[PATCH 7/8] grep: use REG_STARTEND for all matching if available

["René Scharfe" <rene.scharfe@lsrfire.ath.cx>]

Refactor REG_STARTEND handling inlook_ahead() into a new helper,
regmatch(), and use it for line matching, too.  This allows regex
matching beyond NUL characters if regexec() supports the flag.  NUL
characters themselves are not matched in any way, though.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
---
 grep.c                 |   24 ++++++++++++++----------
 t/t7008-grep-binary.sh |   10 ++++++++++
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/grep.c b/grep.c
index b95803b..70a776f 100644
--- a/grep.c
+++ b/grep.c
@@ -356,6 +356,17 @@ static int fixmatch(const char *pattern, 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 strip_timestamp(char *bol, char **eol_p)
 {
 	char *eol = *eol_p;
@@ -408,7 +419,7 @@ static int match_one_pattern(struct grep_pat *p, char *bol, char *eol,
 	if (p->fixed)
 		hit = !fixmatch(p->pattern, bol, eol, p->ignore_case, pmatch);
 	else
-		hit = !regexec(&p->regexp, bol, 1, pmatch, eflags);
+		hit = !regmatch(&p->regexp, bol, eol, pmatch, eflags);
 
 	if (hit && p->word_regexp) {
 		if ((pmatch[0].rm_so < 0) ||
@@ -735,15 +746,8 @@ static int look_ahead(struct grep_opt *opt,
 		if (p->fixed) {
 			hit = !fixmatch(p->pattern, bol, bol + *left_p,
 					p->ignore_case, &m);
-		} else {
-#ifdef REG_STARTEND
-			m.rm_so = 0;
-			m.rm_eo = *left_p;
-			hit = !regexec(&p->regexp, bol, 1, &m, REG_STARTEND);
-#else
-			hit = !regexec(&p->regexp, bol, 1, &m, 0);
-#endif
-		}
+		} else
+			hit = !regmatch(&p->regexp, bol, bol + *left_p, &m, 0);
 		if (!hit || m.rm_so < 0 || m.rm_eo < 0)
 			continue;
 		if (earliest < 0 || m.rm_so < earliest)
diff --git a/t/t7008-grep-binary.sh b/t/t7008-grep-binary.sh
index 9660842..4f5e74f 100755
--- a/t/t7008-grep-binary.sh
+++ b/t/t7008-grep-binary.sh
@@ -59,4 +59,14 @@ test_expect_success 'git grep -Fi iLE a' '
 	git grep -Fi iLE a
 '
 
+# This test actually passes on platforms where regexec() supports the
+# flag REG_STARTEND.
+test_expect_failure 'git grep ile a' '
+	git grep ile a
+'
+
+test_expect_failure 'git grep .fi a' '
+	git grep .fi a
+'
+
 test_done
-- 
1.7.1