diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/libmagic.man | 417 |
1 files changed, 417 insertions, 0 deletions
diff --git a/doc/libmagic.man b/doc/libmagic.man new file mode 100644 index 0000000..f51ccc9 --- /dev/null +++ b/doc/libmagic.man @@ -0,0 +1,417 @@ +.\" $File: libmagic.man,v 1.46 2022/09/15 16:54:14 christos Exp $ +.\" +.\" Copyright (c) Christos Zoulas 2003, 2018, 2022 +.\" All Rights Reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice immediately at the beginning of the file, without modification, +.\" this list of conditions, and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR +.\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.Dd September 15, 2022 +.Dt LIBMAGIC 3 +.Os +.Sh NAME +.Nm magic_open , +.Nm magic_close , +.Nm magic_error , +.Nm magic_errno , +.Nm magic_descriptor , +.Nm magic_buffer , +.Nm magic_getflags , +.Nm magic_setflags , +.Nm magic_check , +.Nm magic_compile , +.Nm magic_list , +.Nm magic_load , +.Nm magic_load_buffers , +.Nm magic_setparam , +.Nm magic_getparam , +.Nm magic_version +.Nd Magic number recognition library +.Sh LIBRARY +.Lb libmagic +.Sh SYNOPSIS +.In magic.h +.Ft magic_t +.Fn magic_open "int flags" +.Ft void +.Fn magic_close "magic_t cookie" +.Ft const char * +.Fn magic_error "magic_t cookie" +.Ft int +.Fn magic_errno "magic_t cookie" +.Ft const char * +.Fn magic_descriptor "magic_t cookie" "int fd" +.Ft const char * +.Fn magic_file "magic_t cookie" "const char *filename" +.Ft const char * +.Fn magic_buffer "magic_t cookie" "const void *buffer" "size_t length" +.Ft int +.Fn magic_getflags "magic_t cookie" +.Ft int +.Fn magic_setflags "magic_t cookie" "int flags" +.Ft int +.Fn magic_check "magic_t cookie" "const char *filename" +.Ft int +.Fn magic_compile "magic_t cookie" "const char *filename" +.Ft int +.Fn magic_list "magic_t cookie" "const char *filename" +.Ft int +.Fn magic_load "magic_t cookie" "const char *filename" +.Ft int +.Fn magic_load_buffers "magic_t cookie" "void **buffers" "size_t *sizes" "size_t nbuffers" +.Ft int +.Fn magic_getparam "magic_t cookie" "int param" "void *value" +.Ft int +.Fn magic_setparam "magic_t cookie" "int param" "const void *value" +.Ft int +.Fn magic_version "void" +.Sh DESCRIPTION +These functions +operate on the magic database file +which is described +in +.Xr magic __FSECTION__ . +.Pp +The function +.Fn magic_open +creates a magic cookie pointer and returns it. +It returns +.Dv NULL +if there was an error allocating the magic cookie. +The +.Ar flags +argument specifies how the other magic functions should behave: +.Bl -tag -width MAGIC_COMPRESS +.It Dv MAGIC_NONE +No special handling. +.It Dv MAGIC_DEBUG +Print debugging messages to stderr. +.It Dv MAGIC_SYMLINK +If the file queried is a symlink, follow it. +.It Dv MAGIC_COMPRESS +If the file is compressed, unpack it and look at the contents. +.It Dv MAGIC_DEVICES +If the file is a block or character special device, then open the device +and try to look in its contents. +.It Dv MAGIC_MIME_TYPE +Return a MIME type string, instead of a textual description. +.It Dv MAGIC_MIME_ENCODING +Return a MIME encoding, instead of a textual description. +.It Dv MAGIC_MIME +A shorthand for MAGIC_MIME_TYPE | MAGIC_MIME_ENCODING. +.It Dv MAGIC_CONTINUE +Return all matches, not just the first. +.It Dv MAGIC_CHECK +Check the magic database for consistency and print warnings to stderr. +.It Dv MAGIC_PRESERVE_ATIME +On systems that support +.Xr utime 3 +or +.Xr utimes 2 , +attempt to preserve the access time of files analysed. +.It Dv MAGIC_RAW +Don't translate unprintable characters to a \eooo octal representation. +.It Dv MAGIC_ERROR +Treat operating system errors while trying to open files and follow symlinks +as real errors, instead of printing them in the magic buffer. +.It Dv MAGIC_APPLE +Return the Apple creator and type. +.It Dv MAGIC_EXTENSION +Return a slash-separated list of extensions for this file type. +.It Dv MAGIC_COMPRESS_TRANSP +Don't report on compression, only report about the uncompressed data. +.It Dv MAGIC_NO_CHECK_APPTYPE +Don't check for +.Dv EMX +application type (only on EMX). +.It Dv MAGIC_NO_COMPRESS_FORK +Don't allow decompressors that use fork. +.It Dv MAGIC_NO_CHECK_CDF +Don't get extra information on MS Composite Document Files. +.It Dv MAGIC_NO_CHECK_COMPRESS +Don't look inside compressed files. +.It Dv MAGIC_NO_CHECK_ELF +Don't print ELF details. +.It Dv MAGIC_NO_CHECK_ENCODING +Don't check text encodings. +.It Dv MAGIC_NO_CHECK_SOFT +Don't consult magic files. +.It Dv MAGIC_NO_CHECK_TAR +Don't examine tar files. +.It Dv MAGIC_NO_CHECK_TEXT +Don't check for various types of text files. +.It Dv MAGIC_NO_CHECK_TOKENS +Don't look for known tokens inside ascii files. +.It Dv MAGIC_NO_CHECK_JSON +Don't examine JSON files. +.It Dv MAGIC_NO_CHECK_CSV +Don't examine CSV files. +.El +.Pp +The +.Fn magic_close +function closes the +.Xr magic __FSECTION__ +database and deallocates any resources used. +.Pp +The +.Fn magic_error +function returns a textual explanation of the last error, or +.Dv NULL +if there was no error. +.Pp +The +.Fn magic_errno +function returns the last operating system error number +.Pq Xr errno 2 +that was encountered by a system call. +.Pp +The +.Fn magic_file +function returns a textual description of the contents of the +.Ar filename +argument, or +.Dv NULL +if an error occurred. +If the +.Ar filename +is +.Dv NULL , +then stdin is used. +.Pp +The +.Fn magic_descriptor +function returns a textual description of the contents of the +.Ar fd +argument, or +.Dv NULL +if an error occurred. +.Pp +The +.Fn magic_buffer +function returns a textual description of the contents of the +.Ar buffer +argument with +.Ar length +bytes size. +.Pp +The +.Fn magic_getflags +functions returns a value representing current +.Ar flags +set. +.Pp +The +.Fn magic_setflags +function sets the +.Ar flags +described above. +Note that using both MIME flags together can also +return extra information on the charset. +.Pp +The +.Fn magic_check +function can be used to check the validity of entries in the colon +separated database files passed in as +.Ar filename , +or +.Dv NULL +for the default database. +It returns 0 on success and \-1 on failure. +.Pp +The +.Fn magic_compile +function can be used to compile the colon +separated list of database files passed in as +.Ar filename , +or +.Dv NULL +for the default database. +It returns 0 on success and \-1 on failure. +The compiled files created are named from the +.Xr basename 1 +of each file argument with +.Dq .mgc +appended to it. +.Pp +The +.Fn magic_list +function dumps all magic entries in a human readable format, +dumping first the entries that are matched against binary files and then the +ones that match text files. +It takes and optional +.Fa filename +argument which is a colon separated list of database files, or +.Dv NULL +for the default database. +.Pp +The +.Fn magic_load +function must be used to load the colon +separated list of database files passed in as +.Ar filename , +or +.Dv NULL +for the default database file before any magic queries can performed. +.Pp +The default database file is named by the MAGIC environment variable. +If that variable is not set, the default database file name is __MAGIC__. +.Fn magic_load +adds +.Dq .mgc +to the database filename as appropriate. +.Pp +The +.Fn magic_load_buffers +function takes an array of size +.Fa nbuffers +of +.Fa buffers +with a respective size for each in the array of +.Fa sizes +loaded with the contents of the magic databases from the filesystem. +This function can be used in environment where the magic library does +not have direct access to the filesystem, but can access the magic +database via shared memory or other IPC means. +.Pp +The +.Fn magic_getparam +and +.Fn magic_setparam +allow getting and setting various limits related to the magic +library. +.Bl -column "MAGIC_PARAM_ELF_PHNUM_MAX" "size_t" "Default" -offset indent +.It Sy "Parameter" Ta Sy "Type" Ta Sy "Default" +.It Li MAGIC_PARAM_INDIR_MAX Ta size_t Ta 15 +.It Li MAGIC_PARAM_NAME_MAX Ta size_t Ta 30 +.It Li MAGIC_PARAM_ELF_NOTES_MAX Ta size_t Ta 256 +.It Li MAGIC_PARAM_ELF_PHNUM_MAX Ta size_t Ta 128 +.It Li MAGIC_PARAM_ELF_SHNUM_MAX Ta size_t Ta 32768 +.It Li MAGIC_PARAM_REGEX_MAX Ta size_t Ta 8192 +.It Li MAGIC_PARAM_BYTES_MAX Ta size_t Ta 1048576 +.El +.Pp +The +.Dv MAGIC_PARAM_INDIR_RECURSION +parameter controls how many levels of recursion will be followed for +indirect magic entries. +.Pp +The +.Dv MAGIC_PARAM_NAME_RECURSION +parameter controls how many levels of recursion will be followed for +for name/use calls. +.Pp +The +.Dv MAGIC_PARAM_NAME_MAX +parameter controls the maximum number of calls for name/use. +.Pp +The +.Dv MAGIC_PARAM_NOTES_MAX +parameter controls how many ELF notes will be processed. +.Pp +The +.Dv MAGIC_PARAM_PHNUM_MAX +parameter controls how many ELF program sections will be processed. +.Pp +The +.Dv MAGIC_PARAM_SHNUM_MAX +parameter controls how many ELF sections will be processed. +.Pp +The +.Fn magic_version +command returns the version number of this library which is compiled into +the shared library using the constant +.Dv MAGIC_VERSION +from +.In magic.h . +This can be used by client programs to verify that the version they compile +against is the same as the version that they run against. +.Sh RETURN VALUES +The function +.Fn magic_open +returns a magic cookie on success and +.Dv NULL +on failure setting errno to an appropriate value. +It will set errno to +.Er EINVAL +if an unsupported value for flags was given. +The +.Fn magic_list , +.Fn magic_load , +.Fn magic_compile , +and +.Fn magic_check +functions return 0 on success and \-1 on failure. +The +.Fn magic_buffer , +.Fn magic_getpath , +and +.Fn magic_file , +functions return a string on success and +.Dv NULL +on failure. +The +.Fn magic_error +function returns a textual description of the errors of the above +functions, or +.Dv NULL +if there was no error. +The +.Fn magic_version +always returns the version number of the library. +Finally, +.Fn magic_setflags +returns \-1 on systems that don't support +.Xr utime 3 , +or +.Xr utimes 2 +when +.Dv MAGIC_PRESERVE_ATIME +is set. +.Sh FILES +.Bl -tag -width __MAGIC__.mgc -compact +.It Pa __MAGIC__ +The non-compiled default magic database. +.It Pa __MAGIC__.mgc +The compiled default magic database. +.El +.Sh SEE ALSO +.Xr file __CSECTION__ , +.Xr magic __FSECTION__ +.Sh BUGS +The results from +.Fn magic_buffer +and +.Fn magic_file +where the buffer and the file contain the same data +can produce different results, because in the +.Fn magic_file +case, the program can +.Xr lseek 2 +and +.Xr stat 2 +the file descriptor. +.Sh AUTHORS +.An M\(oans Rullg\(oard +Initial libmagic implementation, and configuration. +.An Christos Zoulas +API cleanup, error code and allocation handling. |