view tests/test-narrow-shallow.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-reposimplestore

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

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [narrow]
  > serveellipses=True
  > EOF
  $ for x in `$TESTDIR/seq.py 10`
  > do
  >   echo $x > "f$x"
  >   hg add "f$x"
  > done
  $ hg commit -m "Add root files"
  $ mkdir d1 d2
  $ for x in `$TESTDIR/seq.py 10`
  > do
  >   echo d1/$x > "d1/f$x"
  >   hg add "d1/f$x"
  >   echo d2/$x > "d2/f$x"
  >   hg add "d2/f$x"
  > done
  $ hg commit -m "Add d1 and d2"
  $ for x in `$TESTDIR/seq.py 10`
  > do
  >   echo f$x rev2 > "f$x"
  >   echo d1/f$x rev2 > "d1/f$x"
  >   echo d2/f$x rev2 > "d2/f$x"
  >   hg commit -m "Commit rev2 of f$x, d1/f$x, d2/f$x"
  > done
  $ cd ..

narrow and shallow clone the d2 directory

  $ hg clone --narrow ssh://user@dummy/master shallow --include "d2" --depth 2
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 13 changes to 10 files
  new changesets *:* (glob)
  updating to branch default
  10 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd shallow
  $ hg log -T '{rev}{if(ellipsis,"...")}: {desc}\n'
  3: Commit rev2 of f10, d1/f10, d2/f10
  2: Commit rev2 of f9, d1/f9, d2/f9
  1: Commit rev2 of f8, d1/f8, d2/f8
  0...: Commit rev2 of f7, d1/f7, d2/f7
  $ hg update 0
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat d2/f7 d2/f8
  d2/f7 rev2
  d2/8

  $ cd ..

change every upstream file once

  $ cd master
  $ for x in `$TESTDIR/seq.py 10`
  > do
  >   echo f$x rev3 > "f$x"
  >   echo d1/f$x rev3 > "d1/f$x"
  >   echo d2/f$x rev3 > "d2/f$x"
  >   hg commit -m "Commit rev3 of f$x, d1/f$x, d2/f$x"
  > done
  $ cd ..

pull new changes with --depth specified. There were 10 changes to the d2
directory but the shallow pull should only fetch 3.

  $ cd shallow
  $ hg pull --depth 2
  pulling from ssh://user@dummy/master
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 10 changes to 10 files
  new changesets *:* (glob)
  (run 'hg update' to get a working copy)
  $ hg log -T '{rev}{if(ellipsis,"...")}: {desc}\n'
  7: Commit rev3 of f10, d1/f10, d2/f10
  6: Commit rev3 of f9, d1/f9, d2/f9
  5: Commit rev3 of f8, d1/f8, d2/f8
  4...: Commit rev3 of f7, d1/f7, d2/f7
  3: Commit rev2 of f10, d1/f10, d2/f10
  2: Commit rev2 of f9, d1/f9, d2/f9
  1: Commit rev2 of f8, d1/f8, d2/f8
  0...: Commit rev2 of f7, d1/f7, d2/f7

  $ hg update 4
  10 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat d2/f7 d2/f8
  d2/f7 rev3
  d2/f8 rev2
  $ hg update 7
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat d2/f10
  d2/f10 rev3

  $ cd ..

cannot clone with zero or negative depth

  $ hg clone --narrow ssh://user@dummy/master bad --include "d2" --depth 0
  requesting all changes
  remote: abort: depth must be positive, got 0
  abort: pull failed on remote
  [100]
  $ hg clone --narrow ssh://user@dummy/master bad --include "d2" --depth -1
  requesting all changes
  remote: abort: depth must be positive, got -1
  abort: pull failed on remote
  [100]