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 #include "openbsd-compat/getopt_long.c" 29 30 static void err(int, const char *, ...) __attribute__((format(printf, 2, 3))); 31 static void errx(int, const char *, ...) __attribute__((format(printf, 2, 3))); 32 33 static void 34 err(int r, const char *fmt, ...) 35 { 36 va_list args; 37 38 va_start(args, fmt); 39 fprintf(stderr, "%s: ", strerror(errno)); 40 vfprintf(stderr, fmt, args); 41 fputc('\n', stderr); 42 va_end(args); 43 exit(r); 44 } 45 46 static void 47 errx(int r, const char *fmt, ...) 48 { 49 va_list args; 50 51 va_start(args, fmt); 52 vfprintf(stderr, fmt, args); 53 fputc('\n', stderr); 54 va_end(args); 55 exit(r); 56 } 57 58 static void 59 usage(void) 60 { 61 fprintf(stderr, "Usage: modpipe -w [-m modspec ...] < in > out\n"); 62 fprintf(stderr, "modspec is one of:\n"); 63 fprintf(stderr, " xor:offset:value - XOR \"value\" at \"offset\"\n"); 64 fprintf(stderr, " andor:offset:val1:val2 - AND \"val1\" then OR \"val2\" at \"offset\"\n"); 65 exit(1); 66 } 67 68 #define MAX_MODIFICATIONS 256 69 struct modification { 70 enum { MOD_XOR, MOD_AND_OR } what; 71 unsigned long long offset; 72 u_int8_t m1, m2; 73 }; 74 75 static void 76 parse_modification(const char *s, struct modification *m) 77 { 78 char what[16+1]; 79 int n, m1, m2; 80 81 bzero(m, sizeof(*m)); 82 if ((n = sscanf(s, "%16[^:]%*[:]%llu%*[:]%i%*[:]%i", 83 what, &m->offset, &m1, &m2)) < 3) 84 errx(1, "Invalid modification spec \"%s\"", s); 85 if (strcasecmp(what, "xor") == 0) { 86 if (n > 3) 87 errx(1, "Invalid modification spec \"%s\"", s); 88 if (m1 < 0 || m1 > 0xff) 89 errx(1, "Invalid XOR modification value"); 90 m->what = MOD_XOR; 91 m->m1 = m1; 92 } else if (strcasecmp(what, "andor") == 0) { 93 if (n != 4) 94 errx(1, "Invalid modification spec \"%s\"", s); 95 if (m1 < 0 || m1 > 0xff) 96 errx(1, "Invalid AND modification value"); 97 if (m2 < 0 || m2 > 0xff) 98 errx(1, "Invalid OR modification value"); 99 m->what = MOD_AND_OR; 100 m->m1 = m1; 101 m->m2 = m2; 102 } else 103 errx(1, "Invalid modification type \"%s\"", what); 104 } 105 106 int 107 main(int argc, char **argv) 108 { 109 int ch; 110 u_char buf[8192]; 111 size_t total; 112 ssize_t r, s, o; 113 struct modification mods[MAX_MODIFICATIONS]; 114 u_int i, wflag = 0, num_mods = 0; 115 116 while ((ch = getopt(argc, argv, "wm:")) != -1) { 117 switch (ch) { 118 case 'm': 119 if (num_mods >= MAX_MODIFICATIONS) 120 errx(1, "Too many modifications"); 121 parse_modification(optarg, &(mods[num_mods++])); 122 break; 123 case 'w': 124 wflag = 1; 125 break; 126 default: 127 usage(); 128 /* NOTREACHED */ 129 } 130 } 131 for (total = 0;;) { 132 r = s = read(STDIN_FILENO, buf, sizeof(buf)); 133 if (r == 0) 134 break; 135 if (r < 0) { 136 if (errno == EAGAIN || errno == EINTR) 137 continue; 138 err(1, "read"); 139 } 140 for (i = 0; i < num_mods; i++) { 141 if (mods[i].offset < total || 142 mods[i].offset >= total + s) 143 continue; 144 switch (mods[i].what) { 145 case MOD_XOR: 146 buf[mods[i].offset - total] ^= mods[i].m1; 147 break; 148 case MOD_AND_OR: 149 buf[mods[i].offset - total] &= mods[i].m1; 150 buf[mods[i].offset - total] |= mods[i].m2; 151 break; 152 } 153 } 154 for (o = 0; o < s; o += r) { 155 r = write(STDOUT_FILENO, buf, s - o); 156 if (r == 0) 157 break; 158 if (r < 0) { 159 if (errno == EAGAIN || errno == EINTR) 160 continue; 161 err(1, "write"); 162 } 163 } 164 total += s; 165 } 166 /* Warn if modifications not reached in input stream */ 167 r = 0; 168 for (i = 0; wflag && i < num_mods; i++) { 169 if (mods[i].offset < total) 170 continue; 171 r = 1; 172 fprintf(stderr, "modpipe: warning - mod %u not reached\n", i); 173 } 174 return r; 175 } 176