environment: make get_git_namespace() self-contained

The logic to set up and retrieve `git_namespace` is distributed across
different functions which communicate with each other via a global
environment variable. This is rather pointless though, as the value is
always derived from an environment variable, and this environment
variable does not change after we have parsed global options.

Convert the function to be fully self-contained such that it lazily
populates once called.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

environment.c

@@ -122,8 +122,6 @@ int core_preload_index = 1;
 /* This is set by setup_git_dir_gently() and/or git_default_config() */
 char *git_work_tree_cfg;
 
-static char *git_namespace;
-
 /*
  * Repository-local GIT_* environment variables; see environment.h for details.
  */
@@ -146,27 +144,6 @@ const char * const local_repo_env[] = {
 	NULL
 };
 
-static char *expand_namespace(const char *raw_namespace)
-{
-	struct strbuf buf = STRBUF_INIT;
-	struct strbuf **components, **c;
-
-	if (!raw_namespace || !*raw_namespace)
-		return xstrdup("");
-
-	strbuf_addstr(&buf, raw_namespace);
-	components = strbuf_split(&buf, '/');
-	strbuf_reset(&buf);
-	for (c = components; *c; c++)
-		if (strcmp((*c)->buf, "/") != 0)
-			strbuf_addf(&buf, "refs/namespaces/%s", (*c)->buf);
-	strbuf_list_free(components);
-	if (check_refname_format(buf.buf, 0))
-		die(_("bad git namespace path \"%s\""), raw_namespace);
-	strbuf_addch(&buf, '/');
-	return strbuf_detach(&buf, NULL);
-}
-
 const char *getenv_safe(struct strvec *argv, const char *name)
 {
 	const char *value = getenv(name);
@@ -205,8 +182,6 @@ void setup_git_env(const char *git_dir)
 							  : "refs/replace/");
 	update_ref_namespace(NAMESPACE_REPLACE, git_replace_ref_base);
 
-	free(git_namespace);
-	git_namespace = expand_namespace(getenv(GIT_NAMESPACE_ENVIRONMENT));
 	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
 	if (shallow_file)
 		set_alternate_shallow_file(the_repository, shallow_file, 0);
@@ -229,9 +204,35 @@ int have_git_dir(void)
 
 const char *get_git_namespace(void)
 {
-	if (!git_namespace)
-		BUG("git environment hasn't been setup");
-	return git_namespace;
+	static const char *namespace;
+
+	struct strbuf buf = STRBUF_INIT;
+	struct strbuf **components, **c;
+	const char *raw_namespace;
+
+	if (namespace)
+		return namespace;
+
+	raw_namespace = getenv(GIT_NAMESPACE_ENVIRONMENT);
+	if (!raw_namespace || !*raw_namespace) {
+		namespace = "";
+		return namespace;
+	}
+
+	strbuf_addstr(&buf, raw_namespace);
+	components = strbuf_split(&buf, '/');
+	strbuf_reset(&buf);
+	for (c = components; *c; c++)
+		if (strcmp((*c)->buf, "/") != 0)
+			strbuf_addf(&buf, "refs/namespaces/%s", (*c)->buf);
+	strbuf_list_free(components);
+	if (check_refname_format(buf.buf, 0))
+		die(_("bad git namespace path \"%s\""), raw_namespace);
+	strbuf_addch(&buf, '/');
+
+	namespace = strbuf_detach(&buf, NULL);
+
+	return namespace;
 }
 
 const char *strip_namespace(const char *namespaced_ref)