Mercurial > hg
view tests/test-mq-qpush-exact.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 | bbf544b5f2e9 |
| children |
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$ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH make a test repository that looks like this: o 2:28bc7b1afd6a | | @ 1:d7fe2034f71b |/ o 0/62ecad8b70e5 $ hg init r0 $ cd r0 $ touch f0 $ hg ci -m0 -Aq $ touch f1 $ hg ci -m1 -Aq $ hg update 0 -q $ touch f2 $ hg ci -m2 -Aq $ hg update 1 -q make some patches with a parent: 1:d7fe2034f71b -> p0 -> p1 $ echo cp0 >> fp0 $ hg add fp0 $ hg ci -m p0 -d "0 0" $ hg export -r. > p0 $ hg strip -qn . $ hg qimport p0 adding p0 to series file $ hg qpush applying p0 now at: p0 $ echo cp1 >> fp1 $ hg add fp1 $ hg qnew p1 -d "0 0" $ hg qpop -aq patch queue now empty qpush --exact when at the parent $ hg update 1 -q $ hg qpush -e applying p0 now at: p0 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg qpush -e p0 applying p0 now at: p0 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg qpush -e p1 applying p0 applying p1 now at: p1 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty qpush --exact when at another rev $ hg update 0 -q $ hg qpush -e 1 files updated, 0 files merged, 0 files removed, 0 files unresolved applying p0 now at: p0 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg update 0 -q $ hg qpush -e p0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved applying p0 now at: p0 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg update 0 -q $ hg qpush -e p1 1 files updated, 0 files merged, 0 files removed, 0 files unresolved applying p0 applying p1 now at: p1 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg update 0 -q $ hg qpush -ea 1 files updated, 0 files merged, 0 files removed, 0 files unresolved applying p0 applying p1 now at: p1 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty qpush --exact while crossing branches $ hg update 2 -q $ hg qpush -e 1 files updated, 0 files merged, 1 files removed, 0 files unresolved applying p0 now at: p0 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg update 2 -q $ hg qpush -e p0 1 files updated, 0 files merged, 1 files removed, 0 files unresolved applying p0 now at: p0 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg update 2 -q $ hg qpush -e p1 1 files updated, 0 files merged, 1 files removed, 0 files unresolved applying p0 applying p1 now at: p1 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty $ hg update 2 -q $ hg qpush -ea 1 files updated, 0 files merged, 1 files removed, 0 files unresolved applying p0 applying p1 now at: p1 $ hg parents -qr qbase 1:d7fe2034f71b $ hg qpop -aq patch queue now empty qpush --exact --force with changes to an unpatched file $ hg update 1 -q $ echo c0 >> f0 $ hg qpush -e abort: local changes found [255] $ hg qpush -ef applying p0 now at: p0 $ cat f0 c0 $ rm f0 $ touch f0 $ hg qpop -aq patch queue now empty $ hg update 1 -q $ echo c0 >> f0 $ hg qpush -e p1 abort: local changes found [255] $ hg qpush -e p1 -f applying p0 applying p1 now at: p1 $ cat f0 c0 $ rm f0 $ touch f0 $ hg qpop -aq patch queue now empty qpush --exact --force with changes to a patched file $ hg update 1 -q $ echo cp0-bad >> fp0 $ hg add fp0 $ hg qpush -e abort: local changes found [255] $ hg qpush -ef applying p0 file fp0 already exists 1 out of 1 hunks FAILED -- saving rejects to file fp0.rej patch failed, unable to continue (try -v) patch failed, rejects left in working directory errors during apply, please fix and qrefresh p0 [2] $ cat fp0 cp0-bad $ cat fp0.rej --- fp0 +++ fp0 @@ -0,0 +1,1 @@ +cp0 $ hg qpop -aqf patch queue now empty $ rm fp0 $ rm fp0.rej $ hg update 1 -q $ echo cp1-bad >> fp1 $ hg add fp1 $ hg qpush -e p1 abort: local changes found [255] $ hg qpush -e p1 -f applying p0 applying p1 file fp1 already exists 1 out of 1 hunks FAILED -- saving rejects to file fp1.rej patch failed, unable to continue (try -v) patch failed, rejects left in working directory errors during apply, please fix and qrefresh p1 [2] $ cat fp1 cp1-bad $ cat fp1.rej --- fp1 +++ fp1 @@ -0,0 +1,1 @@ +cp1 $ hg qpop -aqf patch queue now empty $ hg forget fp1 $ rm fp1 $ rm fp1.rej qpush --exact when already at a patch $ hg update 1 0 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg qpush -e p0 applying p0 now at: p0 $ hg qpush -e p1 abort: cannot push --exact with applied patches [255] $ hg qpop -aq patch queue now empty qpush --exact --move should fail $ hg qpush -e --move p1 abort: cannot use --exact and --move together [255] qpush --exact a patch without a parent recorded $ hg qpush -q now at: p0 $ grep -v '# Parent' .hg/patches/p0 > p0.new $ mv p0.new .hg/patches/p0 $ hg qpop -aq patch queue now empty $ hg qpush -e abort: p0 does not have a parent recorded [255] $ hg qpush -e p0 abort: p0 does not have a parent recorded [255] $ hg qpush -e p1 abort: p0 does not have a parent recorded [255] $ hg qpush -ea abort: p0 does not have a parent recorded [255] $ cd ..