view tests/test-eol-update.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

Test EOL update

  $ cat >> $HGRCPATH <<EOF
  > [diff]
  > git = 1
  > EOF

  $ seteol () {
  >     if [ $1 = "LF" ]; then
  >         EOL='\n'
  >     else
  >         EOL='\r\n'
  >     fi
  > }

  $ makerepo () {
  >     echo
  >     echo "# ==== setup repository ===="
  >     echo '% hg init'
  >     hg init repo
  >     cd repo
  > 
  >     cat > .hgeol <<EOF
  > [patterns]
  > **.txt = LF
  > EOF
  > 
  >     printf "first\nsecond\nthird\n" > a.txt
  >     printf "f\r\n" > f
  >     hg commit --addremove -m 'LF commit'
  > 
  >     cat > .hgeol <<EOF
  > [patterns]
  > **.txt = CRLF
  > f = LF
  > EOF
  > 
  >     printf "first\r\nsecond\r\nthird\r\n" > a.txt
  >     printf "f\n" > f
  >     hg commit -m 'CRLF commit'
  > 
  >     cd ..
  > }

  $ dotest () {
  >     seteol $1
  > 
  >     echo
  >     echo "% hg clone repo repo-$1"
  >     hg clone --noupdate repo repo-$1
  >     cd repo-$1
  > 
  >     cat > .hg/hgrc <<EOF
  > [extensions]
  > eol =
  > EOF
  > 
  >     hg update
  > 
  >     echo '% a.txt (before)'
  >     cat a.txt
  > 
  >     printf "first${EOL}third${EOL}" > a.txt
  > 
  >     echo '% a.txt (after)'
  >     cat a.txt
  >     echo '% hg diff'
  >     hg diff
  > 
  >     echo '% hg update 0'
  >     hg update 0
  > 
  >     echo '% a.txt'
  >     cat a.txt
  >     echo '% hg diff'
  >     hg diff
  > 
  > 
  >     cd ..
  >     rm -r repo-$1
  > }

  $ makerepo
  
  # ==== setup repository ====
  % hg init
  adding .hgeol
  adding a.txt
  adding f
  $ dotest LF
  
  % hg clone repo repo-LF
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  % a.txt (before)
  first\r (esc)
  second\r (esc)
  third\r (esc)
  % a.txt (after)
  first
  third
  % hg diff
  diff --git a/a.txt b/a.txt
  --- a/a.txt
  +++ b/a.txt
  @@ -1,3 +1,2 @@
   first\r (esc)
  -second\r (esc)
   third\r (esc)
  % hg update 0
  merging a.txt
  2 files updated, 1 files merged, 0 files removed, 0 files unresolved
  % a.txt
  first
  third
  % hg diff
  diff --git a/a.txt b/a.txt
  --- a/a.txt
  +++ b/a.txt
  @@ -1,3 +1,2 @@
   first
  -second
   third
  $ dotest CRLF
  
  % hg clone repo repo-CRLF
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  % a.txt (before)
  first\r (esc)
  second\r (esc)
  third\r (esc)
  % a.txt (after)
  first\r (esc)
  third\r (esc)
  % hg diff
  diff --git a/a.txt b/a.txt
  --- a/a.txt
  +++ b/a.txt
  @@ -1,3 +1,2 @@
   first\r (esc)
  -second\r (esc)
   third\r (esc)
  % hg update 0
  merging a.txt
  2 files updated, 1 files merged, 0 files removed, 0 files unresolved
  % a.txt
  first
  third
  % hg diff
  diff --git a/a.txt b/a.txt
  --- a/a.txt
  +++ b/a.txt
  @@ -1,3 +1,2 @@
   first
  -second
   third

Test in repo using eol extension, while keeping an eye on how filters are
applied:

  $ cd repo

  $ hg up -q -c -r null
  $ cat > .hg/hgrc <<EOF
  > [extensions]
  > eol =
  > EOF

Update to revision 0 which has no .hgeol, shouldn't use any filters, and
obviously should leave things as tidy as they were before the clean update.

  $ hg up -c -r 0 -v --debug
  resolving manifests
   branchmerge: False, force: False, partial: False
   ancestor: 000000000000, local: 000000000000+, remote: 15cbdf8ca3db
  calling hook preupdate.eol: hgext.eol.preupdate
   .hgeol: remote created -> g
  getting .hgeol
  filtering .hgeol through isbinary
   a.txt: remote created -> g
  getting a.txt
  filtering a.txt through tolf
   f: remote created -> g
  getting f
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg st

  $ hg branch b
  marked working directory as branch b
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -m b

Merge changes that apply a filter to f:

  $ hg merge 1
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg st
  M .hgeol
  M a.txt
  M f
  $ hg diff
  diff --git a/.hgeol b/.hgeol
  --- a/.hgeol
  +++ b/.hgeol
  @@ -1,2 +1,3 @@
   [patterns]
  -**.txt = LF
  +**.txt = CRLF
  +f = LF
  diff --git a/a.txt b/a.txt
  --- a/a.txt
  +++ b/a.txt
  @@ -1,3 +1,3 @@
  -first
  -second
  -third
  +first\r (esc)
  +second\r (esc)
  +third\r (esc)
  diff --git a/f b/f
  --- a/f
  +++ b/f
  @@ -1,1 +1,1 @@
  -f\r (esc)
  +f

Abort the merge with up -C to revision 0.
Note that files are filtered correctly for revision 0: f is not filtered, a.txt
is filtered with tolf, and everything is left tidy.

  $ touch .hgeol *  # ensure consistent dirtyness checks ignoring dirstate
  $ hg up -C -r 0 -v --debug
  eol: detected change in .hgeol
  resolving manifests
   branchmerge: False, force: True, partial: False
   ancestor: 1db78bdd3bd6+, local: 1db78bdd3bd6+, remote: 15cbdf8ca3db
  calling hook preupdate.eol: hgext.eol.preupdate
   .hgeol: remote is newer -> g
  getting .hgeol
  filtering .hgeol through isbinary
   a.txt: remote is newer -> g
  getting a.txt
  filtering a.txt through tolf
   f: remote is newer -> g
  getting f
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ touch .hgeol *
  $ hg st --debug
  eol: detected change in .hgeol
  filtering .hgeol through isbinary
  filtering a.txt through tolf
  skip updating dirstate: identity mismatch (?)
  $ hg diff

Things were clean, and updating again will not change anything:

  $ touch .hgeol *
  $ hg up -C -r 0 -v --debug
  eol: detected change in .hgeol
  filtering .hgeol through isbinary
  filtering a.txt through tolf
  resolving manifests
   branchmerge: False, force: True, partial: False
   ancestor: 15cbdf8ca3db+, local: 15cbdf8ca3db+, remote: 15cbdf8ca3db
  calling hook preupdate.eol: hgext.eol.preupdate
  starting 4 threads for background file closing (?)
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ touch .hgeol *
  $ hg st --debug
  eol: detected change in .hgeol
  filtering .hgeol through isbinary
  filtering a.txt through tolf

  $ cd ..

  $ rm -r repo