1 files changed, 142 insertions, 0 deletions
diff --git a/init/sigchld_handler.cpp b/init/sigchld_handler.cpp
new file mode 100644
index 000000000..8fc995606
--- /dev/null
+++ b/init/sigchld_handler.cpp
@@ -0,0 +1,142 @@
+/*
+ * 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)); });
+
+    if (PropertyChildReap(pid)) return true;
+
+    Service* service = ServiceList::GetInstance().FindService(pid, &Service::pid);
+
+    std::string name;
+    std::string wait_string;
+    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(ERROR) << "socketpair failed";
+        exit(1);
+    }
+
+    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