which.c revision 99118 
1/**
2 * Copyright (c) 2000 Dan Papasian.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 *    derived from this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28
29__FBSDID("$FreeBSD: head/usr.bin/which/which.c 99118 2002-06-30 05:48:50Z tjr $");
30
31#include <sys/stat.h>
32#include <sys/param.h>
33
34#include <err.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include <string.h>
38#include <unistd.h>
39
40static void	 usage(void);
41static int	 print_matches(char *, char *);
42
43int 	silent;
44int 	allpaths;
45
46int
47main(int argc, char **argv)
48{
49	char *p, *path;
50	ssize_t pathlen;
51	int opt, status;
52
53	status = EXIT_SUCCESS;
54
55	/* If called without args, die silently to conform */
56	if (argc < 2)
57		exit(EXIT_FAILURE);
58
59	while ((opt = getopt(argc, argv, "as")) != -1) {
60		switch (opt) {
61		case 'a':
62			allpaths = 1;
63			break;
64		case 's':
65			silent = 1;
66			break;
67		default:
68			usage();
69			break;
70		}
71	}
72
73	argv += optind;
74	argc -= optind;
75
76	if ((p = getenv("PATH")) == NULL)
77		exit(EXIT_FAILURE);
78	pathlen = strlen(p) + 1;
79	path = malloc(pathlen);
80	if (path == NULL)
81		err(EXIT_FAILURE, NULL);
82
83	if (argc == 0)
84		status = EXIT_FAILURE;
85
86	while (argc > 0) {
87		memcpy(path, p, pathlen);
88
89		if (strlen(*argv) >= FILENAME_MAX ||
90		    print_matches(path, *argv) == -1)
91			status = EXIT_FAILURE;
92
93		argv++;
94		argc--;
95	}
96
97	exit(status);
98}
99
100static void
101usage(void)
102{
103
104	errx(EXIT_FAILURE, "usage: which [-as] program ...");
105}
106
107static int
108is_there(char *candidate)
109{
110	struct stat fin;
111
112	/* XXX work around access(2) false positives for superuser */
113	if (access(candidate, X_OK) == 0 &&
114	    stat(candidate, &fin) == 0 &&
115	    S_ISREG(fin.st_mode) &&
116	    (getuid() != 0 ||
117	    (fin.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0)) {
118		if (!silent)
119			printf("%s\n", candidate);
120		return (1);
121	}
122	return (0);
123}
124
125static int
126print_matches(char *path, char *filename)
127{
128	char candidate[PATH_MAX];
129	const char *d;
130	int found;
131
132	if (*filename == '/')
133		return (is_there(filename) ? 0 : -1);
134	found = 0;
135	while ((d = strsep(&path, ":")) != NULL) {
136		if (*d == '\0')
137			d = ".";
138		if (snprintf(candidate, sizeof(candidate), "%s/%s", d,
139		    filename) >= (int)sizeof(candidate))
140			continue;
141		if (is_there(candidate)) {
142			found = 1;
143			if (!allpaths)
144				break;
145		}
146	}
147	return (found ? 0 : -1);
148}
149
150