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#include <err.h>
29#include <limits.h>
30#include <spawn.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <unistd.h>
34
35#include "util.h"
36
37extern char **environ;
38static char cmdbuf[CMDBUFMAX]	= "";
39static char shellcmd[PATH_MAX]	= PATH_SHELL;
40static char *shellcmd_argv[6]	= {
41	shellcmd,
42	__DECONST(char *, "-c"),
43	cmdbuf,
44	__DECONST(char *, "--"),
45	shellcmd,
46	NULL,
47};
48
49/*
50 * Spawn a sh(1) command. Writes the resulting process ID to the pid_t pointed
51 * at by `pid'. Returns a file descriptor (int) suitable for writing data to
52 * the spawned command (data written to file descriptor is seen as standard-in
53 * by the spawned sh(1) command). Returns `-1' if unable to spawn command.
54 *
55 * If cmd contains a single "%s" sequence, replace it with label if non-NULL.
56 */
57int
58shell_spawn_pipecmd(const char *cmd, const char *label, pid_t *pid)
59{
60	int error;
61	int len;
62	posix_spawn_file_actions_t action;
63#if SHELL_SPAWN_DEBUG
64	unsigned int i;
65#endif
66	int stdin_pipe[2] = { -1, -1 };
67
68	/* Populate argument array */
69	if (label != NULL && fmtcheck(cmd, "%s") == cmd)
70		len = snprintf(cmdbuf, CMDBUFMAX, cmd, label);
71	else
72		len = snprintf(cmdbuf, CMDBUFMAX, "%s", cmd);
73	if (len >= CMDBUFMAX) {
74		warnx("%s:%d:%s: cmdbuf[%u] too small to hold cmd argument",
75		    __FILE__, __LINE__, __func__, CMDBUFMAX);
76		return (-1);
77	}
78
79	/* Open a pipe to communicate with [X]dialog(1) */
80	if (pipe(stdin_pipe) < 0)
81		err(EXIT_FAILURE, "%s: pipe(2)", __func__);
82
83	/* Fork sh(1) process */
84#if SHELL_SPAWN_DEBUG
85	fprintf(stderr, "%s: spawning `", __func__);
86	for (i = 0; shellcmd_argv[i] != NULL; i++) {
87		if (i == 0)
88			fprintf(stderr, "%s", shellcmd_argv[i]);
89		else if (i == 2)
90			fprintf(stderr, " '%s'", shellcmd_argv[i]);
91		else
92			fprintf(stderr, " %s", shellcmd_argv[i]);
93	}
94	fprintf(stderr, "'\n");
95#endif
96	posix_spawn_file_actions_init(&action);
97	posix_spawn_file_actions_adddup2(&action, stdin_pipe[0], STDIN_FILENO);
98	posix_spawn_file_actions_addclose(&action, stdin_pipe[1]);
99	error = posix_spawnp(pid, shellcmd, &action,
100	    (const posix_spawnattr_t *)NULL, shellcmd_argv, environ);
101	if (error != 0) err(EXIT_FAILURE, "%s", shellcmd);
102
103	return stdin_pipe[1];
104}
105