Convert many resolve_ref() calls to read_ref*() and ref_exists()

resolve_ref() may return a pointer to a static buffer, which is not
safe for long-term use because if another resolve_ref() call happens,
the buffer may be changed.  Many call sites though do not care about
this buffer. They simply check if the return value is NULL or not.

Convert all these call sites to new wrappers to reduce resolve_ref()
calls from 57 to 34. If we change resolve_ref() prototype later on
to avoid passing static buffer out, this helps reduce changes.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

7 files changed, 14 insertions, 17 deletions

diff --git a/builtin/branch.c b/builtin/branch.c
index 51ca6a02d..0fe9c4dfe 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -186,7 +186,7 @@ static int delete_branches(int argc, const char **argv, int force, int kinds)
 		free(name);
 
 		name = xstrdup(mkpath(fmt, bname.buf));
-		if (!resolve_ref(name, sha1, 1, NULL)) {
+		if (read_ref(name, sha1)) {
 			error(_("%sbranch '%s' not found."),
 					remote, bname.buf);
 			ret = 1;
@@ -565,7 +565,6 @@ static int print_ref_list(int kinds, int detached, int verbose, int abbrev, stru
 static void rename_branch(const char *oldname, const char *newname, int force)
 {
 	struct strbuf oldref = STRBUF_INIT, newref = STRBUF_INIT, logmsg = STRBUF_INIT;
-	unsigned char sha1[20];
 	struct strbuf oldsection = STRBUF_INIT, newsection = STRBUF_INIT;
 	int recovery = 0;
 
@@ -577,7 +576,7 @@ static void rename_branch(const char *oldname, const char *newname, int force)
 		 * Bad name --- this could be an attempt to rename a
 		 * ref that we used to allow to be created by accident.
 		 */
-		if (resolve_ref(oldref.buf, sha1, 1, NULL))
+		if (ref_exists(oldref.buf))
 			recovery = 1;
 		else
 			die(_("Invalid branch name: '%s'"), oldname);
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2a8077242..beeaee411 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -288,7 +288,7 @@ static int checkout_paths(struct tree *source_tree, const char **pathspec,
 	    commit_locked_index(lock_file))
 		die(_("unable to write new index file"));
 
-	resolve_ref("HEAD", rev, 0, &flag);
+	read_ref_full("HEAD", rev, 0, &flag);
 	head = lookup_commit_reference_gently(rev, 1);
 
 	errs |= post_checkout_hook(head, head, 0);
@@ -866,7 +866,7 @@ static int parse_branchname_arg(int argc, const char **argv,
 	setup_branch_path(new);
 
 	if (!check_refname_format(new->path, 0) &&
-	    resolve_ref(new->path, branch_rev, 1, NULL))
+	    !read_ref(new->path, branch_rev))
 		hashcpy(rev, branch_rev);
 	else
 		new->path = NULL; /* not an existing branch */
diff --git a/builtin/merge.c b/builtin/merge.c
index dffd5ec12..42b4f9e7b 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -420,7 +420,7 @@ static struct object *want_commit(const char *name)
 static void merge_name(const char *remote, struct strbuf *msg)
 {
 	struct object *remote_head;
-	unsigned char branch_head[20], buf_sha[20];
+	unsigned char branch_head[20];
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf bname = STRBUF_INIT;
 	const char *ptr;
@@ -479,7 +479,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
 		strbuf_addstr(&truname, "refs/heads/");
 		strbuf_addstr(&truname, remote);
 		strbuf_setlen(&truname, truname.len - len);
-		if (resolve_ref(truname.buf, buf_sha, 1, NULL)) {
+		if (ref_exists(truname.buf)) {
 			strbuf_addf(msg,
 				    "%s\t\tbranch '%s'%s of .\n",
 				    sha1_to_hex(remote_head->sha1),
diff --git a/builtin/remote.c b/builtin/remote.c
index c81064381..407abfb0f 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -343,8 +343,7 @@ static int get_ref_states(const struct ref *remote_refs, struct ref_states *stat
 	states->tracked.strdup_strings = 1;
 	states->stale.strdup_strings = 1;
 	for (ref = fetch_map; ref; ref = ref->next) {
-		unsigned char sha1[20];
-		if (!ref->peer_ref || read_ref(ref->peer_ref->name, sha1))
+		if (!ref->peer_ref || !ref_exists(ref->peer_ref->name))
 			string_list_append(&states->new, abbrev_branch(ref->name));
 		else
 			string_list_append(&states->tracked, abbrev_branch(ref->name));
@@ -710,7 +709,7 @@ static int mv(int argc, const char **argv)
 		int flag = 0;
 		unsigned char sha1[20];
 
-		resolve_ref(item->string, sha1, 1, &flag);
+		read_ref_full(item->string, sha1, 1, &flag);
 		if (!(flag & REF_ISSYMREF))
 			continue;
 		if (delete_ref(item->string, NULL, REF_NODEREF))
@@ -1220,10 +1219,9 @@ static int set_head(int argc, const char **argv)
 		usage_with_options(builtin_remote_sethead_usage, options);
 
 	if (head_name) {
-		unsigned char sha1[20];
 		strbuf_addf(&buf2, "refs/remotes/%s/%s", argv[0], head_name);
 		/* make sure it's valid */
-		if (!resolve_ref(buf2.buf, sha1, 1, NULL))
+		if (!ref_exists(buf2.buf))
 			result |= error("Not a valid ref: %s", buf2.buf);
 		else if (create_symref(buf.buf, buf2.buf, "remote set-head"))
 			result |= error("Could not setup %s", buf.buf);
diff --git a/builtin/replace.c b/builtin/replace.c
index 517fa1031..4a8970e9c 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -58,7 +58,7 @@ static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
 			had_error = 1;
 			continue;
 		}
-		if (!resolve_ref(ref, sha1, 1, NULL)) {
+		if (read_ref(ref, sha1)) {
 			error("replace ref '%s' not found.", *p);
 			had_error = 1;
 			continue;
@@ -97,7 +97,7 @@ static int replace_object(const char *object_ref, const char *replace_ref,
 	if (check_refname_format(ref, 0))
 		die("'%s' is not a valid ref name.", ref);
 
-	if (!resolve_ref(ref, prev, 1, NULL))
+	if (read_ref(ref, prev))
 		hashclr(prev);
 	else if (!force)
 		die("replace ref '%s' already exists", ref);
diff --git a/builtin/show-ref.c b/builtin/show-ref.c
index fafb6dd50..391166190 100644
--- a/builtin/show-ref.c
+++ b/builtin/show-ref.c
@@ -225,7 +225,7 @@ int cmd_show_ref(int argc, const char **argv, const char *prefix)
 			unsigned char sha1[20];
 
 			if (!prefixcmp(*pattern, "refs/") &&
-			    resolve_ref(*pattern, sha1, 1, NULL)) {
+			    !read_ref(*pattern, sha1)) {
 				if (!quiet)
 					show_one(*pattern, sha1);
 			}
diff --git a/builtin/tag.c b/builtin/tag.c
index 9b6fd9549..439249d46 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -174,7 +174,7 @@ static int for_each_tag_name(const char **argv, each_tag_name_fn fn)
 			had_error = 1;
 			continue;
 		}
-		if (!resolve_ref(ref, sha1, 1, NULL)) {
+		if (read_ref(ref, sha1)) {
 			error(_("tag '%s' not found."), *p);
 			had_error = 1;
 			continue;
@@ -518,7 +518,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	if (strbuf_check_tag_ref(&ref, tag))
 		die(_("'%s' is not a valid tag name."), tag);
 
-	if (!resolve_ref(ref.buf, prev, 1, NULL))
+	if (read_ref(ref.buf, prev))
 		hashclr(prev);
 	else if (!force)
 		die(_("tag '%s' already exists"), tag);