[PATCH v3 13/15] config: handle NULL value for remote URLs in hasconfig includes

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

From: Thomas Bachem <mail@thomasbachem.com>

When the configuration has an includeIf "hasconfig:remote.*.url:..."
section, a remote.<name>.url without a value makes nearly every git
command segfault, "git log" too: add_remote_url() passes the NULL
value to string_list_append(), which copies it with xstrdup().

Leave such a URL out of the list that hasconfig:remote.*.url patterns
are matched against. It cannot match a pattern, and wherever git
reads its remotes, handle_config() in remote.c already rejects it
with the usual error. Commands that never look at remotes keep
working.

Assisted-by: Claude Opus 5.5
Signed-off-by: Thomas Bachem <mail@thomasbachem.com>
---
 config.c          |  3 ++-
 t/t1300-config.sh | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/config.c b/config.c
index 5976a418d5..5b823b3dcd 100644
--- a/config.c
+++ b/config.c
@@ -342,7 +342,8 @@ static int add_remote_url(const char *var, const char *value,
 	if (!parse_config_key(var, "remote", &remote_name, &remote_name_len,
 			      &key) &&
 	    remote_name &&
-	    !strcmp(key, "url"))
+	    !strcmp(key, "url") &&
+	    value)
 		string_list_append(remote_urls, value);
 	return 0;
 }
diff --git a/t/t1300-config.sh b/t/t1300-config.sh
index e3f8064889..8fb920b1ba 100755
--- a/t/t1300-config.sh
+++ b/t/t1300-config.sh
@@ -2970,6 +2970,28 @@ test_expect_success 'includeIf.hasconfig:remote.*.url forbids remote url in such
 	test_grep "fatal: remote URLs cannot be configured in file directly or indirectly included by includeIf.hasconfig:remote.*.url" err
 '
 
+test_expect_success 'includeIf.hasconfig:remote.*.url skips a url without a value' '
+	git init hasremoteurlTest &&
+	test_when_finished "rm -rf hasremoteurlTest" &&
+
+	cat >include-this <<-\EOF &&
+	[user]
+		this = this-is-included
+	EOF
+	cat >>hasremoteurlTest/.git/config <<-EOF &&
+	[remote "valueless"]
+		url
+	[remote "foo"]
+		url = foourl
+	[includeIf "hasconfig:remote.*.url:foourl"]
+		path = "$(pwd)/include-this"
+	EOF
+
+	echo this-is-included >expect-this &&
+	git -C hasremoteurlTest config --get user.this >actual-this &&
+	test_cmp expect-this actual-this
+'
+
 test_expect_success 'negated mode causes failure' '
 	test_must_fail git config --no-get 2>err &&
 	test_grep "unknown option \`no-get${SQ}" err
-- 
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