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