[PATCH 3/8] builtin/config: extract `handle_value_regex()` from `get_value()`

["Martin Ågren" <martin.agren@gmail.com>]

This is a self-contained and fairly large chunk of code which will soon
gain a few more lines. Prepare by extracting it into a separate
function.

This whole chunk is wrapped in "if (regex_)" -- rewrite it into an early
return path in the new helper function to reduce indentation.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
 I copy the "xmalloc(sizeof(regex_t))" anti-pattern verbatim. We will
 lose it in the next patch.

 builtin/config.c | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index 98d65bc0ad..e675ae0640 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -280,6 +280,28 @@ static int collect_config(const char *key_, const char *value_, void *cb)
 	return format_config(&values->items[values->nr++], key_, value_);
 }
 
+static int handle_value_regex(const char *regex_)
+{
+	if (!regex_) {
+		regexp = NULL;
+		return 0;
+	}
+
+	if (regex_[0] == '!') {
+		do_not_match = 1;
+		regex_++;
+	}
+
+	regexp = (regex_t*)xmalloc(sizeof(regex_t));
+	if (regcomp(regexp, regex_, REG_EXTENDED)) {
+		error(_("invalid pattern: %s"), regex_);
+		FREE_AND_NULL(regexp);
+		return CONFIG_INVALID_PATTERN;
+	}
+
+	return 0;
+}
+
 static int get_value(const char *key_, const char *regex_)
 {
 	int ret = CONFIG_GENERIC_ERROR;
@@ -317,20 +339,9 @@ static int get_value(const char *key_, const char *regex_)
 		}
 	}
 
-	if (regex_) {
-		if (regex_[0] == '!') {
-			do_not_match = 1;
-			regex_++;
-		}
-
-		regexp = (regex_t*)xmalloc(sizeof(regex_t));
-		if (regcomp(regexp, regex_, REG_EXTENDED)) {
-			error(_("invalid pattern: %s"), regex_);
-			FREE_AND_NULL(regexp);
-			ret = CONFIG_INVALID_PATTERN;
-			goto free_strings;
-		}
-	}
+	ret = handle_value_regex(regex_);
+	if (ret)
+		goto free_strings;
 
 	config_with_options(collect_config, &values,
 			    &given_config_source, &config_options);
-- 
2.24.0