Re: [PATCH] Fix NO_LIBPCRE1_JIT to fully disable JIT

> 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;