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git/t/t1404-update-ref-errors.sh
Michael Haggerty da5267f1b6 files_transaction_prepare(): fix handling of ref lock failure 
Since dc39e09942 (files_ref_store: use a transaction to update packed
refs, 2017-09-08), failure to lock a reference has been handled
incorrectly by `files_transaction_prepare()`. If
`lock_ref_for_update()` fails in the lock-acquisition loop of that
function, it sets `ret` then breaks out of that loop. Prior to
dc39e09942, that was OK, because the only thing following the loop was
the cleanup code. But dc39e09942 added another blurb of code between
the loop and the cleanup. That blurb sometimes resets `ret` to zero,
making the cleanup code think that the locking was successful.

Specifically, whenever

* One or more reference deletions have been processed successfully in
  the lock-acquisition loop. (Processing the first such reference
  causes a packed-ref transaction to be initialized.)

* Then `lock_ref_for_update()` fails for a subsequent reference. Such
  a failure can happen for a number of reasons, such as the old SHA-1
  not being correct, lock contention, etc. This causes a `break` out
  of the lock-acquisition loop.

* The `packed-refs` lock is acquired successfully and
  `ref_transaction_prepare()` succeeds for the packed-ref transaction.
  This has the effect of resetting `ret` back to 0, and making the
  cleanup code think that lock acquisition was successful.

In that case, any reference updates that were processed prior to
breaking out of the loop would be carried out (loose and packed), but
the reference that couldn't be locked and any subsequent references
would silently be ignored.

This can easily cause data loss if, for example, the user was trying
to push a new name for an existing branch while deleting the old name.
After the push, the branch could be left unreachable, and could even
subsequently be garbage-collected.

This problem was noticed in the context of deleting one reference and
creating another in a single transaction, when the two references D/F
conflict with each other, like

    git update-ref --stdin <<EOF
    delete refs/foo
    create refs/foo/bar HEAD
    EOF

This triggers the above bug because the deletion is processed
successfully for `refs/foo`, then the D/F conflict causes
`lock_ref_for_update()` to fail when `refs/foo/bar` is processed. In
this case the transaction *should* fail, but instead it causes
`refs/foo` to be deleted without creating `refs/foo`. This could
easily result in data loss.

The fix is simple: instead of just breaking out of the loop, jump
directly to the cleanup code. This fixes some tests in t1404 that were
added in the previous commit.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-25 15:08:26 +09:00

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#!/bin/sh
test_description='Test git update-ref error handling'
. ./test-lib.sh
# Create some references, perhaps run pack-refs --all, then try to
# create some more references. Ensure that the second creation fails
# with the correct error message.
# Usage: test_update_rejected <before> <pack> <create> <error>
# <before> is a ws-separated list of refs to create before the test
# <pack> (true or false) tells whether to pack the refs before the test
# <create> is a list of variables to attempt creating
# <error> is a string to look for in the stderr of update-ref.
# All references are created in the namespace specified by the current
# value of $prefix.
test_update_rejected () {
before="$1" &&
pack="$2" &&
create="$3" &&
error="$4" &&
printf "create $prefix/%s $C\n" $before |
git update-ref --stdin &&
git for-each-ref $prefix >unchanged &&
if $pack
then
git pack-refs --all
fi &&
printf "create $prefix/%s $C\n" $create >input &&
test_must_fail git update-ref --stdin <input 2>output.err &&
grep -F "$error" output.err &&
git for-each-ref $prefix >actual &&
test_cmp unchanged actual
}
Q="'"
# Test adding and deleting D/F-conflicting references in a single
# transaction.
df_test() {
prefix="$1"
pack=: symadd=false symdel=false add_del=false addref= delref=
shift
while test $# -gt 0
do
case "$1" in
--pack)
pack="git pack-refs --all"
shift
;;
--sym-add)
# Perform the add via a symbolic reference
symadd=true
shift
;;
--sym-del)
# Perform the del via a symbolic reference
symdel=true
shift
;;
--del-add)
# Delete first reference then add second
add_del=false
delref="$prefix/r/$2"
addref="$prefix/r/$3"
shift 3
;;
--add-del)
# Add first reference then delete second
add_del=true
addref="$prefix/r/$2"
delref="$prefix/r/$3"
shift 3
;;
*)
echo 1>&2 "Extra args to df_test: $*"
return 1
;;
esac
done
git update-ref "$delref" $C &&
if $symadd
then
addname="$prefix/s/symadd" &&
git symbolic-ref "$addname" "$addref"
else
addname="$addref"
fi &&
if $symdel
then
delname="$prefix/s/symdel" &&
git symbolic-ref "$delname" "$delref"
else
delname="$delref"
fi &&
cat >expected-err <<-EOF &&
fatal: cannot lock ref $Q$addname$Q: $Q$delref$Q exists; cannot create $Q$addref$Q
EOF
$pack &&
if $add_del
then
printf "%s\n" "create $addname $D" "delete $delname"
else
printf "%s\n" "delete $delname" "create $addname $D"
fi >commands &&
test_must_fail git update-ref --stdin <commands 2>output.err &&
test_cmp expected-err output.err &&
printf "%s\n" "$C $delref" >expected-refs &&
git for-each-ref --format="%(objectname) %(refname)" $prefix/r >actual-refs &&
test_cmp expected-refs actual-refs
}
test_expect_success 'setup' '
git commit --allow-empty -m Initial &&
C=$(git rev-parse HEAD) &&
git commit --allow-empty -m Second &&
D=$(git rev-parse HEAD) &&
git commit --allow-empty -m Third &&
E=$(git rev-parse HEAD)
'
test_expect_success 'existing loose ref is a simple prefix of new' '
prefix=refs/1l &&
test_update_rejected "a c e" false "b c/x d" \
"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x$Q"
'
test_expect_success 'existing packed ref is a simple prefix of new' '
prefix=refs/1p &&
test_update_rejected "a c e" true "b c/x d" \
"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x$Q"
'
test_expect_success 'existing loose ref is a deeper prefix of new' '
prefix=refs/2l &&
test_update_rejected "a c e" false "b c/x/y d" \
"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x/y$Q"
'
test_expect_success 'existing packed ref is a deeper prefix of new' '
prefix=refs/2p &&
test_update_rejected "a c e" true "b c/x/y d" \
"$Q$prefix/c$Q exists; cannot create $Q$prefix/c/x/y$Q"
'
test_expect_success 'new ref is a simple prefix of existing loose' '
prefix=refs/3l &&
test_update_rejected "a c/x e" false "b c d" \
"$Q$prefix/c/x$Q exists; cannot create $Q$prefix/c$Q"
'
test_expect_success 'new ref is a simple prefix of existing packed' '
prefix=refs/3p &&
test_update_rejected "a c/x e" true "b c d" \
"$Q$prefix/c/x$Q exists; cannot create $Q$prefix/c$Q"
'
test_expect_success 'new ref is a deeper prefix of existing loose' '
prefix=refs/4l &&
test_update_rejected "a c/x/y e" false "b c d" \
"$Q$prefix/c/x/y$Q exists; cannot create $Q$prefix/c$Q"
'
test_expect_success 'new ref is a deeper prefix of existing packed' '
prefix=refs/4p &&
test_update_rejected "a c/x/y e" true "b c d" \
"$Q$prefix/c/x/y$Q exists; cannot create $Q$prefix/c$Q"
'
test_expect_success 'one new ref is a simple prefix of another' '
prefix=refs/5 &&
test_update_rejected "a e" false "b c c/x d" \
"cannot process $Q$prefix/c$Q and $Q$prefix/c/x$Q at the same time"
'
test_expect_success 'empty directory should not fool rev-parse' '
prefix=refs/e-rev-parse &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
echo "$C" >expected &&
git rev-parse $prefix/foo >actual &&
test_cmp expected actual
'
test_expect_success 'empty directory should not fool for-each-ref' '
prefix=refs/e-for-each-ref &&
git update-ref $prefix/foo $C &&
git for-each-ref $prefix >expected &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
git for-each-ref $prefix >actual &&
test_cmp expected actual
'
test_expect_success 'empty directory should not fool create' '
prefix=refs/e-create &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "create %s $C\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success 'empty directory should not fool verify' '
prefix=refs/e-verify &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "verify %s $C\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success 'empty directory should not fool 1-arg update' '
prefix=refs/e-update-1 &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "update %s $D\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success 'empty directory should not fool 2-arg update' '
prefix=refs/e-update-2 &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "update %s $D $C\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success 'empty directory should not fool 0-arg delete' '
prefix=refs/e-delete-0 &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "delete %s\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success 'empty directory should not fool 1-arg delete' '
prefix=refs/e-delete-1 &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "delete %s $C\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success 'D/F conflict prevents add long + delete short' '
df_test refs/df-al-ds --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents add short + delete long' '
df_test refs/df-as-dl --add-del foo foo/bar
'
test_expect_success 'D/F conflict prevents delete long + add short' '
df_test refs/df-dl-as --del-add foo/bar foo
'
test_expect_success 'D/F conflict prevents delete short + add long' '
df_test refs/df-ds-al --del-add foo foo/bar
'
test_expect_success 'D/F conflict prevents add long + delete short packed' '
df_test refs/df-al-dsp --pack --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents add short + delete long packed' '
df_test refs/df-as-dlp --pack --add-del foo foo/bar
'
test_expect_success 'D/F conflict prevents delete long packed + add short' '
df_test refs/df-dlp-as --pack --del-add foo/bar foo
'
test_expect_success 'D/F conflict prevents delete short packed + add long' '
df_test refs/df-dsp-al --pack --del-add foo foo/bar
'
# Try some combinations involving symbolic refs...
test_expect_success 'D/F conflict prevents indirect add long + delete short' '
df_test refs/df-ial-ds --sym-add --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents indirect add long + indirect delete short' '
df_test refs/df-ial-ids --sym-add --sym-del --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents indirect add short + indirect delete long' '
df_test refs/df-ias-idl --sym-add --sym-del --add-del foo foo/bar
'
test_expect_success 'D/F conflict prevents indirect delete long + indirect add short' '
df_test refs/df-idl-ias --sym-add --sym-del --del-add foo/bar foo
'
test_expect_success 'D/F conflict prevents indirect add long + delete short packed' '
df_test refs/df-ial-dsp --sym-add --pack --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents indirect add long + indirect delete short packed' '
df_test refs/df-ial-idsp --sym-add --sym-del --pack --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents add long + indirect delete short packed' '
df_test refs/df-al-idsp --sym-del --pack --add-del foo/bar foo
'
test_expect_success 'D/F conflict prevents indirect delete long packed + indirect add short' '
df_test refs/df-idlp-ias --sym-add --sym-del --pack --del-add foo/bar foo
'
# Test various errors when reading the old values of references...
test_expect_success 'missing old value blocks update' '
prefix=refs/missing-update &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q
EOF
printf "%s\n" "update $prefix/foo $E $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'incorrect old value blocks update' '
prefix=refs/incorrect-update &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: is at $C but expected $D
EOF
printf "%s\n" "update $prefix/foo $E $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'existing old value blocks create' '
prefix=refs/existing-create &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: reference already exists
EOF
printf "%s\n" "create $prefix/foo $E" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'incorrect old value blocks delete' '
prefix=refs/incorrect-delete &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: is at $C but expected $D
EOF
printf "%s\n" "delete $prefix/foo $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'missing old value blocks indirect update' '
prefix=refs/missing-indirect-update &&
git symbolic-ref $prefix/symref $prefix/foo &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q
EOF
printf "%s\n" "update $prefix/symref $E $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'incorrect old value blocks indirect update' '
prefix=refs/incorrect-indirect-update &&
git symbolic-ref $prefix/symref $prefix/foo &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
EOF
printf "%s\n" "update $prefix/symref $E $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'existing old value blocks indirect create' '
prefix=refs/existing-indirect-create &&
git symbolic-ref $prefix/symref $prefix/foo &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: reference already exists
EOF
printf "%s\n" "create $prefix/symref $E" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'incorrect old value blocks indirect delete' '
prefix=refs/incorrect-indirect-delete &&
git symbolic-ref $prefix/symref $prefix/foo &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
EOF
printf "%s\n" "delete $prefix/symref $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'missing old value blocks indirect no-deref update' '
prefix=refs/missing-noderef-update &&
git symbolic-ref $prefix/symref $prefix/foo &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: reference is missing but expected $D
EOF
printf "%s\n" "option no-deref" "update $prefix/symref $E $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'incorrect old value blocks indirect no-deref update' '
prefix=refs/incorrect-noderef-update &&
git symbolic-ref $prefix/symref $prefix/foo &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
EOF
printf "%s\n" "option no-deref" "update $prefix/symref $E $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'existing old value blocks indirect no-deref create' '
prefix=refs/existing-noderef-create &&
git symbolic-ref $prefix/symref $prefix/foo &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: reference already exists
EOF
printf "%s\n" "option no-deref" "create $prefix/symref $E" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'incorrect old value blocks indirect no-deref delete' '
prefix=refs/incorrect-noderef-delete &&
git symbolic-ref $prefix/symref $prefix/foo &&
git update-ref $prefix/foo $C &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: is at $C but expected $D
EOF
printf "%s\n" "option no-deref" "delete $prefix/symref $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'non-empty directory blocks create' '
prefix=refs/ne-create &&
mkdir -p .git/$prefix/foo/bar &&
: >.git/$prefix/foo/bar/baz.lock &&
test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: there is a non-empty directory $Q.git/$prefix/foo$Q blocking reference $Q$prefix/foo$Q
EOF
printf "%s\n" "update $prefix/foo $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q
EOF
printf "%s\n" "update $prefix/foo $D $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'broken reference blocks create' '
prefix=refs/broken-create &&
mkdir -p .git/$prefix &&
echo "gobbledigook" >.git/$prefix/foo &&
test_when_finished "rm -f .git/$prefix/foo" &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
EOF
printf "%s\n" "update $prefix/foo $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/foo$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
EOF
printf "%s\n" "update $prefix/foo $D $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'non-empty directory blocks indirect create' '
prefix=refs/ne-indirect-create &&
git symbolic-ref $prefix/symref $prefix/foo &&
mkdir -p .git/$prefix/foo/bar &&
: >.git/$prefix/foo/bar/baz.lock &&
test_when_finished "rm -f .git/$prefix/foo/bar/baz.lock" &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: there is a non-empty directory $Q.git/$prefix/foo$Q blocking reference $Q$prefix/foo$Q
EOF
printf "%s\n" "update $prefix/symref $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q
EOF
printf "%s\n" "update $prefix/symref $D $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'broken reference blocks indirect create' '
prefix=refs/broken-indirect-create &&
git symbolic-ref $prefix/symref $prefix/foo &&
echo "gobbledigook" >.git/$prefix/foo &&
test_when_finished "rm -f .git/$prefix/foo" &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
EOF
printf "%s\n" "update $prefix/symref $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err &&
cat >expected <<-EOF &&
fatal: cannot lock ref $Q$prefix/symref$Q: unable to resolve reference $Q$prefix/foo$Q: reference broken
EOF
printf "%s\n" "update $prefix/symref $D $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success 'no bogus intermediate values during delete' '
prefix=refs/slow-transaction &&
# Set up a reference with differing loose and packed versions:
git update-ref $prefix/foo $C &&
git pack-refs --all &&
git update-ref $prefix/foo $D &&
git for-each-ref $prefix >unchanged &&
# Now try to update the reference, but hold the `packed-refs` lock
# for a while to see what happens while the process is blocked:
: >.git/packed-refs.lock &&
test_when_finished "rm -f .git/packed-refs.lock" &&
{
# Note: the following command is intentionally run in the
# background. We increase the timeout so that `update-ref`
# attempts to acquire the `packed-refs` lock for longer than
# it takes for us to do the check then delete it:
git -c core.packedrefstimeout=3000 update-ref -d $prefix/foo &
} &&
pid2=$! &&
# Give update-ref plenty of time to get to the point where it tries
# to lock packed-refs:
sleep 1 &&
# Make sure that update-ref did not complete despite the lock:
kill -0 $pid2 &&
# Verify that the reference still has its old value:
sha1=$(git rev-parse --verify --quiet $prefix/foo || echo undefined) &&
case "$sha1" in
$D)
# This is what we hope for; it means that nothing
# user-visible has changed yet.
: ;;
undefined)
# This is not correct; it means the deletion has happened
# already even though update-ref should not have been
# able to acquire the lock yet.
echo "$prefix/foo deleted prematurely" &&
break
;;
$C)
# This value should never be seen. Probably the loose
# reference has been deleted but the packed reference
# is still there:
echo "$prefix/foo incorrectly observed to be C" &&
break
;;
*)
# WTF?
echo "unexpected value observed for $prefix/foo: $sha1" &&
break
;;
esac >out &&
rm -f .git/packed-refs.lock &&
wait $pid2 &&
test_must_be_empty out &&
test_must_fail git rev-parse --verify --quiet $prefix/foo
'
test_expect_success 'delete fails cleanly if packed-refs file is locked' '
prefix=refs/locked-packed-refs &&
# Set up a reference with differing loose and packed versions:
git update-ref $prefix/foo $C &&
git pack-refs --all &&
git update-ref $prefix/foo $D &&
git for-each-ref $prefix >unchanged &&
# Now try to delete it while the `packed-refs` lock is held:
: >.git/packed-refs.lock &&
test_when_finished "rm -f .git/packed-refs.lock" &&
test_must_fail git update-ref -d $prefix/foo >out 2>err &&
git for-each-ref $prefix >actual &&
test_i18ngrep "Unable to create $Q.*packed-refs.lock$Q: File exists" err &&
test_cmp unchanged actual
'
test_done
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