If kbd_buffer is becoming full, stop reading until it drains (Bug#6571).

* keyboard.c (input_available_signal): Declare.
(kbd_buffer_nr_stored): New function.
(kbd_buffer_store_event_hold): If kbd_buffer_nr_stored returns
more than KBD_BUFFER_SIZE/2, stop reding input (Bug#6571).
(kbd_buffer_get_event): If input is suspended and kbd_buffer_nr_stored
returns less than KBD_BUFFER_SIZE/4, resume reding input (Bug#6571).
(tty_read_avail_input): If input is on hold, return.
Don't read more that free slots in kbd_buffer (Bug#6571).

* process.h (hold_keyboard_input, unhold_keyboard_input)
(kbd_on_hold_p): Declare.

* process.c (kbd_is_on_hold): New variable.
(hold_keyboard_input, unhold_keyboard_input, kbd_on_hold_p): New
functions.
(wait_reading_process_output): If kbd_on_hold_p returns non-zero,
select on empty input mask.
(init_process): Initialize kbd_is_on_hold to 0.

4 files changed, 105 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 63b0dd0a53d..912a5a8d2f2 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,24 @@
+2010-07-07  Jan Djärv  <jan.h.d@swipnet.se>
+
+        * process.c (kbd_is_on_hold): New variable.
+        (hold_keyboard_input, unhold_keyboard_input, kbd_on_hold_p): New
+        functions.
+        (wait_reading_process_output): If kbd_on_hold_p returns non-zero,
+        select on empty input mask.
+        (init_process): Initialize kbd_is_on_hold to 0.
+
+        * process.h (hold_keyboard_input, unhold_keyboard_input)
+        (kbd_on_hold_p): Declare.
+
+        * keyboard.c (input_available_signal): Declare.
+        (kbd_buffer_nr_stored): New function.
+        (kbd_buffer_store_event_hold): If kbd_buffer_nr_stored returns
+        more than KBD_BUFFER_SIZE/2, stop reding input (Bug#6571).
+        (kbd_buffer_get_event): If input is suspended and kbd_buffer_nr_stored
+        returns less than KBD_BUFFER_SIZE/4, resume reding input (Bug#6571).
+        (tty_read_avail_input): If input is on hold, return.
+        Don't read more that free slots in kbd_buffer (Bug#6571).
+
 2010-07-07  Eli Zaretskii  <eliz@gnu.org>
 
         * msdos.h:
diff --git a/src/keyboard.c b/src/keyboard.c
index 2cf7a7b24a6..c7d3ee413cd 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -635,6 +635,7 @@ static Lisp_Object apply_modifiers (int, Lisp_Object);
 static void clear_event (struct input_event *);
 static Lisp_Object restore_kboard_configuration (Lisp_Object);
 static SIGTYPE interrupt_signal (int signalnum);
+static SIGTYPE input_available_signal (int signo);
 static void handle_interrupt (void);
 static void timer_start_idle (void);
 static void timer_stop_idle (void);
@@ -3590,6 +3591,18 @@ event_to_kboard (struct input_event *event)
     return FRAME_KBOARD (XFRAME (frame));
 }
 
+/* Return the number of slots occupied in kbd_buffer.  */
+
+static int
+kbd_buffer_nr_stored ()
+{
+  return kbd_fetch_ptr == kbd_store_ptr
+    ? 0
+    : (kbd_fetch_ptr < kbd_store_ptr
+       ? kbd_store_ptr - kbd_fetch_ptr
+       : ((kbd_buffer + KBD_BUFFER_SIZE) - kbd_fetch_ptr
+          + (kbd_store_ptr - kbd_buffer)));
+}
 
 Lisp_Object Vthrow_on_input;
 
@@ -3711,6 +3724,17 @@ kbd_buffer_store_event_hold (register struct input_event *event,
     {
       *kbd_store_ptr = *event;
       ++kbd_store_ptr;
+      if (kbd_buffer_nr_stored () > KBD_BUFFER_SIZE/2 && ! kbd_on_hold_p ())
+        {
+          /* Don't read keyboard input until we have processed kbd_buffer.
+             This happens when pasting text longer than KBD_BUFFER_SIZE/2.  */
+          hold_keyboard_input ();
+#ifdef SIGIO
+          if (!noninteractive)
+            signal (SIGIO, SIG_IGN);
+#endif
+          stop_polling ();
+        }
     }
 
   /* If we're inside while-no-input, and this event qualifies
@@ -3866,10 +3890,24 @@ clear_event (struct input_event *event)
    We always read and discard one event.  */
 
 static Lisp_Object
-kbd_buffer_get_event (KBOARD **kbp, int *used_mouse_menu, struct timeval *end_time)
+kbd_buffer_get_event (KBOARD **kbp,
+                      int *used_mouse_menu,
+                      struct timeval *end_time)
 {
   register int c;
   Lisp_Object obj;
+  
+  if (kbd_on_hold_p () && kbd_buffer_nr_stored () < KBD_BUFFER_SIZE/4)
+    {
+      /* Start reading input again, we have processed enough so we can
+         accept new events again.  */
+      unhold_keyboard_input ();
+#ifdef SIGIO
+      if (!noninteractive)
+        signal (SIGIO, input_available_signal);
+#endif /* SIGIO */
+      start_polling ();
+    }
 
   if (noninteractive
       /* In case we are running as a daemon, only do this before
@@ -7039,6 +7077,10 @@ tty_read_avail_input (struct terminal *terminal,
   int n_to_read, i;
   struct tty_display_info *tty = terminal->display_info.tty;
   int nread = 0;
+  int buffer_free = KBD_BUFFER_SIZE - kbd_buffer_nr_stored () - 1;
+
+  if (kbd_on_hold_p () || buffer_free <= 0)
+    return 0;
 
   if (!terminal->name)          /* Don't read from a dead terminal. */
     return 0;
@@ -7120,6 +7162,10 @@ tty_read_avail_input (struct terminal *terminal,
 #endif
 #endif
 
+  /* Don't read more than we can store.  */
+  if (n_to_read > buffer_free)
+    n_to_read = buffer_free;
+
   /* Now read; for one reason or another, this will not block.
      NREAD is set to the number of chars read.  */
   do
diff --git a/src/process.c b/src/process.c
index 0807a0e17cb..c7460d81255 100644
--- a/src/process.c
+++ b/src/process.c
@@ -306,6 +306,10 @@ extern int timers_run;
 
 static SELECT_TYPE input_wait_mask;
 
+/* Non-zero if keyboard input is on hold, zero otherwise.  */
+
+static int kbd_is_on_hold;
+
 /* Mask that excludes keyboard input descriptor(s).  */
 
 static SELECT_TYPE non_keyboard_wait_mask;
@@ -4731,7 +4735,10 @@ wait_reading_process_output (time_limit, microsecs, read_kbd, do_display,
           SELECT_TYPE Ctemp;
 #endif
 
-          Atemp = input_wait_mask;
+          if (kbd_on_hold_p ())
+            FD_ZERO (&Atemp);
+          else
+            Atemp = input_wait_mask;
           IF_NON_BLOCKING_CONNECT (Ctemp = connect_wait_mask);
 
           EMACS_SET_SECS_USECS (timeout, 0, 0);
@@ -7010,6 +7017,30 @@ DEFUN ("process-filter-multibyte-p", Fprocess_filter_multibyte_p,
 
 
 
+/* Stop reading input from keyboard sources.  */
+
+void
+hold_keyboard_input (void)
+{
+  kbd_is_on_hold = 1;
+}
+
+/* Resume reading input from keyboard sources.  */
+
+void
+unhold_keyboard_input (void)
+{
+  kbd_is_on_hold = 0;
+}
+
+/* Return non-zero if keyboard input is on hold, zero otherwise.  */
+
+int
+kbd_on_hold_p (void)
+{
+  return kbd_is_on_hold;
+}
+
 /* Add DESC to the set of keyboard input descriptors.  */
 
 void
@@ -7901,6 +7932,7 @@ integer or floating point values.
 void
 init_process ()
 {
+  kbd_is_on_hold = 0;
 }
 
 void
diff --git a/src/process.h b/src/process.h
index a8cd0a02da6..12b91d697b9 100644
--- a/src/process.h
+++ b/src/process.h
@@ -170,5 +170,9 @@ extern Lisp_Object Qtime, Qctime;
 extern Lisp_Object list_system_processes (void);
 extern Lisp_Object system_process_attributes (Lisp_Object);
 
+extern void hold_keyboard_input (void);
+extern void unhold_keyboard_input (void);
+extern int kbd_on_hold_p (void);
+
 /* arch-tag: dffedfc4-d7bc-4b58-a26f-c16155449c72
    (do not change this comment) */