mercurial/pushkey.py

largefiles: access to specific fields only if largefiles enabled (issue4547)

Even if largefiles extension is enabled in a repository, "repo"
object, which isn't "largefiles.reposetup()"-ed, is passed to
overridden functions in the cases below unexpectedly, because
extensions are enabled for each repositories strictly.

  (1) clone without -U:
  (2) pull with -U:
  (3) pull with --rebase:

    combination of "enabled@src", "disabled@dst" and
    "not-required@src" cause this situation.

       largefiles     requirement
    @src     @dst     @src            result
    -------- -------- --------------- --------------------
    enabled  disabled not-required    aborted unexpectedly
                      required        requirement error (intentional)
    -------- -------- --------------- --------------------
    enabled  enabled  *               success
    -------- -------- --------------- --------------------
    disabled enabled  *               success (only for "pull")
    -------- -------- --------------- --------------------
    disabled disabled not-required    success
                      required        requirement error (intentional)
    -------- -------- --------------- --------------------

  (4) update/revert with a subrepo disabling largefiles

In these cases, overridden functions cause accessing to largefiles
specific fields of not "largefiles.reposetup()"-ed "repo" object, and
execution is aborted.

  - (1), (2), (4) cause accessing to "_lfstatuswriters" in
    "getstatuswriter()" invoked via "updatelfiles()"

  - (3) causes accessing to "_lfcommithooks" in "overriderebase()"

For safe accessing to these fields, this patch examines whether passed
"repo" object is "largefiles.reposetup()"-ed or not before accessing
to them.

This patch chooses examining existence of newly introduced
"_largefilesenabled" instead of "_lfcommithooks" and
"_lfstatuswriters" directly, because the former is better name for the
generic "largefiles is enabled in this repo" mark than the latter.

In the future, all other overridden functions should avoid largefiles
specific processing for efficiency, and "_largefilesenabled" is better
also for such purpose.

BTW, "lfstatus" can't be used for such purpose, because some code
paths set it forcibly regardless of existence of it in specified
"repo" object.

# pushkey.py - dispatching for pushing and pulling keys
#
# Copyright 2010 Matt Mackall <[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 bookmarks, phases, obsolete, encoding

def _nslist(repo):
    n = {}
    for k in _namespaces:
        n[k] = ""
    if not obsolete.isenabled(repo, obsolete.exchangeopt):
        n.pop('obsolete')
    return n

_namespaces = {"namespaces": (lambda *x: False, _nslist),
               "bookmarks": (bookmarks.pushbookmark, bookmarks.listbookmarks),
               "phases": (phases.pushphase, phases.listphases),
               "obsolete": (obsolete.pushmarker, obsolete.listmarkers),
              }

def register(namespace, pushkey, listkeys):
    _namespaces[namespace] = (pushkey, listkeys)

def _get(namespace):
    return _namespaces.get(namespace, (lambda *x: False, lambda *x: {}))

def push(repo, namespace, key, old, new):
    '''should succeed iff value was old'''
    pk = _get(namespace)[0]
    return pk(repo, key, old, new)

def list(repo, namespace):
    '''return a dict'''
    lk = _get(namespace)[1]
    return lk(repo)

encode = encoding.fromlocal

decode = encoding.tolocal

def encodekeys(keys):
    """encode the content of a pushkey namespace for exchange over the wire"""
    return '\n'.join(['%s\t%s' % (encode(k), encode(v)) for k, v in keys])

def decodekeys(data):
    """decode the content of a pushkey namespace from exchange over the wire"""
    result = {}
    for l in data.splitlines():
        k, v = l.split('\t')
        result[decode(k)] = decode(v)
    return result