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 <unistd.h>
  25 #include <sys/stat.h>
  26
  27 static char default_pattern[] = "12345678";
  28
  29
  30 int xor_data(uint8_t *data, size_t len, const uint8_t *pattern, int p_len, int p_off)
  31 {
  32         int offset = p_off;
  33         while (len--) {
  34                 *data ^= pattern[offset];
  35                 data++;
  36                 offset = (offset + 1) % p_len;
  37         }
  38         return offset;
  39 }
  40
  41
  42 void usage(void) __attribute__ (( __noreturn__ ));
  43
  44 void usage(void)
  45 {
  46         fprintf(stderr, "Usage: xorimage [-i infile] [-o outfile] [-p <pattern>]\n");
  47         exit(EXIT_FAILURE);
  48 }
  49
  50
  51 int main(int argc, char **argv)
  52 {
  53         char buf[1024]; /* keep this at 1k or adjust garbage calc below */
  54         FILE *in = stdin;
  55         FILE *out = stdout;
  56         char *ifn = NULL;
  57         char *ofn = NULL;
  58         const char *pattern = default_pattern;
  59         int c;
  60         int v0, v1, v2;
  61         size_t n;
  62         int p_len, p_off = 0;
  63
  64         while ((c = getopt(argc, argv, "i:o:p:h")) != -1) {
  65                 switch (c) {
  66                         case 'i':
  67                                 ifn = optarg;
  68                                 break;
  69                         case 'o':
  70                                 ofn = optarg;
  71                                 break;
  72                         case 'p':
  73                                 pattern = optarg;
  74                                 break;
  75                         case 'h':
  76                         default:
  77                                 usage();
  78                 }
  79         }
  80
  81         if (optind != argc || optind == 1) {
  82                 fprintf(stderr, "illegal arg \"%s\"\n", argv[optind]);
  83                 usage();
  84         }
  85
  86         if (ifn && !(in = fopen(ifn, "r"))) {
  87                 fprintf(stderr, "can not open \"%s\" for reading\n", ifn);
  88                 usage();
  89         }
  90
  91         if (ofn && !(out = fopen(ofn, "w"))) {
  92                 fprintf(stderr, "can not open \"%s\" for writing\n", ofn);
  93                 usage();
  94         }
  95
  96         p_len = strlen(pattern);
  97
  98         if (p_len == 0) {
  99                 fprintf(stderr, "pattern cannot be empty\n");
 100                 usage();
 101         }
 102
 103
 104         while ((n = fread(buf, 1, sizeof(buf), in)) > 0) {
 105                 if (n < sizeof(buf)) {
 106                         if (ferror(in)) {
 107                         FREAD_ERROR:
 108                                 fprintf(stderr, "fread error\n");
 109                                 return EXIT_FAILURE;
 110                         }
 111                 }
 112
 113                 p_off = xor_data(buf, n, pattern, p_len, p_off);
 114
 115                 if (!fwrite(buf, n, 1, out)) {
 116                 FWRITE_ERROR:
 117                         fprintf(stderr, "fwrite error\n");
 118                         return EXIT_FAILURE;
 119                 }
 120         }
 121
 122         if (ferror(in)) {
 123                 goto FREAD_ERROR;
 124         }
 125
 126         if (fflush(out)) {
 127                 goto FWRITE_ERROR;
 128         }
 129
 130         fclose(in);
 131         fclose(out);
 132
 133         return EXIT_SUCCESS;
 134 }