platform_bionic/libc/bionic/system.cpp
Elliott Hughes b6b7e2ee2e Add the missing '--' to shell invocations.
This came up with POSIX recently. Doesn't seem like it matters since
everyone's had this wrong for 40 years, but "meh" --- it's a trivial
fix, and it's strictly correct even if nobody needs this, so let's just
do it...

(Geoff Clare pointed out that my app compat concern "what if someone's
relying on this bug to pass flags to the shell?" isn't relevant because
while you can indeed do that, you then can't pass a command!)

Bug: https://austingroupbugs.net/view.php?id=1440
Test: treehugger
Change-Id: I64f6440da55e2dc29d0136ee62007197d2f00d46
2021-11-04 17:29:35 -07:00

71 lines
3 KiB
C++

/*
* Copyright (C) 2018 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <errno.h>
#include <stdlib.h>
#include <spawn.h>
#include <sys/wait.h>
#include <unistd.h>
#include "private/__bionic_get_shell_path.h"
#include "private/ScopedSignalBlocker.h"
#include "private/ScopedSignalHandler.h"
int system(const char* command) {
// "The system() function shall always return non-zero when command is NULL."
// http://pubs.opengroup.org/onlinepubs/9699919799/functions/system.html
if (command == nullptr) return 1;
ScopedSignalBlocker sigchld_blocker(SIGCHLD);
ScopedSignalHandler sigint_ignorer(SIGINT, SIG_IGN);
ScopedSignalHandler sigquit_ignorer(SIGQUIT, SIG_IGN);
sigset64_t default_mask = {};
if (sigint_ignorer.old_action_.sa_handler != SIG_IGN) sigaddset64(&default_mask, SIGINT);
if (sigquit_ignorer.old_action_.sa_handler != SIG_IGN) sigaddset64(&default_mask, SIGQUIT);
static constexpr int flags = POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK;
posix_spawnattr_t attributes;
if ((errno = posix_spawnattr_init(&attributes))) return -1;
if ((errno = posix_spawnattr_setsigdefault64(&attributes, &default_mask))) return -1;
if ((errno = posix_spawnattr_setsigmask64(&attributes, &sigchld_blocker.old_set_))) return -1;
if ((errno = posix_spawnattr_setflags(&attributes, flags))) return -1;
const char* argv[] = {"sh", "-c", "--", command, nullptr};
pid_t child;
if ((errno = posix_spawn(&child, __bionic_get_shell_path(), nullptr, &attributes,
const_cast<char**>(argv), environ)) != 0) {
return -1;
}
posix_spawnattr_destroy(&attributes);
int status;
pid_t pid = TEMP_FAILURE_RETRY(waitpid(child, &status, 0));
return (pid == -1 ? -1 : status);
}