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t3404: prepare 'short SHA-1 collision' tests for SHA-256

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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.

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>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Schindelin 2020-07-29 23:13:53 +00:00 committed by Junio C Hamano
parent 9e3bd8a391
commit 800e6a7041
1 changed files with 40 additions and 9 deletions
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49
t/t3404-rebase-interactive.sh
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@ -1250,7 +1250,7 @@ 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 +1262,54 @@ 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
) &&