1 files changed, 23 insertions, 15 deletions

diff --git a/src/process.c b/src/process.c
index 34966d35160..d60fe1e3bf6 100644
--- a/src/process.c
+++ b/src/process.c
@@ -272,17 +272,19 @@ int update_tick;
 #define READ_OUTPUT_DELAY_MAX       (READ_OUTPUT_DELAY_INCREMENT * 5)
 #define READ_OUTPUT_DELAY_MAX_MAX   (READ_OUTPUT_DELAY_INCREMENT * 7)
 
-/* Number of processes which might be delayed.  */
+/* Number of processes which have a non-zero read_output_delay,
+   and therefore might be delayed for adaptive read buffering.  */
 
 static int process_output_delay_count;
 
-/* Non-zero if any process has non-nil process_output_skip.  */
+/* Non-zero if any process has non-nil read_output_skip.  */
 
 static int process_output_skip;
 
 /* Non-nil means to delay reading process output to improve buffering.
    A value of t means that delay is reset after each send, any other
-   non-nil value does not reset the delay.  */
+   non-nil value does not reset the delay.  A value of nil disables
+   adaptive read buffering completely.  */
 static Lisp_Object Vprocess_adaptive_read_buffering;
 #else
 #define process_output_delay_count 0
@@ -1536,7 +1538,6 @@ usage: (start-process NAME BUFFER PROGRAM &rest PROGRAM-ARGS)  */)
 
   XPROCESS (proc)->childp = Qt;
   XPROCESS (proc)->plist = Qnil;
-  XPROCESS (proc)->command_channel_p = Qnil;
   XPROCESS (proc)->buffer = buffer;
   XPROCESS (proc)->sentinel = Qnil;
   XPROCESS (proc)->filter = Qnil;
@@ -4320,6 +4321,11 @@ wait_reading_process_output (time_limit, microsecs, read_kbd, do_display,
 #endif
 
 #ifdef ADAPTIVE_READ_BUFFERING
+          /* Set the timeout for adaptive read buffering if any
+             process has non-nil read_output_skip and non-zero
+             read_output_delay, and we are not reading output for a
+             specific wait_channel.  It is not executed if
+             Vprocess_adaptive_read_buffering is nil.  */
           if (process_output_skip && check_delay > 0)
             {
               int usecs = EMACS_USECS (timeout);
@@ -4330,6 +4336,8 @@ wait_reading_process_output (time_limit, microsecs, read_kbd, do_display,
                   proc = chan_process[channel];
                   if (NILP (proc))
                     continue;
+                  /* Find minimum non-zero read_output_delay among the
+                     processes with non-nil read_output_skip.  */
                   if (XINT (XPROCESS (proc)->read_output_delay) > 0)
                     {
                       check_delay--;
@@ -4880,10 +4888,10 @@ read_process_output (proc, channel)
         {
           Lisp_Object tem;
           /* Don't clobber the CURRENT match data, either!  */
-          tem = Fmatch_data (Qnil, Qnil);
-          restore_match_data ();
-          record_unwind_protect (Fset_match_data, Fmatch_data (Qnil, Qnil));
-          Fset_match_data (tem);
+          tem = Fmatch_data (Qnil, Qnil, Qnil);
+          restore_search_regs ();
+          record_unwind_save_match_data ();
+          Fset_match_data (tem, Qt);
         }
 
       /* For speed, if a search happens within this code,
@@ -4939,7 +4947,7 @@ read_process_output (proc, channel)
                                    read_process_output_error_handler);
 
       /* If we saved the match data nonrecursively, restore it now.  */
-      restore_match_data ();
+      restore_search_regs ();
       running_asynch_code = outer_running_asynch_code;
 
       /* Handling the process output should not deactivate the mark.  */
@@ -6338,10 +6346,10 @@ exec_sentinel (proc, reason)
   if (outer_running_asynch_code)
     {
       Lisp_Object tem;
-      tem = Fmatch_data (Qnil, Qnil);
-      restore_match_data ();
-      record_unwind_protect (Fset_match_data, Fmatch_data (Qnil, Qnil));
-      Fset_match_data (tem);
+      tem = Fmatch_data (Qnil, Qnil, Qnil);
+      restore_search_regs ();
+      record_unwind_save_match_data ();
+      Fset_match_data (tem, Qt);
     }
 
   /* For speed, if a search happens within this code,
@@ -6355,7 +6363,7 @@ exec_sentinel (proc, reason)
                              exec_sentinel_error_handler);
 
   /* If we saved the match data nonrecursively, restore it now.  */
-  restore_match_data ();
+  restore_search_regs ();
   running_asynch_code = outer_running_asynch_code;
 
   Vdeactivate_mark = odeactivate;
@@ -6709,7 +6717,7 @@ init_process ()
 #endif /* HAVE_SOCKETS */
 
 #if defined (DARWIN) || defined (MAC_OSX)
-  /* PTYs are broken on Darwin < 6, but are sometimes useful for interactive 
+  /* PTYs are broken on Darwin < 6, but are sometimes useful for interactive
      processes.  As such, we only change the default value.  */
  if (initialized)
   {