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Commit 9042cae4 authored by Elliott Hughes's avatar Elliott Hughes
Browse files

Clean up init signal handling a little. 

We can set it up earlier, and error reporting like this helped me find
the SELinux problem with the last change to this code.

Change-Id: If0f38bc5ff0465c4030e2d39d34f31f49b2d8487
parent 662baefb

init/init.cpp

+3 −21
Original line number Diff line number Diff line
@@ -848,16 +848,6 @@ static int property_service_init_action(int nargs, char **args) 
    return 0;

}



static int signal_init_action(int nargs, char **args)

{

    signal_init();

    if (get_signal_fd() < 0) {

        ERROR("signal_init() failed\n");

        exit(1);

    }

    return 0;

}



static int queue_property_triggers_action(int nargs, char **args)

{

    queue_all_property_triggers();
@@ -1061,13 +1051,12 @@ int main(int argc, char** argv) { 
    restorecon("/dev/__properties__");

    restorecon_recursive("/sys");



    signal_init();



    property_load_boot_defaults();



    init_parse_config_file("/init.rc");



    // Setup signal handler before any exec command or we'll deadlock

    queue_builtin_action(signal_init_action, "signal_init");



    action_for_each_trigger("early-init", action_add_queue_tail);



    queue_builtin_action(wait_for_coldboot_done_action, "wait_for_coldboot_done");
@@ -1097,8 +1086,8 @@ int main(int argc, char** argv) { 
    // TODO: why do we only initialize ufds after execute_one_command and restart_processes?

    size_t fd_count = 0;

    struct pollfd ufds[3];

    ufds[fd_count++] = { .fd = get_signal_fd(), .events = POLLIN, .revents = 0 };

    bool property_set_fd_init = false;

    bool signal_fd_init = false;

    bool keychord_fd_init = false;



    for (;;) {
@@ -1114,13 +1103,6 @@ int main(int argc, char** argv) { 
            fd_count++;

            property_set_fd_init = true;

        }

        if (!signal_fd_init && get_signal_fd() > 0) {

            ufds[fd_count].fd = get_signal_fd();

            ufds[fd_count].events = POLLIN;

            ufds[fd_count].revents = 0;

            fd_count++;

            signal_fd_init = true;

        }

        if (!keychord_fd_init && get_keychord_fd() > 0) {

            ufds[fd_count].fd = get_keychord_fd();

            ufds[fd_count].events = POLLIN;

init/signal_handler.cpp

+43 −29
Original line number Diff line number Diff line
@@ -35,14 +35,10 @@ 
#define CRITICAL_CRASH_THRESHOLD    4       /* if we crash >4 times ... */

#define CRITICAL_CRASH_WINDOW       (4*60)  /* ... in 4 minutes, goto recovery */



static int signal_fd = -1;

static int signal_recv_fd = -1;

static int signal_write_fd = -1;

static int signal_read_fd = -1;



static void sigchld_handler(int s) {

    write(signal_fd, &s, 1);

}



std::string DescribeStatus(int status) {

static std::string DescribeStatus(int status) {

    if (WIFEXITED(status)) {

        return android::base::StringPrintf("exited with status %d", WEXITSTATUS(status));

    } else if (WIFSIGNALED(status)) {
@@ -54,11 +50,14 @@ std::string DescribeStatus(int status) { 
    }

}



static int wait_for_one_process() {

static bool wait_for_one_process() {

    int status;

    pid_t pid = TEMP_FAILURE_RETRY(waitpid(-1, &status, WNOHANG));

    if (pid <= 0) {

        return -1;

    if (pid == 0) {

        return false;

    } else if (pid == -1) {

        ERROR("waitpid failed: %s\n", strerror(errno));

        return false;

    }



    service* svc = service_find_by_pid(pid);
@@ -73,7 +72,7 @@ static int wait_for_one_process() { 
    NOTICE("%s %s\n", name.c_str(), DescribeStatus(status).c_str());



    if (!svc) {

        return 0;

        return true;

    }



    // TODO: all the code from here down should be a member function on service.
@@ -96,7 +95,7 @@ static int wait_for_one_process() { 
        list_remove(&svc->slist);

        free(svc->name);

        free(svc);

        return 0;

        return true;

    }



    svc->pid = 0;
@@ -111,7 +110,7 @@ static int wait_for_one_process() { 
    // Disabled and reset processes do not get restarted automatically.

    if (svc->flags & (SVC_DISABLED | SVC_RESET))  {

        svc->NotifyStateChange("stopped");

        return 0;

        return true;

    }



    time_t now = gettime();
@@ -122,7 +121,7 @@ static int wait_for_one_process() { 
                      "rebooting into recovery mode\n", svc->name,

                      CRITICAL_CRASH_THRESHOLD, CRITICAL_CRASH_WINDOW / 60);

                android_reboot(ANDROID_RB_RESTART2, 0, "recovery");

                return 0;

                return true;

            }

        } else {

            svc->time_crashed = now;
@@ -140,34 +139,49 @@ static int wait_for_one_process() { 
        cmd->func(cmd->nargs, cmd->args);

    }

    svc->NotifyStateChange("restarting");

    return 0;

    return true;

}



static void reap_any_outstanding_children() {

    while (wait_for_one_process()) {

    }

}



void handle_signal() {

    // We got a SIGCHLD - reap and restart as needed.

    char tmp[32];

    read(signal_recv_fd, tmp, sizeof(tmp));

    while (!wait_for_one_process()) {

    // Clear outstanding requests.

    char buf[32];

    read(signal_read_fd, buf, sizeof(buf));



    reap_any_outstanding_children();

}



static void SIGCHLD_handler(int) {

    if (TEMP_FAILURE_RETRY(write(signal_write_fd, "1", 1)) == -1) {

        ERROR("write(signal_write_fd) failed: %s\n", strerror(errno));

    }

}



void signal_init() {

    // Create a signalling mechanism for SIGCHLD.

    int s[2];

    if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0, s) == -1) {

        ERROR("socketpair failed: %s\n", strerror(errno));

        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_handler = SIGCHLD_handler;

    act.sa_flags = SA_NOCLDSTOP;

    sigaction(SIGCHLD, &act, 0);



    // Create a signalling mechanism for the sigchld handler.

    int s[2];

    if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0, s) == 0) {

        signal_fd = s[0];

        signal_recv_fd = s[1];

    }



    handle_signal();

    reap_any_outstanding_children();

}



int get_signal_fd() {

    return signal_recv_fd;

    return signal_read_fd;

}