signal_handler.c revision 12541c61311e0488e9873df754f8328cd12f99b4 
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 <stdio.h>
18#include <errno.h>
19#include <signal.h>
20#include <unistd.h>
21#include <fcntl.h>
22#include <sys/types.h>
23#include <sys/socket.h>
24#include <sys/wait.h>
25#include <cutils/sockets.h>
26#include <sys/reboot.h>
27
28#include "init.h"
29#include "util.h"
30
31static int signal_fd = -1;
32static int signal_recv_fd = -1;
33
34static void sigchld_handler(int s)
35{
36    write(signal_fd, &s, 1);
37}
38
39#define CRITICAL_CRASH_THRESHOLD    4       /* if we crash >4 times ... */
40#define CRITICAL_CRASH_WINDOW       (4*60)  /* ... in 4 minutes, goto recovery*/
41
42static int wait_for_one_process(int block)
43{
44    pid_t pid;
45    int status;
46    struct service *svc;
47    struct socketinfo *si;
48    time_t now;
49    struct listnode *node;
50    struct command *cmd;
51
52    while ( (pid = waitpid(-1, &status, block ? 0 : WNOHANG)) == -1 && errno == EINTR );
53    if (pid <= 0) return -1;
54    INFO("waitpid returned pid %d, status = %08x\n", pid, status);
55
56    svc = service_find_by_pid(pid);
57    if (!svc) {
58        ERROR("untracked pid %d exited\n", pid);
59        return 0;
60    }
61
62    NOTICE("process '%s', pid %d exited\n", svc->name, pid);
63
64    if (!(svc->flags & SVC_ONESHOT)) {
65        kill(-pid, SIGKILL);
66        NOTICE("process '%s' killing any children in process group\n", svc->name);
67    }
68
69    /* remove any sockets we may have created */
70    for (si = svc->sockets; si; si = si->next) {
71        char tmp[128];
72        snprintf(tmp, sizeof(tmp), ANDROID_SOCKET_DIR"/%s", si->name);
73        unlink(tmp);
74    }
75
76    svc->pid = 0;
77    svc->flags &= (~SVC_RUNNING);
78
79        /* oneshot processes go into the disabled state on exit */
80    if (svc->flags & SVC_ONESHOT) {
81        svc->flags |= SVC_DISABLED;
82    }
83
84        /* disabled processes do not get restarted automatically */
85    if (svc->flags & SVC_DISABLED) {
86        notify_service_state(svc->name, "stopped");
87        return 0;
88    }
89
90    now = gettime();
91    if (svc->flags & SVC_CRITICAL) {
92        if (svc->time_crashed + CRITICAL_CRASH_WINDOW >= now) {
93            if (++svc->nr_crashed > CRITICAL_CRASH_THRESHOLD) {
94                ERROR("critical process '%s' exited %d times in %d minutes; "
95                      "rebooting into recovery mode\n", svc->name,
96                      CRITICAL_CRASH_THRESHOLD, CRITICAL_CRASH_WINDOW / 60);
97                sync();
98                __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
99                         LINUX_REBOOT_CMD_RESTART2, "recovery");
100                return 0;
101            }
102        } else {
103            svc->time_crashed = now;
104            svc->nr_crashed = 1;
105        }
106    }
107
108    svc->flags |= SVC_RESTARTING;
109
110    /* Execute all onrestart commands for this service. */
111    list_for_each(node, &svc->onrestart.commands) {
112        cmd = node_to_item(node, struct command, clist);
113        cmd->func(cmd->nargs, cmd->args);
114    }
115    notify_service_state(svc->name, "restarting");
116    return 0;
117}
118
119void handle_signal(void)
120{
121    char tmp[32];
122
123    /* we got a SIGCHLD - reap and restart as needed */
124    read(signal_recv_fd, tmp, sizeof(tmp));
125    while (!wait_for_one_process(0))
126        ;
127}
128
129void signal_init(void)
130{
131    int s[2];
132
133    struct sigaction act;
134
135    act.sa_handler = sigchld_handler;
136    act.sa_flags = SA_NOCLDSTOP;
137    act.sa_mask = 0;
138    act.sa_restorer = NULL;
139    sigaction(SIGCHLD, &act, 0);
140
141    /* create a signalling mechanism for the sigchld handler */
142    if (socketpair(AF_UNIX, SOCK_STREAM, 0, s) == 0) {
143        signal_fd = s[0];
144        signal_recv_fd = s[1];
145        fcntl(s[0], F_SETFD, FD_CLOEXEC);
146        fcntl(s[0], F_SETFL, O_NONBLOCK);
147        fcntl(s[1], F_SETFD, FD_CLOEXEC);
148        fcntl(s[1], F_SETFL, O_NONBLOCK);
149    }
150
151    handle_signal();
152}
153
154int get_signal_fd()
155{
156    return signal_recv_fd;
157}
158