root/scripts/binoffset.c

DEFINITIONS

1. usage
2. get_pattern
3. search_pattern
4. get_filesize
5. get_filesize
6. main

/***************************************************************************
 * binoffset.c
 * (C) 2002 Randy Dunlap <rdunlap@xenotime.net>

#   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.

# binoffset.c:
# - searches a (binary) file for a specified (binary) pattern
# - returns the offset of the located pattern or ~0 if not found
# - exits with exit status 0 normally or non-0 if pattern is not found
#   or any other error occurs.

****************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>

#define VERSION         "0.1"
#define BUF_SIZE        (16 * 1024)
#define PAT_SIZE        100

char            *progname;
char            *inputname;
int             inputfd;
unsigned int    bix;                    /* buf index */
unsigned char   patterns [PAT_SIZE] = {0}; /* byte-sized pattern array */
int             pat_len;                /* actual number of pattern bytes */
unsigned char   *madr;                  /* mmap address */
size_t          filesize;
int             num_matches = 0;
off_t           firstloc = 0;

void usage (void)
{
        fprintf (stderr, "%s ver. %s\n", progname, VERSION);
        fprintf (stderr, "usage:  %s filename pattern_bytes\n",
                        progname);
        fprintf (stderr, "        [prints location of pattern_bytes in file]\n");
        exit (1);
}

void get_pattern (int pat_count, char *pats [])
{
        int ix, err, tmp;

#ifdef DEBUG
        fprintf (stderr,"get_pattern: count = %d\n", pat_count);
        for (ix = 0; ix < pat_count; ix++)
                fprintf (stderr, "  pat # %d:  [%s]\n", ix, pats[ix]);
#endif

        for (ix = 0; ix < pat_count; ix++) {
                tmp = 0;
                err = sscanf (pats[ix], "%5i", &tmp);
                if (err != 1 || tmp > 0xff) {
                        fprintf (stderr, "pattern or value error in pattern # %d [%s]\n",
                                        ix, pats[ix]);
                        usage ();
                }
                patterns [ix] = tmp;
        }
        pat_len = pat_count;
}

void search_pattern (void)
{
        for (bix = 0; bix < filesize; bix++) {
                if (madr[bix] == patterns[0]) {
                        if (memcmp (&madr[bix], patterns, pat_len) == 0) {
                                if (num_matches == 0)
                                        firstloc = bix;
                                num_matches++;
                        }
                }
        }
}

#ifdef NOTDEF
size_t get_filesize (int fd)
{
        off_t end_off = lseek (fd, 0, SEEK_END);
        lseek (fd, 0, SEEK_SET);
        return (size_t) end_off;
}
#endif

size_t get_filesize (int fd)
{
        int err;
        struct stat stat;

        err = fstat (fd, &stat);
        fprintf (stderr, "filesize: %ld\n", err < 0 ? (long)err : stat.st_size);
        if (err < 0)
                return err;
        return (size_t) stat.st_size;
}

int main (int argc, char *argv [])
{
        progname = argv[0];

        if (argc < 3)
                usage ();

        get_pattern (argc - 2, argv + 2);

        inputname = argv[1];

        inputfd = open (inputname, O_RDONLY);
        if (inputfd == -1) {
                fprintf (stderr, "%s: cannot open '%s'\n",
                                progname, inputname);
                exit (3);
        }

        filesize = get_filesize (inputfd);

        madr = mmap (0, filesize, PROT_READ, MAP_PRIVATE, inputfd, 0);
        if (madr == MAP_FAILED) {
                fprintf (stderr, "mmap error = %d\n", errno);
                close (inputfd);
                exit (4);
        }

        search_pattern ();

        if (munmap (madr, filesize))
                fprintf (stderr, "munmap error = %d\n", errno);

        if (close (inputfd))
                fprintf (stderr, "%s: error %d closing '%s'\n",
                                progname, errno, inputname);

        fprintf (stderr, "number of pattern matches = %d\n", num_matches);
        if (num_matches == 0)
                firstloc = ~0;
        printf ("%ld\n", firstloc);
        fprintf (stderr, "%ld\n", firstloc);

        exit (num_matches ? 0 : 2);
}

/* end binoffset.c */