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Diffstat (limited to 'examples/rl-fgets.c')
| -rw-r--r-- | examples/rl-fgets.c | 374 |
1 files changed, 374 insertions, 0 deletions
diff --git a/examples/rl-fgets.c b/examples/rl-fgets.c new file mode 100644 index 0000000..5512b94 --- /dev/null +++ b/examples/rl-fgets.c @@ -0,0 +1,374 @@ +/* +Date: Tue, 16 Mar 2004 19:38:40 -0800 +From: Harold Levy <Harold.Levy@synopsys.com> +Subject: fgets(stdin) --> readline() redirector +To: chet@po.cwru.edu + +Hi Chet, + +Here is something you may find useful enough to include in the readline +distribution. It is a shared library that redirects calls to fgets(stdin) +to readline() via LD_PRELOAD, and it supports a custom prompt and list of +command names. Many people have asked me for this file, so I thought I'd +pass it your way in hope of just including it with readline to begin with. + +Best Regards, + +-Harold +*/ + +/****************************************************************************** +******************************************************************************* + + FILE NAME: fgets.c TARGET: libfgets.so + AUTHOR: Harold Levy VERSION: 1.0 + hlevy@synopsys.com + + ABSTRACT: Customize fgets() behavior via LD_PRELOAD in the following ways: + + -- If fgets(stdin) is called, redirect to GNU readline() to obtain + command-line editing, file-name completion, history, etc. + + -- A list of commands for command-name completion can be configured by + setting the environment-variable FGETS_COMMAND_FILE to a file containing + the list of commands to be used. + + -- Command-line editing with readline() works best when the prompt string + is known; you can set this with the FGETS_PROMPT environment variable. + + -- There special strings that libfgets will interpret as internal commands: + + _fgets_reset_ reset the command list + + _fgets_dump_ dump status + + _fgets_debug_ toggle debug messages + + HOW TO BUILD: Here are examples of how to build libfgets.so on various + platforms; you will have to add -I and -L flags to configure access to + the readline header and library files. + + (32-bit builds with gcc) + AIX: gcc -fPIC fgets.c -shared -o libfgets.so -lc -ldl -lreadline -ltermcap + HP-UX: gcc -fPIC fgets.c -shared -o libfgets.so -lc -ldld -lreadline + Linux: gcc -fPIC fgets.c -shared -o libfgets.so -lc -ldl -lreadline + SunOS: gcc -fPIC fgets.c -shared -o libfgets.so -lc -ldl -lgen -lreadline + + (64-bit builds without gcc) + SunOS: SUNWspro/bin/cc -D_LARGEFILE64_SOURCE=1 -xtarget=ultra -xarch=v9 \ + -KPIC fgets.c -Bdynamic -lc -ldl -lgen -ltermcap -lreadline + + HOW TO USE: Different operating systems have different levels of support + for the LD_PRELOAD concept. The generic method for 32-bit platforms is to + put libtermcap.so, libfgets.so, and libreadline.so (with absolute paths) + in the LD_PRELOAD environment variable, and to put their parent directories + in the LD_LIBRARY_PATH environment variable. Unfortunately there is no + generic method for 64-bit platforms; e.g. for 64-bit SunOS, you would have + to build both 32-bit and 64-bit libfgets and libreadline libraries, and + use the LD_FLAGS_32 and LD_FLAGS_64 environment variables with preload and + library_path configurations (a mix of 32-bit and 64-bit calls are made under + 64-bit SunOS). + + EXAMPLE WRAPPER: Here is an example shell script wrapper around the + program "foo" that uses fgets() for command-line input: + + #!/bin/csh + #### replace this with the libtermcap.so directory: + set dir1 = "/usr/lib" + #### replace this with the libfgets.so directory: + set dir2 = "/usr/fgets" + #### replace this with the libreadline.so directory: + set dir3 = "/usr/local/lib" + set lib1 = "${dir1}/libtermcap.so" + set lib2 = "${dir2}/libfgets.so" + set lib3 = "${dir3}/libreadline.so" + if ( "${?LD_PRELOAD}" ) then + setenv LD_PRELOAD "${lib1}:${lib2}:${lib3}:${LD_PRELOAD}" + else + setenv LD_PRELOAD "${lib1}:${lib2}:${lib3}" + endif + if ( "${?LD_LIBRARY_PATH}" ) then + setenv LD_LIBRARY_PATH "${dir1}:${dir2}:${dir3}:${LD_LIBRARY_PATH}" + else + setenv LD_LIBRARY_PATH "${dir1}:${dir2}:${dir3}" + endif + setenv FGETS_COMMAND_FILE "${dir2}/foo.commands" + setenv FGETS_PROMPT "foo> " + exec "foo" $* + + Copyright (C)©2003-2004 Harold Levy. + + This code links to the GNU readline library, and as such is bound by the + terms of the GNU General Public License as published by the Free Software + Foundation, either version 2 or (at your option) any later version. + + The GNU General Public License is often shipped with GNU software, and is + generally kept in a file called COPYING or LICENSE. If you do not have a + copy of the license, write to the Free Software Foundation, 59 Temple Place, + Suite 330, Boston, MA 02111 USA. + + 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. + +******************************************************************************* +******************************************************************************/ + + + +#include <dlfcn.h> +#include <stdio.h> +#include <strings.h> +#include <stdlib.h> +#include <unistd.h> + +#include <readline/readline.h> +#include <readline/history.h> + + + +/* for dynamically connecting to the native fgets() */ +#if defined(RTLD_NEXT) +#define REAL_LIBC RTLD_NEXT +#else +#define REAL_LIBC ((void *) -1L) +#endif +typedef char * ( * fgets_t ) ( char * s, int n, FILE * stream ) ; + + + +/* private data */ +/* -- writeable data is stored in the shared library's data segment + -- every process that uses the shared library gets a private memory copy of + its entire data segment + -- static data in the shared library is not copied to the application + -- only read-only (i.e. 'const') data is stored in the shared library's + text segment +*/ +static char ** my_fgets_names = NULL ; +static int my_fgets_number_of_names = 0 ; +static int my_fgets_debug_flag = 0 ; + + + +/* invoked with _fgets_reset_ */ +static void +my_fgets_reset ( + void +) { + if ( my_fgets_names && (my_fgets_number_of_names > 0) ) { + int i ; + if ( my_fgets_debug_flag ) { + printf ( "libfgets: removing command list\n" ) ; + } + for ( i = 0 ; i < my_fgets_number_of_names ; i ++ ) { + if ( my_fgets_names[i] ) free ( my_fgets_names[i] ) ; + } + free ( my_fgets_names ) ; + } + my_fgets_names = NULL ; + my_fgets_number_of_names = 0 ; +} + + + +/* invoked with _fgets_dump_ */ +static void +my_fgets_dump ( + void +) { + char * s ; + printf ( "\n" ) ; + s = getenv ( "FGETS_PROMPT" ) ; + printf ( "FGETS_PROMPT = %s\n", s ? s : "" ) ; + s = getenv ( "FGETS_COMMAND_FILE" ) ; + printf ( "FGETS_COMMAND_FILE = %s\n", s ? s : "" ) ; + printf ( "debug flag = %d\n", my_fgets_debug_flag ) ; + printf ( "#commands = %d\n", my_fgets_number_of_names ) ; + if ( my_fgets_debug_flag ) { + if ( my_fgets_names && (my_fgets_number_of_names > 0) ) { + int i ; + for ( i = 0 ; i < my_fgets_number_of_names ; i ++ ) { + printf ( "%s\n", my_fgets_names[i] ) ; + } + } + } + printf ( "\n" ) ; +} + + + +/* invoked with _fgets_debug_ */ +static void +my_fgets_debug_toggle ( + void +) { + my_fgets_debug_flag = my_fgets_debug_flag ? 0 : 1 ; + if ( my_fgets_debug_flag ) { + printf ( "libfgets: debug flag = %d\n", my_fgets_debug_flag ) ; + } +} + + + +/* read the command list if needed, return the i-th name */ +static char * +my_fgets_lookup ( + int index +) { + if ( (! my_fgets_names) || (! my_fgets_number_of_names) ) { + char * fname ; + FILE * fp ; + fgets_t _fgets ; + int i ; + char buf1[256], buf2[256] ; + fname = getenv ( "FGETS_COMMAND_FILE" ) ; + if ( ! fname ) { + if ( my_fgets_debug_flag ) { + printf ( "libfgets: empty or unset FGETS_COMMAND_FILE\n" ) ; + } + return NULL ; + } + fp = fopen ( fname, "r" ) ; + if ( ! fp ) { + if ( my_fgets_debug_flag ) { + printf ( "libfgets: cannot open '%s' for reading\n", fname ) ; + } + return NULL ; + } + _fgets = (fgets_t) dlsym ( REAL_LIBC, "fgets" ) ; + if ( ! _fgets ) { + fprintf ( stderr, + "libfgets: failed to dynamically link to native fgets()\n" + ) ; + return NULL ; + } + for ( i = 0 ; _fgets(buf1,255,fp) ; i ++ ) ; + if ( ! i ) { fclose(fp) ; return NULL ; } + my_fgets_names = (char**) calloc ( i, sizeof(char*) ) ; + rewind ( fp ) ; + i = 0 ; + while ( _fgets(buf1,255,fp) ) { + buf1[255] = 0 ; + if ( 1 == sscanf(buf1,"%s",buf2) ) { + my_fgets_names[i] = strdup(buf2) ; + i ++ ; + } + } + fclose ( fp ) ; + my_fgets_number_of_names = i ; + if ( my_fgets_debug_flag ) { + printf ( "libfgets: successfully read %d commands\n", i ) ; + } + } + if ( index < my_fgets_number_of_names ) { + return my_fgets_names[index] ; + } else { + return NULL ; + } +} + + + +/* generate a list of partial name matches for readline() */ +static char * +my_fgets_generator ( + const char * text, + int state +) +{ + static int list_index, len ; + char * name ; + if ( ! state ) { + list_index = 0 ; + len = strlen ( text ) ; + } + while ( ( name = my_fgets_lookup(list_index) ) ) { + list_index ++ ; + if ( ! strncmp ( name, text, len ) ) { + return ( strdup ( name ) ) ; + } + } + return ( NULL ) ; +} + + + +/* partial name completion callback for readline() */ +static char ** +my_fgets_completion ( + const char * text, + int start, + int end +) +{ + char ** matches ; + matches = NULL ; + if ( ! start ) { + matches = rl_completion_matches ( text, my_fgets_generator ) ; + } + return ( matches ) ; +} + + + +/* fgets() intercept */ +char * +fgets ( + char * s, + int n, + FILE * stream +) +{ + if ( ! s ) return NULL ; + if ( stream == stdin ) { + char * prompt ; + char * my_fgets_line ; + rl_already_prompted = 1 ; + rl_attempted_completion_function = my_fgets_completion ; + rl_catch_signals = 1 ; + rl_catch_sigwinch = 1 ; + rl_set_signals () ; + prompt = getenv ( "FGETS_PROMPT" ) ; + for ( + my_fgets_line = 0 ; ! my_fgets_line ; my_fgets_line=readline(prompt) + ) ; + if ( ! strncmp(my_fgets_line, "_fgets_reset_", 13) ) { + my_fgets_reset () ; + free ( my_fgets_line ) ; + strcpy ( s, "\n" ) ; + return ( s ) ; + } + if ( ! strncmp(my_fgets_line, "_fgets_dump_", 12) ) { + my_fgets_dump () ; + free ( my_fgets_line ) ; + strcpy ( s, "\n" ) ; + return ( s ) ; + } + if ( ! strncmp(my_fgets_line, "_fgets_debug_", 13) ) { + my_fgets_debug_toggle () ; + free ( my_fgets_line ) ; + strcpy ( s, "\n" ) ; + return ( s ) ; + } + (void) strncpy ( s, my_fgets_line, n-1 ) ; + (void) strcat ( s, "\n" ) ; + if ( *my_fgets_line ) add_history ( my_fgets_line ) ; + free ( my_fgets_line ) ; + return ( s ) ; + } else { + static fgets_t _fgets ; + _fgets = (fgets_t) dlsym ( REAL_LIBC, "fgets" ) ; + if ( ! _fgets ) { + fprintf ( stderr, + "libfgets: failed to dynamically link to native fgets()\n" + ) ; + strcpy ( s, "\n" ) ; + return ( s ) ; + } + return ( + _fgets ( s, n, stream ) + ) ; + } +} |