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/*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*/
/*
* Copyright (c) 2018 by Delphix. All rights reserved.
*/
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
static void
usage(char *msg, int exit_value)
{
(void) fprintf(stderr, "get_diff file redacted_file\n");
(void) fprintf(stderr, "%s\n", msg);
exit(exit_value);
}
/*
* This utility compares two files, an original and its redacted counterpart
* (in that order). It compares the files 512 bytes at a time, printing out
* any ranges (as offset and length) where the redacted file does not match
* the original. This output is used to verify that the expected ranges of
* a redacted file do not contain the original data.
*/
int
main(int argc, char *argv[])
{
off_t diff_off = 0, diff_len = 0, off = 0;
int fd1, fd2;
char *fname1, *fname2;
char buf1[DEV_BSIZE], buf2[DEV_BSIZE];
ssize_t bytes;
if (argc != 3)
usage("Incorrect number of arguments.", 1);
if ((fname1 = argv[1]) == NULL)
usage("Filename missing.", 1);
if ((fd1 = open(fname1, O_LARGEFILE | O_RDONLY)) < 0) {
perror("open1 failed");
exit(1);
}
if ((fname2 = argv[2]) == NULL)
usage("Redacted filename missing.", 1);
if ((fd2 = open(fname2, O_LARGEFILE | O_RDONLY)) < 0) {
perror("open2 failed");
exit(1);
}
while ((bytes = pread(fd1, buf1, DEV_BSIZE, off)) > 0) {
if (pread(fd2, buf2, DEV_BSIZE, off) < 0) {
if (errno == EIO) {
/*
* A read in a redacted section of a file will
* fail with EIO. If we get EIO, continue on
* but ensure that a comparison of buf1 and
* buf2 will fail, indicating a redacted block.
*/
buf2[0] = ~buf1[0];
} else {
perror("pread failed");
exit(1);
}
}
if (memcmp(buf1, buf2, bytes) == 0) {
if (diff_len != 0) {
(void) fprintf(stdout, "%lld,%lld\n",
(long long)diff_off, (long long)diff_len);
assert(off == diff_off + diff_len);
diff_len = 0;
}
diff_off = 0;
} else {
if (diff_len == 0)
diff_off = off;
assert(off == diff_off + diff_len);
diff_len += bytes;
}
off += bytes;
}
if (diff_len != 0 && diff_len != 0) {
(void) fprintf(stdout, "%lld,%lld\n", (long long)diff_off,
(long long)diff_len);
}
(void) close(fd1);
(void) close(fd2);
return (0);
}
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