git/t/t1404-update-ref-errors.sh

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#!/bin/sh
test_description='Test git update-ref error handling'
TEST_PASSES_SANITIZE_LEAK=true
. ./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" $create >input &&
test_must_fail git update-ref --stdin <input 2>output.err &&
test_i18ngrep -F "$error" output.err &&
git for-each-ref $prefix >actual &&
test_cmp unchanged actual
}
# 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 $SQ$addname$SQ: $SQ$delref$SQ exists; cannot create $SQ$addref$SQ
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" \
"$SQ$prefix/c$SQ exists; cannot create $SQ$prefix/c/x$SQ"
'
test_expect_success 'existing packed ref is a simple prefix of new' '
prefix=refs/1p &&
test_update_rejected "a c e" true "b c/x d" \
"$SQ$prefix/c$SQ exists; cannot create $SQ$prefix/c/x$SQ"
'
test_expect_success 'existing loose ref is a deeper prefix of new' '
prefix=refs/2l &&
test_update_rejected "a c e" false "b c/x/y d" \
"$SQ$prefix/c$SQ exists; cannot create $SQ$prefix/c/x/y$SQ"
'
test_expect_success 'existing packed ref is a deeper prefix of new' '
prefix=refs/2p &&
test_update_rejected "a c e" true "b c/x/y d" \
"$SQ$prefix/c$SQ exists; cannot create $SQ$prefix/c/x/y$SQ"
'
test_expect_success 'new ref is a simple prefix of existing loose' '
prefix=refs/3l &&
test_update_rejected "a c/x e" false "b c d" \
"$SQ$prefix/c/x$SQ exists; cannot create $SQ$prefix/c$SQ"
'
test_expect_success 'new ref is a simple prefix of existing packed' '
prefix=refs/3p &&
test_update_rejected "a c/x e" true "b c d" \
"$SQ$prefix/c/x$SQ exists; cannot create $SQ$prefix/c$SQ"
'
test_expect_success 'new ref is a deeper prefix of existing loose' '
prefix=refs/4l &&
test_update_rejected "a c/x/y e" false "b c d" \
"$SQ$prefix/c/x/y$SQ exists; cannot create $SQ$prefix/c$SQ"
'
test_expect_success 'new ref is a deeper prefix of existing packed' '
prefix=refs/4p &&
test_update_rejected "a c/x/y e" true "b c d" \
"$SQ$prefix/c/x/y$SQ exists; cannot create $SQ$prefix/c$SQ"
'
refs: check for D/F conflicts among refs created in a transaction If two references that D/F conflict (e.g., "refs/foo" and "refs/foo/bar") are created in a single transaction, the old code discovered the problem only after the "commit" phase of ref_transaction_commit() had already begun. This could leave some references updated and others not, which violates the promise of atomicity. Instead, check for such conflicts during the "locking" phase: * Teach is_refname_available() to take an "extras" parameter that can contain extra reference names with which the specified refname must not conflict. * Change lock_ref_sha1_basic() to take an "extras" parameter, which it passes through to is_refname_available(). * Change ref_transaction_commit() to pass "affected_refnames" to lock_ref_sha1_basic() as its "extras" argument. This change fixes a test case in t1404. This code is a bit stricter than it needs to be. We could conceivably allow reference "refs/foo/bar" to be created in the same transaction as "refs/foo" is deleted (or vice versa). But that would be complicated to implement, because it is not possible to lock "refs/foo/bar" while "refs/foo" exists as a loose reference, but on the other hand we don't want to delete some references before adding others (because that could leave a gap during which required objects are unreachable). There is also a complication that reflog files' paths can conflict. Any less-strict implementation would probably require tricks like the packing of all references before the start of the real transaction, or the use of temporary intermediate reference names. So for now let's accept too-strict checks. Some reference update transactions will be rejected unnecessarily, but they will be rejected in their entirety rather than leaving the repository in an intermediate state, as would happen now. Please note that there is still one kind of D/F conflict that is *not* handled correctly. If two processes are running at the same time, and one tries to create "refs/foo" at the same time that the other tries to create "refs/foo/bar", then they can race with each other. Both processes can obtain their respective locks ("refs/foo.lock" and "refs/foo/bar.lock"), proceed to the "commit" phase of ref_transaction_commit(), and then the slower process will discover that it cannot rename its lockfile into place (after possibly having committed changes to other references). There appears to be no way to fix this race without changing the locking policy, which in turn would require a change to *all* Git clients. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
2015-05-11 15:25:12 +00:00
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 $SQ$prefix/c$SQ and $SQ$prefix/c/x$SQ at the same time"
'
test_expect_success REFFILES '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 REFFILES '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 $prefix >actual &&
test_cmp expected actual
'
test_expect_success REFFILES 'empty directory should not fool create' '
prefix=refs/e-create &&
mkdir -p .git/$prefix/foo/bar/baz &&
printf "create %s $C\n" $prefix/foo |
git update-ref --stdin
'
test_expect_success REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES 'D/F conflict prevents add long + delete short' '
df_test refs/df-al-ds --add-del foo/bar foo
'
test_expect_success REFFILES 'D/F conflict prevents add short + delete long' '
df_test refs/df-as-dl --add-del foo foo/bar
'
test_expect_success REFFILES 'D/F conflict prevents delete long + add short' '
df_test refs/df-dl-as --del-add foo/bar foo
'
test_expect_success REFFILES 'D/F conflict prevents delete short + add long' '
df_test refs/df-ds-al --del-add foo foo/bar
'
test_expect_success REFFILES 'D/F conflict prevents add long + delete short packed' '
df_test refs/df-al-dsp --pack --add-del foo/bar foo
'
test_expect_success REFFILES 'D/F conflict prevents add short + delete long packed' '
df_test refs/df-as-dlp --pack --add-del foo foo/bar
'
test_expect_success REFFILES 'D/F conflict prevents delete long packed + add short' '
df_test refs/df-dlp-as --pack --del-add foo/bar foo
'
test_expect_success REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 REFFILES '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 $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ
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 $SQ$prefix/foo$SQ: 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 $SQ$prefix/foo$SQ: 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 $SQ$prefix/foo$SQ: 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 $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ
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 $SQ$prefix/symref$SQ: 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 $SQ$prefix/symref$SQ: 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 $SQ$prefix/symref$SQ: 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 $SQ$prefix/symref$SQ: 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 $SQ$prefix/symref$SQ: 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 $SQ$prefix/symref$SQ: 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 $SQ$prefix/symref$SQ: is at $C but expected $D
EOF
printf "%s\n" "option no-deref" "delete $prefix/symref $D" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success REFFILES 'non-empty directory blocks create' '
prefix=refs/ne-create &&
mkdir -p .git/$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 $SQ$prefix/foo$SQ: there is a non-empty directory $SQ.git/$prefix/foo$SQ blocking reference $SQ$prefix/foo$SQ
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 $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ
EOF
printf "%s\n" "update $prefix/foo $D $C" |
test_must_fail git update-ref --stdin 2>output.err &&
test_cmp expected output.err
'
test_expect_success REFFILES 'broken reference blocks create' '
prefix=refs/broken-create &&
mkdir -p .git/$prefix &&
echo "gobbledigook" >.git/$prefix/foo &&
test_when_finished "rm -f .git/$prefix/foo" &&
cat >expected <<-EOF &&
fatal: cannot lock ref $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ: 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 $SQ$prefix/foo$SQ: unable to resolve reference $SQ$prefix/foo$SQ: 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 REFFILES '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 $SQ$prefix/symref$SQ: there is a non-empty directory $SQ.git/$prefix/foo$SQ blocking reference $SQ$prefix/foo$SQ
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 $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ
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 REFFILES '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 $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ: 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 $SQ$prefix/symref$SQ: unable to resolve reference $SQ$prefix/foo$SQ: 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 REFFILES '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 much longer
# than it takes for us to do the check then delete it:
git -c core.packedrefstimeout=30000 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 REFFILES '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 $SQ.*packed-refs.lock$SQ: " err &&
test_cmp unchanged actual
'
test_expect_success REFFILES 'delete fails cleanly if packed-refs.new write fails' '
refs/files-backend: handle packed transaction prepare failure In files_transaction_prepare(), if we have to delete some refs, we use a subordinate packed_transaction to do so. It's rare for that sub-transaction's prepare step to fail, since we hold the packed-refs lock. But if it does, we trigger a BUG() due to these steps: - we've attached the packed transaction to the files transaction as backend_data->packed_transaction - when the prepare step fails, the packed transaction cleans itself up, putting itself into the CLOSED state - the error value from preparing the packed transaction lets us know in files_transaction_prepare() that we should also clean up and return an error. We call files_transaction_cleanup(), which tries to abort backend_data->packed_transaction. Since it's already CLOSED, that triggers an assertion in ref_transaction_abort(). We can fix that by disconnecting the packed transaction from the outer files transaction, and then free-ing (not aborting!) it ourselves. A few other options/alternatives I considered: - we could just make it a noop to abort a CLOSED transaction. But that seems less safe, since clearly this code expects (and enforces) a particular set of state transitions. - we could have files_transaction_cleanup() selectively call abort() vs free() based on the state of the on the packed transaction. That's basically a more restricted version of the above, but also potentially unsafe. - instead of disconnecting backend_data->packed_transaction on error, we could wait to install it until we successfully prepare. That might make the flow a little simpler, but it introduces a hassle. Earlier parts of files_transaction_prepare() that encounter an error will jump to the cleanup label, and expect that cleaning up the outer transaction will clean up the packed transaction, too. We'd have to adjust those sites to clean up the packed transaction. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-21 09:28:44 +00:00
# Setup and expectations are similar to the test above.
prefix=refs/failed-packed-refs &&
git update-ref $prefix/foo $C &&
git pack-refs --all &&
git update-ref $prefix/foo $D &&
git for-each-ref $prefix >unchanged &&
# This should not happen in practice, but it is an easy way to get a
# reliable error (we open with create_tempfile(), which uses O_EXCL).
: >.git/packed-refs.new &&
test_when_finished "rm -f .git/packed-refs.new" &&
test_must_fail git update-ref -d $prefix/foo &&
git for-each-ref $prefix >actual &&
test_cmp unchanged actual
'
test_done