refs: use ref_namespaces for replace refs base

The git_replace_ref_base global is used to store the value of the
GIT_REPLACE_REF_BASE environment variable or the default of
"refs/replace/". This is initialized within setup_git_env().

The ref_namespaces array is a new centralized location for information
such as the ref namespace used for replace refs. Instead of having this
namespace stored in two places, use the ref_namespaces array instead.

For simplicity, create a local git_replace_ref_base variable wherever
the global was previously used.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/replace.c

@@ -106,6 +106,7 @@ static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
 	size_t base_len;
 	int had_error = 0;
 	struct object_id oid;
+	const char *git_replace_ref_base = ref_namespace[NAMESPACE_REPLACE].ref;
 
 	strbuf_addstr(&ref, git_replace_ref_base);
 	base_len = ref.len;
@@ -147,6 +148,8 @@ static int check_ref_valid(struct object_id *object,
 			    struct strbuf *ref,
 			    int force)
 {
+	const char *git_replace_ref_base = ref_namespace[NAMESPACE_REPLACE].ref;
+
 	strbuf_reset(ref);
 	strbuf_addf(ref, "%s%s", git_replace_ref_base, oid_to_hex(object));
 	if (check_refname_format(ref->buf, 0))

cache.h

@@ -1008,7 +1008,6 @@ void reset_shared_repository(void);
  * commands that do not want replace references to be active.
  */
 extern int read_replace_refs;
-extern char *git_replace_ref_base;
 
 /*
  * These values are used to help identify parts of a repository to fsync.

environment.c

@@ -56,7 +56,6 @@ const char *askpass_program;
 const char *excludes_file;
 enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
 int read_replace_refs = 1;
-char *git_replace_ref_base;
 enum eol core_eol = EOL_UNSET;
 int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
 char *check_roundtrip_encoding = "SHIFT-JIS";
@@ -162,6 +161,7 @@ const char *getenv_safe(struct strvec *argv, const char *name)
 
 void setup_git_env(const char *git_dir)
 {
+	char *git_replace_ref_base;
 	const char *shallow_file;
 	const char *replace_ref_base;
 	struct set_gitdir_args args = { NULL };
@@ -182,7 +182,6 @@ void setup_git_env(const char *git_dir)
 	if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
 		read_replace_refs = 0;
 	replace_ref_base = getenv(GIT_REPLACE_REF_BASE_ENVIRONMENT);
-	free(git_replace_ref_base);
 	git_replace_ref_base = xstrdup(replace_ref_base ? replace_ref_base
 							  : "refs/replace/");
 	update_ref_namespace(NAMESPACE_REPLACE, git_replace_ref_base);

log-tree.c

@@ -141,6 +141,7 @@ static int add_ref_decoration(const char *refname, const struct object_id *oid,
 	enum object_type objtype;
 	enum decoration_type deco_type = DECORATION_NONE;
 	struct decoration_filter *filter = (struct decoration_filter *)cb_data;
+	const char *git_replace_ref_base = ref_namespace[NAMESPACE_REPLACE].ref;
 
 	if (filter && !ref_filter_match(refname, filter))
 		return 0;

refs.c

@@ -1612,6 +1612,7 @@ int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
 
 int for_each_replace_ref(struct repository *r, each_repo_ref_fn fn, void *cb_data)
 {
+	const char *git_replace_ref_base = ref_namespace[NAMESPACE_REPLACE].ref;
 	return do_for_each_repo_ref(r, git_replace_ref_base, fn,
 				    strlen(git_replace_ref_base),
 				    DO_FOR_EACH_INCLUDE_BROKEN, cb_data);