From: Chong Yidong <cyd@gnu.org>
Date: Sat, 3 Nov 2012 15:44:59 +0000 (+0800)
Subject: Fix a race condition in wait_reading_process_output (tiny change).
X-Git-Tag: emacs-24.3.90~173^2~9^2~178
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=893cc4558558db41e16525303023372496a293b7;p=emacs.git

Fix a race condition in wait_reading_process_output (tiny change).

* src/process.c (wait_reading_process_output): Avoid a race condition
with SIGIO delivery.

Fixes: debbugs:11536
---

diff --git a/src/ChangeLog b/src/ChangeLog
index 1595537267d..e26dd561495 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2012-11-03  Jim Paris  <jim@jtan.com>  (tiny change)
+
+	* process.c (wait_reading_process_output): Avoid a race condition
+	with SIGIO delivery (Bug#11536).
+
 2012-11-03  Chong Yidong  <cyd@gnu.org>
 
 	* buffer.c (cursor_type): Untabify docstring.
diff --git a/src/process.c b/src/process.c
index 77e99ead01f..dae687cb59c 100644
--- a/src/process.c
+++ b/src/process.c
@@ -4697,9 +4697,12 @@ wait_reading_process_output (intmax_t time_limit, int nsecs, int read_kbd,
       /*  If we woke up due to SIGWINCH, actually change size now.  */
       do_pending_window_change (0);
 
+      /* The following optimization fails if SIGIO is received between
+	 set_waiting_for_input and select (Bug#11536).
       if ((time_limit || nsecs) && nfds == 0 && ! timeout_reduced_for_timers)
-	/* We waited the full specified time, so return now.  */
 	break;
+      */
+
       if (nfds < 0)
 	{
 	  if (xerrno == EINTR)