1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright (c) 2018 by Delphix. All rights reserved.
14 */
15
16 #include <stdio.h>
17 #include <fcntl.h>
18 #include <unistd.h>
19 #include <stdlib.h>
20 #include <string.h>
21 #include <assert.h>
22 #include <sys/param.h>
23 #include <sys/types.h>
24 #include <sys/stat.h>
25 #include <errno.h>
26
27 static void
usage(const char * msg,int exit_value)28 usage(const char *msg, int exit_value)
29 {
30 (void) fprintf(stderr, "usage: get_diff file redacted_file\n%s\n", msg);
31 exit(exit_value);
32 }
33
34 /*
35 * This utility compares two files, an original and its redacted counterpart
36 * (in that order). It compares the files 512 bytes at a time, printing out
37 * any ranges (as offset and length) where the redacted file does not match
38 * the original. This output is used to verify that the expected ranges of
39 * a redacted file do not contain the original data.
40 */
41 int
main(int argc,char * argv[])42 main(int argc, char *argv[])
43 {
44 off_t diff_off = 0, diff_len = 0, off = 0;
45 int fd1, fd2;
46 char *fname1, *fname2;
47 char buf1[DEV_BSIZE], buf2[DEV_BSIZE];
48 ssize_t bytes;
49
50 if (argc != 3)
51 usage("Incorrect number of arguments.", 1);
52
53 if ((fname1 = argv[1]) == NULL)
54 usage("Filename missing.", 1);
55 if ((fd1 = open(fname1, O_LARGEFILE | O_RDONLY)) < 0) {
56 perror("open1 failed");
57 exit(1);
58 }
59
60 if ((fname2 = argv[2]) == NULL)
61 usage("Redacted filename missing.", 1);
62 if ((fd2 = open(fname2, O_LARGEFILE | O_RDONLY)) < 0) {
63 perror("open2 failed");
64 exit(1);
65 }
66
67 while ((bytes = pread(fd1, buf1, DEV_BSIZE, off)) > 0) {
68 if (pread(fd2, buf2, DEV_BSIZE, off) < 0) {
69 if (errno == EIO) {
70 /*
71 * A read in a redacted section of a file will
72 * fail with EIO. If we get EIO, continue on
73 * but ensure that a comparison of buf1 and
74 * buf2 will fail, indicating a redacted block.
75 */
76 buf2[0] = ~buf1[0];
77 } else {
78 perror("pread failed");
79 exit(1);
80 }
81 }
82 if (memcmp(buf1, buf2, bytes) == 0) {
83 if (diff_len != 0) {
84 (void) fprintf(stdout, "%lld,%lld\n",
85 (long long)diff_off, (long long)diff_len);
86 assert(off == diff_off + diff_len);
87 diff_len = 0;
88 }
89 diff_off = 0;
90 } else {
91 if (diff_len == 0)
92 diff_off = off;
93 assert(off == diff_off + diff_len);
94 diff_len += bytes;
95 }
96 off += bytes;
97 }
98
99 if (diff_len != 0) {
100 (void) fprintf(stdout, "%lld,%lld\n", (long long)diff_off,
101 (long long)diff_len);
102 }
103
104 (void) close(fd1);
105 (void) close(fd2);
106
107 return (0);
108 }
109