cat-file --batch / --batch-check: do not exit if hashes are missing

Previously, cat-file --batch / --batch-check would silently exit if it
was passed a non-existent SHA1 on stdin.  Now it prints "<SHA1>
missing" as in all other cases (and as advertised in the
documentation).

Note that cat-file --batch-check (but not --batch) will still output
"error: unable to find <SHA1>" on stderr if a non-existent SHA1 is
passed, but this does not affect parsing its stdout.

Also, type <= 0 was previously using the potentially uninitialized
type variable (relying on it being 0); it is now being initialized.

Signed-off-by: Lea Wiemann <LeWiemann@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-cat-file.c

@@ -150,7 +150,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 static int batch_one_object(const char *obj_name, int print_contents)
 {
 	unsigned char sha1[20];
-	enum object_type type;
+	enum object_type type = 0;
 	unsigned long size;
 	void *contents = contents;
 
@@ -168,8 +168,11 @@ static int batch_one_object(const char *obj_name, int print_contents)
 	else
 		type = sha1_object_info(sha1, &size);
 
-	if (type <= 0)
-		return 1;
+	if (type <= 0) {
+		printf("%s missing\n", obj_name);
+		fflush(stdout);
+		return 0;
+	}
 
 	printf("%s %s %lu\n", sha1_to_hex(sha1), typename(type), size);
 	fflush(stdout);

t/t1006-cat-file.sh

@@ -174,9 +174,27 @@ do
     '
 done
 
-test_expect_success "--batch-check for a non-existent object" '
-    test "deadbeef missing" = \
-    "$(echo_without_newline deadbeef | git cat-file --batch-check)"
+test_expect_success "--batch-check for a non-existent named object" '
+    test "foobar42 missing
+foobar84 missing" = \
+    "$( ( echo foobar42; echo_without_newline foobar84; ) | git cat-file --batch-check)"
+'
+
+test_expect_success "--batch-check for a non-existent hash" '
+    test "0000000000000000000000000000000000000042 missing
+0000000000000000000000000000000000000084 missing" = \
+    "$( ( echo 0000000000000000000000000000000000000042;
+         echo_without_newline 0000000000000000000000000000000000000084; ) \
+       | git cat-file --batch-check)"
+'
+
+test_expect_success "--batch for an existent and a non-existent hash" '
+    test "$tag_sha1 tag $tag_size
+$tag_content
+0000000000000000000000000000000000000000 missing" = \
+    "$( ( echo $tag_sha1;
+         echo_without_newline 0000000000000000000000000000000000000000; ) \
+       | git cat-file --batch)"
 '
 
 test_expect_success "--batch-check for an emtpy line" '