bug#34910: 27.0.50; Too much matching reentrancy

["Mattias Engdegård" <mattiase@acm.org>]

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Here is another improvement: there should be no reason to keep the
regexp busy during the overflow error processing, so release it first.

By the way, is there any reason why only calls to re_search_2 are made
with a busy-marked regexp buffer, not calls to re_search? Are the
latter guaranteed not to be reentrant?


[-- Attachment #2: 0001-Release-regexp-before-signalling-overflow-error.patch --]
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From 3c7555bf0fc38db94d87923869cb48d57b12605a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Tue, 19 Mar 2019 13:47:13 +0100
Subject: [PATCH] Release regexp before signalling overflow error

src/search.c (looking_at_1, search_buffer_re): Unfreeze the regexp buffer
before signalling a matcher overflow, since the error processing may
require quite some regexp use as well (Bug#34910).
---
 src/search.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/search.c b/src/search.c
index 2c00e6e93f..b61f65a77c 100644
--- a/src/search.c
+++ b/src/search.c
@@ -344,7 +344,10 @@ looking_at_1 (Lisp_Object string, bool posix)
 		  ZV_BYTE - BEGV_BYTE);
 
   if (i == -2)
-    matcher_overflow ();
+    {
+      unbind_to (count, Qnil);
+      matcher_overflow ();
+    }
 
   val = (i >= 0 ? Qt : Qnil);
   if (preserve_match_data && i >= 0)
@@ -1223,6 +1226,7 @@ search_buffer_re (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
                          pos_byte - BEGV_BYTE);
       if (val == -2)
         {
+          unbind_to (count, Qnil);
           matcher_overflow ();
         }
       if (val >= 0)
@@ -1268,6 +1272,7 @@ search_buffer_re (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
                          lim_byte - BEGV_BYTE);
       if (val == -2)
         {
+          unbind_to (count, Qnil);
           matcher_overflow ();
         }
       if (val >= 0)
-- 
2.20.1