Mercurial > hg
view tests/test-issue3084.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 | 9d5c27890790 |
children |
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$ echo "[extensions]" >> $HGRCPATH $ echo "largefiles =" >> $HGRCPATH Create the repository outside $HOME since largefiles write to $HOME/.cache/largefiles. $ hg init test $ cd test $ echo "root" > root $ hg add root $ hg commit -m "Root commit" --config extensions.largefiles=! Ensure that .hg/largefiles isn't created before largefiles are added #if unix-permissions $ chmod 555 .hg #endif $ hg status #if unix-permissions $ chmod 755 .hg #endif $ test -f .hg/largefiles [1] $ echo "large" > foo $ hg add --large foo $ hg commit -m "Add foo as a largefile" $ hg update -r 0 getting changed largefiles 0 largefiles updated, 1 removed 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo "normal" > foo $ hg add foo $ hg commit -m "Add foo as normal file" created new head Normal file in the working copy, keeping the normal version: $ echo "n" | hg merge --config ui.interactive=Yes remote turned local normal file foo into a largefile use (l)argefile or keep (n)ormal file? n 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status $ cat foo normal Normal file in the working copy, keeping the largefile version: $ hg update -q -C $ echo "l" | hg merge --config ui.interactive=Yes remote turned local normal file foo into a largefile use (l)argefile or keep (n)ormal file? l getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status M foo $ hg diff --nodates diff -r fa129ab6b5a7 .hglf/foo --- /dev/null +++ b/.hglf/foo @@ -0,0 +1,1 @@ +7f7097b041ccf68cc5561e9600da4655d21c6d18 diff -r fa129ab6b5a7 foo --- a/foo +++ /dev/null @@ -1,1 +0,0 @@ -normal $ cat foo large Largefile in the working copy, keeping the normal version: $ hg update -q -C -r 1 $ echo "n" | hg merge --config ui.interactive=Yes remote turned local largefile foo into a normal file keep (l)argefile or use (n)ormal file? n getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status M foo $ hg diff --nodates diff -r ff521236428a .hglf/foo --- a/.hglf/foo +++ /dev/null @@ -1,1 +0,0 @@ -7f7097b041ccf68cc5561e9600da4655d21c6d18 diff -r ff521236428a foo --- /dev/null +++ b/foo @@ -0,0 +1,1 @@ +normal $ cat foo normal Largefile in the working copy, keeping the largefile version: $ hg update -q -C -r 1 $ echo "l" | hg merge --config ui.interactive=Yes remote turned local largefile foo into a normal file keep (l)argefile or use (n)ormal file? l 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg status $ cat foo large Whatever ... commit something so we can invoke merge when updating $ hg commit -m '3: Merge' Updating from largefile to normal - no reason to prompt $ hg up -r 2 getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ cat foo normal (the update above used to leave the working dir in a very weird state - clean it $ hg up -qr null $ hg up -qr 2 ) Updating from normal to largefile - no reason to prompt $ hg up -r 3 getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ cat foo large $ cd .. Systematic testing of merges involving largefiles: Ancestor: normal Parent: normal-id Parent: large result: large Ancestor: normal Parent: normal2 Parent: large result: ? Ancestor: large Parent: large-id Parent: normal result: normal Ancestor: large Parent: large2 Parent: normal result: ? All cases should try merging both ways. Prepare test repo: $ hg init merges $ cd merges prepare cases with "normal" ancestor: $ hg up -qr null $ echo normal > f $ hg ci -Aqm "normal-ancestor" $ hg tag -l "normal-ancestor" $ touch f2 $ hg ci -Aqm "normal-id" $ hg tag -l "normal-id" $ echo normal2 > f $ hg ci -m "normal2" $ hg tag -l "normal2" $ echo normal > f $ hg ci -Aqm "normal-same" $ hg tag -l "normal-same" $ hg up -qr "normal-ancestor" $ hg rm f $ echo large > f $ hg add --large f $ hg ci -qm "large" $ hg tag -l "large" prepare cases with "large" ancestor: $ hg up -qr null $ echo large > f $ hg add --large f $ hg ci -qm "large-ancestor" $ hg tag -l "large-ancestor" $ touch f2 $ hg ci -Aqm "large-id" $ hg tag -l "large-id" $ echo large2 > f $ hg ci -m "large2" $ hg tag -l "large2" $ echo large > f $ hg ci -Aqm "large-same" $ hg tag -l "large-same" $ hg up -qr "large-ancestor" $ hg rm f $ echo normal > f $ hg ci -qAm "normal" $ hg tag -l "normal" $ hg log -GT '{tags}' @ normal tip | | o large-same | | | o large2 | | | o large-id |/ o large-ancestor o large | | o normal-same | | | o normal2 | | | o normal-id |/ o normal-ancestor Ancestor: normal Parent: normal-id Parent: large result: large $ hg up -Cqr normal-id $ hg merge -r large getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large swap $ hg up -Cqr large $ hg merge -r normal-id 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large Ancestor: normal Parent: normal-same Parent: large result: large $ hg up -Cqr normal-same $ hg merge -r large getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large swap $ hg up -Cqr large $ hg merge -r normal-same 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large Ancestor: normal Parent: normal2 Parent: large result: ? (annoying extra prompt ... but it do not do any serious harm) $ hg up -Cqr normal2 $ hg merge -r large remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? l getting changed largefiles 1 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large $ hg up -Cqr normal2 $ echo n | hg merge -r large --config ui.interactive=Yes remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? n 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal2 swap $ hg up -Cqr large $ hg merge -r normal2 remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? l 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large $ hg up -Cqr large $ echo n | hg merge -r normal2 --config ui.interactive=Yes remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? n getting changed largefiles 0 largefiles updated, 0 removed 2 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal2 Ancestor: large Parent: large-id Parent: normal result: normal $ hg up -Cqr large-id $ hg merge -r normal getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal swap $ hg up -Cqr normal $ hg merge -r large-id 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal Ancestor: large Parent: large-same Parent: normal result: normal $ hg up -Cqr large-same $ hg merge -r normal getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal swap $ hg up -Cqr normal $ hg merge -r large-same 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal Ancestor: large Parent: large2 Parent: normal result: ? (annoying extra prompt ... but it do not do any serious harm) $ hg up -Cqr large2 $ hg merge -r normal remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? l 0 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large2 $ hg up -Cqr large2 $ echo n | hg merge -r normal --config ui.interactive=Yes remote turned local largefile f into a normal file keep (l)argefile or use (n)ormal file? n getting changed largefiles 0 largefiles updated, 0 removed 1 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal swap $ hg up -Cqr normal $ hg merge -r large2 remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? l getting changed largefiles 1 largefiles updated, 0 removed 2 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f large2 $ hg up -Cqr normal $ echo n | hg merge -r large2 --config ui.interactive=Yes remote turned local normal file f into a largefile use (l)argefile or keep (n)ormal file? n 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ cat f normal $ cd ..