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 "includes.h" 20 21 #include <sys/types.h> 22 #include <unistd.h> 23 #include <stdio.h> 24 #include <string.h> 25 #include <stdarg.h> 26 #include <stdlib.h> 27 #include <errno.h> 28 #ifdef HAVE_ERR_H 29 # include <err.h> 30 #endif 31 #include "openbsd-compat/getopt_long.c" 32 33 static void 34 usage(void) 35 { 36 fprintf(stderr, "Usage: modpipe -w [-m modspec ...] < in > out\n"); 37 fprintf(stderr, "modspec is one of:\n"); 38 fprintf(stderr, " xor:offset:value - XOR \"value\" at \"offset\"\n"); 39 fprintf(stderr, " andor:offset:val1:val2 - AND \"val1\" then OR \"val2\" at \"offset\"\n"); 40 exit(1); 41 } 42 43 #define MAX_MODIFICATIONS 256 44 struct modification { 45 enum { MOD_XOR, MOD_AND_OR } what; 46 unsigned long long offset; 47 u_int8_t m1, m2; 48 }; 49 50 static void 51 parse_modification(const char *s, struct modification *m) 52 { 53 char what[16+1]; 54 int n, m1, m2; 55 56 bzero(m, sizeof(*m)); 57 if ((n = sscanf(s, "%16[^:]%*[:]%llu%*[:]%i%*[:]%i", 58 what, &m->offset, &m1, &m2)) < 3) 59 errx(1, "Invalid modification spec \"%s\"", s); 60 if (strcasecmp(what, "xor") == 0) { 61 if (n > 3) 62 errx(1, "Invalid modification spec \"%s\"", s); 63 if (m1 < 0 || m1 > 0xff) 64 errx(1, "Invalid XOR modification value"); 65 m->what = MOD_XOR; 66 m->m1 = m1; 67 } else if (strcasecmp(what, "andor") == 0) { 68 if (n != 4) 69 errx(1, "Invalid modification spec \"%s\"", s); 70 if (m1 < 0 || m1 > 0xff) 71 errx(1, "Invalid AND modification value"); 72 if (m2 < 0 || m2 > 0xff) 73 errx(1, "Invalid OR modification value"); 74 m->what = MOD_AND_OR; 75 m->m1 = m1; 76 m->m2 = m2; 77 } else 78 errx(1, "Invalid modification type \"%s\"", what); 79 } 80 81 int 82 main(int argc, char **argv) 83 { 84 int ch; 85 u_char buf[8192]; 86 size_t total; 87 ssize_t r, s, o; 88 struct modification mods[MAX_MODIFICATIONS]; 89 u_int i, wflag = 0, num_mods = 0; 90 91 while ((ch = getopt(argc, argv, "wm:")) != -1) { 92 switch (ch) { 93 case 'm': 94 if (num_mods >= MAX_MODIFICATIONS) 95 errx(1, "Too many modifications"); 96 parse_modification(optarg, &(mods[num_mods++])); 97 break; 98 case 'w': 99 wflag = 1; 100 break; 101 default: 102 usage(); 103 /* NOTREACHED */ 104 } 105 } 106 for (total = 0;;) { 107 r = s = read(STDIN_FILENO, buf, sizeof(buf)); 108 if (r == 0) 109 break; 110 if (r < 0) { 111 if (errno == EAGAIN || errno == EINTR) 112 continue; 113 err(1, "read"); 114 } 115 for (i = 0; i < num_mods; i++) { 116 if (mods[i].offset < total || 117 mods[i].offset >= total + s) 118 continue; 119 switch (mods[i].what) { 120 case MOD_XOR: 121 buf[mods[i].offset - total] ^= mods[i].m1; 122 break; 123 case MOD_AND_OR: 124 buf[mods[i].offset - total] &= mods[i].m1; 125 buf[mods[i].offset - total] |= mods[i].m2; 126 break; 127 } 128 } 129 for (o = 0; o < s; o += r) { 130 r = write(STDOUT_FILENO, buf, s - o); 131 if (r == 0) 132 break; 133 if (r < 0) { 134 if (errno == EAGAIN || errno == EINTR) 135 continue; 136 err(1, "write"); 137 } 138 } 139 total += s; 140 } 141 /* Warn if modifications not reached in input stream */ 142 r = 0; 143 for (i = 0; wflag && i < num_mods; i++) { 144 if (mods[i].offset < total) 145 continue; 146 r = 1; 147 fprintf(stderr, "modpipe: warning - mod %u not reached\n", i); 148 } 149 return r; 150 } 151