view tests/test-url-rev.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

Test basic functionality of url#rev syntax

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -qAm 'add a'
  $ hg branch foo
  marked working directory as branch foo
  (branches are permanent and global, did you want a bookmark?)
  $ echo >> a
  $ hg ci -m 'change a'
  $ cd ..

  $ hg clone 'repo#foo' clone
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 1f0dee641bb7:cd2a86ecc814
  updating to branch foo
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg --cwd clone heads
  changeset:   1:cd2a86ecc814
  branch:      foo
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change a
  
  changeset:   0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a
  
  $ hg --cwd clone parents
  changeset:   1:cd2a86ecc814
  branch:      foo
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change a
  
  $ cat clone/.hg/hgrc
  # example repository config (see 'hg help config' for more info)
  [paths]
  default = $TESTTMP/repo#foo
  
  # path aliases to other clones of this repo in URLs or filesystem paths
  # (see 'hg help config.paths' for more info)
  #
  # default:pushurl = ssh://[e-mail]/hg/jdoes-fork
  # my-fork         = ssh://[e-mail]/hg/jdoes-fork
  # my-clone        = /home/jdoe/jdoes-clone
  
  [ui]
  # name and email (local to this repository, optional), e.g.
  # username = Jane Doe <[e-mail]>

Changing original repo:

  $ cd repo

  $ echo >> a
  $ hg ci -m 'new head of branch foo'

  $ hg up -qC default
  $ echo bar > bar
  $ hg ci -qAm 'add bar'

  $ hg log
  changeset:   3:4cd725637392
  tag:         tip
  parent:      0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add bar
  
  changeset:   2:faba9097cad4
  branch:      foo
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     new head of branch foo
  
  changeset:   1:cd2a86ecc814
  branch:      foo
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change a
  
  changeset:   0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a
  
  $ hg -q outgoing '../clone'
  2:faba9097cad4
  3:4cd725637392
  $ hg summary --remote --config paths.default='../clone'
  parent: 3:4cd725637392 tip
   add bar
  branch: default
  commit: (clean)
  update: (current)
  phases: 4 draft
  remote: 2 outgoing
  $ hg -q outgoing '../clone#foo'
  2:faba9097cad4
  $ hg summary --remote --config paths.default='../clone#foo'
  parent: 3:4cd725637392 tip
   add bar
  branch: default
  commit: (clean)
  update: (current)
  phases: 4 draft
  remote: 1 outgoing

  $ hg -q --cwd ../clone incoming '../repo#foo'
  2:faba9097cad4
  $ hg --cwd ../clone summary --remote --config paths.default='../repo#foo'
  parent: 1:cd2a86ecc814 tip
   change a
  branch: foo
  commit: (clean)
  update: (current)
  remote: 1 or more incoming

  $ hg -q push '../clone#foo'

  $ hg --cwd ../clone heads
  changeset:   2:faba9097cad4
  branch:      foo
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     new head of branch foo
  
  changeset:   0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a
  
  $ hg -q --cwd ../clone incoming '../repo#foo'
  [1]
  $ hg --cwd ../clone summary --remote --config paths.default='../repo#foo'
  parent: 1:cd2a86ecc814 
   change a
  branch: foo
  commit: (clean)
  update: 1 new changesets (update)
  remote: (synced)

  $ cd ..

  $ cd clone
  $ hg rollback
  repository tip rolled back to revision 1 (undo push)

  $ hg -q incoming
  2:faba9097cad4

  $ hg -q pull

  $ hg heads
  changeset:   2:faba9097cad4
  branch:      foo
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     new head of branch foo
  
  changeset:   0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a
  
Pull should not have updated:

  $ hg parents -q
  1:cd2a86ecc814

Going back to the default branch:

  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg parents
  changeset:   0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a
  
No new revs, no update:

  $ hg pull -qu

  $ hg parents -q
  0:1f0dee641bb7

  $ hg rollback
  repository tip rolled back to revision 1 (undo pull)

  $ hg parents -q
  0:1f0dee641bb7

Pull -u takes us back to branch foo:

  $ hg pull -qu

  $ hg parents
  changeset:   2:faba9097cad4
  branch:      foo
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     new head of branch foo
  
  $ hg rollback
  repository tip rolled back to revision 1 (undo pull)
  working directory now based on revision 0

  $ hg up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg parents -q
  0:1f0dee641bb7

  $ hg heads -q
  1:cd2a86ecc814
  0:1f0dee641bb7

  $ hg pull -qur default default

  $ hg parents
  changeset:   3:4cd725637392
  tag:         tip
  parent:      0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add bar
  
  $ hg heads
  changeset:   3:4cd725637392
  tag:         tip
  parent:      0:1f0dee641bb7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add bar
  
  changeset:   2:faba9097cad4
  branch:      foo
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     new head of branch foo
  
Test handling of invalid urls

  $ hg id http://foo/?bar
  abort: unsupported URL component: "bar"
  [255]

  $ cd ..

Test handling common incoming revisions between "default" and
"default-push"

  $ hg -R clone rollback
  repository tip rolled back to revision 1 (undo pull)
  working directory now based on revision 0

  $ cd repo

  $ hg update -q -C default
  $ echo modified >> bar
  $ hg commit -m "new head to push current default head"
  $ hg -q push -r ".^1" '../clone'

  $ hg -q outgoing '../clone'
  2:faba9097cad4
  4:d515801a8f3d

  $ hg summary --remote --config paths.default='../clone#default' --config paths.default-push='../clone#foo'
  parent: 4:d515801a8f3d tip
   new head to push current default head
  branch: default
  commit: (clean)
  update: (current)
  phases: 1 draft
  remote: 1 outgoing

  $ hg summary --remote --config paths.default='../clone#foo' --config paths.default-push='../clone'
  parent: 4:d515801a8f3d tip
   new head to push current default head
  branch: default
  commit: (clean)
  update: (current)
  phases: 1 draft
  remote: 2 outgoing

  $ hg summary --remote --config paths.default='../clone' --config paths.default-push='../clone#foo'
  parent: 4:d515801a8f3d tip
   new head to push current default head
  branch: default
  commit: (clean)
  update: (current)
  phases: 1 draft
  remote: 1 outgoing

  $ hg clone -q -r 0 . ../another
  $ hg -q outgoing '../another#default'
  3:4cd725637392
  4:d515801a8f3d

  $ hg summary --remote --config paths.default='../another#default' --config paths.default-push='../clone#default'
  parent: 4:d515801a8f3d tip
   new head to push current default head
  branch: default
  commit: (clean)
  update: (current)
  phases: 1 draft
  remote: 1 outgoing

  $ cd ..

Test url#rev syntax of local destination path, which should be taken as
a 'url#rev' path

  $ hg clone repo '#foo'
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg root -R '#foo'
  $TESTTMP/#foo