config: teach "git -c" to recognize an empty string

In a config file, you can do:

  [foo]
  bar

to turn the "foo.bar" boolean flag on, and you can do:

  [foo]
  bar=

to set "foo.bar" to the empty string. However, git's "-c"
parameter treats both:

  git -c foo.bar

and

  git -c foo.bar=

as the boolean flag, and there is no way to set a variable
to the empty string. This patch enables the latter form to
do that.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/config.c b/config.c
index e1d66a1..5390a63 100644
--- a/config.c
+++ b/config.c
@@ -164,19 +164,27 @@ void git_config_push_parameter(const char *text)
 int git_config_parse_parameter(const char *text,
 			       config_fn_t fn, void *data)
 {
+	const char *value;
 	struct strbuf **pair;
+
 	pair = strbuf_split_str(text, '=', 2);
 	if (!pair[0])
 		return error("bogus config parameter: %s", text);
-	if (pair[0]->len && pair[0]->buf[pair[0]->len - 1] == '=')
+
+	if (pair[0]->len && pair[0]->buf[pair[0]->len - 1] == '=') {
 		strbuf_setlen(pair[0], pair[0]->len - 1);
+		value = pair[1] ? pair[1]->buf : "";
+	} else {
+		value = NULL;
+	}
+
 	strbuf_trim(pair[0]);
 	if (!pair[0]->len) {
 		strbuf_list_free(pair);
 		return error("bogus config parameter: %s", text);
 	}
 	lowercase(pair[0]->buf);
-	if (fn(pair[0]->buf, pair[1] ? pair[1]->buf : NULL, data) < 0) {
+	if (fn(pair[0]->buf, value, data) < 0) {
 		strbuf_list_free(pair);
 		return -1;
 	}