mercurial/txnutil.py

sslutil: be less strict about which ciphers are allowed when using --insecure

Python 3.10 restricted which ciphers are enabled by default, leading to
no available ciphers for TLS < 1.2.  When using the --insecure flag we
allow old TLS, so also adjust the cipher list to give connections a
chance to work.

On the server side, also loosen the cipher selection in tests (when
using the devel.serverexactprotocol option).

Differential Revision: https://phab.mercurial-scm.org/D12489

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.


import errno

from . import encoding


def mayhavepending(root):
    """return whether 'root' may have pending changes, which are
    visible to this process.
    """
    return root == encoding.environ.get(b'HG_PENDING')


def trypending(root, vfs, filename, **kwargs):
    """Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    """
    if mayhavepending(root):
        try:
            return (vfs(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)