[PATCH 11/15] pseudo-merge: handle NULL value for bitmapPseudoMerge.<name>.pattern

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

From: Thomas Bachem <mail@thomasbachem.com>

A bitmapPseudoMerge.<name>.pattern without a value makes
"git pack-objects" segfault while it writes a bitmap, e.g. during
"git repack -adb": pseudo_merge_config() dereferences the NULL value
to see whether the pattern starts with "^".

Reject a missing value with config_error_nonbool(), as the callback
already does through git_config_expiry_date() for the threshold keys.

Assisted-by: Claude Opus 5.5
Signed-off-by: Thomas Bachem <mail@thomasbachem.com>
---
 pseudo-merge.c                  | 4 ++++
 t/t5333-pseudo-merge-bitmaps.sh | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/pseudo-merge.c b/pseudo-merge.c
index 22b8600d68..19fae9233a 100644
--- a/pseudo-merge.c
+++ b/pseudo-merge.c
@@ -150,6 +150,10 @@ static int pseudo_merge_config(const char *var, const char *value,
 	if (!strcmp(key, "pattern")) {
 		struct strbuf re = STRBUF_INIT;
 
+		if (!value) {
+			ret = config_error_nonbool(var);
+			goto done;
+		}
 		if (group->pattern) {
 			regfree(group->pattern);
 			free(group->pattern);
diff --git a/t/t5333-pseudo-merge-bitmaps.sh b/t/t5333-pseudo-merge-bitmaps.sh
index 5b2a17f90a..e7e6b2f8a8 100755
--- a/t/t5333-pseudo-merge-bitmaps.sh
+++ b/t/t5333-pseudo-merge-bitmaps.sh
@@ -233,6 +233,11 @@ test_expect_success 'out of order thresholds are rejected' '
 	test_cmp expect err
 '
 
+test_expect_success 'pseudo-merge pattern without a value is rejected' '
+	test_must_fail git -c bitmapPseudoMerge.test.pattern repack -adb 2>err &&
+	test_grep "missing value for .bitmappseudomerge.test.pattern." err
+'
+
 test_expect_success 'pseudo-merge pattern with capture groups' '
 	git init pseudo-merge-captures &&
 	(
-- 
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