usr/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[] = "@(#)cmp.c       5.3 (Berkeley) 6/1/90";
#endif /* not lint */

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

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

int     all, fd1, fd2, silent;
u_char  buf1[MAXBSIZE], buf2[MAXBSIZE];
char    *file1, *file2;

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 = 1;
                        break;
                case 's':               /* silent run */
                        silent = 1;
                        break;
                case '-':               /* must be after any flags */
                        --optind;
                        goto endargs;
                case '?':
                default:
                        usage();
                }
endargs:
        argv += optind;
        argc -= optind;

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

        if (all && silent) {
                fprintf(stderr,
                    "cmp: only one of -l and -s may be specified.\n");
                exit(EXITERR);
        }
        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(otoi(argv[2]), fd1, file1);
                if (argc == 4)
                        skip(otoi(argv[3]), fd2, file2);
        }
        cmp();
        /*NOTREACHED*/
}

/*
 * skip --
 *      skip first part of file
 */
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(buf1));
                if ((nread = read(fd, buf1, rlen)) != rlen) {
                        if (nread < 0)
                                error(fname);
                        else
                                endoffile(fname);
                }
        }
}

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

        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);
                                        /* NOTREACHED */
                                case 0:
                                        exit(dfound ? EXITDIFF : EXITNODIFF);
                                        /* NOTREACHED */
                                default:
                                        endoffile(file1);
                                        break;
                        }
                }
                /*
                 * 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.
                 */
                if ((len2 = read(fd2, buf2, len1)) == -1)
                        error(file2);
                if (bcmp(buf1, buf2, len2)) {
                        if (silent)
                                exit(EXITDIFF);
                        if (all) {
                                dfound = 1;
                                for (p1 = buf1, p2 = buf2, cnt = len2; 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 += 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 (p1 = buf1, cnt = len2; cnt--; )
                                        if (*p1++ == '\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
 */
u_long
otoi(s)
        register char *s;
{
        register u_long val;
        register int base;

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

/*
 * error --
 *      print I/O error message and die
 */
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
 */
endoffile(filename)
        char *filename;
{
        /* 32V put this message on stdout, S5 does it on stderr. */
        /* POSIX.2 currently does it on stdout-- Hooray! */
        if (!silent)
                (void) printf("cmp: EOF on %s\n", filename);
        exit(EXITDIFF);
}

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