view tests/test-remotefilelog-local.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 no-windows

  $ . "$TESTDIR/remotefilelog-library.sh"

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > EOF
  $ echo x > x
  $ echo y > y
  $ echo z > z
  $ hg commit -qAm xy

  $ cd ..

  $ hgcloneshallow ssh://user@dummy/master shallow -q
  3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
  $ cd shallow

# status

  $ clearcache
  $ echo xx > x
  $ echo yy > y
  $ touch a
  $ hg status
  M x
  M y
  ? a
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ hg add a
  $ hg status
  M x
  M y
  A a

# diff

  $ hg debugrebuilddirstate # fixes dirstate non-determinism
  $ hg add a
  $ clearcache
  $ hg diff
  diff -r f3d0bb0d1e48 x
  --- a/x* (glob)
  +++ b/x* (glob)
  @@ -1,1 +1,1 @@
  -x
  +xx
  diff -r f3d0bb0d1e48 y
  --- a/y* (glob)
  +++ b/y* (glob)
  @@ -1,1 +1,1 @@
  -y
  +yy
  3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)

# local commit

  $ clearcache
  $ echo a > a
  $ echo xxx > x
  $ echo yyy > y
  $ hg commit -m a
  ? files fetched over 1 fetches - (? misses, 0.00% hit ratio) over *s (glob)

# local commit where the dirstate is clean -- ensure that we do just one fetch
# (update to a commit on the server first)

  $ hg --config debug.dirstate.delaywrite=1 up 0
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ clearcache
  $ hg debugdirstate
  n 644          2 * x (glob)
  n 644          2 * y (glob)
  n 644          2 * z (glob)
  $ echo xxxx > x
  $ echo yyyy > y
  $ hg commit -m x
  created new head
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)

# restore state for future tests

  $ hg -q strip .
  $ hg -q up tip

# rebase

  $ clearcache
  $ cd ../master
  $ echo w > w
  $ hg commit -qAm w

  $ cd ../shallow
  $ hg pull
  pulling from ssh://user@dummy/master
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  new changesets fed61014d323
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg rebase -d tip
  rebasing 1:9abfe7bca547 "a"
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/9abfe7bca547-8b11e5ff-rebase.hg (glob)
  3 files fetched over 2 fetches - (3 misses, 0.00% hit ratio) over *s (glob)

# strip

  $ clearcache
  $ hg debugrebuilddirstate # fixes dirstate non-determinism
  $ hg strip -r .
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/19edf50f4de7-df3d0f74-backup.hg (glob)
  3 files fetched over 2 fetches - (3 misses, 0.00% hit ratio) over *s (glob)

# unbundle

  $ clearcache
  $ ls -A
  .hg
  w
  x
  y
  z

  $ hg debugrebuilddirstate # fixes dirstate non-determinism
  $ hg unbundle .hg/strip-backup/19edf50f4de7-df3d0f74-backup.hg
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets 19edf50f4de7 (1 drafts)
  (run 'hg update' to get a working copy)
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)

  $ hg up
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ cat a
  a

# revert

  $ clearcache
  $ hg revert -r .~2 y z
  no changes needed to z
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ hg checkout -C -r . -q

# explicit bundle should produce full bundle file

  $ hg bundle -r 2 --base 1 ../local.bundle
  1 changesets found
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ cd ..

  $ hgcloneshallow ssh://user@dummy/master shallow2 -q
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
  $ cd shallow2
  $ hg unbundle ../local.bundle
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets 19edf50f4de7 (1 drafts)
  (run 'hg update' to get a working copy)

  $ hg log -r 2 --stat
  changeset:   2:19edf50f4de7
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
   a |  1 +
   x |  2 +-
   y |  2 +-
   3 files changed, 3 insertions(+), 2 deletions(-)
  
# Merge

  $ echo merge >> w
  $ hg commit -m w
  created new head
  $ hg merge 2
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m merge
  $ hg strip -q -r ".^"

# commit without producing new node

  $ cd $TESTTMP
  $ hgcloneshallow ssh://user@dummy/master shallow3 -q
  $ cd shallow3
  $ echo 1 > A
  $ hg commit -m foo -A A
  $ hg log -r . -T '{node}\n'
  383ce605500277f879b7460a16ba620eb6930b7f
  $ hg update -r '.^' -q
  $ echo 1 > A
  $ hg commit -m foo -A A
  warning: commit already existed in the repository!
  $ hg log -r . -T '{node}\n'
  383ce605500277f879b7460a16ba620eb6930b7f