repository: Refine repository_head() error report

include/git2/repository.h

@@ -273,7 +273,7 @@ GIT_EXTERN(int) git_repository_init_ext(
  * @param repo a repository object
  *
  * @return 0 on success, GIT_EORPHANEDHEAD when HEAD points to a non existing
- * branch, an error code otherwise
+ * branch, GIT_ENOTFOUND when HEAD is missing; an error code otherwise
  */
 GIT_EXTERN(int) git_repository_head(git_reference **head_out, git_repository *repo);
 

src/branch.c

@@ -317,7 +317,7 @@ int git_branch_is_head(
 
 	error = git_repository_head(&head, git_reference_owner(branch));
 
-	if (error == GIT_EORPHANEDHEAD)
+	if (error == GIT_EORPHANEDHEAD || error == GIT_ENOTFOUND)
 		return false;
 
 	if (error < 0)

src/repository.c

@@ -1207,9 +1207,19 @@ int git_repository_head_detached(git_repository *repo)
 
 int git_repository_head(git_reference **head_out, git_repository *repo)
 {
+	git_reference *head;
 	int error;
 
-	error = git_reference_lookup_resolved(head_out, repo, GIT_HEAD_FILE, -1);
+	if ((error = git_reference_lookup(&head, repo, GIT_HEAD_FILE)) < 0)
+		return error;
+
+	if (git_reference_type(head) == GIT_REF_OID) {
+		*head_out = head;
+		return 0;
+	}
+
+	error = git_reference_lookup_resolved(head_out, repo, git_reference_target(head), -1);
+	git_reference_free(head);
 
 	return error == GIT_ENOTFOUND ? GIT_EORPHANEDHEAD : error;
 }

tests-clar/refs/branches/ishead.c

@@ -39,6 +39,22 @@ void test_refs_branches_ishead__can_properly_handle_orphaned_HEAD(void)
 	repo = NULL;
 }
 
+void test_refs_branches_ishead__can_properly_handle_missing_HEAD(void)
+{
+	git_repository_free(repo);
+
+	repo = cl_git_sandbox_init("testrepo.git");
+
+	delete_head(repo);
+
+	cl_git_pass(git_reference_lookup(&branch, repo, "refs/heads/master"));
+
+	cl_assert_equal_i(false, git_branch_is_head(branch));
+
+	cl_git_sandbox_cleanup();
+	repo = NULL;
+}
+
 void test_refs_branches_ishead__can_tell_if_a_branch_is_not_pointed_at_by_HEAD(void)
 {
 	cl_git_pass(git_reference_lookup(&branch, repo, "refs/heads/br2"));

tests-clar/repo/head.c

 #include "clar_libgit2.h"
 #include "refs.h"
 #include "repo_helpers.h"
+#include "posix.h"
 
 git_repository *repo;
 
@@ -178,6 +179,15 @@ void test_repo_head__retrieving_an_orphaned_head_returns_GIT_EORPHANEDHEAD(void)
 	cl_assert_equal_i(GIT_EORPHANEDHEAD, git_repository_head(&head, repo));
 }
 
+void test_repo_head__retrieving_a_missing_head_returns_GIT_ENOTFOUND(void)
+{
+	git_reference *head;
+
+	delete_head(repo);
+
+	cl_assert_equal_i(GIT_ENOTFOUND, git_repository_head(&head, repo));
+}
+
 void test_repo_head__can_tell_if_an_orphaned_head_is_detached(void)
 {
 	make_head_orphaned(repo, NON_EXISTING_HEAD);

tests-clar/repo/repo_helpers.c

 #include "clar_libgit2.h"
 #include "refs.h"
 #include "repo_helpers.h"
+#include "posix.h"
 
 void make_head_orphaned(git_repository* repo, const char *target)
 {
@@ -9,3 +10,13 @@ void make_head_orphaned(git_repository* repo, const char *target)
 	cl_git_pass(git_reference_create_symbolic(&head, repo, GIT_HEAD_FILE, target, 1));
 	git_reference_free(head);
 }
+
+void delete_head(git_repository* repo)
+{
+	git_buf head_path = GIT_BUF_INIT;
+
+	cl_git_pass(git_buf_joinpath(&head_path, git_repository_path(repo), GIT_HEAD_FILE));
+	cl_git_pass(p_unlink(git_buf_cstr(&head_path)));
+
+	git_buf_free(&head_path);
+}

tests-clar/repo/repo_helpers.h

@@ -3,3 +3,4 @@
 #define NON_EXISTING_HEAD "refs/heads/hide/and/seek"
 
 extern void make_head_orphaned(git_repository* repo, const char *target);
+extern void delete_head(git_repository* repo);