1 /* 2 * Copyright (c) 2012 Damien Miller <djm@mindrot.org> 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 /* $OpenBSD: modpipe.c,v 1.6 2013/11/21 03:16:47 djm Exp $ */ 18 19 #include <sys/types.h> 20 #include <unistd.h> 21 #include <stdio.h> 22 #include <string.h> 23 #include <stdlib.h> 24 #include <err.h> 25 #include <errno.h> 26 27 static void 28 usage(void) 29 { 30 fprintf(stderr, "Usage: modpipe -w [-m modspec ...] < in > out\n"); 31 fprintf(stderr, "modspec is one of:\n"); 32 fprintf(stderr, " xor:offset:value - XOR \"value\" at \"offset\"\n"); 33 fprintf(stderr, " andor:offset:val1:val2 - AND \"val1\" then OR \"val2\" at \"offset\"\n"); 34 exit(1); 35 } 36 37 #define MAX_MODIFICATIONS 256 38 struct modification { 39 enum { MOD_XOR, MOD_AND_OR } what; 40 unsigned long long offset; 41 u_int8_t m1, m2; 42 }; 43 44 static void 45 parse_modification(const char *s, struct modification *m) 46 { 47 char what[16+1]; 48 int n, m1, m2; 49 50 bzero(m, sizeof(*m)); 51 if ((n = sscanf(s, "%16[^:]%*[:]%llu%*[:]%i%*[:]%i", 52 what, &m->offset, &m1, &m2)) < 3) 53 errx(1, "Invalid modification spec \"%s\"", s); 54 if (strcasecmp(what, "xor") == 0) { 55 if (n > 3) 56 errx(1, "Invalid modification spec \"%s\"", s); 57 if (m1 < 0 || m1 > 0xff) 58 errx(1, "Invalid XOR modification value"); 59 m->what = MOD_XOR; 60 m->m1 = m1; 61 } else if (strcasecmp(what, "andor") == 0) { 62 if (n != 4) 63 errx(1, "Invalid modification spec \"%s\"", s); 64 if (m1 < 0 || m1 > 0xff) 65 errx(1, "Invalid AND modification value"); 66 if (m2 < 0 || m2 > 0xff) 67 errx(1, "Invalid OR modification value"); 68 m->what = MOD_AND_OR; 69 m->m1 = m1; 70 m->m2 = m2; 71 } else 72 errx(1, "Invalid modification type \"%s\"", what); 73 } 74 75 int 76 main(int argc, char **argv) 77 { 78 int ch; 79 u_char buf[8192]; 80 size_t total; 81 ssize_t r, s, o; 82 struct modification mods[MAX_MODIFICATIONS]; 83 u_int i, wflag = 0, num_mods = 0; 84 85 while ((ch = getopt(argc, argv, "wm:")) != -1) { 86 switch (ch) { 87 case 'm': 88 if (num_mods >= MAX_MODIFICATIONS) 89 errx(1, "Too many modifications"); 90 parse_modification(optarg, &(mods[num_mods++])); 91 break; 92 case 'w': 93 wflag = 1; 94 break; 95 default: 96 usage(); 97 /* NOTREACHED */ 98 } 99 } 100 for (total = 0;;) { 101 r = s = read(STDIN_FILENO, buf, sizeof(buf)); 102 if (r == 0) 103 break; 104 if (r < 0) { 105 if (errno == EAGAIN || errno == EINTR) 106 continue; 107 err(1, "read"); 108 } 109 for (i = 0; i < num_mods; i++) { 110 if (mods[i].offset < total || 111 mods[i].offset >= total + s) 112 continue; 113 switch (mods[i].what) { 114 case MOD_XOR: 115 buf[mods[i].offset - total] ^= mods[i].m1; 116 break; 117 case MOD_AND_OR: 118 buf[mods[i].offset - total] &= mods[i].m1; 119 buf[mods[i].offset - total] |= mods[i].m2; 120 break; 121 } 122 } 123 for (o = 0; o < s; o += r) { 124 r = write(STDOUT_FILENO, buf, s - o); 125 if (r == 0) 126 break; 127 if (r < 0) { 128 if (errno == EAGAIN || errno == EINTR) 129 continue; 130 err(1, "write"); 131 } 132 } 133 total += s; 134 } 135 /* Warn if modifications not reached in input stream */ 136 r = 0; 137 for (i = 0; wflag && i < num_mods; i++) { 138 if (mods[i].offset < total) 139 continue; 140 r = 1; 141 fprintf(stderr, "modpipe: warning - mod %u not reached\n", i); 142 } 143 return r; 144 } 145