Fix bug #11519 with relocation of buffer text during regex search.

 src/lisp.h [REL_ALLOC]: Add prototypes for external functions
 defined on ralloc.c.
 src/buffer.c [REL_ALLOC]: Remove prototypes of
 r_alloc_reset_variable, r_alloc, r_re_alloc, and r_alloc_free,
 they are now on lisp.h.
 src/ralloc.c (r_alloc_inhibit_buffer_relocation): New function.
 src/search.c (search_buffer): Use it to inhibit relocation of buffer
 text while re_search_2 is doing its job, because re_search_2 is
 passed C pointers to buffer text.

src/ChangeLog

+2012-05-23  Eli Zaretskii  <eliz@gnu.org>
+
+	* lisp.h [REL_ALLOC]: Add prototypes for external functions
+	defined on ralloc.c.
+
+	* buffer.c [REL_ALLOC]: Remove prototypes of
+	r_alloc_reset_variable, r_alloc, r_re_alloc, and r_alloc_free,
+	they are now on lisp.h.
+
+	* ralloc.c (r_alloc_inhibit_buffer_relocation): New function.
+
+	* search.c (search_buffer): Use it to inhibit relocation of buffer
+	text while re_search_2 is doing its job, because re_search_2 is
+	passed C pointers to buffer text.  (Bug#11519)
+
 2012-05-21  Eli Zaretskii  <eliz@gnu.org>
 
 	* msdos.c (internal_terminal_init) <Vwindow_system_version>:

src/buffer.c

@@ -2014,10 +2014,6 @@ advance_to_char_boundary (EMACS_INT byte_pos)
   return byte_pos;
 }
 
-#ifdef REL_ALLOC
-extern void r_alloc_reset_variable (POINTER_TYPE *, POINTER_TYPE *);
-#endif /* REL_ALLOC */
-
 DEFUN ("buffer-swap-text", Fbuffer_swap_text, Sbuffer_swap_text,
        1, 1, 0,
        doc: /* Swap the text between current buffer and BUFFER.  */)
@@ -4779,13 +4775,6 @@ mmap_realloc (POINTER_TYPE **var, size_t nbytes)
 			    Buffer-text Allocation
  ***********************************************************************/
 
-#ifdef REL_ALLOC
-extern POINTER_TYPE *r_alloc (POINTER_TYPE **, size_t);
-extern POINTER_TYPE *r_re_alloc (POINTER_TYPE **, size_t);
-extern void r_alloc_free (POINTER_TYPE **ptr);
-#endif /* REL_ALLOC */
-
-
 /* Allocate NBYTES bytes for buffer B's text buffer.  */
 
 static void

src/lisp.h

@@ -3565,6 +3565,15 @@ void syms_of_dbusbind (void);
 /* Defined in msdos.c, w32.c */
 extern char *emacs_root_dir (void);
 #endif /* DOS_NT */
+
+#ifdef REL_ALLOC
+/* Defined in ralloc.c */
+extern void r_alloc_reset_variable (POINTER_TYPE **, POINTER_TYPE **);
+extern POINTER_TYPE *r_alloc (POINTER_TYPE **, size_t);
+extern POINTER_TYPE *r_re_alloc (POINTER_TYPE **, size_t);
+extern void r_alloc_free (POINTER_TYPE **ptr);
+extern void r_alloc_inhibit_buffer_relocation (int);
+#endif	/* REL_ALLOC */
 
 /* Nonzero means Emacs has already been initialized.
    Used during startup to detect startup of dumped Emacs.  */

src/ralloc.c

@@ -1201,6 +1201,12 @@ r_alloc_reset_variable (POINTER *old, POINTER *new)
   bloc->variable = new;
 }
 
+void
+r_alloc_inhibit_buffer_relocation (int inhibit)
+{
+  use_relocatable_buffers = !inhibit;
+}
+
 
 /***********************************************************************
 			    Initialization

src/search.c

@@ -1158,12 +1158,25 @@ search_buffer (Lisp_Object string, EMACS_INT pos, EMACS_INT pos_byte,
       while (n < 0)
 	{
 	  EMACS_INT val;
+
+#ifdef REL_ALLOC
+	  /* re_search_2 below is passed C pointers to buffer text.
+	     If some code called by it causes memory (re)allocation,
+	     buffer text could be relocated on platforms that use
+	     REL_ALLOC, which invalidates those C pointers.  So we
+	     inhibit relocation of buffer text for as long as
+	     re_search_2 runs.  */
+	  r_alloc_inhibit_buffer_relocation (1);
+#endif
 	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
 			     pos_byte - BEGV_BYTE, lim_byte - pos_byte,
 			     (NILP (Vinhibit_changing_match_data)
 			      ? &search_regs : &search_regs_1),
 			     /* Don't allow match past current point */
 			     pos_byte - BEGV_BYTE);
+#ifdef REL_ALLOC
+	  r_alloc_inhibit_buffer_relocation (0);
+#endif
 	  if (val == -2)
 	    {
 	      matcher_overflow ();
@@ -1202,11 +1215,20 @@ search_buffer (Lisp_Object string, EMACS_INT pos, EMACS_INT pos_byte,
       while (n > 0)
 	{
 	  EMACS_INT val;
+
+#ifdef REL_ALLOC
+	  /* See commentary above for the reasons for inhibiting
+	     buffer text relocation here.  */
+	  r_alloc_inhibit_buffer_relocation (1);
+#endif
 	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
 			     pos_byte - BEGV_BYTE, lim_byte - pos_byte,
 			     (NILP (Vinhibit_changing_match_data)
 			      ? &search_regs : &search_regs_1),
 			     lim_byte - BEGV_BYTE);
+#ifdef REL_ALLOC
+	  r_alloc_inhibit_buffer_relocation (0);
+#endif
 	  if (val == -2)
 	    {
 	      matcher_overflow ();