[PATCH 16/38] resolve_gitlink_ref(): implement using resolve_ref_recursively()

[Michael Haggerty <mhagger@alum.mit.edu>]

resolve_ref_recursively() can handle references in arbitrary files
reference stores, so use it to resolve "gitlink" (i.e., submodule)
references. Aside from removing redundant code, this allows submodule
lookups to benefit from the much more robust code that we use for
reading non-submodule references. And, since the code is now agnostic
about reference backends, it will work for any future references
backend (so move its definition to refs.c).

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
---
 refs.c               | 24 +++++++++++++++++++
 refs/files-backend.c | 67 ----------------------------------------------------
 2 files changed, 24 insertions(+), 67 deletions(-)

diff --git a/refs.c b/refs.c
index 93f2e4d..5e0777a 100644
--- a/refs.c
+++ b/refs.c
@@ -1299,6 +1299,30 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
 				       resolve_flags, sha1, flags);
 }
 
+int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
+{
+	int len = strlen(path);
+	struct strbuf submodule = STRBUF_INIT;
+	struct ref_store *refs;
+	int flags;
+
+	while (len && path[len-1] == '/')
+		len--;
+	if (!len)
+		return -1;
+
+	strbuf_add(&submodule, path, len);
+	refs = get_ref_store(submodule.buf);
+	strbuf_release(&submodule);
+	if (!refs)
+		return -1;
+
+	if (!resolve_ref_recursively(refs, refname, 0, sha1, &flags) ||
+	    is_null_sha1(sha1))
+		return -1;
+	return 0;
+}
+
 static struct ref_store *main_ref_store = NULL;
 
 static struct ref_store *submodule_ref_stores = NULL;
diff --git a/refs/files-backend.c b/refs/files-backend.c
index ff7ee7d..d6d83d2 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -1498,73 +1498,6 @@ static void unlock_ref(struct ref_lock *lock)
 	free(lock);
 }
 
-#define MAXREFLEN (1024)
-
-static int resolve_gitlink_ref_recursive(struct files_ref_store *refs,
-					 const char *refname, unsigned char *sha1,
-					 int recursion)
-{
-	int fd, len;
-	char buffer[128], *p;
-	char *path;
-
-	if (recursion > SYMREF_MAXDEPTH || strlen(refname) > MAXREFLEN)
-		return -1;
-	path = *refs->base.submodule
-		? git_pathdup_submodule(refs->base.submodule, "%s", refname)
-		: git_pathdup("%s", refname);
-	fd = open(path, O_RDONLY);
-	free(path);
-	if (fd < 0) {
-		unsigned int flags;
-
-		return resolve_packed_ref(refs, refname, sha1, &flags);
-	}
-
-	len = read(fd, buffer, sizeof(buffer)-1);
-	close(fd);
-	if (len < 0)
-		return -1;
-	while (len && isspace(buffer[len-1]))
-		len--;
-	buffer[len] = 0;
-
-	/* Was it a detached head or an old-fashioned symlink? */
-	if (!get_sha1_hex(buffer, sha1))
-		return 0;
-
-	/* Symref? */
-	if (strncmp(buffer, "ref:", 4))
-		return -1;
-	p = buffer + 4;
-	while (isspace(*p))
-		p++;
-
-	return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
-}
-
-int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
-{
-	int len = strlen(path);
-	struct strbuf submodule = STRBUF_INIT;
-	struct files_ref_store *refs;
-
-	while (len && path[len-1] == '/')
-		len--;
-	if (!len)
-		return -1;
-
-	strbuf_add(&submodule, path, len);
-	refs = get_files_ref_store(submodule.buf, "resolve_gitlink_ref");
-	if (!refs) {
-		strbuf_release(&submodule);
-		return -1;
-	}
-	strbuf_release(&submodule);
-
-	return resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
-}
-
 /*
  * Lock refname, without following symrefs, and set *lock_p to point
  * at a newly-allocated lock object. Fill in lock->old_oid, referent,
-- 
2.8.1