1 /*
2 * Copyright (C) 2018 The Android Open Source Project
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 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <errno.h>
30 #include <stdlib.h>
31 #include <spawn.h>
32 #include <sys/wait.h>
33 #include <unistd.h>
34
35 #include "private/__bionic_get_shell_path.h"
36 #include "private/ScopedSignalBlocker.h"
37 #include "private/ScopedSignalHandler.h"
38
system(const char * command)39 int system(const char* command) {
40 // "The system() function shall always return non-zero when command is NULL."
41 // http://pubs.opengroup.org/onlinepubs/9699919799/functions/system.html
42 if (command == nullptr) return 1;
43
44 ScopedSignalBlocker sigchld_blocker(SIGCHLD);
45 ScopedSignalHandler sigint_ignorer(SIGINT, SIG_IGN);
46 ScopedSignalHandler sigquit_ignorer(SIGQUIT, SIG_IGN);
47
48 sigset64_t default_mask = {};
49 if (sigint_ignorer.old_action_.sa_handler != SIG_IGN) sigaddset64(&default_mask, SIGINT);
50 if (sigquit_ignorer.old_action_.sa_handler != SIG_IGN) sigaddset64(&default_mask, SIGQUIT);
51
52 static constexpr int flags = POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK;
53 posix_spawnattr_t attributes;
54 if ((errno = posix_spawnattr_init(&attributes))) return -1;
55 if ((errno = posix_spawnattr_setsigdefault64(&attributes, &default_mask))) return -1;
56 if ((errno = posix_spawnattr_setsigmask64(&attributes, &sigchld_blocker.old_set_))) return -1;
57 if ((errno = posix_spawnattr_setflags(&attributes, flags))) return -1;
58
59 const char* argv[] = {"sh", "-c", "--", command, nullptr};
60 pid_t child;
61 if ((errno = posix_spawn(&child, __bionic_get_shell_path(), nullptr, &attributes,
62 const_cast<char**>(argv), environ)) != 0) {
63 return -1;
64 }
65
66 posix_spawnattr_destroy(&attributes);
67
68 int status;
69 pid_t pid = TEMP_FAILURE_RETRY(waitpid(child, &status, 0));
70 return (pid == -1 ? -1 : status);
71 }
72