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

2 files changed, 9 insertions, 1 deletions

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)