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 <stdbool.h>
  24 #include <stdint.h>
  25 #include <unistd.h>
  26 #include <sys/stat.h>
  27
  28 static char default_pattern[] = "12345678";
  29 static int is_hex_pattern;
  30
  31
  32 int xor_data(void *data, size_t len, const void *pattern, int p_len, int p_off)
  33 {
  34         const uint8_t *key = pattern;
  35         uint8_t *d = data;
  36
  37         while (len--) {
  38                 *d ^= key[p_off];
  39                 d++;
  40                 p_off = (p_off + 1) % p_len;
  41         }
  42         return p_off;
  43 }
  44
  45
  46 void usage(void) __attribute__ (( __noreturn__ ));
  47
  48 void usage(void)
  49 {
  50         fprintf(stderr, "Usage: xorimage [-i infile] [-o outfile] [-p <pattern>] [-x]\n");
  51         exit(EXIT_FAILURE);
  52 }
  53
  54
  55 int main(int argc, char **argv)
  56 {
  57         char buf[1024]; /* keep this at 1k or adjust garbage calc below */
  58         FILE *in = stdin;
  59         FILE *out = stdout;
  60         char *ifn = NULL;
  61         char *ofn = NULL;
  62         const char *pattern = default_pattern;
  63         char hex_pattern[128];
  64         unsigned int hex_buf;
  65         int c;
  66         size_t n;
  67         int p_len, p_off = 0;
  68
  69         while ((c = getopt(argc, argv, "i:o:p:xh")) != -1) {
  70                 switch (c) {
  71                         case 'i':
  72                                 ifn = optarg;
  73                                 break;
  74                         case 'o':
  75                                 ofn = optarg;
  76                                 break;
  77                         case 'p':
  78                                 pattern = optarg;
  79                                 break;
  80                         case 'x':
  81                                 is_hex_pattern = true;
  82                                 break;
  83                         case 'h':
  84                         default:
  85                                 usage();
  86                 }
  87         }
  88
  89         if (optind != argc || optind == 1) {
  90                 fprintf(stderr, "illegal arg \"%s\"\n", argv[optind]);
  91                 usage();
  92         }
  93
  94         if (ifn && !(in = fopen(ifn, "r"))) {
  95                 fprintf(stderr, "can not open \"%s\" for reading\n", ifn);
  96                 usage();
  97         }
  98
  99         if (ofn && !(out = fopen(ofn, "w"))) {
 100                 fprintf(stderr, "can not open \"%s\" for writing\n", ofn);
 101                 usage();
 102         }
 103
 104         p_len = strlen(pattern);
 105
 106         if (p_len == 0) {
 107                 fprintf(stderr, "pattern cannot be empty\n");
 108                 usage();
 109         }
 110
 111         if (is_hex_pattern) {
 112                 int i;
 113
 114                 if ((p_len / 2) > sizeof(hex_pattern)) {
 115                         fprintf(stderr, "provided hex pattern is too long\n");
 116                         usage();
 117                 }
 118
 119                 if (p_len % 2 != 0) {
 120                         fprintf(stderr, "the number of characters (hex) is incorrect\n");
 121                         usage();
 122                 }
 123
 124                 for (i = 0; i < (p_len / 2); i++) {
 125                         if (sscanf(pattern + (i * 2), "%2x", &hex_buf) < 0) {
 126                                 fprintf(stderr, "invalid hex digit around %d\n", i * 2);
 127                                 usage();
 128                         }
 129                         hex_pattern[i] = (char)hex_buf;
 130                 }
 131         }
 132
 133         while ((n = fread(buf, 1, sizeof(buf), in)) > 0) {
 134                 if (n < sizeof(buf)) {
 135                         if (ferror(in)) {
 136                         FREAD_ERROR:
 137                                 fprintf(stderr, "fread error\n");
 138                                 return EXIT_FAILURE;
 139                         }
 140                 }
 141
 142                 if (is_hex_pattern) {
 143                         p_off = xor_data(buf, n, hex_pattern, (p_len / 2),
 144                                          p_off);
 145                 } else {
 146                         p_off = xor_data(buf, n, pattern, p_len, p_off);
 147                 }
 148
 149                 if (!fwrite(buf, n, 1, out)) {
 150                 FWRITE_ERROR:
 151                         fprintf(stderr, "fwrite error\n");
 152                         return EXIT_FAILURE;
 153                 }
 154         }
 155
 156         if (ferror(in)) {
 157                 goto FREAD_ERROR;
 158         }
 159
 160         if (fflush(out)) {
 161                 goto FWRITE_ERROR;
 162         }
 163
 164         fclose(in);
 165         fclose(out);
 166
 167         return EXIT_SUCCESS;
 168 }