cmp.c revision 24360 
1/*
2 * Copyright (c) 1987, 1990, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static char copyright[] =
36"@(#) Copyright (c) 1987, 1990, 1993, 1994\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41static char sccsid[] = "@(#)cmp.c	8.3 (Berkeley) 4/2/94";
42#endif /* not lint */
43
44#include <sys/types.h>
45#include <sys/stat.h>
46
47#include <err.h>
48#include <fcntl.h>
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52#include <unistd.h>
53
54#include "extern.h"
55
56int	lflag, sflag;
57
58static void usage __P((void));
59
60int
61main(argc, argv)
62	int argc;
63	char *argv[];
64{
65	struct stat sb1, sb2;
66	off_t skip1, skip2;
67	int ch, fd1, fd2, special;
68	char *file1, *file2;
69
70	while ((ch = getopt(argc, argv, "-ls")) != -1)
71		switch (ch) {
72		case 'l':		/* print all differences */
73			lflag = 1;
74			break;
75		case 's':		/* silent run */
76			sflag = 1;
77			break;
78		case '-':		/* stdin (must be after options) */
79			--optind;
80			goto endargs;
81		case '?':
82		default:
83			usage();
84		}
85endargs:
86	argv += optind;
87	argc -= optind;
88
89	if (lflag && sflag)
90		errx(ERR_EXIT, "only one of -l and -s may be specified");
91
92	if (argc < 2 || argc > 4)
93		usage();
94
95	/* Backward compatibility -- handle "-" meaning stdin. */
96	special = 0;
97	if (strcmp(file1 = argv[0], "-") == 0) {
98		special = 1;
99		fd1 = 0;
100		file1 = "stdin";
101	}
102	else if ((fd1 = open(file1, O_RDONLY, 0)) < 0) {
103		if (!sflag)
104			err(ERR_EXIT, "%s", file1);
105		else
106			exit(1);
107	}
108	if (strcmp(file2 = argv[1], "-") == 0) {
109		if (special)
110			errx(ERR_EXIT,
111				"standard input may only be specified once");
112		special = 1;
113		fd2 = 0;
114		file2 = "stdin";
115	}
116	else if ((fd2 = open(file2, O_RDONLY, 0)) < 0) {
117		if (!sflag)
118			err(ERR_EXIT, "%s", file2);
119		else
120			exit(1);
121	}
122
123	skip1 = argc > 2 ? strtol(argv[2], NULL, 10) : 0;
124	skip2 = argc == 4 ? strtol(argv[3], NULL, 10) : 0;
125
126	if (!special) {
127		if (fstat(fd1, &sb1)) {
128			if (!sflag)
129				err(ERR_EXIT, "%s", file1);
130			else
131				exit(1);
132		}
133		if (!S_ISREG(sb1.st_mode))
134			special = 1;
135		else {
136			if (fstat(fd2, &sb2)) {
137				if (!sflag)
138					err(ERR_EXIT, "%s", file2);
139				else
140					exit(1);
141			}
142			if (!S_ISREG(sb2.st_mode))
143				special = 1;
144		}
145	}
146
147	if (special)
148		c_special(fd1, file1, skip1, fd2, file2, skip2);
149	else
150		c_regular(fd1, file1, skip1, sb1.st_size,
151		    fd2, file2, skip2, sb2.st_size);
152	exit(0);
153}
154
155static void
156usage()
157{
158
159	(void)fprintf(stderr,
160	    "usage: cmp [-l | s] file1 file2 [skip1 [skip2]]\n");
161	exit(ERR_EXIT);
162}
163