comm.c revision 1.1 
1/*
2 * Copyright (c) 1989 The Regents of the University of California.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Case Larsen.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#ifndef lint
38char copyright[] =
39"@(#) Copyright (c) 1989 The Regents of the University of California.\n\
40 All rights reserved.\n";
41#endif /* not lint */
42
43#ifndef lint
44static char sccsid[] = "@(#)comm.c	5.7 (Berkeley) 11/1/90";
45#endif /* not lint */
46
47#include <sys/file.h>
48#include <limits.h>
49#include <stdio.h>
50
51#define	MAXLINELEN	(_POSIX2_LINE_MAX + 1)
52
53char *tabs[] = { "", "\t", "\t\t" };
54
55main(argc,argv)
56	int argc;
57	char *argv[];
58{
59	register int comp, file1done, file2done, read1, read2;
60	register char *col1, *col2, *col3;
61	int ch, flag1, flag2, flag3;
62	FILE *fp1, *fp2, *file();
63	char **p, line1[MAXLINELEN], line2[MAXLINELEN];
64	extern int optind;
65
66	flag1 = flag2 = flag3 = 1;
67	while ((ch = getopt(argc, argv, "-123")) != EOF)
68		switch(ch) {
69		case '-':
70			--optind;
71			goto done;
72		case '1':
73			flag1 = 0;
74			break;
75		case '2':
76			flag2 = 0;
77			break;
78		case '3':
79			flag3 = 0;
80			break;
81		case '?':
82		default:
83			usage();
84		}
85done:	argc -= optind;
86	argv += optind;
87
88	if (argc != 2)
89		usage();
90
91	fp1 = file(argv[0]);
92	fp2 = file(argv[1]);
93
94	/* for each column printed, add another tab offset */
95	p = tabs;
96	col1 = col2 = col3 = NULL;
97	if (flag1)
98		col1 = *p++;
99	if (flag2)
100		col2 = *p++;
101	if (flag3)
102		col3 = *p;
103
104	for (read1 = read2 = 1;;) {
105		/* read next line, check for EOF */
106		if (read1)
107			file1done = !fgets(line1, MAXLINELEN, fp1);
108		if (read2)
109			file2done = !fgets(line2, MAXLINELEN, fp2);
110
111		/* if one file done, display the rest of the other file */
112		if (file1done) {
113			if (!file2done && col2)
114				show(fp2, col2, line2);
115			break;
116		}
117		if (file2done) {
118			if (!file1done && col1)
119				show(fp1, col1, line1);
120			break;
121		}
122
123		/* lines are the same */
124		if (!(comp = strcmp(line1, line2))) {
125			read1 = read2 = 1;
126			if (col3)
127				(void)printf("%s%s", col3, line1);
128			continue;
129		}
130
131		/* lines are different */
132		if (comp < 0) {
133			read1 = 1;
134			read2 = 0;
135			if (col1)
136				(void)printf("%s%s", col1, line1);
137		} else {
138			read1 = 0;
139			read2 = 1;
140			if (col2)
141				(void)printf("%s%s", col2, line2);
142		}
143	}
144	exit(0);
145}
146
147show(fp, offset, buf)
148	FILE *fp;
149	char *offset, *buf;
150{
151	do {
152		(void)printf("%s%s", offset, buf);
153	} while (fgets(buf, MAXLINELEN, fp));
154}
155
156FILE *
157file(name)
158	char *name;
159{
160	FILE *fp;
161
162	if (!strcmp(name, "-"))
163		return(stdin);
164	if (!(fp = fopen(name, "r"))) {
165		(void)fprintf(stderr, "comm: can't read %s.\n", name);
166		exit(1);
167	}
168	return(fp);
169}
170
171usage()
172{
173	(void)fprintf(stderr, "usage: comm [-123] [ - ] file1 file2\n");
174	exit(1);
175}
176