freebsd-nq/usr.bin/cmp/cmp.c
Ed Maste 80445b7a3f cmp: fix -s (silent) when used with skip offsets
-s causes cmp to print nothing for differing files, for use when only
the exit status is of interest.

-z compares the file size first, for regular files, and fails the
comparison early if they do not match.

Prior to this change -s implied -z as an optimization, but this is not
valid when file offsets are specified.  Now, enable the -z optimization
for -s only if both skip arguments are not provided / 0.

Note that using -z with differing skip values will currently always
fail.  We may want to compare size1 - skip1 with size2 - skip2 instaead,
and in any case the man page should be clarified.

PR:		252542
Fixes:		3e6902efc8
Reported by:	William Ahern
Reviewed by:	markj
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D28071
2021-01-10 19:02:56 -05:00

216 lines
5.5 KiB
C

/*
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1987, 1990, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1987, 1990, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n";
#endif
#if 0
#ifndef lint
static char sccsid[] = "@(#)cmp.c 8.3 (Berkeley) 4/2/94";
#endif
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/stat.h>
#include <capsicum_helpers.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <nl_types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
bool lflag, sflag, xflag, zflag;
static const struct option long_opts[] =
{
{"verbose", no_argument, NULL, 'l'},
{"silent", no_argument, NULL, 's'},
{"quiet", no_argument, NULL, 's'},
{NULL, no_argument, NULL, 0}
};
static void usage(void);
int
main(int argc, char *argv[])
{
struct stat sb1, sb2;
off_t skip1, skip2;
int ch, fd1, fd2, oflag;
bool special;
const char *file1, *file2;
oflag = O_RDONLY;
while ((ch = getopt_long(argc, argv, "+hlsxz", long_opts, NULL)) != -1)
switch (ch) {
case 'h': /* Don't follow symlinks */
oflag |= O_NOFOLLOW;
break;
case 'l': /* print all differences */
lflag = true;
break;
case 's': /* silent run */
sflag = true;
break;
case 'x': /* hex output */
lflag = true;
xflag = true;
break;
case 'z': /* compare size first */
zflag = true;
break;
case '?':
default:
usage();
}
argv += optind;
argc -= optind;
if (lflag && sflag)
errx(ERR_EXIT, "specifying -s with -l or -x is not permitted");
if (argc < 2 || argc > 4)
usage();
/* Don't limit rights on stdin since it may be one of the inputs. */
if (caph_limit_stream(STDOUT_FILENO, CAPH_WRITE | CAPH_IGNORE_EBADF))
err(ERR_EXIT, "unable to limit rights on stdout");
if (caph_limit_stream(STDERR_FILENO, CAPH_WRITE | CAPH_IGNORE_EBADF))
err(ERR_EXIT, "unable to limit rights on stderr");
/* Backward compatibility -- handle "-" meaning stdin. */
special = false;
if (strcmp(file1 = argv[0], "-") == 0) {
special = true;
fd1 = STDIN_FILENO;
file1 = "stdin";
} else if ((fd1 = open(file1, oflag, 0)) < 0 && errno != EMLINK) {
if (!sflag)
err(ERR_EXIT, "%s", file1);
else
exit(ERR_EXIT);
}
if (strcmp(file2 = argv[1], "-") == 0) {
if (special)
errx(ERR_EXIT,
"standard input may only be specified once");
special = true;
fd2 = STDIN_FILENO;
file2 = "stdin";
} else if ((fd2 = open(file2, oflag, 0)) < 0 && errno != EMLINK) {
if (!sflag)
err(ERR_EXIT, "%s", file2);
else
exit(ERR_EXIT);
}
skip1 = argc > 2 ? strtol(argv[2], NULL, 0) : 0;
skip2 = argc == 4 ? strtol(argv[3], NULL, 0) : 0;
if (sflag && skip1 == 0 && skip2 == 0)
zflag = true;
if (fd1 == -1) {
if (fd2 == -1) {
c_link(file1, skip1, file2, skip2);
exit(0);
} else if (!sflag)
errx(ERR_EXIT, "%s: Not a symbolic link", file2);
else
exit(ERR_EXIT);
} else if (fd2 == -1) {
if (!sflag)
errx(ERR_EXIT, "%s: Not a symbolic link", file1);
else
exit(ERR_EXIT);
}
/* FD rights are limited in c_special() and c_regular(). */
caph_cache_catpages();
if (!special) {
if (fstat(fd1, &sb1)) {
if (!sflag)
err(ERR_EXIT, "%s", file1);
else
exit(ERR_EXIT);
}
if (!S_ISREG(sb1.st_mode))
special = true;
else {
if (fstat(fd2, &sb2)) {
if (!sflag)
err(ERR_EXIT, "%s", file2);
else
exit(ERR_EXIT);
}
if (!S_ISREG(sb2.st_mode))
special = true;
}
}
if (special)
c_special(fd1, file1, skip1, fd2, file2, skip2);
else {
if (zflag && sb1.st_size != sb2.st_size) {
if (!sflag)
(void) printf("%s %s differ: size\n",
file1, file2);
exit(DIFF_EXIT);
}
c_regular(fd1, file1, skip1, sb1.st_size,
fd2, file2, skip2, sb2.st_size);
}
exit(0);
}
static void
usage(void)
{
(void)fprintf(stderr,
"usage: cmp [-l | -s | -x] [-hz] file1 file2 [skip1 [skip2]]\n");
exit(ERR_EXIT);
}