fexec.c revision 1.4 
1/*	$NetBSD: fexec.c,v 1.4 2024/06/11 09:26:57 wiz Exp $	*/
2
3/*-
4 * Copyright (c) 2003 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Matthias Scheler.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32
33#if HAVE_CONFIG_H
34#include "config.h"
35#endif
36#include <nbcompat.h>
37#if HAVE_SYS_CDEFS_H
38#include <sys/cdefs.h>
39#endif
40#if HAVE_SYS_TYPES_H
41#include <sys/types.h>
42#endif
43#if HAVE_SYS_STAT_H
44#include <sys/stat.h>
45#endif
46#if HAVE_SYS_WAIT_H
47#include <sys/wait.h>
48#endif
49
50#if HAVE_ERR_H
51#include <err.h>
52#endif
53#if HAVE_ERRNO_H
54#include <errno.h>
55#endif
56#if HAVE_FCNTL_H
57#include <fcntl.h>
58#endif
59#if HAVE_STDARG_H
60#include <stdarg.h>
61#endif
62#if HAVE_STDLIB_H
63#include <stdlib.h>
64#endif
65#if HAVE_UNISTD_H
66#include <unistd.h>
67#endif
68
69#include "lib.h"
70
71/*
72 * Newer macOS releases are not able to correctly handle vfork() when the
73 * underlying file is changed or removed, as is the case when upgrading
74 * pkg_install itself.  The manual pages suggest using posix_spawn()
75 * instead, which seems to work ok.
76 */
77#if defined(__APPLE__) && \
78	((__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__-0) >= 1050)
79#define FEXEC_USE_POSIX_SPAWN	1
80#else
81#define FEXEC_USE_POSIX_SPAWN	0
82#endif
83
84#if FEXEC_USE_POSIX_SPAWN
85#include <spawn.h>
86extern char **environ;
87
88#ifndef O_CLOEXEC
89#define O_CLOEXEC	0
90#endif
91
92#ifndef O_DIRECTORY
93#define O_DIRECTORY	0
94#endif
95#endif
96
97__RCSID("$NetBSD: fexec.c,v 1.4 2024/06/11 09:26:57 wiz Exp $");
98
99static int	vfcexec(const char *, int, const char *, va_list);
100
101/*
102 * fork, then change current working directory to path and
103 * execute the command and arguments in the argv array.
104 * wait for the command to finish, then return the exit status.
105 *
106 * macOS uses posix_spawn() instead due to reasons explained above.
107 */
108int
109pfcexec(const char *path, const char *file, const char **argv)
110{
111	pid_t			child;
112	int			status;
113
114#if FEXEC_USE_POSIX_SPAWN
115	int prevcwd;
116
117	if ((prevcwd = open(".", O_RDONLY|O_CLOEXEC|O_DIRECTORY)) < 0) {
118		warn("open prevcwd failed");
119		return -1;
120	}
121
122	if ((path != NULL) && (chdir(path) < 0)) {
123		warn("chdir %s failed", path);
124		return -1;
125	}
126
127	if (posix_spawn(&child, file, NULL, NULL, (char **)argv, environ) < 0) {
128		warn("posix_spawn failed");
129		return -1;
130	}
131
132	if (fchdir(prevcwd) < 0) {
133		warn("fchdir prevcwd failed");
134		return -1;
135	}
136
137	(void)close(prevcwd);
138#else
139	child = vfork();
140	switch (child) {
141	case 0:
142		if ((path != NULL) && (chdir(path) < 0))
143			_exit(127);
144
145		(void)execvp(file, __UNCONST(argv));
146		_exit(127);
147		/* NOTREACHED */
148	case -1:
149		return -1;
150	}
151#endif
152
153	while (waitpid(child, &status, 0) < 0) {
154		if (errno != EINTR)
155			return -1;
156	}
157
158	if (!WIFEXITED(status))
159		return -1;
160
161	return WEXITSTATUS(status);
162}
163
164static int
165vfcexec(const char *path, int skipempty, const char *arg, va_list ap)
166{
167	const char **argv;
168	size_t argv_size, argc;
169	int retval;
170
171	argv_size = 16;
172	argv = xcalloc(argv_size, sizeof(*argv));
173
174	argv[0] = arg;
175	argc = 1;
176
177	do {
178		if (argc == argv_size) {
179			argv_size *= 2;
180			argv = xrealloc(argv, argv_size * sizeof(*argv));
181		}
182		arg = va_arg(ap, const char *);
183		if (skipempty && arg && strlen(arg) == 0)
184		    continue;
185		argv[argc++] = arg;
186	} while (arg != NULL);
187
188	retval = pfcexec(path, argv[0], argv);
189	free(argv);
190	return retval;
191}
192
193int
194fexec(const char *arg, ...)
195{
196	va_list	ap;
197	int	result;
198
199	va_start(ap, arg);
200	result = vfcexec(NULL, 0, arg, ap);
201	va_end(ap);
202
203	return result;
204}
205
206int
207fexec_skipempty(const char *arg, ...)
208{
209	va_list	ap;
210	int	result;
211
212	va_start(ap, arg);
213	result = vfcexec(NULL, 1, arg, ap);
214	va_end(ap);
215
216	return result;
217}
218
219int
220fcexec(const char *path, const char *arg, ...)
221{
222	va_list	ap;
223	int	result;
224
225	va_start(ap, arg);
226	result = vfcexec(path, 0, arg, ap);
227	va_end(ap);
228
229	return result;
230}
231