tools/firmware-utils/src/xorimage.c

   1 /*
   2  * xorimage.c - partially based on OpenWrt's addpattern.c
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  */
  18
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <stdint.h>
  24 #include <time.h>
  25 #include <unistd.h>
  26 #include <sys/stat.h>
  27
  28 static char default_pattern[] = "12345678";
  29
  30
  31 int xor_data(uint8_t *data, size_t len, const uint8_t *pattern, int p_len, int p_off)
  32 {
  33         int offset = p_off;
  34         while (len--) {
  35                 *data ^= pattern[offset];
  36                 data++;
  37                 offset = (offset + 1) % p_len;
  38         }
  39         return offset;
  40 }
  41
  42
  43 void usage(void) __attribute__ (( __noreturn__ ));
  44
  45 void usage(void)
  46 {
  47         fprintf(stderr, "Usage: xorimage [-i infile] [-o outfile] [-p <pattern>]\n");
  48         exit(EXIT_FAILURE);
  49 }
  50
  51
  52 int main(int argc, char **argv)
  53 {
  54         char buf[1024]; /* keep this at 1k or adjust garbage calc below */
  55         FILE *in = stdin;
  56         FILE *out = stdout;
  57         char *ifn = NULL;
  58         char *ofn = NULL;
  59         const char *pattern = default_pattern;
  60         int c;
  61         int v0, v1, v2;
  62         size_t n;
  63         int p_len, p_off = 0;
  64
  65         while ((c = getopt(argc, argv, "i:o:p:h")) != -1) {
  66                 switch (c) {
  67                         case 'i':
  68                                 ifn = optarg;
  69                                 break;
  70                         case 'o':
  71                                 ofn = optarg;
  72                                 break;
  73                         case 'p':
  74                                 pattern = optarg;
  75                                 break;
  76                         case 'h':
  77                         default:
  78                                 usage();
  79                 }
  80         }
  81
  82         if (optind != argc || optind == 1) {
  83                 fprintf(stderr, "illegal arg \"%s\"\n", argv[optind]);
  84                 usage();
  85         }
  86
  87         if (ifn && !(in = fopen(ifn, "r"))) {
  88                 fprintf(stderr, "can not open \"%s\" for reading\n", ifn);
  89                 usage();
  90         }
  91
  92         if (ofn && !(out = fopen(ofn, "w"))) {
  93                 fprintf(stderr, "can not open \"%s\" for writing\n", ofn);
  94                 usage();
  95         }
  96
  97         p_len = strlen(pattern);
  98
  99         if (p_len == 0) {
 100                 fprintf(stderr, "pattern cannot be empty\n");
 101                 usage();
 102         }
 103
 104
 105         while ((n = fread(buf, 1, sizeof(buf), in)) > 0) {
 106                 if (n < sizeof(buf)) {
 107                         if (ferror(in)) {
 108                         FREAD_ERROR:
 109                                 fprintf(stderr, "fread error\n");
 110                                 return EXIT_FAILURE;
 111                         }
 112                 }
 113
 114                 p_off = xor_data(buf, n, pattern, p_len, p_off);
 115
 116                 if (!fwrite(buf, n, 1, out)) {
 117                 FWRITE_ERROR:
 118                         fprintf(stderr, "fwrite error\n");
 119                         return EXIT_FAILURE;
 120                 }
 121         }
 122
 123         if (ferror(in)) {
 124                 goto FREAD_ERROR;
 125         }
 126
 127         if (fflush(out)) {
 128                 goto FWRITE_ERROR;
 129         }
 130
 131         fclose(in);
 132         fclose(out);
 133
 134         return EXIT_SUCCESS;
 135 }