mercurial/py3kcompat.py

windows: allow readpipe() to actually read data out of the pipe

It appears that the read() in readpipe() never actually ran before (in
test-ssh.t anyway).  A print of the size returned from os.fstat() is 0 for every
single print output in test-ssh.t, so the data in the pipe ends up being read
later instead of when it is available.  This is the same problem as Linux, as
mentioned in 331cbf088c4c.

There are several places in the Windows SSH tests where the order of local
output vs remote output differ from the other platforms.  This only fixes one of
those cases (and interstingly, not the one added in order to test 331cbf088c4c),
so there is more investigation needed.  However, without this patch, test-ssh.t
also has this diff:

    --- c:/Users/Matt/Projects/hg/tests/test-ssh.t
    +++ c:/Users/Matt/Projects/hg/tests/test-ssh.t.err
    @@ -397,11 +397,11 @@
       $ hg push --ssh "sh ../ssh.sh"
       pushing to ssh://user@dummy/*/remote (glob)
       searching for changes
    -  remote: Permission denied
    -  remote: abort: prechangegroup.hg-ssh hook failed
    -  remote: Permission denied
    -  remote: pushkey-abort: prepushkey.hg-ssh hook failed
       updating 6c0482d977a3 to public failed!
    +  remote: Permission denied
    +  remote: abort: prechangegroup.hg-ssh hook failed
    +  remote: Permission denied
    +  remote: pushkey-abort: prepushkey.hg-ssh hook failed
       [1]

       $ cd ..

Output with this change was stable over 600+ runs of test-ssh.t.  I initially
tried a background thread to read the pipe[1], but this was simpler and the test
results were exactly the same.  I also tried SetNamedPipeHandleState(), but the
PIPE_NOWAIT is for compatibility with LANMAN 2.0, not for async I/O (the results
were identical though).

[1] http://eyalarubas.com/python-subproc-nonblock.html

# py3kcompat.py - compatibility definitions for running hg in py3k
#
# Copyright 2010 Renato Cunha <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import builtins

from numbers import Number

def bytesformatter(format, args):
    '''Custom implementation of a formatter for bytestrings.

    This function currently relies on the string formatter to do the
    formatting and always returns bytes objects.

    >>> bytesformatter(20, 10)
    0
    >>> bytesformatter('unicode %s, %s!', ('string', 'foo'))
    b'unicode string, foo!'
    >>> bytesformatter(b'test %s', 'me')
    b'test me'
    >>> bytesformatter('test %s', 'me')
    b'test me'
    >>> bytesformatter(b'test %s', b'me')
    b'test me'
    >>> bytesformatter('test %s', b'me')
    b'test me'
    >>> bytesformatter('test %d: %s', (1, b'result'))
    b'test 1: result'
    '''
    # The current implementation just converts from bytes to unicode, do
    # what's needed and then convert the results back to bytes.
    # Another alternative is to use the Python C API implementation.
    if isinstance(format, Number):
        # If the fixer erroneously passes a number remainder operation to
        # bytesformatter, we just return the correct operation
        return format % args
    if isinstance(format, bytes):
        format = format.decode('utf-8', 'surrogateescape')
    if isinstance(args, bytes):
        args = args.decode('utf-8', 'surrogateescape')
    if isinstance(args, tuple):
        newargs = []
        for arg in args:
            if isinstance(arg, bytes):
                arg = arg.decode('utf-8', 'surrogateescape')
            newargs.append(arg)
        args = tuple(newargs)
    ret = format % args
    return ret.encode('utf-8', 'surrogateescape')
builtins.bytesformatter = bytesformatter

origord = builtins.ord
def fakeord(char):
    if isinstance(char, int):
        return char
    return origord(char)
builtins.ord = fakeord

if __name__ == '__main__':
    import doctest
    doctest.testmod()