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