view tests/test-mq-safety.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

  $ echo '[extensions]' >> $HGRCPATH
  $ echo 'hgext.mq =' >> $HGRCPATH

  $ hg init repo
  $ cd repo

  $ echo foo > foo
  $ hg ci -qAm 'add a file'

  $ hg qinit

  $ hg qnew foo
  $ echo foo >> foo
  $ hg qrefresh -m 'append foo'

  $ hg qnew bar
  $ echo bar >> foo
  $ hg qrefresh -m 'append bar'

Try to operate on public mq changeset

  $ hg qpop
  popping bar
  now at: foo
  $ hg phase --public qbase
  $ echo babar >> foo
  $ hg qref
  abort: cannot qrefresh public revision
  (see 'hg help phases' for details)
  [255]
  $ hg revert -a
  reverting foo
  $ hg qpop
  abort: popping would remove a public revision
  (see 'hg help phases' for details)
  [255]
  $ hg qfold bar
  abort: cannot qrefresh public revision
  (see 'hg help phases' for details)
  [255]
  $ hg revert -a
  reverting foo

restore state for remaining test

  $ hg qpush
  applying bar
  now at: bar

try to commit on top of a patch

  $ echo quux >> foo
  $ hg ci -m 'append quux'
  abort: cannot commit over an applied mq patch
  [255]


cheat a bit...

  $ mv .hg/patches .hg/patches2
  $ hg ci -m 'append quux'
  $ mv .hg/patches2 .hg/patches


qpop/qrefresh on the wrong revision

  $ hg qpop
  abort: popping would remove a revision not managed by this patch queue
  [255]
  $ hg qpop -n patches
  using patch queue: $TESTTMP/repo/.hg/patches
  abort: popping would remove a revision not managed by this patch queue
  [255]
  $ hg qrefresh
  abort: working directory revision is not qtip
  [255]

  $ hg up -C qtip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg qpop
  abort: popping would remove a revision not managed by this patch queue
  [255]
  $ hg qrefresh
  abort: cannot qrefresh a revision with children
  [255]
  $ hg tip --template '{rev} {desc}\n'
  3 append quux


qpush warning branchheads

  $ cd ..
  $ hg init branchy
  $ cd branchy
  $ echo q > q
  $ hg add q
  $ hg qnew -f qp
  $ hg qpop
  popping qp
  patch queue now empty
  $ echo a > a
  $ hg ci -Ama
  adding a
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branch b
  marked working directory as branch b
  (branches are permanent and global, did you want a bookmark?)
  $ echo c > c
  $ hg ci -Amc
  adding c
  $ hg merge default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -mmerge
  $ hg up default
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg log
  changeset:   2:65309210bf4e
  branch:      b
  tag:         tip
  parent:      1:707adb4c8ae1
  parent:      0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     merge
  
  changeset:   1:707adb4c8ae1
  branch:      b
  parent:      -1:000000000000
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
  $ hg qpush
  applying qp
  now at: qp

Testing applied patches, push and --force

  $ cd ..
  $ hg init forcepush
  $ cd forcepush
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ hg ci -m changea
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg branch branch
  marked working directory as branch branch
  (branches are permanent and global, did you want a bookmark?)
  $ echo b > b
  $ hg ci -Am addb
  adding b
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg --cwd .. clone -r 0 forcepush forcepush2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 07f494440405
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a >> a
  $ hg qnew patch

Pushing applied patch with --rev without --force

  $ hg push -r . ../forcepush2
  pushing to ../forcepush2
  abort: source has mq patches applied
  [255]

Pushing applied patch with branchhash, without --force

  $ hg push ../forcepush2#default
  pushing to ../forcepush2
  abort: source has mq patches applied
  [255]

Pushing revs excluding applied patch

  $ hg push --new-branch -r 'branch(branch)' -r 2 ../forcepush2
  pushing to ../forcepush2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

Pushing applied patch with --force

  $ hg phase --force --secret 'mq()'
  $ hg push --force -r default ../forcepush2
  pushing to ../forcepush2
  searching for changes
  no changes found (ignored 1 secret changesets)
  [1]
  $ hg phase --draft 'mq()'
  $ hg push --force -r default ../forcepush2
  pushing to ../forcepush2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)

  $ cd ..