xref: /src/usr.bin/cmp/cmp.c

/*
 * Copyright (c) 1987 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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
char copyright[] =
"@(#) Copyright (c) 1987, 1990 Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
/*static char sccsid[] = "from: @(#)cmp.c	5.3 (Berkeley) 6/1/90";*/
static char rcsid[] = "$Id: cmp.c,v 1.6 1994/03/25 17:07:02 mycroft Exp $";
#endif /* not lint */

#include <sys/param.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <locale.h>
#include <unistd.h>

#define	EXITNODIFF	0
#define	EXITDIFF	1
#define	EXITERR		2

void skip		__P(());
__dead void cmp		__P(());
__dead void error	__P(());
__dead void endoffile	__P(());
__dead void usage	__P(());

int	all, fd1, fd2, silent;
u_char	buffer1[MAXBSIZE], buffer2[MAXBSIZE];
char	*file1, *file2;

int
main(argc, argv)
	int argc;
	char **argv;
{
	int ch;

	setlocale(LC_ALL, "");

	while ((ch = getopt(argc, argv, "ls")) != -1)
		switch (ch) {
		case 'l':		/* print all differences */
			all = 1;
			break;
		case 's':		/* silent run */
			silent = 1;
			break;
		case '?':
		default:
			usage();
		}
	argv += optind;
	argc -= optind;

	if (argc < 2 || argc > 4)
		usage();

	if (all && silent)
		usage ();

	if (strcmp(file1 = argv[0], "-") == 0)
		fd1 = 0;
	else if ((fd1 = open(file1, O_RDONLY, 0)) < 0)
		error(file1);
	if (strcmp(file2 = argv[1], "-") == 0)
		fd2 = 0;
	else if ((fd2 = open(file2, O_RDONLY, 0)) < 0)
		error(file2);
	if (fd1 == fd2) {
		fprintf(stderr,
		    "cmp: standard input may only be specified once.\n");
		exit(EXITERR);
	}

	/* handle skip arguments */
	if (argc > 2) {
		skip(strtoul(argv[2], NULL, 0), fd1, file1);
		if (argc == 4)
			skip(strtoul(argv[3], NULL, 0), fd2, file2);
	}
	cmp();
	/*NOTREACHED*/
}

/*
 * skip --
 *	skip first part of file
 */
void
skip(dist, fd, fname)
	register u_long dist;
	register int fd;
	char *fname;
{
	register int rlen, nread;

	for (; dist; dist -= rlen) {
		rlen = MIN(dist, sizeof(buffer1));
		if ((nread = read(fd, buffer1, rlen)) != rlen) {
			if (nread < 0)
				error(fname);
			else
				endoffile(fname);
		}
	}
}

void
cmp()
{
	register u_char	*p1, *p2;
	u_char *buf1, *buf2;
	register int cnt;
	int len = 0, len1 = 0, len2 = 0;
	register long byte, line;
	int dfound = 0;

	for (byte = 0, line = 1; ; ) {
		len1 -= len;
		len2 -= len;
		if (len1)
			buf1 += len;
		else
			switch (len1 = read(fd1, buf1 = buffer1, MAXBSIZE)) {
			case -1:
				error(file1);
			case 0:
				if (len2)
					endoffile(file1);
				/*
				 * read of file 1 just failed, find out
				 * if there's anything left in file 2
				 */
				switch (read(fd2, buf2 = buffer2, 1)) {
				case -1:
					error(file2);
					/* NOTREACHED */
				case 0:
					exit(dfound ? EXITDIFF : EXITNODIFF);
					/* NOTREACHED */
				default:
					endoffile(file1);
					break;
				}
			}
		if (len2)
			buf2 += len;
		else
			switch (len2 = read(fd2, buf2 = buffer2, MAXBSIZE)) {
			case -1:
				error(file2);
			case 0:
				/*
				 * read of file 2 just failed; we know there is
				 * data left in file 1 if we got this far
				 */
				endoffile(file2);
				break;
			}
		/*
		 * Either file might be stdio.  We compare only the minimum
		 * number of bytes we know are common, then loop back to the
		 * top.  This avoids blocking on input if a difference is
		 * found early.
		 */
		if (len1 < len2)
			len = len1;
		else
			len = len2;
		if (memcmp(buf1, buf2, len)) {
			if (silent)
				exit(EXITDIFF);
			if (all) {
				dfound = 1;
				for (p1 = buf1, p2 = buf2, cnt = len; cnt--;
				    ++p1, ++p2) {
					++byte;
					if (*p1 != *p2)
						printf("%6ld %3o %3o\n",
						    byte, *p1, *p2);
				}
			} else for (p1 = buf1, p2 = buf2; ; ++p1, ++p2) {
				++byte;
				if (*p1 != *p2) {
					printf("%s %s differ: char %ld, line %ld\n", file1, file2, byte, line);
					exit(EXITDIFF);
				}
				if (*p1 == '\n')
					++line;
			}
		} else {
			byte += len;
			/*
			 * here's the real performance problem, we've got to
			 * count the stupid lines, which means that -l is a
			 * *much* faster version, i.e., unless you really
			 * *want* to know the line number, run -s or -l.
			 */
			if (!silent && !all)
				for (p1 = buf1, cnt = len; cnt--; )
					if (*p1++ == '\n')
						++line;
		}
	}
}

/*
 * error --
 *	print I/O error message and die
 */
void
error(filename)
	char *filename;
{
	extern int errno;
	char *strerror();

	if (!silent)
		(void) fprintf(stderr, "cmp: %s: %s\n",
		    filename, strerror(errno));
	exit(EXITERR);
}

/*
 * endoffile --
 *	print end-of-file message and exit indicating the files were different
 */
void
endoffile(filename)
	char *filename;
{
	if (!silent)
		(void) fprintf(stderr, "cmp: EOF on %s\n", filename);
	exit(EXITDIFF);
}

/*
 * usage --
 *	print usage and die
 */
void
usage()
{
	fputs("usage: cmp [-l | -s] file1 file2 [skip1] [skip2]\n", stderr);
	exit(EXITERR);
}