cmp.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 310 行

#ifndef lint
static char *sccsid = "@(#)cmp.c	4.1	ULTRIX	7/17/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1989 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 * Copyright (c) 1987 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific written prior permission. This software
 * is provided ``as is'' without express or implied warranty.
 *
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/************************************************************************
 *	Modification History
 *      --------------------
 *	25-Oct-89		Tim N
 *	    Changed to work with either file1 or file2 to be a device
 *	    or pipe.  Removes previous method used where we were switching
 *	    handles.
 *
 *	16-Mar-89		Tim N
 *	    Started with BSD 4.3-5 version of cmp.  Added in checks
 *	    to disallow use of both -s and -l options.  Also added
 *	    1003.2 use of file2 as '-' to be stdin.
 *	    This file had ident:
 *		"@(#)cmp.c	4.7 (Berkeley) 11/24/87"
 ************************************************************************/

#include <sys/param.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>

#define DIFF	1			/* found differences */
#define ERR	2			/* error during run */
#define NO	0			/* no/false */
#define OK	0			/* didn't find differences */
#define YES	1			/* yes/true */

static int	fd1, fd2;		/* file descriptors */
		silent = NO;		/* if silent run */
static short	all = NO;		/* if report all differences */
static u_char	buf1[MAXBSIZE],		/* read buffers */
		buf2[MAXBSIZE];
static char	*file1, *file2;		/* file names */

main(argc, argv)
	int	argc;
	char	**argv;
{
	extern char	*optarg;
	extern int	optind;
	int	ch;
	u_long	otoi();

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

	if( all && silent )
		usage();

	argv += optind;
	argc -= optind;

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

	/* open up files; "-" is stdin */
	file1 = argv[0];
	if (strcmp(file1, "-")) {
		if ((fd1 = open(file1, O_RDONLY, 0)) < 0) {
			error(file1);
		}
	} else {
		fd1 = 0;   /* stdin */
	}

	file2 = argv[1];
	if (strcmp(file2, "-")) {
		if ((fd2 = open(file2, O_RDONLY, 0)) < 0) {
			error(file2);
		}
	} else {
		/* both files can't be stdin */
		if (fd1==0){
		    usage();
		} else {
		    fd2 = 0;
		}
	}

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

/*
 * skip --
 *	skip first part of file
 */
static
skip(dist, fd, fname)
	register u_long	dist;		/* length in bytes, to skip */
	register int	fd;		/* file descriptor */
	char	*fname;			/* file name for error */
{
	register int	rlen;		/* read length */
	register int	nread;

	for (; dist; dist -= nread){
		rlen = MIN(dist, sizeof(buf1));
		if ((nread = read(fd, buf1, rlen)) < 0 )
			error(fname);
		if (nread == 0)
			endoffile(fname);
	}
}

static
cmp()
{
	register u_char	*C1, *C2;	/* traveling pointers */
	register int	cnt,		/* counter */
			len1, len2;	/* read lengths */
	register long	byte,		/* byte count */
			line;		/* line count */
	short	dfound = NO;		/* if difference found */

	for (byte = 0, line = 1;;) {
		switch(len1 = read(fd1, buf1, MAXBSIZE)) {
		case -1:
			error(file1);
		case 0:
			/*
			 * read of file 1 just failed, find out
			 * if there's anything left in file 2
			 */
			switch(read(fd2, buf2, 1)) {
				case -1:
					error(file2);
				case 0:
					exit(dfound ? DIFF : OK);
				default:
					endoffile(file1);
			}
		}
		/*
		 * file1 might be stdio, which means that a read of less than
		 * MAXBSIZE might not mean an EOF.  So, read whatever we read
		 * from file1 from file2.
		 */
		len2 = 0;
		while(len2 < len1){
			if((cnt = read(fd2, &buf2[len2], len1 - len2)) < 0)
				error(file2);
			if(cnt == 0)
				break;
			len2 += cnt;
		}

		if (bcmp(buf1, buf2, len2)) {
			if (silent)
				exit(DIFF);
			if (all) {
				dfound = YES;
				for (C1 = buf1, C2 = buf2, cnt = len2; cnt--;
				     ++C1, ++C2) {
					++byte;
					if (*C1 != *C2)
						printf("%6ld %3o %3o\n", byte,
						  *C1,*C2);
				}
			}
			else for (C1 = buf1, C2 = buf2;; ++C1, ++C2) {
				++byte;
				if (*C1 != *C2) {
				   printf("%s %s differ: char %ld, line %ld\n",
					file1,file2,byte, line);
					exit(DIFF);
				}
				if (*C1 == '\n')
					++line;
			}
		}
		else {
			byte += len2;
			/*
			 * 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 (C1 = buf1, cnt = len2; cnt--;)
					if (*C1++ == '\n')
						++line;
		}
		/*
		 * couldn't read as much from file2 as from file1; checked
		 * here because there might be a difference before we got
		 * to this point, which would have precedence.
		 */
		if (len2 < len1)
			endoffile(file2);
	}
}

/*
 * otoi --
 *	octal/decimal string to u_long
 */
static u_long
otoi(C)
	register char	*C;		/* argument string */
{
	register u_long	val;		/* return value */
	register int	base;		/* number base */

	base = (*C == '0') ? 8 : 10;
	for (val = 0; isdigit(*C); ++C)
		val = val * base + *C - '0';
	return(val);
}

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

	if (!silent) {
		sverrno = errno;
		(void)fprintf(stderr, "cmp: %s: ", filename);
		errno = sverrno;
		perror((char *)NULL);
	}
	exit(ERR);
}

/*
 * endofffile --
 *	print end-of-file message and exit indicating the files were different
 */
static
endoffile(filename)
	char *filename;
{
	/* 32V put this message on stdout, S5 does it on stderr. */
	if (!silent)
		(void)fprintf(stderr, "cmp: EOF on %s\n", filename);
	exit(DIFF);
}

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