odb: Teach loose backend to return EAMBIGUOUS

src/odb_loose.c

@@ -499,7 +499,7 @@ static int fn_locate_object_short_oid(void *state, git_buf *pathbuf) {
 	}
 
 	if (sstate->found > 1)
-		return git_odb__error_ambiguous("multiple matches in loose objects");
+		return GIT_EAMBIGUOUS;
 
 	return 0;
 }
@@ -545,12 +545,16 @@ static int locate_object_short_oid(
 	/* Explore directory to find a unique object matching short_oid */
 	error = git_path_direach(
 		object_location, fn_locate_object_short_oid, &state);
-	if (error)
+
+	if (error && error != GIT_EUSER)
 		return error;
 
 	if (!state.found)
 		return git_odb__error_notfound("no matching loose object for prefix", short_oid);
 
+	if (state.found > 1)
+		return git_odb__error_ambiguous("multiple matches in loose objects");
+
 	/* Convert obtained hex formatted oid to raw */
 	error = git_oid_fromstr(res_oid, (char *)state.res_oid);
 	if (error)

tests-clar/refs/revparse.c

@@ -544,6 +544,37 @@ void test_refs_revparse__a_too_short_objectid_returns_EAMBIGUOUS(void)
 		GIT_EAMBIGUOUS, git_revparse_single(&g_obj, g_repo, "e90"));
 }
 
+/*
+ * $ echo "aabqhq" | git hash-object -t blob --stdin
+ * dea509d0b3cb8ee0650f6ca210bc83f4678851ba
+ * 
+ * $ echo "aaazvc" | git hash-object -t blob --stdin
+ * dea509d097ce692e167dfc6a48a7a280cc5e877e
+ */
+void test_refs_revparse__a_not_precise_enough_objectid_returns_EAMBIGUOUS(void)
+{
+	git_repository *repo;
+	git_index *index;
+	git_object *obj;
+
+	repo = cl_git_sandbox_init("testrepo");
+
+	cl_git_mkfile("testrepo/one.txt", "aabqhq\n");
+	cl_git_mkfile("testrepo/two.txt", "aaazvc\n");
+	
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_add_bypath(index, "one.txt"));
+	cl_git_pass(git_index_add_bypath(index, "two.txt"));
+	
+	cl_git_fail_with(git_revparse_single(&obj, repo, "dea509d0"), GIT_EAMBIGUOUS);
+
+	cl_git_pass(git_revparse_single(&obj, repo, "dea509d09"));
+
+	git_object_free(obj);
+	git_index_free(index);
+	cl_git_sandbox_cleanup();
+}
+
 void test_refs_revparse__issue_994(void)
 {
 	git_repository *repo;