regex: use regexec_buf()

The new regexec_buf() function operates on buffers with an explicitly
specified length, rather than NUL-terminated strings.

We need to use this function whenever the buffer we want to pass to
regexec(3) may have been mmap(2)ed (and is hence not NUL-terminated).

Note: the original motivation for this patch was to fix a bug where
`git diff -G <regex>` would crash. This patch converts more callers,
though, some of which allocated to construct NUL-terminated strings,
or worse, modified buffers to temporarily insert NULs while calling
regexec(3).  By converting them to use regexec_buf(), the code has
become much cleaner.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/grep.c b/grep.c
index 528b652f71..8ed56236f0 100644
--- a/grep.c
+++ b/grep.c
@@ -848,17 +848,6 @@ static int fixmatch(struct grep_pat *p, char *line, char *eol,
 	}
 }
 
-static int regmatch(const regex_t *preg, char *line, char *eol,
-		    regmatch_t *match, int eflags)
-{
-#ifdef REG_STARTEND
-	match->rm_so = 0;
-	match->rm_eo = eol - line;
-	eflags |= REG_STARTEND;
-#endif
-	return regexec(preg, line, 1, match, eflags);
-}
-
 static int patmatch(struct grep_pat *p, char *line, char *eol,
 		    regmatch_t *match, int eflags)
 {
@@ -869,7 +858,8 @@ static int patmatch(struct grep_pat *p, char *line, char *eol,
 	else if (p->pcre_regexp)
 		hit = !pcrematch(p, line, eol, match, eflags);
 	else
-		hit = !regmatch(&p->regexp, line, eol, match, eflags);
+		hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
+				   eflags);
 
 	return hit;
 }