popen.c revision 332597 
1/*
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1988, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 * Copyright (c) 2014 The FreeBSD Foundation
7 * All rights reserved.
8 *
9 * This code is derived from software written by Ken Arnold and
10 * published in UNIX Review, Vol. 6, No. 8.
11 *
12 * Portions of this software were developed by Edward Tomasz Napierala
13 * under sponsorship from the FreeBSD Foundation.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 *    notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 *    notice, this list of conditions and the following disclaimer in the
22 *    documentation and/or other materials provided with the distribution.
23 * 4. Neither the name of the University nor the names of its contributors
24 *    may be used to endorse or promote products derived from this software
25 *    without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 *
39 */
40
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: stable/11/usr.sbin/autofs/popen.c 332597 2018-04-16 16:16:24Z trasz $");
43
44#include <sys/param.h>
45#include <sys/queue.h>
46#include <sys/wait.h>
47
48#include <errno.h>
49#include <fcntl.h>
50#include <unistd.h>
51#include <stdarg.h>
52#include <stdio.h>
53#include <stdlib.h>
54#include <string.h>
55#include <paths.h>
56
57#include "common.h"
58
59extern char **environ;
60
61struct pid {
62	SLIST_ENTRY(pid) next;
63	FILE *outfp;
64	pid_t pid;
65	char *command;
66};
67static SLIST_HEAD(, pid) pidlist = SLIST_HEAD_INITIALIZER(pidlist);
68
69#define	ARGV_LEN	42
70
71/*
72 * Replacement for popen(3), without stdin (which we do not use), but with
73 * stderr, proper logging, and improved command line arguments passing.
74 * Error handling is built in - if it returns, then it succeeded.
75 */
76FILE *
77auto_popen(const char *argv0, ...)
78{
79	va_list ap;
80	struct pid *cur, *p;
81	pid_t pid;
82	int error, i, nullfd, outfds[2];
83	char *arg, *argv[ARGV_LEN], *command;
84
85	nullfd = open(_PATH_DEVNULL, O_RDWR, 0);
86	if (nullfd < 0)
87		log_err(1, "cannot open %s", _PATH_DEVNULL);
88
89	error = pipe(outfds);
90	if (error != 0)
91		log_err(1, "pipe");
92
93	cur = malloc(sizeof(struct pid));
94	if (cur == NULL)
95		log_err(1, "malloc");
96
97	argv[0] = checked_strdup(argv0);
98	command = argv[0];
99
100	va_start(ap, argv0);
101	for (i = 1;; i++) {
102		if (i >= ARGV_LEN)
103			log_errx(1, "too many arguments to auto_popen");
104		arg = va_arg(ap, char *);
105		argv[i] = arg;
106		if (arg == NULL)
107			break;
108
109		command = concat(command, ' ', arg);
110	}
111	va_end(ap);
112
113	cur->command = checked_strdup(command);
114
115	switch (pid = fork()) {
116	case -1:			/* Error. */
117		log_err(1, "fork");
118		/* NOTREACHED */
119	case 0:				/* Child. */
120		dup2(nullfd, STDIN_FILENO);
121		dup2(outfds[1], STDOUT_FILENO);
122
123		close(nullfd);
124		close(outfds[0]);
125		close(outfds[1]);
126
127		SLIST_FOREACH(p, &pidlist, next)
128			close(fileno(p->outfp));
129		execvp(argv[0], argv);
130		log_err(1, "failed to execute %s", argv[0]);
131		/* NOTREACHED */
132	}
133
134	log_debugx("executing \"%s\" as pid %d", command, pid);
135
136	/* Parent; assume fdopen cannot fail. */
137	cur->outfp = fdopen(outfds[0], "r");
138	close(nullfd);
139	close(outfds[1]);
140
141	/* Link into list of file descriptors. */
142	cur->pid = pid;
143	SLIST_INSERT_HEAD(&pidlist, cur, next);
144
145	return (cur->outfp);
146}
147
148int
149auto_pclose(FILE *iop)
150{
151	struct pid *cur, *last = NULL;
152	int status;
153	pid_t pid;
154
155	/*
156	 * Find the appropriate file pointer and remove it from the list.
157	 */
158	SLIST_FOREACH(cur, &pidlist, next) {
159		if (cur->outfp == iop)
160			break;
161		last = cur;
162	}
163	if (cur == NULL) {
164		return (-1);
165	}
166	if (last == NULL)
167		SLIST_REMOVE_HEAD(&pidlist, next);
168	else
169		SLIST_REMOVE_AFTER(last, next);
170
171	fclose(cur->outfp);
172
173	do {
174		pid = wait4(cur->pid, &status, 0, NULL);
175	} while (pid == -1 && errno == EINTR);
176
177	if (WIFSIGNALED(status)) {
178		log_warnx("\"%s\", pid %d, terminated with signal %d",
179		    cur->command, pid, WTERMSIG(status));
180		return (status);
181	}
182
183	if (WEXITSTATUS(status) != 0) {
184		log_warnx("\"%s\", pid %d, terminated with exit status %d",
185		    cur->command, pid, WEXITSTATUS(status));
186		return (status);
187	}
188
189	log_debugx("\"%s\", pid %d, terminated gracefully", cur->command, pid);
190
191	free(cur->command);
192	free(cur);
193
194	return (pid == -1 ? -1 : status);
195}
196