cat-file: use GET_OID_ONLY_TO_DIE in --(textconv|filters)

Change the cat_one_file() logic that calls get_oid_with_context()
under --textconv and --filters to use the GET_OID_ONLY_TO_DIE flag,
thus improving the error messaging emitted when e.g. <path> is missing
but <rev> is not.

To service the "cat-file" use-case we need to introduce a new
"GET_OID_REQUIRE_PATH" flag, otherwise it would exit early as soon as
a valid "HEAD" was resolved, but in the "cat-file" case being changed
we always need a valid revision and path.

This arguably makes the "<bad rev>:<bad path>" and "<bad
rev>:<good (in HEAD) path>" use cases worse, as we won't quote the
<path> component at the user anymore, but let's just use the existing
logic "git log" et al use for now. We can improve the messaging for
those cases as a follow-up for all callers.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 10 deletions

diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index b5b130d79c..ad9b3eef4f 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -73,14 +73,17 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	struct object_info oi = OBJECT_INFO_INIT;
 	struct strbuf sb = STRBUF_INIT;
 	unsigned flags = OBJECT_INFO_LOOKUP_REPLACE;
+	unsigned get_oid_flags = GET_OID_RECORD_PATH | GET_OID_ONLY_TO_DIE;
 	const char *path = force_path;
+	const int opt_cw = (opt == 'c' || opt == 'w');
+	if (!path && opt_cw)
+		get_oid_flags |= GET_OID_REQUIRE_PATH;
 
 	if (unknown_type)
 		flags |= OBJECT_INFO_ALLOW_UNKNOWN_TYPE;
 
-	if (get_oid_with_context(the_repository, obj_name,
-				 GET_OID_RECORD_PATH,
-				 &oid, &obj_context))
+	if (get_oid_with_context(the_repository, obj_name, get_oid_flags, &oid,
+				 &obj_context))
 		die("Not a valid object name %s", obj_name);
 
 	if (!path)
@@ -112,9 +115,6 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		return !has_object_file(&oid);
 
 	case 'w':
-		if (!path)
-			die("git cat-file --filters %s: <object> must be "
-			    "<sha1:path>", obj_name);
 
 		if (filter_object(path, obj_context.mode,
 				  &oid, &buf, &size))
@@ -122,10 +122,6 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 		break;
 
 	case 'c':
-		if (!path)
-			die("git cat-file --textconv %s: <object> must be <sha1:path>",
-			    obj_name);
-
 		if (textconv_object(the_repository, path, obj_context.mode,
 				    &oid, 1, &buf, &size))
 			break;