blob: 072a0fb0b092645a7bb73c2e9dd80c87ec0c08c1 [file] [log] [blame]
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "sigchld_handler.h"
#include <signal.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <android-base/chrono_utils.h>
#include <android-base/logging.h>
#include <android-base/scopeguard.h>
#include <android-base/stringprintf.h>
#include "init.h"
#include "property_service.h"
#include "service.h"
using android::base::StringPrintf;
using android::base::boot_clock;
using android::base::make_scope_guard;
namespace android {
namespace init {
static int signal_write_fd = -1;
static int signal_read_fd = -1;
static bool ReapOneProcess() {
siginfo_t siginfo = {};
// This returns a zombie pid or informs us that there are no zombies left to be reaped.
// It does NOT reap the pid; that is done below.
if (TEMP_FAILURE_RETRY(waitid(P_ALL, 0, &siginfo, WEXITED | WNOHANG | WNOWAIT)) != 0) {
PLOG(ERROR) << "waitid failed";
return false;
}
auto pid = siginfo.si_pid;
if (pid == 0) return false;
// At this point we know we have a zombie pid, so we use this scopeguard to reap the pid
// whenever the function returns from this point forward.
// We do NOT want to reap the zombie earlier as in Service::Reap(), we kill(-pid, ...) and we
// want the pid to remain valid throughout that (and potentially future) usages.
auto reaper = make_scope_guard([pid] { TEMP_FAILURE_RETRY(waitpid(pid, nullptr, WNOHANG)); });
std::string name;
std::string wait_string;
Service* service = nullptr;
if (PropertyChildReap(pid)) {
name = "Async property child";
} else if (SubcontextChildReap(pid)) {
name = "Subcontext";
} else {
service = ServiceList::GetInstance().FindService(pid, &Service::pid);
if (service) {
name = StringPrintf("Service '%s' (pid %d)", service->name().c_str(), pid);
if (service->flags() & SVC_EXEC) {
auto exec_duration = boot_clock::now() - service->time_started();
auto exec_duration_ms =
std::chrono::duration_cast<std::chrono::milliseconds>(exec_duration).count();
wait_string = StringPrintf(" waiting took %f seconds", exec_duration_ms / 1000.0f);
}
} else {
name = StringPrintf("Untracked pid %d", pid);
}
}
auto status = siginfo.si_status;
if (WIFEXITED(status)) {
LOG(INFO) << name << " exited with status " << WEXITSTATUS(status) << wait_string;
} else if (WIFSIGNALED(status)) {
LOG(INFO) << name << " killed by signal " << WTERMSIG(status) << wait_string;
}
if (!service) return true;
service->Reap();
if (service->flags() & SVC_TEMPORARY) {
ServiceList::GetInstance().RemoveService(*service);
}
return true;
}
static void handle_signal() {
// Clear outstanding requests.
char buf[32];
read(signal_read_fd, buf, sizeof(buf));
ReapAnyOutstandingChildren();
}
static void SIGCHLD_handler(int) {
if (TEMP_FAILURE_RETRY(write(signal_write_fd, "1", 1)) == -1) {
PLOG(ERROR) << "write(signal_write_fd) failed";
}
}
void ReapAnyOutstandingChildren() {
while (ReapOneProcess()) {
}
}
void sigchld_handler_init() {
// Create a signalling mechanism for SIGCHLD.
int s[2];
if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0, s) == -1) {
PLOG(FATAL) << "socketpair failed in sigchld_handler_init";
}
signal_write_fd = s[0];
signal_read_fd = s[1];
// Write to signal_write_fd if we catch SIGCHLD.
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = SIGCHLD_handler;
act.sa_flags = SA_NOCLDSTOP;
sigaction(SIGCHLD, &act, 0);
ReapAnyOutstandingChildren();
register_epoll_handler(signal_read_fd, handle_signal);
}
} // namespace init
} // namespace android