Add git_repository_is_detached, git_repository_is_orphan

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>

include/git2/repository.h

@@ -218,6 +218,30 @@ GIT_EXTERN(void) git_repository_free(git_repository *repo);
  */
 GIT_EXTERN(int) git_repository_init(git_repository **repo_out, const char *path, unsigned is_bare);
 
+/**
+ * Check if a repository's HEAD is detached
+ *
+ * A repository's HEAD is detached when it points directly to a commit
+ * instead of a branch.
+ *
+ * @param repo Repo to test
+ * @return 1 if HEAD is detached, 0 if i'ts not; error code if there
+ * was an error.
+ */
+int git_repository_is_detached(git_repository *repo);
+
+/**
+ * Check if the current branch is an orphan
+ *
+ * An orphan branch is one named from HEAD but which doesn't exist in
+ * the refs namespace, because it doesn't have any commit to point to.
+ *
+ * @param repo Repo to test
+ * @return 1 if the current branch is an orphan, 0 if it's not; error
+ * code if therewas an error
+ */
+int git_repository_is_orphan(git_repository *repo);
+
 /**
  * Check if a repository is empty
  *

src/repository.c

@@ -752,6 +752,47 @@ cleanup:
 	return git__rethrow(error, "Failed to (re)init the repository `%s`", path);
 }
 
+int git_repository_is_detached(git_repository *repo)
+{
+	git_reference *ref;
+	int error;
+	size_t GIT_UNUSED(_size);
+	git_otype type;
+
+	error = git_reference_lookup(&ref, repo, GIT_HEAD_FILE);
+	if (error < GIT_SUCCESS)
+		return error;
+
+	if (git_reference_type(ref) == GIT_REF_SYMBOLIC)
+		return 0;
+
+	error = git_odb_read_header(&_size, &type, repo->db, git_reference_oid(ref));
+	if (error < GIT_SUCCESS)
+		return error;
+
+	if (type != GIT_OBJ_COMMIT)
+		return git__throw(GIT_EOBJCORRUPTED, "HEAD is not a commit");
+
+	return 1;
+}
+
+int git_repository_is_orphan(git_repository *repo)
+{
+	git_reference *ref;
+	int error;
+
+	error = git_reference_lookup(&ref, repo, GIT_HEAD_FILE);
+	if (error < GIT_SUCCESS)
+		return error;
+
+	if (git_reference_type(ref) == GIT_REF_OID)
+		return 0;
+
+	error = git_reference_resolve(&ref, ref);
+
+	return error == GIT_ENOTFOUND ? 1 : error;
+}
+
 int git_repository_is_empty(git_repository *repo)
 {
 	git_reference *head, *branch;