view tests/test-bad-pull.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 clone http://localhost:$HGPORT/ copy
  abort: error: Connection refused
  [255]

  $ test -d copy || echo copy: No such file or directory
  copy: No such file or directory

  $ cat > dumb.py <<EOF
  > import BaseHTTPServer, SimpleHTTPServer, os, signal
  > def run(server_class=BaseHTTPServer.HTTPServer,
  >         handler_class=SimpleHTTPServer.SimpleHTTPRequestHandler):
  >     server_address = ('localhost', int(os.environ['HGPORT']))
  >     httpd = server_class(server_address, handler_class)
  >     httpd.serve_forever()
  > signal.signal(signal.SIGTERM, lambda x: sys.exit(0))
  > run()
  > EOF

  $ python dumb.py 2>/dev/null &
  $ echo $! >> $DAEMON_PIDS

give the server some time to start running

  $ sleep 1

  $ hg clone http://localhost:$HGPORT/foo copy2 2>&1
  abort: HTTP Error 404: * (glob)
  [255]

  $ kill $!