extra/scanlzma/scanlzma.c

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 /*
   4     scanlzma, scan for lzma compressed data in stdin and echo it to stdout.
   5     Copyright (C) 2006 Timo Lindfors
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16 */
  17
  18 /* Usage example:
  19
  20    $ wget http://www.wifi-shop.cz/Files/produkty/wa2204/wa2204av1.4.1.zip
  21    $ unzip wa2204av1.4.1.zip
  22    $ gcc scanlzma.c -o scanlzma -Wall
  23    $ ./scanlzma 0 < WA2204-FW1.4.1/linux-1.4.bin | lzma -c -d | strings | grep -i "copyright"
  24    UpdateDD version 2.5, Copyright (C) 2005 Philipp Benner.
  25    Copyright (C) 2005 Philipp Benner.
  26    Copyright (C) 2005 Philipp Benner.
  27    mawk 1.3%s%s %s, Copyright (C) Michael D. Brennan
  28    # Copyright (C) 1998, 1999, 2001  Henry Spencer.
  29    ...
  30
  31 */
  32
  33
  34 /* LZMA compressed file format */
  35 /* --------------------------- */
  36 /* Offset Size Description */
  37 /*   0     1   Special LZMA properties for compressed data */
  38 /*   1     4   Dictionary size (little endian) */
  39 /*   5     8   Uncompressed size (little endian). -1 means unknown size */
  40 /*  13         Compressed data */
  41
  42 #include <stdlib.h>
  43 #include <stdio.h>
  44 #include <string.h>
  45
  46 #define BUFSIZE 4096
  47
  48 int find_lzma_header(unsigned char *buf) {
  49         return (buf[0] < 0xE1
  50                 && buf[0] == 0x5d
  51                 && buf[4] < 0x20
  52                 && (memcmp (buf + 10 , "\x00\x00\x00", 3) == 0
  53                     || (memcmp (buf + 5, "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF", 8) == 0)));
  54 }
  55
  56 int main(int argc, char *argv[]) {
  57         unsigned char buf[BUFSIZE];
  58         int ret, i, numlzma, blocks=0;
  59
  60         if (argc != 2) {
  61                 printf("usage: %s numlzma < infile | lzma -c -d > outfile\n"
  62                        "where numlzma is index of lzma file to extract, starting from zero.\n",
  63                        argv[0]);
  64                 exit(1);
  65         }
  66         numlzma = atoi(argv[1]);
  67
  68         for (;;) {
  69                 /* Read data. */
  70                 ret = fread(buf, BUFSIZE, 1, stdin);
  71                 if (ret != 1)
  72                         break;
  73
  74                 /* Scan for signature. */
  75                 for (i = 0; i<BUFSIZE-23; i++) {
  76                         if (find_lzma_header(buf+i) && numlzma-- <= 0) {
  77                                 fwrite(buf+i, (BUFSIZE-i), 1, stdout);
  78                                 for (;;) {
  79                                         int ch;
  80                                         ch = getchar();
  81                                         if (ch == EOF)
  82                                                 exit(0);
  83                                         putchar(ch);
  84                                 }
  85                         }
  86                 }
  87                 blocks++;
  88         }
  89         return 1;
  90 }