view tests/test-revlog-v2.t @ 49000:dd6b67d5c256 stable

rust: fix unsound `OwningDirstateMap`

As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.

The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.

I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.

In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.

Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.

Differential Revision: https://phab.mercurial-scm.org/D12429

#require reporevlogstore

A repo with unknown revlogv2 requirement string cannot be opened

  $ hg init invalidreq
  $ cd invalidreq
  $ echo exp-revlogv2.unknown >> .hg/requires
  $ hg log
  abort: repository requires features unknown to this Mercurial: exp-revlogv2.unknown
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]
  $ cd ..

Can create and open repo with revlog v2 requirement

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > revlogv2 = enable-unstable-format-and-corrupt-my-data
  > EOF

  $ hg init new-repo
  $ cd new-repo
  $ hg debugrequires | grep revlogv2
  exp-revlogv2.2
  dirstate-v2 (dirstate-v2 !)

  $ hg log

Unknown flags to revlog are rejected

  >>> with open('.hg/store/00changelog.i', 'wb') as fh:
  ...     fh.write(b'\xff\x00\xde\xad') and None

  $ hg log
  abort: unknown flags (0xff00) in version 57005 revlog 00changelog
  [50]

  $ cd ..

Writing a simple revlog v2 works

  $ hg init simple
  $ cd simple
  $ touch foo
  $ hg -q commit -A -m initial

  $ hg log
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  

Header written as expected

  $ f --hexdump --bytes 4 .hg/store/00changelog.i
  .hg/store/00changelog.i:
  0000: 00 00 de ad                                     |....|

  $ f --hexdump --bytes 4 .hg/store/data/foo.i
  .hg/store/data/foo.i:
  0000: 00 00 de ad                                     |....|

Bundle use a compatible changegroup format
------------------------------------------

  $ hg bundle --all ../basic.hg
  1 changesets found
  $ hg debugbundle --spec ../basic.hg
  bzip2-v2

The expected files are generated
--------------------------------

We should have have:
- a docket
- a index file with a unique name
- a data file

  $ ls .hg/store/00changelog* .hg/store/00manifest*
  .hg/store/00changelog-1335303a.sda
  .hg/store/00changelog-6b8ab34b.idx
  .hg/store/00changelog-b875dfc5.dat
  .hg/store/00changelog.i
  .hg/store/00manifest-05a21d65.idx
  .hg/store/00manifest-43c37dde.dat
  .hg/store/00manifest-e2c9362a.sda
  .hg/store/00manifest.i

Local clone works
-----------------

  $ hg clone . ../cloned-repo
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tip | tee ../tip-new
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  
  $ hg tip -R ../cloned-repo | tee ../tip-cloned
  changeset:   0:96ee1d7354c4
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  

The two repository should be identical, this diff MUST be empty

  $ cmp ../tip-new ../tip-cloned || diff -U8 ../tip-new ../tip-cloned


hg verify should be happy
-------------------------

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files

  $ hg verify -R ../cloned-repo
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files