Fix handling of pending signals in wait_reading_process_output (Bug#8869).

* process.c (wait_reading_process_output): Bypass select if
waiting for a cell while ignoring keyboard input, and input is
pending.  Suggested by Jan Djärv.

2 files changed, 16 insertions, 4 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index e21412187c7..2c8b22dc321 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2011-06-26  Chong Yidong  <cyd@stupidchicken.com>
+
+        * process.c (wait_reading_process_output): Bypass select if
+        waiting for a cell while ignoring keyboard input, and input is
+        pending.  Suggested by Jan Djärv (Bug#8869).
+
 2011-06-25  Paul Eggert  <eggert@cs.ucla.edu>
 
         Use gnulib's dup2 module instead of rolling our own.
@@ -351,7 +357,7 @@
 
 2011-06-22  Jim Meyering  <meyering@redhat.com>
 
-        don't leak an XBM-image-sized buffer
+        Don't leak an XBM-image-sized buffer
         * image.c (xbm_load): Free the image buffer after using it.
 
 2011-06-21  Paul Eggert  <eggert@cs.ucla.edu>
diff --git a/src/process.c b/src/process.c
index c46437fe8cb..0fe7068af3b 100644
--- a/src/process.c
+++ b/src/process.c
@@ -4479,13 +4479,19 @@ wait_reading_process_output (int time_limit, int microsecs, int read_kbd,
             set_waiting_for_input (&timeout);
         }
 
+      /* Skip the `select' call if input is available and we're
+         waiting for keyboard input or a cell change (which can be
+         triggered by processing X events).  In the latter case, set
+         nfds to 1 to avoid breaking the loop.  */
       no_avail = 0;
-      if (read_kbd && detect_input_pending ())
+      if ((read_kbd || !NILP (wait_for_cell))
+          && detect_input_pending ())
         {
-          nfds = 0;
+          nfds = read_kbd ? 0 : 1;
           no_avail = 1;
         }
-      else
+
+      if (!no_avail)
         {
 
 #ifdef ADAPTIVE_READ_BUFFERING