1/*	$NetBSD: execvp.c,v 1.32 2024/01/20 14:52:47 christos Exp $	*/
2
3/*-
4 * Copyright (c) 1991, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#if defined(LIBC_SCCS) && !defined(lint)
34#if 0
35static char sccsid[] = "@(#)exec.c	8.1 (Berkeley) 6/4/93";
36#else
37__RCSID("$NetBSD: execvp.c,v 1.32 2024/01/20 14:52:47 christos Exp $");
38#endif
39#endif /* LIBC_SCCS and not lint */
40
41#include "namespace.h"
42#include <assert.h>
43#include <errno.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <limits.h>
48#include <unistd.h>
49#include <paths.h>
50#include "reentrant.h"
51#include "extern.h"
52
53#ifdef __weak_alias
54__weak_alias(execvp,_execvp)
55__weak_alias(execvpe,_execvpe)
56#endif
57
58int
59execvpe(const char *name, char * const *argv, char * const * envp)
60{
61	const char **memp;
62	int cnt;
63	size_t lp, ln;
64	int eacces = 0;
65	unsigned int etxtbsy = 0;
66	char buf[PATH_MAX];
67	const char *bp, *path, *p;
68
69	_DIAGASSERT(name != NULL);
70
71	/* "" is not a valid filename; check this before traversing PATH. */
72	if (name[0] == '\0') {
73		errno = ENOENT;
74		goto done;
75	}
76	ln = strlen(name);
77	/* If it's an absolute or relative path name, it's easy. */
78	if (strchr(name, '/')) {
79		bp = name;
80		path = "";
81		goto retry;
82	}
83	bp = buf;
84
85	/* Get the path we're searching. */
86	if (!(path = getenv("PATH")))
87		path = _PATH_DEFPATH;
88
89	do {
90		/* Find the end of this path element. */
91		for (p = path; *path != 0 && *path != ':'; path++)
92			continue;
93		/*
94		 * It's a SHELL path -- double, leading and trailing colons
95		 * mean the current directory.
96		 */
97		if (p == path) {
98			p = ".";
99			lp = 1;
100		} else
101			lp = path - p;
102
103		/*
104		 * If the path is too long complain.  This is a possible
105		 * security issue; given a way to make the path too long
106		 * the user may execute the wrong program.
107		 */
108		if (lp + ln + 2 > sizeof(buf)) {
109			(void)write(STDERR_FILENO, "execvp: ", 8);
110			(void)write(STDERR_FILENO, p, lp);
111			(void)write(STDERR_FILENO, ": path too long\n", 16);
112			continue;
113		}
114		memcpy(buf, p, lp);
115		buf[lp] = '/';
116		memcpy(buf + lp + 1, name, ln);
117		buf[lp + ln + 1] = '\0';
118
119retry:		(void)execve(bp, argv, envp);
120		switch (errno) {
121		case EACCES:
122			eacces = 1;
123			break;
124		case ENOTDIR:
125		case ENOENT:
126			break;
127		case ENOEXEC:
128			for (cnt = 0; argv[cnt] != NULL; ++cnt)
129				continue;
130			/*
131			 * we can't use malloc here because, if we are doing
132			 * vfork+exec, it leaks memory in the parent.
133			 */
134			if ((memp = alloca((cnt + 2) * sizeof(*memp))) == NULL)
135				goto done;
136			memp[0] = _PATH_BSHELL;
137			memp[1] = bp;
138			(void)memcpy(&memp[2], &argv[1], cnt * sizeof(*memp));
139			(void)execve(_PATH_BSHELL, __UNCONST(memp), envp);
140			goto done;
141		case ETXTBSY:
142			if (etxtbsy < 3)
143				(void)sleep(++etxtbsy);
144			goto retry;
145		default:
146			goto done;
147		}
148	} while (*path++ == ':');	/* Otherwise, *path was NUL */
149	if (eacces)
150		errno = EACCES;
151	else if (!errno)
152		errno = ENOENT;
153done:
154	return (-1);
155}
156
157int
158execvp(const char *name, char * const *argv)
159{
160	return execvpe(name, argv, environ);
161}
162