Mercurial > hg
view tests/test-mq-qfold.t @ 46607:e9901d01d135
revlog: add a mechanism to verify expected file position before appending
If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.
The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)
When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.
For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.
This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.
Differential Revision: https://phab.mercurial-scm.org/D9952
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Wed, 03 Feb 2021 16:33:10 -0800 |
parents | 768056549737 |
children |
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$ cat <<EOF >> $HGRCPATH > [extensions] > mq = > [mq] > git = keep > [diff] > nodates = 1 > EOF init: $ hg init repo $ cd repo $ echo a > a $ hg ci -Am adda adding a $ echo a >> a $ hg qnew -f p1 $ echo b >> a $ hg qnew -f p2 $ echo c >> a $ hg qnew -f p3 Fold in the middle of the queue: (this tests also that editor is not invoked if '--edit' is not specified) $ hg qpop p1 popping p3 popping p2 now at: p1 $ hg qdiff diff -r 07f494440405 a --- a/a +++ b/a @@ -1,1 +1,2 @@ a +a $ HGEDITOR=cat hg qfold p2 $ grep git .hg/patches/p1 && echo 'git patch found!' [1] $ hg qser p1 p3 $ hg qdiff diff -r 07f494440405 a --- a/a +++ b/a @@ -1,1 +1,3 @@ a +a +b Fold with local changes: $ echo d >> a $ hg qfold p3 abort: local changes found, qrefresh first [255] $ hg diff -c . diff -r 07f494440405 -r ???????????? a (glob) --- a/a +++ b/a @@ -1,1 +1,3 @@ a +a +b $ hg revert -a --no-backup reverting a Fold git patch into a regular patch, expect git patch: $ echo a >> a $ hg qnew -f regular $ hg cp a aa $ hg qnew --git -f git $ hg qpop popping git now at: regular $ hg qfold git $ cat .hg/patches/regular # HG changeset patch # Parent ???????????????????????????????????????? (glob) diff --git a/a b/a --- a/a +++ b/a @@ -1,3 +1,4 @@ a a b +a diff --git a/a b/aa copy from a copy to aa --- a/a +++ b/aa @@ -1,3 +1,4 @@ a a b +a $ hg qpop popping regular now at: p1 $ hg qdel regular Fold regular patch into a git patch, expect git patch: $ hg cp a aa $ hg qnew --git -f git $ echo b >> aa $ hg qnew -f regular $ hg qpop popping regular now at: git $ hg qfold regular $ cat .hg/patches/git # HG changeset patch # Parent ???????????????????????????????????????? (glob) diff --git a/a b/aa copy from a copy to aa --- a/a +++ b/aa @@ -1,3 +1,4 @@ a a b +b Test saving last-message.txt: $ hg qrefresh -m "original message" $ cat > $TESTTMP/commitfailure.py <<EOF > from mercurial import error > def reposetup(ui, repo): > class commitfailure(repo.__class__): > def commit(self, *args, **kwargs): > raise error.Abort(b'emulating unexpected abort') > repo.__class__ = commitfailure > EOF $ cat >> .hg/hgrc <<EOF > [extensions] > # this failure occurs before editor invocation > commitfailure = $TESTTMP/commitfailure.py > EOF $ cat > $TESTTMP/editor.sh << EOF > echo "==== before editing" > cat \$1 > echo "====" > (echo; echo "test saving last-message.txt") >> \$1 > EOF $ hg qapplied p1 git $ hg tip --template "{files}\n" aa (test that editor is not invoked before transaction starting, and that combination of '--edit' and '--message' doesn't abort execution) $ rm -f .hg/last-message.txt $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e -m MESSAGE p3 qrefresh interrupted while patch was popped! (revert --all, qpush to recover) abort: emulating unexpected abort [255] $ test -f .hg/last-message.txt [1] (reset applied patches and directory status) $ cat >> .hg/hgrc <<EOF > [extensions] > # this failure occurs after editor invocation > commitfailure = ! > EOF $ hg qapplied p1 $ hg status -A aa ? aa $ rm aa $ hg status -m M a $ hg revert --no-backup -q a $ hg qpush -q git now at: git (test that editor is invoked and commit message is saved into "last-message.txt") $ cat >> .hg/hgrc <<EOF > [hooks] > # this failure occurs after editor invocation > pretxncommit.unexpectedabort = false > EOF $ rm -f .hg/last-message.txt $ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e p3 ==== before editing original message HG: Enter commit message. Lines beginning with 'HG:' are removed. HG: Leave message empty to use default message. HG: -- HG: user: test HG: branch 'default' HG: added aa HG: changed a ==== note: commit message saved in .hg/last-message.txt note: use 'hg commit --logfile .hg/last-message.txt --edit' to reuse it transaction abort! rollback completed qrefresh interrupted while patch was popped! (revert --all, qpush to recover) abort: pretxncommit.unexpectedabort hook exited with status 1 [40] $ cat .hg/last-message.txt original message test saving last-message.txt (confirm whether files listed up in the commit message editing are correct) $ cat >> .hg/hgrc <<EOF > [hooks] > pretxncommit.unexpectedabort = > EOF $ hg status -u | while read f; do rm ${f}; done $ hg revert --no-backup -q --all $ hg qpush -q git now at: git $ hg qpush -q --move p3 now at: p3 $ hg status --rev "git^1" --rev . -arm M a A aa $ cd ..