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      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 <cutils/android_reboot.h>
     27 #include <cutils/list.h>
     28 
     29 #include "init.h"
     30 #include "util.h"
     31 #include "log.h"
     32 
     33 static int signal_fd = -1;
     34 static int signal_recv_fd = -1;
     35 
     36 static void sigchld_handler(int s)
     37 {
     38     write(signal_fd, &s, 1);
     39 }
     40 
     41 #define CRITICAL_CRASH_THRESHOLD    4       /* if we crash >4 times ... */
     42 #define CRITICAL_CRASH_WINDOW       (4*60)  /* ... in 4 minutes, goto recovery*/
     43 
     44 static int wait_for_one_process(int block)
     45 {
     46     pid_t pid;
     47     int status;
     48     struct service *svc;
     49     struct socketinfo *si;
     50     time_t now;
     51     struct listnode *node;
     52     struct command *cmd;
     53 
     54     while ( (pid = waitpid(-1, &status, block ? 0 : WNOHANG)) == -1 && errno == EINTR );
     55     if (pid <= 0) return -1;
     56     INFO("waitpid returned pid %d, status = %08x\n", pid, status);
     57 
     58     svc = service_find_by_pid(pid);
     59     if (!svc) {
     60         ERROR("untracked pid %d exited\n", pid);
     61         return 0;
     62     }
     63 
     64     NOTICE("process '%s', pid %d exited\n", svc->name, pid);
     65 
     66     if (!(svc->flags & SVC_ONESHOT) || (svc->flags & SVC_RESTART)) {
     67         kill(-pid, SIGKILL);
     68         NOTICE("process '%s' killing any children in process group\n", svc->name);
     69     }
     70 
     71     /* remove any sockets we may have created */
     72     for (si = svc->sockets; si; si = si->next) {
     73         char tmp[128];
     74         snprintf(tmp, sizeof(tmp), ANDROID_SOCKET_DIR"/%s", si->name);
     75         unlink(tmp);
     76     }
     77 
     78     svc->pid = 0;
     79     svc->flags &= (~SVC_RUNNING);
     80 
     81         /* oneshot processes go into the disabled state on exit,
     82          * except when manually restarted. */
     83     if ((svc->flags & SVC_ONESHOT) && !(svc->flags & SVC_RESTART)) {
     84         svc->flags |= SVC_DISABLED;
     85     }
     86 
     87         /* disabled and reset processes do not get restarted automatically */
     88     if (svc->flags & (SVC_DISABLED | SVC_RESET) )  {
     89         notify_service_state(svc->name, "stopped");
     90         return 0;
     91     }
     92 
     93     now = gettime();
     94     if ((svc->flags & SVC_CRITICAL) && !(svc->flags & SVC_RESTART)) {
     95         if (svc->time_crashed + CRITICAL_CRASH_WINDOW >= now) {
     96             if (++svc->nr_crashed > CRITICAL_CRASH_THRESHOLD) {
     97                 ERROR("critical process '%s' exited %d times in %d minutes; "
     98                       "rebooting into recovery mode\n", svc->name,
     99                       CRITICAL_CRASH_THRESHOLD, CRITICAL_CRASH_WINDOW / 60);
    100                 android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
    101                 return 0;
    102             }
    103         } else {
    104             svc->time_crashed = now;
    105             svc->nr_crashed = 1;
    106         }
    107     }
    108 
    109     svc->flags &= (~SVC_RESTART);
    110     svc->flags |= SVC_RESTARTING;
    111 
    112     /* Execute all onrestart commands for this service. */
    113     list_for_each(node, &svc->onrestart.commands) {
    114         cmd = node_to_item(node, struct command, clist);
    115         cmd->func(cmd->nargs, cmd->args);
    116     }
    117     notify_service_state(svc->name, "restarting");
    118     return 0;
    119 }
    120 
    121 void handle_signal(void)
    122 {
    123     char tmp[32];
    124 
    125     /* we got a SIGCHLD - reap and restart as needed */
    126     read(signal_recv_fd, tmp, sizeof(tmp));
    127     while (!wait_for_one_process(0))
    128         ;
    129 }
    130 
    131 void signal_init(void)
    132 {
    133     int s[2];
    134 
    135     struct sigaction act;
    136     memset(&act, 0, sizeof(act));
    137     act.sa_handler = sigchld_handler;
    138     act.sa_flags = SA_NOCLDSTOP;
    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 
    154 int get_signal_fd()
    155 {
    156     return signal_recv_fd;
    157 }
    158