Change regular-expression primitives to treat failure-stack overflow

as equivalent to "no match".  Also, increase the maximum size of the
failure stack from 1000 to 20000.  This is important because it is far
too easy to overflow the stack, the stack-overflow errors cause Edwin
to bomb out.  This is a problem because stack-overflow errors can be
caused by user data -- the proximate example being a News message that
bombed out the News reader because it had a header line was too
complicated to match.  Better to fail in these situations than to
error.

diff --git a/v7/src/microcode/rgxprim.c b/v7/src/microcode/rgxprim.c
index 4b05c28b484eeb272220a221253b8d8431e40c5c..fb86e7a15f78eb25f049591e208f80e4c2586487 100644 (file)
--- a/v7/src/microcode/rgxprim.c
+++ b/v7/src/microcode/rgxprim.c
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: rgxprim.c,v 1.11 1997/01/02 05:21:41 cph Exp $
+$Id: rgxprim.c,v 1.12 1997/06/06 07:00:53 cph Exp $
 
 Copyright (c) 1987-97 Massachusetts Institute of Technology
 
@@ -39,6 +39,8 @@ MIT in each case. */
 #include "edwin.h"
 #include "syntax.h"
 #include "regex.h"
+
+extern int re_max_failures;
 \f
 #define RE_CHAR_SET_P(object)                                          \
   ((STRING_P (object)) &&                                              \
@@ -84,7 +86,7 @@ MIT in each case. */
        }                                                               \
       PRIMITIVE_RETURN (long_to_integer (result));                     \
     }                                                                  \
-  else if ((result) == (-1))                                           \
+  else if (((result) == (-1)) || ((result) == (-4)))                   \
     PRIMITIVE_RETURN (SHARP_F);                                                \
   else if ((result) == (-2))                                           \
     error_bad_range_arg (1);                                           \
@@ -161,6 +163,7 @@ DEFINE_PRIMITIVE ("RE-COMPILE-FASTMAP", Prim_re_compile_fastmap, 4, 4, 0)
   text_end = (STRING_LENGTH (ARG_REF (5)));                            \
   if (match_end > text_end) error_bad_range_arg (7);                   \
   if (match_start > match_end) error_bad_range_arg (6);                        \
+  re_max_failures = 20000;                                             \
   re_buffer_initialize                                                 \
     ((& buffer), (STRING_LOC ((ARG_REF (2)), 0)), (ARG_REF (3)),       \
      text, 0, text_end, text_end, text_end);                           \
@@ -216,6 +219,7 @@ DEFINE_PRIMITIVE ("RE-SEARCH-SUBSTRING-BACKWARD", Prim_re_search_substr_backward
   if (match_start > match_end) error_bad_range_arg (6);                        \
   if (match_end > text_end) error_bad_range_arg (7);                   \
   if (match_start < text_start) error_bad_range_arg (6);               \
+  re_max_failures = 20000;                                             \
   re_buffer_initialize                                                 \
     ((& buffer), (STRING_LOC ((ARG_REF (2)), 0)), (ARG_REF (3)),       \
      text, text_start, text_end, gap_start, (GROUP_GAP_END (group)));  \