1/*-
2 * Copyright (c) 2013-2018 Devin Teske <dteske@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: stable/11/lib/libdpv/util.c 335406 2018-06-20 05:45:41Z dteske $");
29
30#include <err.h>
31#include <limits.h>
32#include <spawn.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <unistd.h>
36
37#include "util.h"
38
39extern char **environ;
40static char cmdbuf[CMDBUFMAX]	= "";
41static char shellcmd[PATH_MAX]	= PATH_SHELL;
42static char *shellcmd_argv[6]	= {
43	shellcmd,
44	__DECONST(char *, "-c"),
45	cmdbuf,
46	__DECONST(char *, "--"),
47	shellcmd,
48	NULL,
49};
50
51/*
52 * Spawn a sh(1) command. Writes the resulting process ID to the pid_t pointed
53 * at by `pid'. Returns a file descriptor (int) suitable for writing data to
54 * the spawned command (data written to file descriptor is seen as standard-in
55 * by the spawned sh(1) command). Returns `-1' if unable to spawn command.
56 *
57 * If cmd contains a single "%s" sequence, replace it with label if non-NULL.
58 */
59int
60shell_spawn_pipecmd(const char *cmd, const char *label, pid_t *pid)
61{
62	int error;
63	int len;
64	posix_spawn_file_actions_t action;
65#if SHELL_SPAWN_DEBUG
66	unsigned int i;
67#endif
68	int stdin_pipe[2] = { -1, -1 };
69
70	/* Populate argument array */
71	if (label != NULL && fmtcheck(cmd, "%s") == cmd)
72		len = snprintf(cmdbuf, CMDBUFMAX, cmd, label);
73	else
74		len = snprintf(cmdbuf, CMDBUFMAX, "%s", cmd);
75	if (len >= CMDBUFMAX) {
76		warnx("%s:%d:%s: cmdbuf[%u] too small to hold cmd argument",
77		    __FILE__, __LINE__, __func__, CMDBUFMAX);
78		return (-1);
79	}
80
81	/* Open a pipe to communicate with [X]dialog(1) */
82	if (pipe(stdin_pipe) < 0)
83		err(EXIT_FAILURE, "%s: pipe(2)", __func__);
84
85	/* Fork sh(1) process */
86#if SHELL_SPAWN_DEBUG
87	fprintf(stderr, "%s: spawning `", __func__);
88	for (i = 0; shellcmd_argv[i] != NULL; i++) {
89		if (i == 0)
90			fprintf(stderr, "%s", shellcmd_argv[i]);
91		else if (i == 2)
92			fprintf(stderr, " '%s'", shellcmd_argv[i]);
93		else
94			fprintf(stderr, " %s", shellcmd_argv[i]);
95	}
96	fprintf(stderr, "'\n");
97#endif
98	posix_spawn_file_actions_init(&action);
99	posix_spawn_file_actions_adddup2(&action, stdin_pipe[0], STDIN_FILENO);
100	posix_spawn_file_actions_addclose(&action, stdin_pipe[1]);
101	error = posix_spawnp(pid, shellcmd, &action,
102	    (const posix_spawnattr_t *)NULL, shellcmd_argv, environ);
103	if (error != 0) err(EXIT_FAILURE, "%s", shellcmd);
104
105	return stdin_pipe[1];
106}
107