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From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: <git@vger.kernel.org>
Cc: Eric Sunshine <sunshine@sunshineco.com>
Subject: [PATCH v4 04/39] t3404: prepare 'short SHA-1 collision' tests for SHA-256
Date: Sun, 26 Jul 2020 19:53:49 +0000	[thread overview]
Message-ID: <20200726195424.626969-5-sandals@crustytoothpaste.net> (raw)
In-Reply-To: <20200726195424.626969-1-sandals@crustytoothpaste.net>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

The idea of the magic value "ac4f2ee" in this test is to make the
reworded commit `collide2` have the same shortened ID as the commit
`collide3`.

To port the same idea to the SHA-256 version of Git, we therefore need
another magic value that causes the same collision, but this time with
the SHA-256 version of the commit IDs.

In this patch, we add code guarded by `GIT_TEST_FIND_COLLIDER` to do
exactly that. Essentially, a large number of integers is appended to the
commit message "collide2" to find such a collision. To make it easier to
find such a collision, we reduce the number of digits to 4.

The `t/oid-info/oid` file now lists the values found in that way, and
the test cases are modified to use those values.

As the tests are no longer dependent on SHA-1, we also rename their
titles to talk about "commit IDs" instead of "SHA-1s".

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 t/t3404-rebase-interactive.sh | 50 ++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 9 deletions(-)

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 4a7d21f898..2fb2c581cb 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -30,6 +30,7 @@ Initial setup:
 . "$TEST_DIRECTORY"/lib-rebase.sh
 
 test_expect_success 'setup' '
+	test_oid_init &&
 	test_commit A file1 &&
 	test_commit B file1 &&
 	test_commit C file2 &&
@@ -1250,7 +1251,7 @@ test_expect_success 'rebase -i error on commits with \ in message' '
 	test_expect_code 1 grep  "	emp" error
 '
 
-test_expect_success SHA1 'short SHA-1 setup' '
+test_expect_success 'short commit ID setup' '
 	test_when_finished "git checkout master" &&
 	git checkout --orphan collide &&
 	git rm -rf . &&
@@ -1262,23 +1263,54 @@ test_expect_success SHA1 'short SHA-1 setup' '
 	)
 '
 
-test_expect_success SHA1 'short SHA-1 collide' '
+if test -n "$GIT_TEST_FIND_COLLIDER"
+then
+	author="$(unset test_tick; test_tick; git var GIT_AUTHOR_IDENT)"
+	committer="$(unset test_tick; test_tick; git var GIT_COMMITTER_IDENT)"
+	blob="$(git rev-parse collide2:collide)"
+	from="$(git rev-parse collide1^0)"
+	repl="commit refs/heads/collider-&\\n"
+	repl="${repl}author $author\\ncommitter $committer\\n"
+	repl="${repl}data <<EOF\\ncollide2 &\\nEOF\\n"
+	repl="${repl}from $from\\nM 100644 $blob collide\\n"
+	test_seq 1 32768 | sed "s|.*|$repl|" >script &&
+	git fast-import <script &&
+	git pack-refs &&
+	git for-each-ref >refs &&
+	grep "^$(test_oid t3404_collision)" <refs >matches &&
+	cat matches &&
+	test_line_count -gt 2 matches || {
+		echo "Could not find a collider" >&2
+		exit 1
+	}
+fi
+
+test_expect_success 'short commit ID collide' '
+	test_oid_cache <<-EOF &&
+	# collision-related constants
+	t3404_collision	sha1:6bcd
+	t3404_collision	sha256:0161
+	t3404_collider	sha1:ac4f2ee
+	t3404_collider	sha256:16697
+	EOF
 	test_when_finished "reset_rebase && git checkout master" &&
 	git checkout collide &&
-	colliding_sha1=6bcda37 &&
-	test $colliding_sha1 = "$(git rev-parse HEAD | cut -c 1-7)" &&
+	colliding_id=$(test_oid t3404_collision) &&
+	hexsz=$(test_oid hexsz) &&
+	test $colliding_id = "$(git rev-parse HEAD | cut -c 1-4)" &&
+	test_config core.abbrev 4 &&
 	(
 		unset test_tick &&
 		test_tick &&
 		set_fake_editor &&
-		FAKE_COMMIT_MESSAGE="collide2 ac4f2ee" \
+		FAKE_COMMIT_MESSAGE="collide2 $(test_oid t3404_collider)" \
 		FAKE_LINES="reword 1 break 2" git rebase -i HEAD~2 &&
-		test $colliding_sha1 = "$(git rev-parse HEAD | cut -c 1-7)" &&
-		grep "^pick $colliding_sha1 " \
+		test $colliding_id = "$(git rev-parse HEAD | cut -c 1-4)" &&
+		grep "^pick $colliding_id " \
 			.git/rebase-merge/git-rebase-todo.tmp &&
-		grep "^pick [0-9a-f]\{40\}" \
+		grep "^pick [0-9a-f]\{$hexsz\}" \
 			.git/rebase-merge/git-rebase-todo &&
-		grep "^pick [0-9a-f]\{40\}" \
+		grep "^pick [0-9a-f]\{$hexsz\}" \
 			.git/rebase-merge/git-rebase-todo.backup &&
 		git rebase --continue
 	) &&

  parent reply	other threads:[~2020-07-26 19:55 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-26 19:53 [PATCH v4 00/39] SHA-256, part 3/3 brian m. carlson
2020-07-26 19:53 ` [PATCH v4 01/39] t: make test-bloom initialize repository brian m. carlson
2020-07-26 19:53 ` [PATCH v4 02/39] t1001: use $ZERO_OID brian m. carlson
2020-07-26 19:53 ` [PATCH v4 03/39] t3305: make hash agnostic brian m. carlson
2020-07-26 19:53 ` brian m. carlson [this message]
2020-07-26 22:31   ` [PATCH v4 04/39] t3404: prepare 'short SHA-1 collision' tests for SHA-256 Eric Sunshine
2020-07-26 19:53 ` [PATCH v4 05/39] t6100: make hash size independent brian m. carlson
2020-07-26 19:53 ` [PATCH v4 06/39] t6101: " brian m. carlson
2020-07-26 19:53 ` [PATCH v4 07/39] t6301: " brian m. carlson
2020-07-26 19:53 ` [PATCH v4 08/39] t6500: specify test values for SHA-256 brian m. carlson
2020-07-26 19:53 ` [PATCH v4 09/39] t6501: avoid hard-coded objects brian m. carlson
2020-07-26 19:53 ` [PATCH v4 10/39] t7003: compute appropriate length constant brian m. carlson
2020-07-26 19:53 ` [PATCH v4 11/39] t7063: make hash size independent brian m. carlson
2020-07-26 22:40   ` Eric Sunshine
2020-07-26 19:53 ` [PATCH v4 12/39] t7201: abstract away SHA-1-specific constants brian m. carlson
2020-07-26 22:54   ` Eric Sunshine
2020-07-26 19:53 ` [PATCH v4 13/39] t7102: " brian m. carlson
2020-07-26 19:53 ` [PATCH v4 14/39] t7400: make hash size independent brian m. carlson
2020-07-26 19:54 ` [PATCH v4 15/39] t7405: " brian m. carlson
2020-07-26 19:54 ` [PATCH v4 16/39] t7506: avoid checking for SHA-1-specific constants brian m. carlson
2020-07-26 19:54 ` [PATCH v4 17/39] t7508: use $ZERO_OID instead of hard-coded constant brian m. carlson
2020-07-26 19:54 ` [PATCH v4 18/39] t8002: make hash size independent brian m. carlson
2020-07-26 22:49   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 19/39] t8003: " brian m. carlson
2020-07-26 19:54 ` [PATCH v4 20/39] t8011: " brian m. carlson
2020-07-26 23:00   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 21/39] t9300: abstract away SHA-1-specific constants brian m. carlson
2020-07-26 23:14   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 22/39] t9300: use $ZERO_OID instead of hard-coded object ID brian m. carlson
2020-07-26 19:54 ` [PATCH v4 23/39] t9301: make hash size independent brian m. carlson
2020-07-26 19:54 ` [PATCH v4 24/39] t9350: " brian m. carlson
2020-07-26 19:54 ` [PATCH v4 25/39] t9500: ensure that algorithm info is preserved in config brian m. carlson
2020-07-26 19:54 ` [PATCH v4 26/39] t9700: make hash size independent brian m. carlson
2020-07-26 19:54 ` [PATCH v4 27/39] t5308: make test work with SHA-256 brian m. carlson
2020-07-26 19:54 ` [PATCH v4 28/39] t0410: mark test with SHA1 prerequisite brian m. carlson
2020-07-26 19:54 ` [PATCH v4 29/39] http-fetch: set up git directory before parsing pack hashes brian m. carlson
2020-07-26 23:28   ` Eric Sunshine
2020-07-26 23:30     ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 30/39] builtin/verify-pack: implement an --object-format option brian m. carlson
2020-07-26 21:29   ` Eric Sunshine
2020-07-26 22:56     ` brian m. carlson
2020-07-26 19:54 ` [PATCH v4 31/39] bundle: add new version for use with SHA-256 brian m. carlson
2020-07-26 22:18   ` Eric Sunshine
2020-07-26 22:59     ` brian m. carlson
2020-07-26 19:54 ` [PATCH v4 32/39] setup: add support for reading extensions.objectformat brian m. carlson
2020-07-26 23:34   ` Eric Sunshine
2020-07-26 23:41     ` brian m. carlson
2020-07-26 19:54 ` [PATCH v4 33/39] Enable SHA-256 support by default brian m. carlson
2020-07-26 23:41   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 34/39] t: add test_oid option to select hash algorithm brian m. carlson
2020-07-26 19:54 ` [PATCH v4 35/39] t: allow testing different hash algorithms via environment brian m. carlson
2020-07-26 19:54 ` [PATCH v4 36/39] t: make SHA1 prerequisite depend on default hash brian m. carlson
2020-07-26 23:52   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 37/39] ci: run tests with SHA-256 brian m. carlson
2020-07-26 23:54   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 38/39] docs: add documentation for extensions.objectFormat brian m. carlson
2020-07-26 23:56   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 39/39] t: remove test_oid_init in tests brian m. carlson

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