drop support for "experimental" loose objects

In git v1.4.3, we introduced a new loose object format that
encoded some object information outside of the zlib stream.
Ultimately the format was dropped in v1.5.3, but we kept the
reading side around to help people migrate objects. Each
time we open a loose object, we use a heuristic to check
whether it is in the normal loose format, or the
experimental one.

This heuristic is robust in the face of valid data, but it
tends to treat corrupted or garbage data as an experimental
object. With the regular format, we would notice quickly
that zlib's crc does not check out and complain. With the
experimental object, we are likely to extract a nonsensical
object size and try to allocate a huge buffer, resulting in
xmalloc calling "die".

This latter behavior is much worse, for two reasons. One,
git reports an allocation error when the real error is
corruption. And two, the program dies unconditionally, so
you cannot even run fsck (which would otherwise ignore the
broken object and keep going).

We could try to improve the heuristic to err on the side of
normal objects in the face of corruption, but there is
really little point. The experimental format is long-dead,
and was never enabled by default to begin with. We can
instead simply remove it. The only affected repository would
be one that explicitly set core.legacyheaders in 2007, and
then never repacked in the intervening 6 years.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

18 files changed, 0 insertions, 69 deletions

diff --git a/t/t1013-loose-object-format.sh b/t/t1013-loose-object-format.sh
deleted file mode 100755
index fbf5f2f..0000000
--- a/t/t1013-loose-object-format.sh
+++ /dev/null
@@ -1,66 +0,0 @@
-#!/bin/sh
-#
-# Copyright (c) 2011 Roberto Tyley
-#
-
-test_description='Correctly identify and parse loose object headers
-
-There are two file formats for loose objects - the original standard
-format, and the experimental format introduced with Git v1.4.3, later
-deprecated with v1.5.3. Although Git no longer writes the
-experimental format, objects in both formats must be read, with the
-format for a given file being determined by the header.
-
-Detecting file format based on header is not entirely trivial, not
-least because the first byte of a zlib-deflated stream will vary
-depending on how much memory was allocated for the deflation window
-buffer when the object was written out (for example 4KB on Android,
-rather that 32KB on a normal PC).
-
-The loose objects used as test vectors have been generated with the
-following Git versions:
-
-standard format: Git v1.7.4.1
-experimental format: Git v1.4.3 (legacyheaders=false)
-standard format, deflated with 4KB window size: Agit/JGit on Android
-'
-
-. ./test-lib.sh
-
-assert_blob_equals() {
-	printf "%s" "$2" >expected &&
-	git cat-file -p "$1" >actual &&
-	test_cmp expected actual
-}
-
-test_expect_success setup '
-	cp -R "$TEST_DIRECTORY/t1013/objects" .git/ &&
-	git --version
-'
-
-test_expect_success 'read standard-format loose objects' '
-	git cat-file tag 8d4e360d6c70fbd72411991c02a09c442cf7a9fa &&
-	git cat-file commit 6baee0540ea990d9761a3eb9ab183003a71c3696 &&
-	git ls-tree 7a37b887a73791d12d26c0d3e39568a8fb0fa6e8 &&
-	assert_blob_equals "257cc5642cb1a054f08cc83f2d943e56fd3ebe99" "foo$LF"
-'
-
-test_expect_success 'read experimental-format loose objects' '
-	git cat-file tag 76e7fa9941f4d5f97f64fea65a2cba436bc79cbb &&
-	git cat-file commit 7875c6237d3fcdd0ac2f0decc7d3fa6a50b66c09 &&
-	git ls-tree 95b1625de3ba8b2214d1e0d0591138aea733f64f &&
-	assert_blob_equals "2e65efe2a145dda7ee51d1741299f848e5bf752e" "a" &&
-	assert_blob_equals "9ae9e86b7bd6cb1472d9373702d8249973da0832" "ab" &&
-	assert_blob_equals "85df50785d62d3b05ab03d9cbf7e4a0b49449730" "abcd" &&
-	assert_blob_equals "1656f9233d999f61ef23ef390b9c71d75399f435" "abcdefgh" &&
-	assert_blob_equals "1e72a6b2c4a577ab0338860fa9fe87f761fc9bbd" "abcdefghi" &&
-	assert_blob_equals "70e6a83d8dcb26fc8bc0cf702e2ddeb6adca18fd" "abcdefghijklmnop" &&
-	assert_blob_equals "bd15045f6ce8ff75747562173640456a394412c8" "abcdefghijklmnopqrstuvwx"
-'
-
-test_expect_success 'read standard-format objects deflated with smaller window buffer' '
-	git cat-file tag f816d5255855ac160652ee5253b06cd8ee14165a &&
-	git cat-file tag 149cedb5c46929d18e0f118e9fa31927487af3b6
-'
-
-test_done
diff --git a/t/t1013/objects/14/9cedb5c46929d18e0f118e9fa31927487af3b6 b/t/t1013/objects/14/9cedb5c46929d18e0f118e9fa31927487af3b6
deleted file mode 100644
index 472fd14..0000000
--- a/t/t1013/objects/14/9cedb5c46929d18e0f118e9fa31927487af3b6
+++ /dev/null
diff --git a/t/t1013/objects/16/56f9233d999f61ef23ef390b9c71d75399f435 b/t/t1013/objects/16/56f9233d999f61ef23ef390b9c71d75399f435
deleted file mode 100644
index c379d74..0000000
--- a/t/t1013/objects/16/56f9233d999f61ef23ef390b9c71d75399f435
+++ /dev/null
diff --git a/t/t1013/objects/1e/72a6b2c4a577ab0338860fa9fe87f761fc9bbd b/t/t1013/objects/1e/72a6b2c4a577ab0338860fa9fe87f761fc9bbd
deleted file mode 100644
index 9370630..0000000
--- a/t/t1013/objects/1e/72a6b2c4a577ab0338860fa9fe87f761fc9bbd
+++ /dev/null
diff --git a/t/t1013/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99 b/t/t1013/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
deleted file mode 100644
index bdcf704..0000000
--- a/t/t1013/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
+++ /dev/null
diff --git a/t/t1013/objects/2e/65efe2a145dda7ee51d1741299f848e5bf752e b/t/t1013/objects/2e/65efe2a145dda7ee51d1741299f848e5bf752e
deleted file mode 100644
index ad62c43..0000000
--- a/t/t1013/objects/2e/65efe2a145dda7ee51d1741299f848e5bf752e
+++ /dev/null
diff --git a/t/t1013/objects/6b/aee0540ea990d9761a3eb9ab183003a71c3696 b/t/t1013/objects/6b/aee0540ea990d9761a3eb9ab183003a71c3696
deleted file mode 100644
index 3d2f033..0000000
--- a/t/t1013/objects/6b/aee0540ea990d9761a3eb9ab183003a71c3696
+++ /dev/null
diff --git a/t/t1013/objects/70/e6a83d8dcb26fc8bc0cf702e2ddeb6adca18fd b/t/t1013/objects/70/e6a83d8dcb26fc8bc0cf702e2ddeb6adca18fd
deleted file mode 100644
index b3f71a6..0000000
--- a/t/t1013/objects/70/e6a83d8dcb26fc8bc0cf702e2ddeb6adca18fd
+++ /dev/null
diff --git a/t/t1013/objects/76/e7fa9941f4d5f97f64fea65a2cba436bc79cbb b/t/t1013/objects/76/e7fa9941f4d5f97f64fea65a2cba436bc79cbb
deleted file mode 100644
index af4e9a7..0000000
--- a/t/t1013/objects/76/e7fa9941f4d5f97f64fea65a2cba436bc79cbb
+++ /dev/null
@@ -1,2 +0,0 @@
-�x�%�A�0@�}O1{cSZ(��ν��th���Z��ޠ��?
�m�6d�i��9��G�h�ب�ZR'Q���R������p���qL9��=g���sI�oop���eϫ_1����$��*Si��NwpP�RB�����
-��[(�d-���L9�
\ No newline at end of file
diff --git a/t/t1013/objects/78/75c6237d3fcdd0ac2f0decc7d3fa6a50b66c09 b/t/t1013/objects/78/75c6237d3fcdd0ac2f0decc7d3fa6a50b66c09
deleted file mode 100644
index 3dd28be..0000000
--- a/t/t1013/objects/78/75c6237d3fcdd0ac2f0decc7d3fa6a50b66c09
+++ /dev/null
diff --git a/t/t1013/objects/7a/37b887a73791d12d26c0d3e39568a8fb0fa6e8 b/t/t1013/objects/7a/37b887a73791d12d26c0d3e39568a8fb0fa6e8
deleted file mode 100644
index 2b97b26..0000000
--- a/t/t1013/objects/7a/37b887a73791d12d26c0d3e39568a8fb0fa6e8
+++ /dev/null
diff --git a/t/t1013/objects/85/df50785d62d3b05ab03d9cbf7e4a0b49449730 b/t/t1013/objects/85/df50785d62d3b05ab03d9cbf7e4a0b49449730
deleted file mode 100644
index 6dff746..0000000
--- a/t/t1013/objects/85/df50785d62d3b05ab03d9cbf7e4a0b49449730
+++ /dev/null
diff --git a/t/t1013/objects/8d/4e360d6c70fbd72411991c02a09c442cf7a9fa b/t/t1013/objects/8d/4e360d6c70fbd72411991c02a09c442cf7a9fa
deleted file mode 100644
index cb41e92..0000000
--- a/t/t1013/objects/8d/4e360d6c70fbd72411991c02a09c442cf7a9fa
+++ /dev/null
diff --git a/t/t1013/objects/95/b1625de3ba8b2214d1e0d0591138aea733f64f b/t/t1013/objects/95/b1625de3ba8b2214d1e0d0591138aea733f64f
deleted file mode 100644
index 7ac46b4..0000000
--- a/t/t1013/objects/95/b1625de3ba8b2214d1e0d0591138aea733f64f
+++ /dev/null
diff --git a/t/t1013/objects/9a/e9e86b7bd6cb1472d9373702d8249973da0832 b/t/t1013/objects/9a/e9e86b7bd6cb1472d9373702d8249973da0832
deleted file mode 100644
index 9d8316d..0000000
--- a/t/t1013/objects/9a/e9e86b7bd6cb1472d9373702d8249973da0832
+++ /dev/null
diff --git a/t/t1013/objects/bd/15045f6ce8ff75747562173640456a394412c8 b/t/t1013/objects/bd/15045f6ce8ff75747562173640456a394412c8
deleted file mode 100644
index eebf239..0000000
--- a/t/t1013/objects/bd/15045f6ce8ff75747562173640456a394412c8
+++ /dev/null
diff --git a/t/t1013/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391 b/t/t1013/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
deleted file mode 100644
index 134cf19..0000000
--- a/t/t1013/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
+++ /dev/null
diff --git a/t/t1013/objects/f8/16d5255855ac160652ee5253b06cd8ee14165a b/t/t1013/objects/f8/16d5255855ac160652ee5253b06cd8ee14165a
deleted file mode 100644
index 26b75ae..0000000
--- a/t/t1013/objects/f8/16d5255855ac160652ee5253b06cd8ee14165a
+++ /dev/null
@@ -1 +0,0 @@
-H����0�a�{��
I�e&��*��
G��^�����D�҆wU�җ�S�4������ ,f�[��VAۺ��x���6[wtG�Lu�?������@�"g�{�+by�%M
\ No newline at end of file