view tests/test-histedit-base.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

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [alias]
  > tglog = log -G --template "{rev}:{node}:{phase} '{desc}'\n"
  > [extensions]
  > histedit=
  > EOF

Create repo a:

  $ hg init a
  $ cd a
  $ hg unbundle "$TESTDIR/bundles/rebase.hg"
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 7 files (+2 heads)
  new changesets cd010b8cd998:02de42196ebe (8 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg tglog
  @  7:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  |
  | o  6:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  |/|
  o |  5:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  | |
  | o  4:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  | o  3:32af7686d403cf45b5d95f2d70cebea587ac806a:draft 'D'
  | |
  | o  2:5fddd98957c8a54a4d436dfe1da9d87f21a1b97b:draft 'C'
  | |
  | o  1:42ccdea3bb16d28e1848c95fe2e44c000f3f21b1:draft 'B'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Verify that implicit base command and help are listed

  $ HGEDITOR=cat hg histedit |grep base
  #  b, base = checkout changeset and apply further changesets from there

Go to D
  $ hg update 3
  3 files updated, 0 files merged, 2 files removed, 0 files unresolved
edit the history to rebase B onto H


Rebase B onto H
  $ hg histedit 1 --commands - 2>&1 << EOF | fixbundle
  > base 02de42196ebe
  > pick 42ccdea3bb16 B
  > pick 5fddd98957c8 C
  > pick 32af7686d403 D
  > EOF

  $ hg tglog
  @  7:0937e82309df47d14176ee15e45dbec5fbdef340:draft 'D'
  |
  o  6:f778d1cbddac4ab679d9983c9bb92e4c5e09e7fa:draft 'C'
  |
  o  5:3d41b7cc708545206213a842f96d812d2e73d818:draft 'B'
  |
  o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  |
  | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  |/|
  o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  | |
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Rebase back and drop something
  $ hg histedit 5 --commands - 2>&1 << EOF | fixbundle
  > base cd010b8cd998
  > pick 3d41b7cc7085 B
  > drop f778d1cbddac C
  > pick 0937e82309df D
  > EOF

  $ hg tglog
  @  6:476cc3e4168da2d036b141f7f7dcff7f8e3fe846:draft 'D'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Split stack
  $ hg histedit 5 --commands - 2>&1 << EOF | fixbundle
  > base cd010b8cd998
  > pick d273e35dcdf2 B
  > base cd010b8cd998
  > pick 476cc3e4168d D
  > EOF

  $ hg tglog
  @  6:d7a6f907a822c4ce6f15662ae45a42aa46d3818a:draft 'D'
  |
  | o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |/
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Abort
  $ echo x > B
  $ hg add B
  $ hg commit -m "X"
  $ hg tglog
  @  7:591369deedfdcbf57471e894999a70d7f676186d:draft 'X'
  |
  o  6:d7a6f907a822c4ce6f15662ae45a42aa46d3818a:draft 'D'
  |
  | o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |/
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
  $ hg histedit 6 --commands - 2>&1 << EOF | fixbundle
  > base d273e35dcdf2 B
  > drop d7a6f907a822 D
  > pick 591369deedfd X
  > EOF
  merging B
  warning: conflicts while merging B! (edit, then use 'hg resolve --mark')
  Fix up the change (pick 591369deedfd)
  (hg histedit --continue to resume)
  $ hg histedit --abort | fixbundle
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tglog
  @  7:591369deedfdcbf57471e894999a70d7f676186d:draft 'X'
  |
  o  6:d7a6f907a822c4ce6f15662ae45a42aa46d3818a:draft 'D'
  |
  | o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |/
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
Continue
  $ hg histedit 6 --commands - 2>&1 << EOF | fixbundle
  > base d273e35dcdf2 B
  > drop d7a6f907a822 D
  > pick 591369deedfd X
  > EOF
  merging B
  warning: conflicts while merging B! (edit, then use 'hg resolve --mark')
  Fix up the change (pick 591369deedfd)
  (hg histedit --continue to resume)
  $ echo b2 > B
  $ hg resolve --mark B
  (no more unresolved files)
  continue: hg histedit --continue
  $ hg histedit --continue | fixbundle
  $ hg tglog
  @  6:03772da75548bb42a8f1eacd8c91d0717a147fcd:draft 'X'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  

base on a previously picked changeset
  $ echo i > i
  $ hg add i
  $ hg commit -m "I"
  $ echo j > j
  $ hg add j
  $ hg commit -m "J"
  $ hg tglog
  @  8:e8c55b19d366b335626e805484110d1d5f6f2ea3:draft 'J'
  |
  o  7:b2f90fd8aa85db5569e3cfc30cd1d7739546368e:draft 'I'
  |
  o  6:03772da75548bb42a8f1eacd8c91d0717a147fcd:draft 'X'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'
  
  $ hg histedit 5 --commands - 2>&1 << EOF | fixbundle
  > pick d273e35dcdf2 B
  > pick 03772da75548 X
  > base d273e35dcdf2 B
  > pick e8c55b19d366 J
  > base d273e35dcdf2 B
  > pick b2f90fd8aa85 I
  > EOF
  hg: parse error: base "d273e35dcdf2" changeset was an edited list candidate
  (base must only use unlisted changesets)

  $ hg tglog
  @  8:e8c55b19d366b335626e805484110d1d5f6f2ea3:draft 'J'
  |
  o  7:b2f90fd8aa85db5569e3cfc30cd1d7739546368e:draft 'I'
  |
  o  6:03772da75548bb42a8f1eacd8c91d0717a147fcd:draft 'X'
  |
  o  5:d273e35dcdf21a7eb305192ef2e362887cd0a6f8:draft 'B'
  |
  | o  4:02de42196ebee42ef284b6780a87cdc96e8eaab6:draft 'H'
  | |
  | | o  3:eea13746799a9e0bfd88f29d3c2e9dc9389f524f:draft 'G'
  | |/|
  | o |  2:24b6387c8c8cae37178880f3fa95ded3cb1cf785:draft 'F'
  |/ /
  | o  1:9520eea781bcca16c1e15acc0ba14335a0e8e5ba:draft 'E'
  |/
  o  0:cd010b8cd998f3981a5a8115f94f8da4ab506089:draft 'A'