FPM: Postpone child freeing in event loop

This is to prevent after free accessing of the child event that might
happen when child is killed and the message is delivered at that same
time.

Author: bukka

sapi/fpm/fpm/fpm_children.c

@@ -63,11 +63,29 @@ static void fpm_child_free(struct fpm_child_s *child) /* {{{ */
 }
 /* }}} */
 
+static void fpm_postponed_child_free(struct fpm_event_s *ev, short which, void *arg)
+{
+	struct fpm_child_s *child = (struct fpm_child_s *) arg;
+
+	if (child->fd_stdout != -1) {
+		fpm_event_del(&child->ev_stdout);
+		close(child->fd_stdout);
+	}
+	if (child->fd_stderr != -1) {
+		fpm_event_del(&child->ev_stderr);
+		close(child->fd_stderr);
+	}
+
+	fpm_child_free((struct fpm_child_s *) child);
+}
+
 static void fpm_child_close(struct fpm_child_s *child, int in_event_loop) /* {{{ */
 {
+	bool postponed_free = false;
 	if (child->fd_stdout != -1) {
 		if (in_event_loop) {
 			fpm_event_fire(&child->ev_stdout);
+			postponed_free = true;
 		}
 		if (child->fd_stdout != -1) {
 			close(child->fd_stdout);
@@ -77,13 +95,19 @@ static void fpm_child_close(struct fpm_child_s *child, int in_event_loop) /* {{{
 	if (child->fd_stderr != -1) {
 		if (in_event_loop) {
 			fpm_event_fire(&child->ev_stderr);
+			postponed_free = true;
 		}
 		if (child->fd_stderr != -1) {
 			close(child->fd_stderr);
 		}
 	}
 
-	fpm_child_free(child);
+	if (postponed_free) {
+		fpm_event_set_timer(&child->ev_free, 0, &fpm_postponed_child_free, child);
+		fpm_event_add(&child->ev_free, 1000);
+	} else {
+		fpm_child_free(child);
+	}
 }
 /* }}} */
 

sapi/fpm/fpm/fpm_children.h

@@ -23,12 +23,13 @@ struct fpm_child_s {
 	struct fpm_child_s *prev, *next;
 	struct timeval started;
 	struct fpm_worker_pool_s *wp;
-	struct fpm_event_s ev_stdout, ev_stderr;
+	struct fpm_event_s ev_stdout, ev_stderr, ev_free;
 	int shm_slot_i;
 	int fd_stdout, fd_stderr;
 	void (*tracer)(struct fpm_child_s *);
 	struct timeval slow_logged;
-	int idle_kill;
+	bool idle_kill;
+	bool burried;
 	pid_t pid;
 	int scoreboard_i;
 	struct zlog_stream *log_stream;

sapi/fpm/fpm/fpm_stdio.c

@@ -181,10 +181,7 @@ static void fpm_stdio_child_said(struct fpm_event_s *ev, short which, void *arg)
 	if (!arg) {
 		return;
 	}
-	child = fpm_child_find((intptr_t) arg);
-	if (!child) {
-		return;
-	}
+	child = (struct fpm_child_s *) arg;
 
 	is_stdout = (fd == child->fd_stdout);
 	if (is_stdout) {
@@ -330,10 +327,10 @@ int fpm_stdio_parent_use_pipes(struct fpm_child_s *child) /* {{{ */
 	child->fd_stdout = fd_stdout[0];
 	child->fd_stderr = fd_stderr[0];
 
-	fpm_event_set(&child->ev_stdout, child->fd_stdout, FPM_EV_READ, fpm_stdio_child_said, (void *) (intptr_t) child->pid);
+	fpm_event_set(&child->ev_stdout, child->fd_stdout, FPM_EV_READ, fpm_stdio_child_said, child);
 	fpm_event_add(&child->ev_stdout, 0);
 
-	fpm_event_set(&child->ev_stderr, child->fd_stderr, FPM_EV_READ, fpm_stdio_child_said, (void *) (intptr_t) child->pid);
+	fpm_event_set(&child->ev_stderr, child->fd_stderr, FPM_EV_READ, fpm_stdio_child_said, child);
 	fpm_event_add(&child->ev_stderr, 0);
 	return 0;
 }