[PATCH] Fix NO_LIBPCRE1_JIT to fully disable JIT

[Charles Bailey <charles@hashpling.org>]

From: Charles Bailey <cbailey32@bloomberg.net>

If you have a pcre1 library which is compiled with JIT enabled then
PCRE_STUDY_JIT_COMPILE will be defined whether or not the
NO_LIBPCRE1_JIT configuration is set.

This means that we enable JIT functionality when calling pcre_study
even if NO_LIBPCRE1_JIT has been explicitly set and we just use plain
pcre_exec later.

Fix this by using own macro (GIT_PCRE_STUDY_JIT_COMPILE) which we set to
PCRE_STUDY_JIT_COMPILE only if NO_LIBPCRE1_JIT is not set and define to
0 otherwise, as before.
---

I was bisecting an issue with the PCRE support that was causing a test
suite failure on our Solaris builds and reached fbaceaac47 ("grep: add
support for the PCRE v1 JIT API"). It appeared to be a misaligned memory
access somewhere inside the libpcre code. I tried disabling the use of
JIT with NO_LIBPCRE1_JIT but it turned out that even with this set we
were still triggering the JIT code path in the call to pcre_study.

Yes, we probably should fix our PCRE1 library build on Solaris or move
to PCRE2, but really NO_LIBPCRE1_JIT should have prevented us from
triggering this crash.

 grep.c | 2 +-
 grep.h | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/grep.c b/grep.c
index ce6a48e..d0b9b6c 100644
--- a/grep.c
+++ b/grep.c
@@ -387,7 +387,7 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 	if (!p->pcre1_regexp)
 		compile_regexp_failed(p, error);
 
-	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, PCRE_STUDY_JIT_COMPILE, &error);
+	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, GIT_PCRE_STUDY_JIT_COMPILE, &error);
 	if (!p->pcre1_extra_info && error)
 		die("%s", error);
 
diff --git a/grep.h b/grep.h
index 52aecfa..399381c 100644
--- a/grep.h
+++ b/grep.h
@@ -7,11 +7,12 @@
 #if PCRE_MAJOR >= 8 && PCRE_MINOR >= 32
 #ifndef NO_LIBPCRE1_JIT
 #define GIT_PCRE1_USE_JIT
+#define GIT_PCRE_STUDY_JIT_COMPILE PCRE_STUDY_JIT_COMPILE
 #endif
 #endif
 #endif
-#ifndef PCRE_STUDY_JIT_COMPILE
-#define PCRE_STUDY_JIT_COMPILE 0
+#ifndef GIT_PCRE_STUDY_JIT_COMPILE
+#define GIT_PCRE_STUDY_JIT_COMPILE 0
 #endif
 #if PCRE_MAJOR <= 8 && PCRE_MINOR < 20
 typedef int pcre_jit_stack;
-- 
2.10.2