Mercurial > hg
view tests/test-clone-r.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 | f1186c292d03 |
children | ccd76e292be5 |
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$ hg init test $ cd test $ echo 0 >> afile $ hg add afile $ hg commit -m "0.0" $ echo 1 >> afile $ hg commit -m "0.1" $ echo 2 >> afile $ hg commit -m "0.2" $ echo 3 >> afile $ hg commit -m "0.3" $ hg update -C 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ echo 1 >> afile $ hg commit -m "1.1" created new head $ echo 2 >> afile $ hg commit -m "1.2" $ echo a line > fred $ echo 3 >> afile $ hg add fred $ hg commit -m "1.3" $ hg mv afile adifferentfile $ hg commit -m "1.3m" $ hg update -C 3 1 files updated, 0 files merged, 2 files removed, 0 files unresolved $ hg mv afile anotherfile $ hg commit -m "0.3m" $ hg debugrevlogindex -f 1 afile rev flag size link p1 p2 nodeid 0 0000 2 0 -1 -1 362fef284ce2 1 0000 4 1 0 -1 125144f7e028 2 0000 6 2 1 -1 4c982badb186 3 0000 8 3 2 -1 19b1fc555737 $ hg debugindex adifferentfile rev linkrev nodeid p1 p2 0 7 2565f3199a74 000000000000 000000000000 $ hg debugindex anotherfile rev linkrev nodeid p1 p2 0 8 2565f3199a74 000000000000 000000000000 $ hg debugindex fred rev linkrev nodeid p1 p2 0 6 12ab3bcc5ea4 000000000000 000000000000 $ hg debugindex --manifest rev linkrev nodeid p1 p2 0 0 43eadb1d2d06 000000000000 000000000000 1 1 8b89697eba2c 43eadb1d2d06 000000000000 2 2 626a32663c2f 8b89697eba2c 000000000000 3 3 f54c32f13478 626a32663c2f 000000000000 4 6 de68e904d169 626a32663c2f 000000000000 5 7 09bb521d218d de68e904d169 000000000000 6 8 1fde233dfb0f f54c32f13478 000000000000 $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 9 changesets with 7 changes to 4 files $ cd .. $ for i in 0 1 2 3 4 5 6 7 8; do > echo > echo ---- hg clone -r "$i" test test-"$i" > hg clone -r "$i" test test-"$i" > cd test-"$i" > hg verify > cd .. > done ---- hg clone -r 0 test test-0 adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files new changesets f9ee2f85a263 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 1 changesets with 1 changes to 1 files ---- hg clone -r 1 test test-1 adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 1 files new changesets f9ee2f85a263:34c2bf6b0626 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 2 changesets with 2 changes to 1 files ---- hg clone -r 2 test test-2 adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files new changesets f9ee2f85a263:e38ba6f5b7e0 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 3 changesets with 3 changes to 1 files ---- hg clone -r 3 test test-3 adding changesets adding manifests adding file changes added 4 changesets with 4 changes to 1 files new changesets f9ee2f85a263:eebf5a27f8ca updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 4 changesets with 4 changes to 1 files ---- hg clone -r 4 test test-4 adding changesets adding manifests adding file changes added 2 changesets with 2 changes to 1 files new changesets f9ee2f85a263:095197eb4973 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 2 changesets with 2 changes to 1 files ---- hg clone -r 5 test test-5 adding changesets adding manifests adding file changes added 3 changesets with 3 changes to 1 files new changesets f9ee2f85a263:1bb50a9436a7 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 3 changesets with 3 changes to 1 files ---- hg clone -r 6 test test-6 adding changesets adding manifests adding file changes added 4 changesets with 5 changes to 2 files new changesets f9ee2f85a263:7373c1169842 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 4 changesets with 5 changes to 2 files ---- hg clone -r 7 test test-7 adding changesets adding manifests adding file changes added 5 changesets with 6 changes to 3 files new changesets f9ee2f85a263:a6a34bfa0076 updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 5 changesets with 6 changes to 3 files ---- hg clone -r 8 test test-8 adding changesets adding manifests adding file changes added 5 changesets with 5 changes to 2 files new changesets f9ee2f85a263:aa35859c02ea updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 5 changesets with 5 changes to 2 files $ cd test-8 $ hg pull ../test-7 pulling from ../test-7 searching for changes adding changesets adding manifests adding file changes added 4 changesets with 2 changes to 3 files (+1 heads) new changesets 095197eb4973:a6a34bfa0076 (run 'hg heads' to see heads, 'hg merge' to merge) $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files checked 9 changesets with 7 changes to 4 files $ cd .. $ hg clone test test-9 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd test-9 $ hg branch foobar marked working directory as branch foobar (branches are permanent and global, did you want a bookmark?) $ echo file2 >> file2 $ hg add file2 $ hg commit -m "changeset9" $ echo file3 >> file3 $ hg add file3 $ hg commit -m "changeset10" $ cd .. $ hg clone -r 9 -u foobar test-9 test-10 adding changesets adding manifests adding file changes added 6 changesets with 6 changes to 3 files new changesets f9ee2f85a263:7100abb79635 updating to branch foobar 2 files updated, 0 files merged, 0 files removed, 0 files unresolved