view tests/test-push-validation.t @ 14007:d764463b433e

atomictempfile: avoid infinite recursion in __del__().

The problem is that a programmer using atomictempfile directly can
make an innocent everyday mistake -- not enough args to the
constructor -- which escalates badly.  You would expect a simple
TypeError crash in that case, but you actually get an infinite
recursion that is surprisingly difficult to kill: it happens between
__del__() and __getattr__(), and Python does not handle infinite
recursion from __del__() well.

The fix is to not implement __getattr__(), but instead assign instance
attributes for the methods we wish to delegate to the builtin file
type: write() and fileno(). I've audited mercurial.* and hgext.* and
found no users of atomictempfile using methods other than write() and
rename(). I audited third-party extensions and found one (snap)
passing an atomictempfile to util.fstat(), so I also threw in
fileno().

The last time I submitted a similar patch, Matt proposed that we make
atomictempfile a subclass of file instead of wrapping it. Rejected on
grounds of unnecessary complexity: for one thing, it would make the
Windows implementation of posixfile quite a bit more complex. It would
have to become a subclass of file rather than a simple function -- but
since it's written in C, this is non-obvious and non-trivial.
Furthermore, there's nothing wrong with wrapping objects and
delegating methods: it's a well-established pattern that works just
fine in many cases. Subclassing is not the answer to all of life's
problems.

  $ hg init test
  $ cd test

  $ cat > .hg/hgrc <<EOF
  > [server]
  > validate=1
  > EOF

  $ echo alpha > alpha
  $ echo beta > beta
  $ hg addr
  adding alpha
  adding beta
  $ hg ci -m 1

  $ cd ..
  $ hg clone test test-clone
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd test-clone
  $ cp .hg/store/data/beta.i tmp
  $ echo blah >> beta
  $ hg ci -m '2 (corrupt)'
  $ mv tmp .hg/store/data/beta.i

Expected to fail:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   beta@1: dddc47b3ba30 in manifests not found
  2 files, 2 changesets, 2 total revisions
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]

Expected to fail:

  $ hg push
  pushing to $TESTTMP/test
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  transaction abort!
  rollback completed
  abort: missing file data for beta:dddc47b3ba30e54484720ce0f4f768a0f4b6efb9 - run hg verify
  [255]