credential: handle `credential.<partial-URL>.<key>` again

In the patches for CVE-2020-11008, the ability to specify credential
settings in the config for partial URLs got lost. For example, it used
to be possible to specify a credential helper for a specific protocol:

	[credential "https://"]
		helper = my-https-helper

Likewise, it used to be possible to configure settings for a specific
host, e.g.:

	[credential "dev.azure.com"]
		useHTTPPath = true

Let's reinstate this behavior.

While at it, increase the test coverage to document and verify the
behavior with a couple other categories of partial URLs.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/urlmatch.h b/urlmatch.h
index 2407520..6ff42f8 100644
--- a/urlmatch.h
+++ b/urlmatch.h
@@ -59,6 +59,11 @@ struct urlmatch_config {
 	 * specificity rules) than existing.
 	 */
 	int (*select_fn)(const struct urlmatch_item *found, const struct urlmatch_item *existing);
+	/*
+	 * An optional callback to allow e.g. for partial URLs; it shall
+	 * return 1 or 0 depending whether `url` matches or not.
+	 */
+	int (*fallback_match_fn)(const char *url, void *cb);
 };
 
 int urlmatch_config_entry(const char *var, const char *value, void *cb);