From fecbff83c4ca773815965f4ebdc7e6d9769a87dc Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@systemlinux.org>
Date: Sun, 18 Apr 2010 14:55:04 +0200
Subject: [PATCH] Use non-blocking API for signal handling.

This gets rid of a couple of calls to FD_ISSET() and simplifies
para_next_signal() a bit.
---
 afs.c    |  5 ++---
 audiod.c |  8 ++------
 gui.c    |  8 +++-----
 server.c | 11 ++++-------
 signal.c | 29 +++++++++++++----------------
 signal.h |  2 +-
 6 files changed, 25 insertions(+), 38 deletions(-)

diff --git a/afs.c b/afs.c
index e2a517ec..e491e307 100644
--- a/afs.c
+++ b/afs.c
@@ -709,16 +709,15 @@ static void signal_pre_select(struct sched *s, struct task *t)
 
 static void afs_signal_post_select(struct sched *s, struct task *t)
 {
-	struct signal_task *st = container_of(t, struct signal_task, task);
 	int signum;
 
 	if (getppid() == 1) {
 		PARA_EMERG_LOG("para_server died\n");
 		goto shutdown;
 	}
-	if (!FD_ISSET(st->fd, &s->rfds))
+	signum = para_next_signal(&s->rfds);
+	if (signum == 0)
 		return;
-	signum = para_next_signal();
 	if (signum == SIGHUP) {
 		close_afs_tables();
 		parse_config_or_die(1);
diff --git a/audiod.c b/audiod.c
index 99b4c7df..012f6344 100644
--- a/audiod.c
+++ b/audiod.c
@@ -980,15 +980,11 @@ static void signal_pre_select(struct sched *s, struct task *t)
 	para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 }
 
-static void signal_post_select(struct sched *s, struct task *t)
+static void signal_post_select(struct sched *s, __a_unused struct task *t)
 {
-	struct signal_task *st = container_of(t, struct signal_task, task);
 	int signum;
 
-	if (!FD_ISSET(st->fd, &s->rfds))
-		return;
-
-	signum = para_next_signal();
+	signum = para_next_signal(&s->rfds);
 	switch (signum) {
 	case SIGINT:
 	case SIGTERM:
diff --git a/gui.c b/gui.c
index 64fab61b..f2098d45 100644
--- a/gui.c
+++ b/gui.c
@@ -955,11 +955,9 @@ repeat:
 	if (ret <= 0)
 		goto check_return; /* skip fd checks */
 	/* signals */
-	if (FD_ISSET(signal_pipe, &rfds)) {
-		int sig_nr = para_next_signal();
-		if (sig_nr > 0)
-			handle_signal(sig_nr);
-	}
+	ret = para_next_signal(&rfds);
+	if (ret > 0)
+		handle_signal(ret);
 	/* read command pipe if ready */
 	if (command_pipe >= 0 && mode == COMMAND_MODE &&
 			FD_ISSET(command_pipe, &rfds)) {
diff --git a/server.c b/server.c
index ba5dabde..bc143039 100644
--- a/server.c
+++ b/server.c
@@ -276,16 +276,13 @@ static void handle_sighup(void)
 		kill(mmd->afs_pid, SIGHUP);
 }
 
-static void signal_post_select(struct sched *s, struct task *t)
+static void signal_post_select(struct sched *s, __a_unused struct task *t)
 {
-	struct signal_task *st = container_of(t, struct signal_task, task);
-	int signum;
-
-	if (!FD_ISSET(st->fd, &s->rfds))
-		return;
+	int signum = para_next_signal(&s->rfds);
 
-	signum = para_next_signal();
 	switch (signum) {
+	case 0:
+		return;
 	case SIGHUP:
 		handle_sighup();
 		break;
diff --git a/signal.c b/signal.c
index bded532e..0b4b6f0b 100644
--- a/signal.c
+++ b/signal.c
@@ -151,27 +151,24 @@ void para_install_sighandler(int sig)
 /**
  * Return the number of the next pending signal.
  *
- * This should be called if the fd for the signal pipe is ready for reading.
+ * \param rfds Th fd_set containing the signal pipe.
  *
- * \return On success, the number of the received signal is returned.  If the
- * read returned zero or was interrupted by another signal the function returns
- * 0.  Otherwise, a negative error value is returned.
+ * \return On success, the number of the received signal is returned. If there
+ * is no signal currently pending, the function returns zero. On read errors
+ * from the signal pipe, the process is terminated.
  */
-int para_next_signal(void)
+int para_next_signal(fd_set *rfds)
 {
-	int s;
-	ssize_t r = read(signal_pipe[0], &s, sizeof(s));
+	size_t n;
+	int s, ret = read_nonblock(signal_pipe[0], &s, sizeof(s), rfds, &n);
 
-	if (!r) {
-		PARA_CRIT_LOG("read from signal pipe returned zero\n");
-		return 0;
-	}
-	if (r < 0) {
-		if (errno == EAGAIN || errno == EINTR)
-			return 0;
-		return -ERRNO_TO_PARA_ERROR(errno);
+	if (ret < 0) {
+		PARA_EMERG_LOG("%s\n", para_strerror(-ret));
+		exit(EXIT_FAILURE);
 	}
-	assert(r == sizeof(s));
+	if (n == 0)
+		return 0;
+	assert(n == sizeof(s));
 	PARA_DEBUG_LOG("next signal: %d\n", s);
 	return s;
 }
diff --git a/signal.h b/signal.h
index a628df45..1dbfc981 100644
--- a/signal.h
+++ b/signal.h
@@ -20,5 +20,5 @@ int para_signal_init(void);
 void para_sigaction(int sig, void (*handler)(int));
 void para_install_sighandler(int);
 int para_reap_child(pid_t *pid);
-int para_next_signal(void);
+int para_next_signal(fd_set *rfds);
 void para_signal_shutdown(void);
-- 
2.39.2