rust-hg-core: move from `ouroboros` to `self_cell`
`ouroboros` has a fundamental soundness problem that, while not applicable
today, could become applicable given new compiler optimizations.ยน
`self_cell` is a crate that accomplishes a lot of the same things that
`ouroboros` did while remaining sound (that is, unless a new soundness issue
is discovered) by not assuming as much about the memory layout of the program.
`self_cell` has been scrutinized heavily in the past few months by very
competent people, some from the compiler team and has shown no weaknesses
for a while, with a 1.0 stable release coming out a couple months ago.
Our internal API is exactly the same, this is just an implementation detail.
To reiterate, no actual soundness issue was found with our use of `ouroboros`,
but there might be evolutions of `rustc` (or even a future separate compiler)
that could generate unsound code.
[1] https://github.com/joshua-maros/ouroboros/issues/88
# 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.
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