Adding git_config_foreach_match() iteration fn

Adding a new config iteration function that let's you iterate
over just the config entries that match a particular regular
expression.  The old foreach becomes a simple use of this with
an empty pattern.

This also fixes an apparent bug in the existing `git_config_foreach`
where returning a non-zero value from the iteration callback was
not correctly aborting the iteration and the returned value was
not being propogated back to the caller of foreach.

Added to tests to cover all these changes.

1 files changed, 19 insertions, 1 deletions

diff --git a/include/git2/config.h b/include/git2/config.h
index 36946c4a5..c46e7fc9d 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -33,7 +33,7 @@ struct git_config_file {
 	int (*set)(struct git_config_file *, const char *key, const char *value);
 	int (*set_multivar)(git_config_file *cfg, const char *name, const char *regexp, const char *value);
 	int (*del)(struct git_config_file *, const char *key);
-	int (*foreach)(struct git_config_file *, int (*fn)(const char *, const char *, void *), void *data);
+	int (*foreach)(struct git_config_file *, const char *, int (*fn)(const char *, const char *, void *), void *data);
 	void (*free)(struct git_config_file *);
 };
 
@@ -314,6 +314,24 @@ GIT_EXTERN(int) git_config_foreach(
 	int (*callback)(const char *var_name, const char *value, void *payload),
 	void *payload);
 
+/**
+ * Perform an operation on each config variable matching a regular expression.
+ *
+ * This behaviors like `git_config_foreach` with an additional filter of a
+ * regular expression that filters which config keys are passed to the
+ * callback.
+ *
+ * @param cfg where to get the variables from
+ * @param regexp regular expression to match against config names
+ * @param callback the function to call on each variable
+ * @param payload the data to pass to the callback
+ * @return 0 or the return value of the callback which didn't return 0
+ */
+GIT_EXTERN(int) git_config_foreach_match(
+	git_config *cfg,
+	const char *regexp,
+	int (*callback)(const char *var_name, const char *value, void *payload),
+	void *payload);
 
 /**
  * Query the value of a config variable and return it mapped to