[PATCH v2 05/15] grep: handle NULL value for grep.patternType

["Thomas Bachem via GitGitGadget" <gitgitgadget@gmail.com>]

From: Thomas Bachem <mail@thomasbachem.com>

A grep.patternType without a value makes "git grep", "git log" and
"git show" segfault: grep_config(), which all three use, passes the
NULL value to parse_pattern_type_arg(), which hands it to strcmp().

Reject a missing value with config_error_nonbool(), as grep_config()
already does for the color.grep.* slots.

Assisted-by: Claude Fable 5.1
Signed-off-by: Thomas Bachem <mail@thomasbachem.com>
---
 grep.c          | 2 ++
 t/t7810-grep.sh | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/grep.c b/grep.c
index 1d75d31421..ab082f963e 100644
--- a/grep.c
+++ b/grep.c
@@ -71,6 +71,8 @@ int grep_config(const char *var, const char *value,
 	}
 
 	if (!strcmp(var, "grep.patterntype")) {
+		if (!value)
+			return config_error_nonbool(var);
 		opt->pattern_type_option = parse_pattern_type_arg(var, value);
 		return 0;
 	}
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index ac7ea9cf8d..d323927e54 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -1551,6 +1551,11 @@ test_expect_success PCRE 'grep invalidpattern properly dies with grep.patternTyp
 	test_must_fail git -c grep.patterntype=perl grep "a["
 '
 
+test_expect_success 'grep.patternType without a value is rejected' '
+	test_must_fail git -c grep.patternType grep "a" 2>err &&
+	test_grep "missing value for .grep.patterntype." err
+'
+
 test_expect_success 'grep -G -E -F pattern' '
 	echo "ab:a+b*c" >expected &&
 	git grep -G -E -F "a+b*c" ab >actual &&
-- 
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