submodule--helper: refactor get_submodule_displaypath()

We create a function called `do_get_submodule_displaypath()` that
generates the display path required by several submodule functions, and
takes a custom superprefix parameter, instead of reading it from the
environment.

We then redefine the existing `get_submodule_displaypath()` function
as a call to this new function, where the superprefix is obtained from
the environment.

Mentored-by: Christian Couder <[email protected]>
Mentored-by: Shourya Shukla <[email protected]>
Signed-off-by: Atharva Raykar <[email protected]>
Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: tfidfwastaken

builtin/submodule--helper.c

@@ -247,11 +247,10 @@ static int resolve_relative_url_test(int argc, const char **argv, const char *pr
 	return 0;
 }
 
-/* the result should be freed by the caller. */
-static char *get_submodule_displaypath(const char *path, const char *prefix)
+static char *do_get_submodule_displaypath(const char *path,
+					  const char *prefix,
+					  const char *super_prefix)
 {
-	const char *super_prefix = get_super_prefix();
-
 	if (prefix && super_prefix) {
 		BUG("cannot have prefix '%s' and superprefix '%s'",
 		    prefix, super_prefix);
@@ -267,6 +266,13 @@ static char *get_submodule_displaypath(const char *path, const char *prefix)
 	}
 }
 
+/* the result should be freed by the caller. */
+static char *get_submodule_displaypath(const char *path, const char *prefix)
+{
+	const char *super_prefix = get_super_prefix();
+	return do_get_submodule_displaypath(path, prefix, super_prefix);
+}
+
 static char *compute_rev_name(const char *sub_path, const char* object_id)
 {
 	struct strbuf sb = STRBUF_INIT;