cat-file: use streaming API to print blobs

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/cat-file.c

@@ -11,6 +11,7 @@
 #include "parse-options.h"
 #include "diff.h"
 #include "userdiff.h"
+#include "streaming.h"
 
 #define BATCH 1
 #define BATCH_CHECK 2
@@ -127,6 +128,8 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 			return cmd_ls_tree(2, ls_args, NULL);
 		}
 
+		if (type == OBJ_BLOB)
+			return stream_blob_to_fd(1, sha1, NULL, 0);
 		buf = read_sha1_file(sha1, &type, &size);
 		if (!buf)
 			die("Cannot read object %s", obj_name);
@@ -149,6 +152,28 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 		break;
 
 	case 0:
+		if (type_from_string(exp_type) == OBJ_BLOB) {
+			unsigned char blob_sha1[20];
+			if (sha1_object_info(sha1, NULL) == OBJ_TAG) {
+				enum object_type type;
+				unsigned long size;
+				char *buffer = read_sha1_file(sha1, &type, &size);
+				if (memcmp(buffer, "object ", 7) ||
+				    get_sha1_hex(buffer + 7, blob_sha1))
+					die("%s not a valid tag", sha1_to_hex(sha1));
+				free(buffer);
+			} else
+				hashcpy(blob_sha1, sha1);
+
+			if (sha1_object_info(blob_sha1, NULL) == OBJ_BLOB)
+				return stream_blob_to_fd(1, blob_sha1, NULL, 0);
+			/*
+			 * we attempted to dereference a tag to a blob
+			 * and failed; there may be new dereference
+			 * mechanisms this code is not aware of.
+			 * fall-back to the usual case.
+			 */
+		}
 		buf = read_object_with_reference(sha1, exp_type, &size, NULL);
 		break;
 

t/t1050-large.sh

@@ -116,11 +116,11 @@ test_expect_success 'hash-object' '
 	git hash-object large1
 '
 
-test_expect_failure 'cat-file a large file' '
+test_expect_success 'cat-file a large file' '
 	git cat-file blob :large1 >/dev/null
 '
 
-test_expect_failure 'cat-file a large file from a tag' '
+test_expect_success 'cat-file a large file from a tag' '
 	git tag -m largefile largefiletag :large1 &&
 	git cat-file blob largefiletag >/dev/null
 '