/* * Copyright (c) 2012 Damien Miller <djm@mindrot.org> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* $OpenBSD: modpipe.c,v 1.6 2013/11/21 03:16:47 djm Exp $ */ #include "includes.h" #include <sys/types.h> #include <unistd.h> #include <stdio.h> #include <string.h> #include <stdarg.h> #include <stdlib.h> #include <errno.h> #ifdef HAVE_ERR_H # include <err.h> #endif #include "openbsd-compat/getopt_long.c" static void usage(void) { fprintf(stderr, "Usage: modpipe -w [-m modspec ...] < in > out\n"); fprintf(stderr, "modspec is one of:\n"); fprintf(stderr, " xor:offset:value - XOR \"value\" at \"offset\"\n"); fprintf(stderr, " andor:offset:val1:val2 - AND \"val1\" then OR \"val2\" at \"offset\"\n"); exit(1); } #define MAX_MODIFICATIONS 256 struct modification { enum { MOD_XOR, MOD_AND_OR } what; unsigned long long offset; u_int8_t m1, m2; }; static void parse_modification(const char *s, struct modification *m) { char what[16+1]; int n, m1, m2; bzero(m, sizeof(*m)); if ((n = sscanf(s, "%16[^:]%*[:]%llu%*[:]%i%*[:]%i", what, &m->offset, &m1, &m2)) < 3) errx(1, "Invalid modification spec \"%s\"", s); if (strcasecmp(what, "xor") == 0) { if (n > 3) errx(1, "Invalid modification spec \"%s\"", s); if (m1 < 0 || m1 > 0xff) errx(1, "Invalid XOR modification value"); m->what = MOD_XOR; m->m1 = m1; } else if (strcasecmp(what, "andor") == 0) { if (n != 4) errx(1, "Invalid modification spec \"%s\"", s); if (m1 < 0 || m1 > 0xff) errx(1, "Invalid AND modification value"); if (m2 < 0 || m2 > 0xff) errx(1, "Invalid OR modification value"); m->what = MOD_AND_OR; m->m1 = m1; m->m2 = m2; } else errx(1, "Invalid modification type \"%s\"", what); } int main(int argc, char **argv) { int ch; u_char buf[8192]; size_t total; ssize_t r, s, o; struct modification mods[MAX_MODIFICATIONS]; u_int i, wflag = 0, num_mods = 0; while ((ch = getopt(argc, argv, "wm:")) != -1) { switch (ch) { case 'm': if (num_mods >= MAX_MODIFICATIONS) errx(1, "Too many modifications"); parse_modification(optarg, &(mods[num_mods++])); break; case 'w': wflag = 1; break; default: usage(); /* NOTREACHED */ } } for (total = 0;;) { r = s = read(STDIN_FILENO, buf, sizeof(buf)); if (r == 0) break; if (r < 0) { if (errno == EAGAIN || errno == EINTR) continue; err(1, "read"); } for (i = 0; i < num_mods; i++) { if (mods[i].offset < total || mods[i].offset >= total + s) continue; switch (mods[i].what) { case MOD_XOR: buf[mods[i].offset - total] ^= mods[i].m1; break; case MOD_AND_OR: buf[mods[i].offset - total] &= mods[i].m1; buf[mods[i].offset - total] |= mods[i].m2; break; } } for (o = 0; o < s; o += r) { r = write(STDOUT_FILENO, buf, s - o); if (r == 0) break; if (r < 0) { if (errno == EAGAIN || errno == EINTR) continue; err(1, "write"); } } total += s; } /* Warn if modifications not reached in input stream */ r = 0; for (i = 0; wflag && i < num_mods; i++) { if (mods[i].offset < total) continue; r = 1; fprintf(stderr, "modpipe: warning - mod %u not reached\n", i); } return r; }