1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <errno.h> 18 #include <fcntl.h> 19 #include <signal.h> 20 #include <stdio.h> 21 #include <sys/socket.h> 22 #include <sys/types.h> 23 #include <sys/wait.h> 24 #include <unistd.h> 25 26 #include <android-base/stringprintf.h> 27 28 #include "action.h" 29 #include "init.h" 30 #include "log.h" 31 #include "service.h" 32 #include "util.h" 33 34 static int signal_write_fd = -1; 35 static int signal_read_fd = -1; 36 37 static void handle_signal() { 38 // Clear outstanding requests. 39 char buf[32]; 40 read(signal_read_fd, buf, sizeof(buf)); 41 42 ServiceManager::GetInstance().ReapAnyOutstandingChildren(); 43 } 44 45 static void SIGCHLD_handler(int) { 46 if (TEMP_FAILURE_RETRY(write(signal_write_fd, "1", 1)) == -1) { 47 PLOG(ERROR) << "write(signal_write_fd) failed"; 48 } 49 } 50 51 void signal_handler_init() { 52 // Create a signalling mechanism for SIGCHLD. 53 int s[2]; 54 if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0, s) == -1) { 55 PLOG(ERROR) << "socketpair failed"; 56 exit(1); 57 } 58 59 signal_write_fd = s[0]; 60 signal_read_fd = s[1]; 61 62 // Write to signal_write_fd if we catch SIGCHLD. 63 struct sigaction act; 64 memset(&act, 0, sizeof(act)); 65 act.sa_handler = SIGCHLD_handler; 66 act.sa_flags = SA_NOCLDSTOP; 67 sigaction(SIGCHLD, &act, 0); 68 69 ServiceManager::GetInstance().ReapAnyOutstandingChildren(); 70 71 register_epoll_handler(signal_read_fd, handle_signal); 72 } 73
