2 * xorimage.c - partially based on OpenWrt's addpattern.c
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.
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.
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
27 static char default_pattern
[] = "12345678";
30 int xor_data(uint8_t *data
, size_t len
, const uint8_t *pattern
, int p_len
, int p_off
)
34 *data
^= pattern
[offset
];
36 offset
= (offset
+ 1) % p_len
;
42 void usage(void) __attribute__ (( __noreturn__
));
46 fprintf(stderr
, "Usage: xorimage [-i infile] [-o outfile] [-p <pattern>]\n");
51 int main(int argc
, char **argv
)
53 char buf
[1024]; /* keep this at 1k or adjust garbage calc below */
58 const char *pattern
= default_pattern
;
64 while ((c
= getopt(argc
, argv
, "i:o:p:h")) != -1) {
81 if (optind
!= argc
|| optind
== 1) {
82 fprintf(stderr
, "illegal arg \"%s\"\n", argv
[optind
]);
86 if (ifn
&& !(in
= fopen(ifn
, "r"))) {
87 fprintf(stderr
, "can not open \"%s\" for reading\n", ifn
);
91 if (ofn
&& !(out
= fopen(ofn
, "w"))) {
92 fprintf(stderr
, "can not open \"%s\" for writing\n", ofn
);
96 p_len
= strlen(pattern
);
99 fprintf(stderr
, "pattern cannot be empty\n");
104 while ((n
= fread(buf
, 1, sizeof(buf
), in
)) > 0) {
105 if (n
< sizeof(buf
)) {
108 fprintf(stderr
, "fread error\n");
113 p_off
= xor_data(buf
, n
, pattern
, p_len
, p_off
);
115 if (!fwrite(buf
, n
, 1, out
)) {
117 fprintf(stderr
, "fwrite error\n");