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>

Author: avar

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)
@@ -112,20 +115,13 @@ 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))
 			return -1;
 		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;

cache.h

@@ -1377,6 +1377,7 @@ struct object_context {
 #define GET_OID_FOLLOW_SYMLINKS 0100
 #define GET_OID_RECORD_PATH     0200
 #define GET_OID_ONLY_TO_DIE    04000
+#define GET_OID_REQUIRE_PATH  010000
 
 #define GET_OID_DISAMBIGUATORS \
 	(GET_OID_COMMIT | GET_OID_COMMITTISH | \

object-name.c

@@ -1799,6 +1799,9 @@ static enum get_oid_result get_oid_with_context_1(struct repository *repo,
 	oc->mode = S_IFINVALID;
 	strbuf_init(&oc->symlink_path, 0);
 	ret = get_oid_1(repo, name, namelen, oid, flags);
+	if (!ret && flags & GET_OID_REQUIRE_PATH)
+		die(_("<object>:<path> required, only <object> '%s' given"),
+		    name);
 	if (!ret)
 		return ret;
 	/*

t/t8007-cat-file-textconv.sh

@@ -29,15 +29,15 @@ test_expect_success 'usage: <bad rev>' '
 
 test_expect_success 'usage: <bad rev>:<bad path>' '
 	cat >expect <<-\EOF &&
-	fatal: Not a valid object name HEAD2:two.bin
+	fatal: invalid object name '\''HEAD2'\''.
 	EOF
 	test_must_fail git cat-file --textconv HEAD2:two.bin 2>actual &&
 	test_cmp expect actual
 '
 
 test_expect_success 'usage: <rev>:<bad path>' '
 	cat >expect <<-\EOF &&
-	fatal: Not a valid object name HEAD:two.bin
+	fatal: path '\''two.bin'\'' does not exist in '\''HEAD'\''
 	EOF
 	test_must_fail git cat-file --textconv HEAD:two.bin 2>actual &&
 	test_cmp expect actual
@@ -46,7 +46,7 @@ test_expect_success 'usage: <rev>:<bad path>' '
 
 test_expect_success 'usage: <rev> with no <path>' '
 	cat >expect <<-\EOF &&
-	fatal: git cat-file --textconv HEAD: <object> must be <sha1:path>
+	fatal: <object>:<path> required, only <object> '\''HEAD'\'' given
 	EOF
 	test_must_fail git cat-file --textconv HEAD 2>actual &&
 	test_cmp expect actual
@@ -55,7 +55,7 @@ test_expect_success 'usage: <rev> with no <path>' '
 
 test_expect_success 'usage: <bad rev>:<good (in HEAD) path>' '
 	cat >expect <<-\EOF &&
-	fatal: Not a valid object name HEAD2:one.bin
+	fatal: invalid object name '\''HEAD2'\''.
 	EOF
 	test_must_fail git cat-file --textconv HEAD2:one.bin 2>actual &&
 	test_cmp expect actual