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-rw-r--r--corrupt.c177
1 files changed, 0 insertions, 177 deletions
diff --git a/corrupt.c b/corrupt.c
deleted file mode 100644
index 0d29453..0000000
--- a/corrupt.c
+++ /dev/null
@@ -1,177 +0,0 @@
-/*
- * Copyright (C) 2009 Lars Wirzenius
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-
-#define _LARGEFILE64_SOURCE
-#define _GNU_SOURCE
-
-#include <errno.h>
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <getopt.h>
-
-
-/* Number of bits to corrupt. */
-static int num_bits = 1;
-
-
-/* Choose a random integer in [0..n-1]. */
-static long choose(long n)
-{
- if (n == 0)
- return 0;
-
- long buckets = (RAND_MAX + 1L) / n;
- long max = buckets * n;
- long r;
-
- do {
- r = random();
- } while (r >= max);
- return r / buckets;
-}
-
-
-static int seek(const char *filename, int fd, off_t offset)
-{
- if (lseek(fd, offset, SEEK_SET) == (off_t) -1) {
- fprintf(stderr, "Can't seek in %s: %s", filename, strerror(errno));
- return -1;
- }
- return 0;
-}
-
-
-static int corrupt_one_bit(const char *filename, int fd, struct stat st)
-{
- long offset;
- long bit;
- unsigned char byte;
-
- offset = choose(st.st_size);
- bit = choose(CHAR_BIT);
-
- if (seek(filename, fd, offset) == -1)
- return -1;
- if (read(fd, &byte, 1) == -1) {
- fprintf(stderr, "Can't read %s: %s", filename, strerror(errno));
- return -1;
- }
-
- /* This is where we toggle the bit. */
- unsigned mask = 1 << bit; // All zeroes, except for the interesting bit.
- unsigned interesting = byte & mask; // Only the interesting bit can be 1.
- unsigned toggled = interesting ^ mask; // Interesting bit has been toggled.
- unsigned others = byte & (~mask); // Interesting bit is 0.
- byte = others | toggled;
-
- /* Now write it back. */
- if (seek(filename, fd, offset) == -1)
- return -1;
- if (write(fd, &byte, 1) != 1) {
- fprintf(stderr, "Can't write %s: %s", filename, strerror(errno));
- return -1;
- }
-
- return 0;
-}
-
-
-static int corrupt(const char *filename)
-{
- int fd;
- struct stat st;
-
- fd = open(filename, O_RDWR | O_LARGEFILE);
- if (fd == -1) {
- fprintf(stderr, "Can't open %s: %s\n", filename, strerror(errno));
- return -1;
- }
-
- if (fstat(fd, &st) == -1) {
- fprintf(stderr, "Can't find length of %s: %s", filename,
- strerror(errno));
- return -1;
- }
-
- for (int i = 0; i < num_bits; ++i)
- if (corrupt_one_bit(filename, fd, st) == -1)
- return -1;
-
- if (close(fd) == -1) {
- fprintf(stderr, "Can't close %s: %s", filename, strerror(errno));
- return -1;
- }
-
- return 0;
-}
-
-
-static int parse_args(int argc, char **argv)
-{
- const char optstring[] = "n:";
- const struct option longopts[] = {
- { "bits", required_argument, NULL, 'n' },
- { 0 },
- };
- char *endptr;
-
- for (;;) {
- int opt = getopt_long(argc, argv, optstring, longopts, NULL);
- switch (opt) {
- case -1:
- return optind;
-
- case 'n':
- num_bits = strtol(optarg, &endptr, 10);
- if (*endptr != '\0') {
- fprintf(stderr, "Invalid number of bits: %s\n", optarg);
- exit(1);
- }
- break;
-
- default:
- case '?':
- exit(1);
- }
- }
-}
-
-
-int main(int argc, char **argv)
-{
- int exit_code;
- int i;
-
- i = parse_args(argc, argv);
- if (i == -1)
- return 1;
-
- srandom(time(NULL) + getpid());
- exit_code = 0;
- for (; i < argc; ++i)
- if (corrupt(argv[i]) == -1)
- exit_code = 1;
- return exit_code;
-}