114 lines
2.0 KiB
C
114 lines
2.0 KiB
C
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#define _SHRED_C
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#include <stdio.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include "config.h"
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char f_flag;
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char u_flag;
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char z_flag;
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int n_loops = 3;
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int shred(int rand_fd, int fd) {
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/* Get size */
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off_t size = lseek(fd, 0, SEEK_END);
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if (size <= 0)
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return 1;
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void *buf = mmap(NULL, size, PROT_WRITE, MAP_SHARED, fd, 0);
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if (buf == MAP_FAILED) {
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fprintf(stderr, "shred: mmap: %s\n", strerror(errno));
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return 1;
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}
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for (char n = 0; n < n_loops; n++) {
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if (read(rand_fd, buf, size) == 0)
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fprintf(stderr, "shred: %s", strerror(errno));
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fsync(fd);
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}
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if (z_flag)
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memset(buf, 0, size);
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if (munmap(buf, size)) {
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fprintf(stderr, "shred: munmap: %s\n", strerror(errno));
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return 1;
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}
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return 0;
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}
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int main(int argc, char **argv) {
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int opt;
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while ((opt = getopt(argc, argv, "fuzn:")) != -1) {
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switch (opt) {
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case 'f':
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f_flag = 1;
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break;
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case 'u':
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u_flag = 1;
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break;
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case 'z':
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z_flag = 1;
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break;
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case 'n':
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n_loops = atoi(optarg);
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break;
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default:
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printf("shred [fuzn] [file1 file2...]\n\t-n N Overwrite N times, default 3\n\t-z Final overwrite with zeros\n\t-u Remove file\n\t-f Chmod to ensure writability\n");
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return 0;
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}
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}
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argv += optind;
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argc -= optind;
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if (argc == 0) {
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fprintf(stderr, "shred: missing operand\n");
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return 1;
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}
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int rand_fd = open(RAND_SOURCE, O_RDONLY);
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if (rand_fd < 0) {
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fprintf(stderr, "shred: %s: %s\n", RAND_SOURCE, strerror(errno));
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return 1;
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}
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for (int i = 0; i < argc; i++) {
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int fd = open(argv[i], O_RDWR);
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if (fd < 0) {
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fprintf(stderr, "shred: %s is %s\n", argv[i], strerror(errno));
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continue;
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}
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shred(rand_fd, fd);
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fsync(fd);
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close(fd);
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if (f_flag) {
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if (chmod(argv[i], 0) < 0)
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fprintf(stderr, "shred: %s is %s\n", argv[i], strerror(errno));
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}
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if (u_flag) {
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if (unlink(argv[i]) < 0)
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fprintf(stderr, "shred: %s is %s\n", argv[i], strerror(errno));
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}
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}
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close(rand_fd);
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return 0;
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}
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