Add config read fns with controlled error behavior

This adds `git_config__lookup_entry` which will look up a key in
a config and return either the entry or NULL if the key was not
present.  Optionally, it can either suppress all errors or can
return them (although not finding the key is not an error for this
function).  Unlike other accessors, this does not normalize the
config key string, so it must only be used when the key is known
to be in normalized form (i.e. all lower-case before the first dot
and after the last dot, with no invalid characters).

This also adds three high-level helper functions to look up config
values with no errors and a fallback value.  The three functions
are for string, bool, and int values, and will resort to the
fallback value for any error that arises.  They are:

* `git_config__get_string_force`
* `git_config__get_bool_force`
* `git_config__get_int_force`

None of them normalize the config `key` either, so they can only
be used for internal cases where the key is known to be in normal
format.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/config.h b/src/config.h
index 01e8465cc..3cd888c88 100644
--- a/src/config.h
+++ b/src/config.h
@@ -51,5 +51,26 @@ extern int git_config_file__ondisk(git_config_backend **out, const char *path);
 
 extern int git_config__normalize_name(const char *in, char **out);
 
+/* internal only: does not normalize key and sets out to NULL if not found */
+extern int git_config__lookup_entry(
+	const git_config_entry **out,
+	const git_config *cfg,
+	const char *key,
+	bool no_errors);
+
+/*
+ * Lookup functions that cannot fail.  These functions look up a config
+ * value and return a fallback value if the value is missing or if any
+ * failures occur while trying to access the value.
+ */
+
+extern const char *git_config__get_string_force(
+	const git_config *cfg, const char *key, const char *fallback_value);
+
+extern int git_config__get_bool_force(
+	const git_config *cfg, const char *key, int fallback_value);
+
+extern int git_config__get_int_force(
+	const git_config *cfg, const char *key, int fallback_value);
 
 #endif