Rewrite system(3) to use posix_spawn(3).
We saw crashes from pthread_exit+debuggerd on LP32
(https://issuetracker.google.com/72291624), and it seems like the
equivalent problem should exist with system(3). I fixed posix_spawn(3)
as part of that bug, so the easiest fix is probably to reuse that.
Bug: http://b/72470344
Test: ran tests
Change-Id: I05f838706f2b4a14ac3ee21292833e6c8579b0d4
diff --git a/libc/bionic/system.cpp b/libc/bionic/system.cpp
new file mode 100644
index 0000000..7411ae5
--- /dev/null
+++ b/libc/bionic/system.cpp
@@ -0,0 +1,71 @@
+/*
+ * 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 <paths.h>
+#include <stdlib.h>
+#include <spawn.h>
+#include <sys/wait.h>
+#include <unistd.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, _PATH_BSHELL, 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);
+}