tests/test-permissions.t

matcher: use re2 bindings if available

There are two sets of Python re2 bindings available on the internet;
this code works with both.

Using re2 can greatly improve "hg status" performance when a .hgignore
file becomes even modestly complex.

Example: "hg status" on a clean tree with 134K files, where "hg
debugignore" reports a regexp 4256 bytes in size.

  no .hgignore: 1.76 sec
  Python re:    2.79
  re2:          1.82

The overhead of regexp matching drops from 1.03 seconds with stock
re to 0.06 with re2.

(For comparison, a git repo with the same contents and .gitignore
file runs "git status -s" in 1.71 seconds, i.e. only slightly faster
than hg with re2.)

  $ "$TESTDIR/hghave" unix-permissions || exit 80

  $ hg init t
  $ cd t

  $ echo foo > a
  $ hg add a

  $ hg commit -m "1"

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ chmod -r .hg/store/data/a.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
  [255]

  $ chmod +r .hg/store/data/a.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ chmod -w .hg/store/data/a.i

  $ echo barber > a
  $ hg commit -m "2"
  trouble committing a!
  abort: Permission denied: $TESTTMP/t/.hg/store/data/a.i
  [255]

  $ chmod -w .

  $ hg diff --nodates
  diff -r 2a18120dc1c9 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,1 @@
  -foo
  +barber

  $ chmod +w .

  $ chmod +w .hg/store/data/a.i
  $ mkdir dir
  $ touch dir/a
  $ hg status
  M a
  ? dir/a
  $ chmod -rx dir
  $ hg status
  dir: Permission denied
  M a

Reenable perm to allow deletion:

  $ chmod +rx dir

  $ cd ..