view tests/test-rebase-mq.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

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > mq=
  > 
  > [mq]
  > plain=true
  > 
  > [alias]
  > tglog = log -G --template "{rev}: {node|short} '{desc}' tags: {tags}\n"
  > EOF


  $ hg init a
  $ cd a
  $ hg qinit -c

  $ echo c1 > f
  $ hg add f
  $ hg ci -m C1

  $ echo r1 > f
  $ hg ci -m R1

  $ hg up -q 0

  $ hg qnew f.patch -d '1 0'
  $ echo mq1 > f
  $ hg qref -m P0

  $ hg qnew f2.patch
  $ echo mq2 > f
  $ hg qref -m P1 -d '2 0'

  $ hg tglog
  @  3: 929394423cd3 'P1' tags: f2.patch qtip tip
  |
  o  2: 3504f44bffc0 'P0' tags: f.patch qbase
  |
  | o  1: bac9ed9960d8 'R1' tags:
  |/
  o  0: 36f36ddbca61 'C1' tags: qparent
  

Rebase - try to rebase on an applied mq patch:

  $ hg rebase -s 1 -d 3
  abort: cannot rebase onto an applied mq patch
  [255]

Rebase - same thing, but mq patch is default dest:

  $ hg up -q 1
  $ hg rebase
  abort: cannot rebase onto an applied mq patch
  [255]
  $ hg up -q qtip

Rebase - generate a conflict:

  $ hg rebase -s 2 -d 1
  rebasing 2:3504f44bffc0 f.patch qbase "P0"
  merging f
  warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

Fix the 1st conflict:

  $ echo mq1r1 > f
  $ hg resolve -m f
  (no more unresolved files)
  continue: hg rebase --continue
  $ hg rebase -c
  rebasing 2:3504f44bffc0 f.patch qbase "P0"
  rebasing 3:929394423cd3 f2.patch qtip tip "P1"
  merging f
  warning: conflicts while merging f! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see 'hg resolve', then 'hg rebase --continue')
  [240]

Fix the 2nd conflict:

  $ echo mq1r1mq2 > f
  $ hg resolve -m f
  (no more unresolved files)
  continue: hg rebase --continue
  $ hg rebase -c
  already rebased 2:3504f44bffc0 f.patch qbase "P0" as ebe9914c0d1c
  rebasing 3:929394423cd3 f2.patch qtip "P1"
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/3504f44bffc0-30595b40-rebase.hg

  $ hg tglog
  @  3: 462012cf340c 'P1' tags: f2.patch qtip tip
  |
  o  2: ebe9914c0d1c 'P0' tags: f.patch qbase
  |
  o  1: bac9ed9960d8 'R1' tags: qparent
  |
  o  0: 36f36ddbca61 'C1' tags:
  
  $ hg up -q qbase

  $ cat f
  mq1r1

  $ cat .hg/patches/f.patch
  # HG changeset patch
  # User test
  # Date 1 0
  #      Thu Jan 01 00:00:01 1970 +0000
  # Node ID ebe9914c0d1c3f60096e952fa4dbb3d377dea3ab
  # Parent  bac9ed9960d8992bcad75864a879fa76cadaf1b0
  P0
  
  diff -r bac9ed9960d8 -r ebe9914c0d1c f
  --- a/f	Thu Jan 01 00:00:00 1970 +0000
  +++ b/f	Thu Jan 01 00:00:01 1970 +0000
  @@ -1,1 +1,1 @@
  -r1
  +mq1r1

Update to qtip:

  $ hg up -q qtip

  $ cat f
  mq1r1mq2

  $ cat .hg/patches/f2.patch
  # HG changeset patch
  # User test
  # Date 2 0
  #      Thu Jan 01 00:00:02 1970 +0000
  # Node ID 462012cf340c97d44d62377c985a423f6bb82f07
  # Parent  ebe9914c0d1c3f60096e952fa4dbb3d377dea3ab
  P1
  
  diff -r ebe9914c0d1c -r 462012cf340c f
  --- a/f	Thu Jan 01 00:00:01 1970 +0000
  +++ b/f	Thu Jan 01 00:00:02 1970 +0000
  @@ -1,1 +1,1 @@
  -mq1r1
  +mq1r1mq2

Adding one git-style patch and one normal:

  $ hg qpop -a
  popping f2.patch
  popping f.patch
  patch queue now empty

  $ rm -fr .hg/patches
  $ hg qinit -c

  $ hg up -q 0

  $ hg qnew --git f_git.patch -d '3 0'
  $ echo mq1 > p
  $ hg add p
  $ hg qref --git -m 'P0 (git)'

  $ hg qnew f.patch -d '4 0'
  $ echo mq2 > p
  $ hg qref -m P1
  $ hg qci -m 'save patch state'

  $ hg qseries -s
  f_git.patch: P0 (git)
  f.patch: P1

  $ hg -R .hg/patches manifest
  .hgignore
  f.patch
  f_git.patch
  series

  $ cat .hg/patches/f_git.patch
  Date: 3 0
  
  P0 (git)
  
  diff --git a/p b/p
  new file mode 100644
  --- /dev/null
  +++ b/p
  @@ -0,0 +1,1 @@
  +mq1

  $ cat .hg/patches/f.patch
  Date: 4 0
  
  P1
  
  diff -r ???????????? p (glob)
  --- a/p	??? ??? ?? ??:??:?? ???? ????? (glob)
  +++ b/p	??? ??? ?? ??:??:?? ???? ????? (glob)
  @@ -1,1 +1,1 @@
  -mq1
  +mq2


Rebase the applied mq patches:

  $ hg rebase -s 2 -d 1
  rebasing 2:0c587ffcb480 f_git.patch qbase "P0 (git)"
  rebasing 3:c7f18665e4bc f.patch qtip tip "P1"
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/0c587ffcb480-0ea5695f-rebase.hg

  $ hg qci -m 'save patch state'

  $ hg qseries -s
  f_git.patch: P0 (git)
  f.patch: P1

  $ hg -R .hg/patches manifest
  .hgignore
  f.patch
  f_git.patch
  series

  $ cat .hg/patches/f_git.patch
  # HG changeset patch
  # User test
  # Date 3 0
  #      Thu Jan 01 00:00:03 1970 +0000
  # Node ID 12d9f6a3bbe560dee50c7c454d434add7fb8e837
  # Parent  bac9ed9960d8992bcad75864a879fa76cadaf1b0
  P0 (git)
  
  diff --git a/p b/p
  new file mode 100644
  --- /dev/null
  +++ b/p
  @@ -0,0 +1,1 @@
  +mq1

  $ cat .hg/patches/f.patch
  # HG changeset patch
  # User test
  # Date 4 0
  #      Thu Jan 01 00:00:04 1970 +0000
  # Node ID c77a2661c64c60d82f63c4f7aefd95b3a948a557
  # Parent  12d9f6a3bbe560dee50c7c454d434add7fb8e837
  P1
  
  diff -r 12d9f6a3bbe5 -r c77a2661c64c p
  --- a/p	Thu Jan 01 00:00:03 1970 +0000
  +++ b/p	Thu Jan 01 00:00:04 1970 +0000
  @@ -1,1 +1,1 @@
  -mq1
  +mq2

  $ cd ..

Rebase with guards

  $ hg init foo
  $ cd foo
  $ echo a > a
  $ hg ci -Am a
  adding a

Create mq repo with guarded patches foo and bar and empty patch:

  $ hg qinit
  $ echo guarded > guarded
  $ hg add guarded
  $ hg qnew guarded
  $ hg qnew empty-important -m 'important commit message' -d '1 0'
  $ echo bar > bar
  $ hg add bar
  $ hg qnew bar -d '2 0'
  $ echo foo > foo
  $ hg add foo
  $ hg qnew foo
  $ hg qpop -a
  popping foo
  popping bar
  popping empty-important
  popping guarded
  patch queue now empty
  $ hg qguard guarded +guarded
  $ hg qguard bar +baz
  $ hg qguard foo +baz
  $ hg qselect baz
  number of unguarded, unapplied patches has changed from 1 to 3
  $ hg qpush bar
  applying empty-important
  patch empty-important is empty
  applying bar
  now at: bar

  $ hg qguard -l
  guarded: +guarded
  empty-important: unguarded
  bar: +baz
  foo: +baz

  $ hg tglog
  @  2: 4f44b861d38c 'imported patch bar' tags: bar qtip tip
  |
  o  1: 0aaf4c3af7eb 'important commit message' tags: empty-important qbase
  |
  o  0: cb9a9f314b8b 'a' tags: qparent
  
Create new head to rebase bar onto:

  $ hg up -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo b > b
  $ hg add b
  $ hg ci -m b
  created new head
  $ hg up -C 2
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a >> a
  $ hg qref

  $ hg tglog
  @  3: d526d4536ed6 '[mq]: bar' tags: bar qtip tip
  |
  | o  2: d2ae7f538514 'b' tags:
  | |
  o |  1: 0aaf4c3af7eb 'important commit message' tags: empty-important qbase
  |/
  o  0: cb9a9f314b8b 'a' tags: qparent
  

Rebase bar (make sure series order is preserved and empty-important also is
removed from the series):

  $ hg qseries
  guarded
  empty-important
  bar
  foo
  $ [ -f .hg/patches/empty-important ]
  $ hg -q rebase -d 2
  note: not rebasing 1:0aaf4c3af7eb empty-important qbase "important commit message", its destination already has all its changes
  $ hg qseries
  guarded
  bar
  foo
  $ [ -f .hg/patches/empty-important ]
  [1]

  $ hg qguard -l
  guarded: +guarded
  bar: +baz
  foo: +baz

  $ hg tglog
  @  2: 477d948bb2af '[mq]: bar' tags: bar qbase qtip tip
  |
  o  1: d2ae7f538514 'b' tags: qparent
  |
  o  0: cb9a9f314b8b 'a' tags:
  
  $ cd ..