.::libgbsed.c(3)

NAME
libgbsed - Search/Replace in binary files.

SYNOPSIS
    #include <libgbsed.h>

    // using file names.
    struct gbsed_arguments
    {
        char *search;
        char *replace;
        char *infilename;
        char *outfilename;
        int  minmatch;
        int  maxmatch;
    };

    typedef struct gbsed_arguments GBSEDargs;

    int
    gbsed_binary_search_replace(struct gbsed_arguments *)

    // using FILE*s
    struct fgbsed_arguments
    {
        char *search;
        char *replace;
        FILE *infile;
        FILE *outfile;
        int   minmatch;
        int   maxmatch;
    };
    typedef struct fgbsed_arguments fGBSEDargs;

    int
    gbsed_fbinary_search_replace(struct fgbsed_arguments *);

    // Error handling

    extern int
    gbsed_errno;

    const char*
    gbsed_errtostr(int);

DESCRIPTION
This is <libgbsed>, a binary stream editor.

"gbsed" lets you search and replace binary data in binary files by using hex values in text strings as search patterns. You can also use wildcard matches with "??", which will match any wide byte.

These are all valid search strings:

    search = "0xffc300193ab2f63a";
    search = "0xff??00??3ab2f??a";
    search = "FF??00??3AB2F??A";

while these are not:

    search = "the quick brown fox"; // only hex, no text. you would have to
                                    // convert the text to hex first.
    search = "0xff?c33ab3?accc";    // no nybbles only wide bytes. (?? not ?).

FUNCTIONS
ARGUMENTS

"gbsed_binary_search_replace" uses a struct for it's arguments. The members of the argument struct is as follows:

"char *search"
    What to search for. This must be a string with hex values or the wildcard character sequence "??", which will match any byte. The string can start with "0x", but this is optional.

"char *replace"
    What to replace with. Must also be a string with hex values, but no wildcards allowed. It must also be of the same length as the search string (This is by intention, as binary data is always in structured form. If you add extra information to a binary executable it will be rendered useless as address offsets will be shifted and relocation tables and internal address references will point to the wrong place).

"char *infilename"
    The file name of the file to search in.

"char *outfilename"
    The file name to save the modified binary as.

"int minmatch"
    Need at least "minmatch" matches before any work.

"int maxmatch"
    Stop after "maxmatch" matches. A value of "-1" means no limit.

EXAMPLE USAGE

    #include <stdlib.h>
    #include <stdio.h>
    #include <libgbsed.h>

    extern int gbsed_errno;

    int main(int argc, char **argv) {

        int         gbsed_ret;
        int         sysret;
        const char *errmessage;
        GBSEDargs   *bargs;

        sysret  = EXIT_SUCCESS;
        bargs   = (GBSEDargs *)malloc(sizeof(GBSEDargs));
        if (bargs == NULL) {
            fprintf(stderr, "Out of memory!\n");
            exit(1);
        }

        bargs->search      = "0xff";
        bargs->replace     = "0x00";
        bargs->infilename  = "/bin/ls";
        bargs->outfilename = "bsed.out";
        bargs->minmatch    =  1;                        // atleast one match.
        bargs->maxmatch    = GBSED_MAXMATCH_NO_LIMIT;   // no limit.

        if (argc > 1)
            bargs->infilename  = argv[1];

        gbsed_ret = gbsed_binary_search_replace(bargs);

        switch (gbsed_ret) {

            case GBSED_ERROR:
                errmessage = gbsed_errtostr(gbsed_errno);
                fprintf(stderr, "ERROR: %s\n", errmessage);
                sysret = EXIT_FAILURE;
                break;
            case GBSED_NO_MATCH:
                fprintf(stderr, "No match for %s found in %s\n",
                    bargs->search, bargs->infilename
                );
                sysret = EXIT_FAILURE;
                break;

            default:
                printf("Search for '%s' in '%s' matched %d times.\n",
                    bargs->search, bargs->infilename, gbsed_ret
                );
                break;
        }

        free(bargs);
        return sysret;
    }
This function returns a string describing what happened. if an error has occurred with either "gbsed_binary_search_replace" or "binary_file_matches".

Example:

    extern int gbsed_errno;

    const char *errmessage;
    errmessage = gbsed_errtostr(gbsed_errno);
    fprintf(stderr, "ERROR: %s\n", errmessage);

RETURN VALUES
"gbsed_binary_search_replace" returns "GBSED_ERROR" on failure. The error code can then be found in "gbsed_errno", error codes are defined in libgbsed.h. and they all start with "GBSED_" and is "int". To get a string containing the error message you have to call "bsed_errtomsg" with "bsed_errno" as argument. "GBSED_NO_MATCH"

No matches found.

"GBSED_ERROR"

An error has occurred and a error code has been left in "gbsed_errno". "GBSED_ESEARCH_TOO_LONG"

Search string was longer than the limit.

"GBSED_EREPLACE_TOO_LONG"

Replace string was longer than the limit.

"GBSED_ENULL_SEARCH"

Missing search string.

"GBSED_ENULL_REPLACE"

Missing replace string.

"GBSED_EMISSING_INPUT"

Missing input filename.

"GBSED_EMISSING_OUTPUT"

Missing output filename.

"GBSED_EINVALID_CHAR"

Invalid characters in search string. Only hex values and wildcards are allowed.

"GBSED_ENIBBLE_NOT_BYTE"

Wildcard must be wild byte, not nibble. ("??" not "?").

CONFIGURATION AND ENVIRONMENT
"libgbsed" requires no configuration file or environment variables.

INCOMPATIBILITIES
None known.

BUGS AND LIMITATIONS
No bugs have been reported.

Please report any bugs or feature requests to "bug-file-bsed@rt.cpan.org", or through the web interface at <http://rt.cpan.org>.

SEE ALSO

•   gbsed

AUTHOR
Ask Solem, "ask@0x61736b.net".

ACKNOWLEDGEMENTS
Dave Dykstra "dwdbsed@drdykstra.us". for "bsed" the original program,

0xfeedface for the wildcards patch.

LICENSE AND COPYRIGHT
Copyright (C) 2007 Ask Solem <ask@0x61736b.net>

gbsed 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 3 of the License, or (at your option) any later version.

gbsed 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, see <http://www.gnu.org/licenses/>.

DISCLAIMER OF WARRANTY
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

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 SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (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 SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.