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
diff --git a/init/signal_handler.cpp b/init/signal_handler.cpp
index 8be4af5..37d21bc 100644
--- a/init/signal_handler.cpp
+++ b/init/signal_handler.cpp
@@ -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 @@
}
}
-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 @@
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 @@
list_remove(&svc->slist);
free(svc->name);
free(svc);
- return 0;
+ return true;
}
svc->pid = 0;
@@ -111,7 +110,7 @@
// 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 @@
"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 @@
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;
}