From 7074fde6640c88db886be0fcc4182e3790936d7d Mon Sep 17 00:00:00 2001
From: =?utf8?q?Francesco=20Potort=C3=AC?= <pot@gnu.org>
Date: Mon, 21 Nov 1994 12:50:27 +0000
Subject: [PATCH] Added code for automatically saving and restoring the match
 data when a filter or sentinel tries to modify it.

---
 src/emacs.c   |  5 +++++
 src/lisp.h    |  3 +++
 src/process.c |  9 ++++++++-
 src/search.c  | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/src/emacs.c b/src/emacs.c
index bfc83b87087..ae13412fc80 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -98,6 +98,10 @@ int inhibit_window_system;
    priority; Those functions have their own extern declaration.  */
 int emacs_priority;
 
+/* If non-zero a filter or a sentinel is running.  Tested to save the match
+   data on the first attempt to change it inside asynchronous code. */
+int running_asynch_code;
+
 #ifdef BSD_PGRPS
 /* See sysdep.c.  */
 extern int inherited_pgroup;
@@ -697,6 +701,7 @@ Usage: %s [-t term] [--terminal term]  [-nw] [--no-windows]  [--batch]\n\
   init_alloc ();
   init_eval ();
   init_data ();
+  running_asynch_code = 0;
 
 #ifdef MSDOS
   /* Call early 'cause init_environment needs it.  */
diff --git a/src/lisp.h b/src/lisp.h
index 1b773b2fa65..f946da5e5f4 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1404,6 +1404,7 @@ extern Lisp_Object Vfundamental_mode_abbrev_table;
 /* defined in search.c */
 extern Lisp_Object Fstring_match ();
 extern Lisp_Object Fscan_buffer ();
+extern void restore_match_data ();
 
 /* defined in minibuf.c */
 
@@ -1499,6 +1500,8 @@ void shut_down_emacs ( /* int signal, int no_x, Lisp_Object stuff */ );
 extern int noninteractive;
 /* Nonzero means don't do use window-system-specific display code */
 extern int inhibit_window_system;
+/* Nonzero means that a filter or a sentinel is running. */
+extern int running_asynch_code;
 
 /* defined in process.c */
 extern Lisp_Object Fget_process (), Fget_buffer_process (), Fprocessp ();
diff --git a/src/process.c b/src/process.c
index db4b31ad57c..526f46f0db2 100644
--- a/src/process.c
+++ b/src/process.c
@@ -2350,13 +2350,17 @@ read_process_output (proc, channel)
       specbind (Qinhibit_quit, Qt);
       specbind (Qlast_nonmenu_event, Qt);
 
+      running_asynch_code = 1;
       internal_condition_case_1 (read_process_output_call,
 				 Fcons (outstream,
 					Fcons (proc,
-					       Fcons (make_string (chars, nchars),
+					       Fcons (make_string (chars,
+								   nchars),
 						      Qnil))),
 				 !NILP (Vdebug_on_error) ? Qnil : Qerror,
 				 read_process_output_error_handler);
+      running_asynch_code = 0;
+      restore_match_data ();
 
       /* Handling the process output should not deactivate the mark.  */
       Vdeactivate_mark = odeactivate;
@@ -3233,11 +3237,14 @@ exec_sentinel (proc, reason)
   specbind (Qinhibit_quit, Qt);
   specbind (Qlast_nonmenu_event, Qt);
 
+  running_asynch_code = 1;
   internal_condition_case_1 (read_process_output_call,
 			     Fcons (sentinel,
 				    Fcons (proc, Fcons (reason, Qnil))),
 			     !NILP (Vdebug_on_error) ? Qnil : Qerror,
 			     exec_sentinel_error_handler);
+  running_asynch_code = 0;
+  restore_match_data ();
 
   Vdeactivate_mark = odeactivate;
   if (! EQ (Fcurrent_buffer (), obuffer))
diff --git a/src/search.c b/src/search.c
index 622df821c70..2aa645047c6 100644
--- a/src/search.c
+++ b/src/search.c
@@ -206,6 +206,9 @@ looking_at_1 (string, posix)
   register int i;
   struct re_pattern_buffer *bufp;
 
+  if (running_asynch_code)
+    save_search_regs ();
+
   CHECK_STRING (string, 0);
   bufp = compile_pattern (string, &search_regs,
 			  (!NILP (current_buffer->case_fold_search)
@@ -284,6 +287,9 @@ string_match_1 (regexp, string, start, posix)
   int s;
   struct re_pattern_buffer *bufp;
 
+  if (running_asynch_code)
+    save_search_regs ();
+
   CHECK_STRING (regexp, 0);
   CHECK_STRING (string, 1);
 
@@ -928,6 +934,9 @@ search_buffer (string, pos, lim, n, RE, trt, inverse_trt, posix)
   unsigned char *p1, *p2;
   int s1, s2;
 
+  if (running_asynch_code)
+    save_search_regs ();
+
   /* Null string is found at starting position.  */
   if (len == 0)
     {
@@ -1845,6 +1854,9 @@ LIST should have been created by calling `match-data' previously.")
   register int i;
   register Lisp_Object marker;
 
+  if (running_asynch_code)
+    save_search_regs ();
+
   if (!CONSP (list) && !NILP (list))
     list = wrong_type_argument (Qconsp, list);
 
@@ -1914,6 +1926,46 @@ LIST should have been created by calling `match-data' previously.")
   return Qnil;  
 }
 
+/* If non-zero the match data have been saved in saved_search_regs
+   during the execution of a sentinel or filter. */
+static int search_regs_saved = 0;
+static struct re_registers saved_search_regs;
+
+/* Called from Flooking_at, Fstring_match, search_buffer, Fstore_match_data
+   if asynchronous code (filter or sentinel) is running. */
+static void
+save_search_regs ()
+{
+  if (!search_regs_saved)
+    {
+      saved_search_regs.num_regs = search_regs.num_regs;
+      saved_search_regs.start = search_regs.start;
+      saved_search_regs.end = search_regs.end;
+      search_regs.num_regs = 0;
+
+      search_regs_saved = 1;
+    }
+}
+
+/* Called upon exit from filters and sentinels. */
+void
+restore_match_data ()
+{
+  if (search_regs_saved)
+    {
+      if (search_regs.num_regs > 0)
+	{
+	  xfree (search_regs.start);
+	  xfree (search_regs.end);
+	}
+      search_regs.num_regs = saved_search_regs.num_regs;
+      search_regs.start = saved_search_regs.start;
+      search_regs.end = saved_search_regs.end;
+
+      search_regs_saved = 0;
+    }
+}
+
 /* Quote a string to inactivate reg-expr chars */
 
 DEFUN ("regexp-quote", Fregexp_quote, Sregexp_quote, 1, 1, 0,
-- 
2.39.5