Re: improve performance of PCRE2 bug 2642 bug workaround

From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mar 22, 2022, 21:12 UTC
Message-ID: <325b7ba6-04a8-0010-a288-a118a820f3c3@cs.ucla.edu>
In-Reply-To: <99b0adb6-26ba-293c-3a8f-679f59e7cb4d@web.de>

On 3/22/22 13:26, René Scharfe wrote:

> However, the looser check works around another bug, if only by accident.

Thanks for letting me know. In that case, GNU grep should use a looser check too, like Git grep does. I installed the attached into GNU grep.

From ff2d24b08223e6c7b704a91127bac4391a9b8adb Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 22 Mar 2022 14:09:05 -0700
Subject: [PATCH] grep: work around another potential PCRE2 bug
MIME-Version: 1.0
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Potential problem reported by René Scharfe in:
https://lore.kernel.org/git/99b0adb6-26ba-293c-3a8f-679f59e7cb4d@web.de/T
* src/pcresearch.c (Pcompile): Mimic git grep’s workarounds
for PCRE2 bugs more closely; this is more conservative.
---
 src/pcresearch.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/pcresearch.c b/src/pcresearch.c
index 0cf804d..6947838 100644
--- a/src/pcresearch.c
+++ b/src/pcresearch.c
@@ -154,15 +154,16 @@ Pcompile (char *pattern, idx_t size, reg_syntax_t ignored, bool exact)
 #ifdef PCRE2_MATCH_INVALID_UTF
       /* Consider invalid UTF-8 as a barrier, instead of error.  */
       flags |= PCRE2_MATCH_INVALID_UTF;
-
-# if ! (10 < PCRE2_MAJOR + (36 <= PCRE2_MINOR))
-      /* Work around PCRE2 bug 2642.  */
-      if (flags & PCRE2_CASELESS)
-        flags |= PCRE2_NO_START_OPTIMIZE;
-# endif
 #endif
     }
 
+#if defined PCRE2_MATCH_INVALID_UTF && !(10 < PCRE2_MAJOR + (36 <= PCRE2_MINOR))
+  /* Work around PCRE2 bug 2642, and another bug reportedly fixed in
+     PCRE2 commit e0c6029a62db9c2161941ecdf459205382d4d379.  */
+  if (flags & (PCRE2_UTF | PCRE2_CASELESS))
+    flags |= PCRE2_NO_START_OPTIMIZE;
+#endif
+
   /* FIXME: Remove this restriction.  */
   if (rawmemchr (pattern, '\n') != patlim)
     die (EXIT_TROUBLE, 0, _("the -P option only supports a single pattern"));

-- 
2.32.0