view hgext/infinitepush/common.py @ 45095:8e04607023e5

procutil: ensure that procutil.std{out,err}.write() writes all bytes

Python 3 offers different kind of streams and it’s not guaranteed for all of
them that calling write() writes all bytes.

When Python is started in unbuffered mode, sys.std{out,err}.buffer are
instances of io.FileIO, whose write() can write less bytes for
platform-specific reasons (e.g. Linux has a 0x7ffff000 bytes maximum and could
write less if interrupted by a signal; when writing to Windows consoles, it’s
limited to 32767 bytes to avoid the "not enough space" error). This can lead to
silent loss of data, both when using sys.std{out,err}.buffer (which may in fact
not be a buffered stream) and when using the text streams sys.std{out,err}
(I’ve created a CPython bug report for that:
https://bugs.python.org/issue41221).

Python may fix the problem at some point. For now, we implement our own wrapper
for procutil.std{out,err} that calls the raw stream’s write() method until all
bytes have been written. We don’t use sys.std{out,err} for larger writes, so I
think it’s not worth the effort to patch them.

# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import os

from mercurial.node import hex

from mercurial import (
    error,
    extensions,
    pycompat,
)


def isremotebooksenabled(ui):
    return b'remotenames' in extensions._extensions and ui.configbool(
        b'remotenames', b'bookmarks'
    )


def downloadbundle(repo, unknownbinhead):
    index = repo.bundlestore.index
    store = repo.bundlestore.store
    bundleid = index.getbundle(hex(unknownbinhead))
    if bundleid is None:
        raise error.Abort(b'%s head is not known' % hex(unknownbinhead))
    bundleraw = store.read(bundleid)
    return _makebundlefromraw(bundleraw)


def _makebundlefromraw(data):
    fp = None
    fd, bundlefile = pycompat.mkstemp()
    try:  # guards bundlefile
        try:  # guards fp
            fp = os.fdopen(fd, 'wb')
            fp.write(data)
        finally:
            fp.close()
    except Exception:
        try:
            os.unlink(bundlefile)
        except Exception:
            # we would rather see the original exception
            pass
        raise

    return bundlefile