[PATCH] config: preserve <subsection> case for one-shot config on the command line

[Junio C Hamano <gitster@pobox.com>]

The "git -c <var>=<val> cmd" mechanism is to pretend that a
configuration variable <var> is set to <val> while the cmd is
running.  The code to do so however downcased <var> in its entirety,
which is wrong for a three-level <section>.<subsection>.<variable>.

The <subsection> part needs to stay as-is.

Reported-by: Lars Schneider <larsxschneider@gmail.com>
Diagnosed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 config.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/config.c b/config.c
index 0dfed682b8..e9b93b5304 100644
--- a/config.c
+++ b/config.c
@@ -199,6 +199,26 @@ void git_config_push_parameter(const char *text)
 	strbuf_release(&env);
 }
 
+/*
+ * downcase the <section> and <variable> in <section>.<variable> or
+ * <section>.<subsection>.<variable> and do so in place.  <subsection>
+ * is left intact.
+ */
+static void canonicalize_config_variable_name(char *varname)
+{
+	char *dot, *cp;
+
+	dot = strchr(varname, '.');
+	if (dot)
+		for (cp = varname; cp < dot; cp++)
+			*cp = tolower(*cp);
+	dot = strrchr(varname, '.');
+	if (dot)
+		for (cp = dot + 1; *cp; cp++)
+			*cp = tolower(*cp);
+}
+
+
 int git_config_parse_parameter(const char *text,
 			       config_fn_t fn, void *data)
 {
@@ -221,7 +241,7 @@ int git_config_parse_parameter(const char *text,
 		strbuf_list_free(pair);
 		return error("bogus config parameter: %s", text);
 	}
-	strbuf_tolower(pair[0]);
+	canonicalize_config_variable_name(pair[0]->buf);
 	if (fn(pair[0]->buf, value, data) < 0) {
 		strbuf_list_free(pair);
 		return -1;
-- 
2.12.0-rc1-258-g3d3d1e383b