view tests/test-extdata.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

  $ hg init repo
  $ cd repo
  $ for n in 0 1 2 3 4 5 6 7 8 9 10 11; do
  >   echo $n > $n
  >   hg ci -qAm $n
  > done

test revset support

  $ cat <<'EOF' >> .hg/hgrc
  > [extdata]
  > filedata = file:extdata.txt
  > notes = notes.txt
  > shelldata = shell:cat extdata.txt | grep 2
  > emptygrep = shell:cat extdata.txt | grep empty
  > badparse = shell:cat badparse.txt
  > EOF
  $ cat <<'EOF' > extdata.txt
  > 2 another comment on 2
  > 3
  > EOF
  $ cat <<'EOF' > notes.txt
  > f6ed this change is great!
  > e834 this is buggy :(
  > 0625 first post
  > bogusnode gives no error
  > a ambiguous node gives no error
  > EOF

  $ hg log -qr "extdata(filedata)"
  2:f6ed99a58333
  3:9de260b1e88e
  $ hg log -qr "extdata(shelldata)"
  2:f6ed99a58333

test weight of extdata() revset

  $ hg debugrevspec -p optimized "extdata(filedata) & 3"
  * optimized:
  (andsmally
    (func
      (symbol 'extdata')
      (symbol 'filedata'))
    (symbol '3'))
  3

test non-zero exit of shell command

  $ hg log -qr "extdata(emptygrep)"
  abort: extdata command 'cat extdata.txt | grep empty' failed: exited with status 1
  [255]

test bad extdata() revset source

  $ hg log -qr "extdata()"
  hg: parse error: extdata takes at least 1 string argument
  [10]
  $ hg log -qr "extdata(unknown)"
  abort: unknown extdata source 'unknown'
  [255]

test a zero-exiting source that emits garbage to confuse the revset parser

  $ cat > badparse.txt <<'EOF'
  > +---------------------------------------+
  > 9de260b1e88e
  > EOF

It might be nice if this error message mentioned where the bad string
came from (eg line X of extdata source S), but the important thing is
that we don't crash before we can print the parse error.
  $ hg log -qr "extdata(badparse)"
  hg: parse error at 0: not a prefix: +
  (+---------------------------------------+
   ^ here)
  [10]

test template support:

  $ hg log -r:3 -T "{node|short}{if(extdata('notes'), ' # {extdata('notes')}')}\n"
  06254b906311 # first post
  e8342c9a2ed1 # this is buggy :(
  f6ed99a58333 # this change is great!
  9de260b1e88e

test template cache:

  $ hg log -r:3 -T '{rev} "{extdata("notes")}" "{extdata("shelldata")}"\n'
  0 "first post" ""
  1 "this is buggy :(" ""
  2 "this change is great!" "another comment on 2"
  3 "" ""

test bad extdata() template source

  $ hg log -T "{extdata()}\n"
  hg: parse error: extdata expects one argument
  [10]
  $ hg log -T "{extdata('unknown')}\n"
  abort: unknown extdata source 'unknown'
  [255]
  $ hg log -T "{extdata(unknown)}\n"
  hg: parse error: empty data source specified
  (did you mean extdata('unknown')?)
  [10]
  $ hg log -T "{extdata('{unknown}')}\n"
  hg: parse error: empty data source specified
  [10]

we don't fix up relative file URLs, but we do run shell commands in repo root

  $ mkdir sub
  $ cd sub
  $ hg log -qr "extdata(filedata)"
  abort: error: $ENOENT$
  [100]
  $ hg log -qr "extdata(shelldata)"
  2:f6ed99a58333

  $ cd ..