_line [80]; + int quit=0; + + noecho(); + cbreak(); + wtimeout(command_win, 100); + keypad(command_win, 1); + + while (!quit) { + /* Terminal screen size has changed */ + if (redraw_request) { + redraw_all(); + redraw_request=0; + } + + wmove (command_win,0,0);wclrtoeol (command_win); + + wmove(command_win, 0, 0); + wprintw(command_win, "ext2ed > "); + read_line(command_line); + + /* If only enter was pressed, recall the last command */ + if (*command_line==0) + strcpy (command_line,last_command_line); + + mvcur (-1,-1,LINES-COMMAND_WIN_LINES + 1,0); + + strcpy (last_command_line,command_line); /* Save this command in our tiny cache */ + + /* And call dispatch to do the actual job */ + quit=dispatch (command_line); + } +} +#endif + + +/* + * This is a very important function. Its task is to receive a command + * name and link it to a C function. There are three types of commands: + * + * 1. General commands - Always available and accessed through + * general_commands. + * 2. Ext2 specific commands - Available when editing an ext2 + * filesystem, accessed through ext2_commands. + * 3. Type specific commands - Those are changing according to the + * current type. The global variable current_type points to the + * current object definition (of type struct_descriptor). In it, the + * struct_commands entry contains the type specific commands links. + * + * Overriding is an important feature - Much like in C++ : The same + * command name can dispatch to different functions. The overriding + * priority is 3,2,1; That is - A type specific command will always + * override a general command. This is used through the program to + * allow fine tuned operation. + * + * When an handling function is found, it is called along with the + * command line that was passed to us. The handling function is then + * free to interpret the arguments in its own style. + */ +int dispatch (char *command_line) +{ + int i,found=0; + + char command [80]; + + parse_word (command_line,command); + + if (strcasecmp (command,"quit")==0) return (1); + + /* 1. Search for type specific commands FIRST - Allows + overriding of a general command */ + + if (current_type != NULL) + for (i=0; + i<=current_type->type_commands.last_command && !found; + i++) { + if (strcasecmp (command,current_type->type_commands.names [i])==0) { + (*current_type->type_commands.callback [i]) (command_line); + found=1; + } + } + + /* 2. Now search for ext2 filesystem general commands */ + + if (!found) + for (i=0;i<=ext2_commands.last_command && !found;i++) { + if (strcasecmp (command,ext2_commands.names [i])==0) { + (*ext2_commands.callback [i]) (command_line); + found=1; + } + } + + + /* 3. If not found, search the general commands */ + + if (!found) + for (i=0;i<=general_commands.last_command && !found;i++) { + if (strcasecmp (command,general_commands.names [i])==0) { + (*general_commands.callback [i]) (command_line); + found=1; + } + } + + /* 4. If not found, issue an error message and return */ + + if (!found) { + wprintw (command_win,"Error: Unknown command\n"); + refresh_command_win (); + } + + return (0); +} + + +/* + * + * This function copies the next word in source to the variable dest, + * ignoring whitespaces. It returns a pointer to the next word in + * source. It is used to split the command line into command and arguments. + */ +char *parse_word (char *source,char *dest) +{ + char ch,*source_ptr,*target_ptr; + + if (*source==0) { + *dest=0; + return (source); + }; + + source_ptr=source;target_ptr=dest; + do { + ch=*source_ptr++; + } while (! (ch>' ' && ch<='z') && ch!=0); + + while (ch>' ' && ch<='z') { + *target_ptr++=ch; + ch=*source_ptr++; + } + + *target_ptr=0; + + source_ptr--; + do { + ch=*source_ptr++; + } while (! (ch>' ' && ch<='z') && ch!=0); + + return (--source_ptr); +} + +/* + * text is the partial command entered by the user; We assume that it + * is a part of a command - I didn't write code for smarter completion. + * + * The state variable is an index which tells us how many possible + * completions we already returned to readline. + * + * We return only one possible completion or (char *) NULL if there + * are no more completions. This function will be called by readline + * over and over until we tell it to stop. + * + * While scanning for possible completions, we use the same priority + * definition which was used in dispatch. + */ +#if HAVE_READLINE +char *complete_command (char *text,int state) +{ + int state_index=-1; + int i,len; + + len=strlen (text); + + /* Is the command type specific ? */ + + if (current_type != NULL) + for (i=0;i<=current_type->type_commands.last_command;i++) { + if (strncmp (current_type->type_commands.names [i],text,len)==0) { + state_index++; + if (state==state_index) { + return (dupstr (current_type->type_commands.names [i])); + } + } + } + + /* No, perhaps ext2 specific command then ? */ + + for (i=0;i<=ext2_commands.last_command;i++) { + if (strncmp (ext2_commands.names [i],text,len)==0) { + state_index++; + if (state==state_index) + return (dupstr (ext2_commands.names [i])); + } + } + + + /* Check for a general command */ + + for (i=0;i<=general_commands.last_command;i++) { + if (strncmp (general_commands.names [i],text,len)==0) { + state_index++; + if (state==state_index) + return (dupstr (general_commands.names [i])); + } + } + + /* quit is handled differently */ + + if (strncmp ("quit",text,len)==0) { + state_index++; + if (state==state_index) + return (dupstr ("quit")); + } + + /* No more completions */ + + return ((char *) NULL); +} +#endif + + +/* + * Nothing special - Just allocates enough space and copy the string. + */ +char *dupstr (char *src) +{ + char *ptr; + + ptr=(char *) malloc (strlen (src)+1); + if (!ptr) + return NULL; + strcpy (ptr,src); + return (ptr); +} + +#ifdef DEBUG +/* + * This function reports an internal error. It is almost not used. One + * place in which I do check for internal errors is disk.c. + * + * We just report the error, and try to continue ... + */ +void internal_error (char *description,char *source_name,char *function_name) +{ + wprintw (command_win,"Internal error - Found by source: %s.c , function: %s\n",source_name,function_name); + wprintw (command_win,"\t%s\n",description); + wprintw (command_win,"Press enter to (hopefully) continue\n"); + refresh_command_win ();getch ();werase (command_win); +} + +#endif diff --git a/ext2ed/super_com.c b/ext2ed/super_com.c new file mode 100644 index 0000000..a998970 --- /dev/null +++ b/ext2ed/super_com.c @@ -0,0 +1,156 @@ +/* + +/usr/src/ext2ed/super_com.c + +A part of the extended file system 2 disk editor. + +---------------------- +Handles the superblock +---------------------- + +First written on: April 9 1995 + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +#include "ext2ed.h" + +void type_ext2_super_block___show (char *command_line) + +{ + struct ext2_super_block *super; + super=&type_data.u.t_ext2_super_block; + + show (command_line); + + if (ext2fs_blocks_count(super) != 0) { + wmove (show_pad,2,40);wprintw (show_pad,"%2.2f%%",100*(float) ext2fs_r_blocks_count(super)/ (float) ext2fs_blocks_count(super)); + wmove (show_pad,3,40);wprintw (show_pad,"%2.2f%%",100*(float) ext2fs_free_blocks_count(super)/ (float) ext2fs_blocks_count(super)); + } + + if (super->s_inodes_count != 0) { + wmove (show_pad,4,40);wprintw (show_pad,"%2.2f%%",100*(float) super->s_free_inodes_count/ (float) super->s_inodes_count); + } + + wmove (show_pad,6,40); + switch (super->s_log_block_size) { + case 0: wprintw (show_pad,"1024 bytes");break; + case 1: wprintw (show_pad,"2048 bytes");break; + case 2: wprintw (show_pad,"4096 bytes");break; + } + wmove (show_pad,11,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_super_block.s_mtime)); + wmove (show_pad,12,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_super_block.s_wtime)); + wmove (show_pad,19,40);wprintw (show_pad,"%s",ctime ((time_t *) &type_data.u.t_ext2_super_block.s_lastcheck)); + wmove (show_pad,15,40); + + switch (type_data.u.t_ext2_super_block.s_magic) { + case EXT2_SUPER_MAGIC: + wprintw (show_pad,"ext2 >= 0.2B"); + break; + case EXT2_PRE_02B_MAGIC: + wprintw (show_pad,"ext2 < 0.2B (not supported)"); + break; + default: + wprintw (show_pad,"Unknown"); + break; + } + + wmove (show_pad,16,40); + if (type_data.u.t_ext2_super_block.s_state & 0x1) + wprintw (show_pad,"clean "); + else + wprintw (show_pad,"not clean "); + + if (type_data.u.t_ext2_super_block.s_state & 0x2) + wprintw (show_pad,"with errors "); + else + wprintw (show_pad,"with no errors"); + + wmove (show_pad,17,40); + + switch (type_data.u.t_ext2_super_block.s_errors) { + case EXT2_ERRORS_CONTINUE: + wprintw (show_pad,"Continue"); + break; + case EXT2_ERRORS_RO: + wprintw (show_pad,"Remount read only"); + break; + case EXT2_ERRORS_PANIC: + wprintw (show_pad,"Issue kernel panic"); + break; + default: + wprintw (show_pad,"Unknown"); + break; + } + + wmove (show_pad,21,40); + + switch (type_data.u.t_ext2_super_block.s_creator_os) { + + case EXT2_OS_LINUX: + wprintw (show_pad,"Linux :-)"); + break; + + case EXT2_OS_HURD: + wprintw (show_pad,"Hurd"); + break; + + default: + wprintw (show_pad,"Unknown"); + break; + } + + refresh_show_pad (); + + wmove (show_win,1,0);wprintw (show_win,"\n");wmove (show_win,2,0); + wprintw (show_win,"Superblock copy %ld ",super_info.copy_num); + if (super_info.copy_num==0) + wprintw (show_win,"(main copy)"); + wprintw (show_win,"\n"); + refresh_show_win (); +} + +void type_ext2_super_block___gocopy (char *command_line) + +{ + unsigned long copy_num,offset; + char *ptr,buffer [80]; + + ptr=parse_word (command_line,buffer); + if (*ptr==0) { + wprintw (command_win,"Error - No argument specified\n");refresh_command_win ();return; + } + ptr=parse_word (ptr,buffer); + + copy_num=atol (buffer); + + offset=file_system_info.super_block_offset+copy_num*file_system_info.no_blocks_in_group*file_system_info.block_size; + + if (offset > file_system_info.file_system_size) { + wprintw (command_win,"Error - Copy number out of bounds\n");refresh_command_win ();return; + } + + super_info.copy_num=copy_num; + device_offset=offset; + + sprintf (buffer,"setoffset %ld",device_offset);dispatch (buffer); + strcpy (buffer,"show");dispatch (buffer); +} + +void type_ext2_super_block___setactivecopy (char *command_line) + +{ + struct ext2_super_block sb; + + sb=type_data.u.t_ext2_super_block; + dispatch ("gocopy 0"); + type_data.u.t_ext2_super_block=sb; + dispatch ("show"); +} diff --git a/ext2ed/win.c b/ext2ed/win.c new file mode 100644 index 0000000..23d0da1 --- /dev/null +++ b/ext2ed/win.c @@ -0,0 +1,232 @@ +/* + +/usr/src/ext2ed/win.c + +A part of the extended file system 2 disk editor. + +-------------------------------------------------------- +Window management - Interfacing with the ncurses library +-------------------------------------------------------- + +First written on: April 17 1995 +Modified on : April 05 2001 Christian.Bac@int-evry.fr +it looks like readline does not like that initscr decides to set the tty to +noecho. + +Copyright (C) 1995 Gadi Oxman + +*/ + +#include "config.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <termios.h> +#include <unistd.h> +#include <sys/ioctl.h> + +#include "ext2ed.h" +#include "../version.h" + +struct struct_pad_info show_pad_info; +WINDOW *title_win,*show_win,*command_win,*mt_win1,*mt_win2,*show_pad; + +/* to remember configuration after initscr + * and modify it + */ +struct termios termioInit, termioCurrent; + +void draw_title_win (void) +{ + char title_string [128]; + + werase(title_win); + box (title_win,0,0); + sprintf (title_string,"EXT2ED - Extended-2 File System editor ver %s (%s)", E2FSPROGS_VERSION, E2FSPROGS_DATE); + wmove (title_win,TITLE_WIN_LINES/2,(COLS-strlen (title_string))/2); + wprintw (title_win,title_string); + wrefresh(title_win); +} + +void setup_show_win(void) +{ + wbkgdset (show_win,A_REVERSE);werase (show_win); + show_pad_info.line=0; + show_pad_info.col=0; + show_pad_info.display_lines=LINES-TITLE_WIN_LINES-SHOW_WIN_LINES-COMMAND_WIN_LINES-2; + show_pad_info.display_cols=COLS; + show_pad_info.max_line=show_pad_info.display_lines-1;show_pad_info.max_col=show_pad_info.display_cols-1; + show_pad_info.disable_output=0; +} + +void init_windows (void) +{ + initscr (); + tcgetattr(0,&termioInit); /* save initial config */ + termioCurrent = termioInit; + termioCurrent.c_lflag |= ECHO; /* set echo on */ + tcsetattr(0,TCSANOW,&termioCurrent); + + if (LINES<TITLE_WIN_LINES+SHOW_WIN_LINES+COMMAND_WIN_LINES+3) { + printf ("Sorry, your terminal screen is too small\n"); + printf ("Error - Can not initialize windows\n"); + exit (1); + } + + title_win=newwin (TITLE_WIN_LINES,COLS,0,0); + show_win=newwin (SHOW_WIN_LINES,COLS,TITLE_WIN_LINES,0); + show_pad=newpad (SHOW_PAD_LINES,SHOW_PAD_COLS); + mt_win1=newwin (1,COLS,TITLE_WIN_LINES+SHOW_WIN_LINES,0); + mt_win2=newwin (1,COLS,LINES-COMMAND_WIN_LINES-1,0); + command_win=newwin (COMMAND_WIN_LINES,COLS,LINES-COMMAND_WIN_LINES,0); + + if (title_win==NULL || show_win==NULL || show_pad==NULL || command_win==NULL) { + printf ("Error - Not enough memory - Can not initialize windows\n");exit (1); + } + + draw_title_win(); + + setup_show_win(); + + scrollok (command_win,TRUE); + + refresh_title_win (); + refresh_show_win (); + refresh_show_pad(); + refresh_command_win (); + wrefresh(mt_win1); + wrefresh(mt_win2); +} + +void refresh_title_win (void) +{ + wrefresh (title_win); +} + +void refresh_show_win (void) +{ + int current_page,total_pages; + + current_page=show_pad_info.line/show_pad_info.display_lines+1; + if (show_pad_info.line%show_pad_info.display_lines) + current_page++; + total_pages=show_pad_info.max_line/show_pad_info.display_lines+1; + + wmove (show_win,2,COLS-18); + wprintw (show_win,"Page %d of %d\n",current_page,total_pages); + + wmove (show_win,2,COLS-18); + wrefresh (show_win); +} + + +void refresh_show_pad (void) + +{ + int left,top,right,bottom,i; + + if (show_pad_info.disable_output) + return; + + if (show_pad_info.max_line < show_pad_info.display_lines-1) { + for (i=show_pad_info.max_line+1;i<show_pad_info.display_lines;i++) { + wmove (show_pad,i,0);wprintw (show_pad,"\n"); + } + } + left=0;right=show_pad_info.display_cols-1; + top=TITLE_WIN_LINES+SHOW_WIN_LINES+1;bottom=top+show_pad_info.display_lines-1; + + if (show_pad_info.line > show_pad_info.max_line-show_pad_info.display_lines+1) + show_pad_info.line=show_pad_info.max_line-show_pad_info.display_lines+1; + + if (show_pad_info.line < 0) + show_pad_info.line=0; + +#ifdef OLD_NCURSES + prefresh (show_pad,show_pad_info.line,show_pad_info.col,top,left,show_pad_info.display_lines-1,show_pad_info.display_cols-1); +#else + prefresh (show_pad,show_pad_info.line,show_pad_info.col,top,left,top+show_pad_info.display_lines-1,left+show_pad_info.display_cols-1); +#endif +} + +void refresh_command_win (void) +{ + wrefresh (command_win); +} + +void close_windows (void) +{ +// echo (); + tcsetattr(0,TCSANOW,&termioInit); + + delwin (title_win); + delwin (command_win); + delwin (show_win); + delwin (show_pad); + + endwin (); +} + +void show_info (void) +{ + int block_num,block_offset; + + block_num=device_offset/file_system_info.block_size; + block_offset=device_offset%file_system_info.block_size; + + wmove (show_win,0,0); + wprintw (show_win,"Offset %-3ld in block %ld. ",block_offset,block_num); + if (current_type != NULL) + wprintw (show_win,"Type: %s\n",current_type->name); + else + wprintw (show_win,"Type: %s\n","none"); + + refresh_show_win (); +} + + +void redraw_all (void) +{ + int min_lines = TITLE_WIN_LINES+SHOW_WIN_LINES+COMMAND_WIN_LINES+3; + struct winsize ws; + int save_col, save_lines; + + /* get the size of the terminal connected to stdout */ + ioctl(1, TIOCGWINSZ, &ws); + /* + * Do it again because GDB doesn't stop before the first ioctl + * call, we want an up-to-date size when we're + * single-stepping. + */ + if (ioctl(1, TIOCGWINSZ, &ws) == 0) { + if (ws.ws_row < min_lines) + ws.ws_row = min_lines; + if ((ws.ws_row != LINES) || (ws.ws_col != COLS)) { + wmove (show_win,2,COLS-18); + wclrtoeol(show_win); + wrefresh(show_win); + resizeterm(ws.ws_row, ws.ws_col); + wresize(title_win, TITLE_WIN_LINES,COLS); + wresize(show_win, SHOW_WIN_LINES,COLS); + wresize(command_win, COMMAND_WIN_LINES,COLS); + wresize(mt_win1, 1,COLS); + wresize(mt_win2, 1,COLS); + mvwin(mt_win2, LINES-COMMAND_WIN_LINES-1,0); + mvwin(command_win, LINES-COMMAND_WIN_LINES,0); + draw_title_win(); + show_pad_info.display_lines=LINES-TITLE_WIN_LINES-SHOW_WIN_LINES-COMMAND_WIN_LINES-2; + show_pad_info.display_cols=COLS; + } + } + clearok(title_win, 1); + clearok(show_win, 1); + clearok(command_win, 1); + clearok(mt_win1, 1); + clearok(mt_win2, 1); + wrefresh(mt_win1); + wrefresh(mt_win2); + refresh_show_pad(); + refresh_show_win(); + refresh_title_win (); + refresh_command_win (); +} |