Mercurial > hg
view tests/test-patchbomb-bookmark.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 | d7007b807fa2 |
children |
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Create @ bookmark as main reference $ hg init repo $ cd repo $ echo "[extensions]" >> $HGRCPATH $ echo "patchbomb=" >> $HGRCPATH $ hg book @ Create a dummy revision that must never be exported $ echo no > no $ hg ci -Amno -d '6 0' adding no Create a feature and use -B $ hg book booktest $ echo first > a $ hg ci -Amfirst -d '7 0' adding a $ echo second > b $ hg ci -Amsecond -d '8 0' adding b $ hg email --date '1981-1-1 0:1' -n -t foo -s bookmark -B booktest From [test]: test this patch series consists of 2 patches. Write the introductory message for the patch series. Cc: displaying [PATCH 0 of 2] bookmark ... MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Subject: [PATCH 0 of 2] bookmark Message-Id: <patchbomb.347155260@test-hostname> User-Agent: Mercurial-patchbomb/* (glob) Date: Thu, 01 Jan 1981 00:01:00 +0000 From: test To: foo displaying [PATCH 1 of 2] first ... MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Subject: [PATCH 1 of 2] first X-Mercurial-Node: accde9b8b6dce861c185d0825c1affc09a79cb26 X-Mercurial-Series-Index: 1 X-Mercurial-Series-Total: 2 Message-Id: <accde9b8b6dce861c185.347155261@test-hostname> X-Mercurial-Series-Id: <accde9b8b6dce861c185.347155261@test-hostname> In-Reply-To: <patchbomb.347155260@test-hostname> References: <patchbomb.347155260@test-hostname> User-Agent: Mercurial-patchbomb/* (glob) Date: Thu, 01 Jan 1981 00:01:01 +0000 From: test To: foo # HG changeset patch # User test # Date 7 0 # Thu Jan 01 00:00:07 1970 +0000 # Node ID accde9b8b6dce861c185d0825c1affc09a79cb26 # Parent 043bd3889e5aaf7d88fe3713cf425f782ad2fb71 first diff -r 043bd3889e5a -r accde9b8b6dc a --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/a Thu Jan 01 00:00:07 1970 +0000 @@ -0,0 +1,1 @@ +first displaying [PATCH 2 of 2] second ... MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Subject: [PATCH 2 of 2] second X-Mercurial-Node: 417defd1559c396ba06a44dce8dc1c2d2d653f3f X-Mercurial-Series-Index: 2 X-Mercurial-Series-Total: 2 Message-Id: <417defd1559c396ba06a.347155262@test-hostname> X-Mercurial-Series-Id: <accde9b8b6dce861c185.347155261@test-hostname> In-Reply-To: <patchbomb.347155260@test-hostname> References: <patchbomb.347155260@test-hostname> User-Agent: Mercurial-patchbomb/* (glob) Date: Thu, 01 Jan 1981 00:01:02 +0000 From: test To: foo # HG changeset patch # User test # Date 8 0 # Thu Jan 01 00:00:08 1970 +0000 # Node ID 417defd1559c396ba06a44dce8dc1c2d2d653f3f # Parent accde9b8b6dce861c185d0825c1affc09a79cb26 second diff -r accde9b8b6dc -r 417defd1559c b --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/b Thu Jan 01 00:00:08 1970 +0000 @@ -0,0 +1,1 @@ +second Do the same and combine with -o only one must be exported $ cd .. $ hg clone repo repo2 updating to bookmark @ 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd repo $ hg up @ 0 files updated, 0 files merged, 2 files removed, 0 files unresolved (activating bookmark @) $ hg book outgoing $ echo 1 > x $ hg ci -Am1 -d '8 0' adding x created new head $ hg push ../repo2 -B outgoing pushing to ../repo2 searching for changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files (+1 heads) exporting bookmark outgoing $ echo 2 > y $ hg ci -Am2 -d '9 0' adding y $ hg email --date '1982-1-1 0:1' -n -t foo -s bookmark -B outgoing -o ../repo2 comparing with ../repo2 From [test]: test this patch series consists of 1 patches. Cc: displaying [PATCH] bookmark ... MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Subject: [PATCH] bookmark X-Mercurial-Node: 8dab2639fd35f1e337ad866c372a5c44f1064e3c X-Mercurial-Series-Index: 1 X-Mercurial-Series-Total: 1 Message-Id: <8dab2639fd35f1e337ad.378691260@test-hostname> X-Mercurial-Series-Id: <8dab2639fd35f1e337ad.378691260@test-hostname> User-Agent: Mercurial-patchbomb/* (glob) Date: Fri, 01 Jan 1982 00:01:00 +0000 From: test To: foo # HG changeset patch # User test # Date 9 0 # Thu Jan 01 00:00:09 1970 +0000 # Node ID 8dab2639fd35f1e337ad866c372a5c44f1064e3c # Parent 0b24b8316483bf30bfc3e4d4168e922b169dbe66 2 diff -r 0b24b8316483 -r 8dab2639fd35 y --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/y Thu Jan 01 00:00:09 1970 +0000 @@ -0,0 +1,1 @@ +2