view mercurial/bookmarks.py @ 33436:9bb4decd43b0

repovfs: add a ward to check if locks are properly taken

When the appropriate developer warnings are enabled, We wrap 'repo.vfs.audit' to
check for locks when accessing file in '.hg' for writing. Another changeset will
add a 'ward' for the store vfs (svfs).

This check system has caught a handful of locking issues that have been fixed
in previous series (mostly in 4.0). I expect another batch to be caught in third
party extensions.

We introduce two real exceptions from extensions 'blackbox.log' (because a lot of
read-only operations add entry to it), and 'last-email.txt' (because 'hg email'
is currently a read only operation and there is value to keep it this way).

In addition we are currently allowing bisect to operate outside of the lock
because the current code is a bit hard to get properly locked for now. Multiple
clean up have been made but there is still a couple of them to do and the freeze
is coming.

# Mercurial bookmark support code
#
# Copyright 2008 David Soria Parra <[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.

from __future__ import absolute_import

import errno

from .i18n import _
from .node import (
    bin,
    hex,
    short,
)
from . import (
    encoding,
    error,
    lock as lockmod,
    obsutil,
    pycompat,
    scmutil,
    txnutil,
    util,
)

# label constants
# until 3.5, bookmarks.current was the advertised name, not
# bookmarks.active, so we must use both to avoid breaking old
# custom styles
activebookmarklabel = 'bookmarks.active bookmarks.current'

def _getbkfile(repo):
    """Hook so that extensions that mess with the store can hook bm storage.

    For core, this just handles wether we should see pending
    bookmarks or the committed ones. Other extensions (like share)
    may need to tweak this behavior further.
    """
    fp, pending = txnutil.trypending(repo.root, repo.vfs, 'bookmarks')
    return fp

class bmstore(dict):
    """Storage for bookmarks.

    This object should do all bookmark-related reads and writes, so
    that it's fairly simple to replace the storage underlying
    bookmarks without having to clone the logic surrounding
    bookmarks. This type also should manage the active bookmark, if
    any.

    This particular bmstore implementation stores bookmarks as
    {hash}\s{name}\n (the same format as localtags) in
    .hg/bookmarks. The mapping is stored as {name: nodeid}.
    """

    def __init__(self, repo):
        dict.__init__(self)
        self._repo = repo
        self._clean = True
        self._aclean = True
        nm = repo.changelog.nodemap
        tonode = bin # force local lookup
        setitem = dict.__setitem__
        try:
            with _getbkfile(repo) as bkfile:
                for line in bkfile:
                    line = line.strip()
                    if not line:
                        continue
                    try:
                        sha, refspec = line.split(' ', 1)
                        node = tonode(sha)
                        if node in nm:
                            refspec = encoding.tolocal(refspec)
                            setitem(self, refspec, node)
                    except (TypeError, ValueError):
                        # TypeError:
                        # - bin(...)
                        # ValueError:
                        # - node in nm, for non-20-bytes entry
                        # - split(...), for string without ' '
                        repo.ui.warn(_('malformed line in .hg/bookmarks: %r\n')
                                     % line)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
        self._active = _readactive(repo, self)

    @property
    def active(self):
        return self._active

    @active.setter
    def active(self, mark):
        if mark is not None and mark not in self:
            raise AssertionError('bookmark %s does not exist!' % mark)

        self._active = mark
        self._aclean = False

    def __setitem__(self, *args, **kwargs):
        self._clean = False
        return dict.__setitem__(self, *args, **kwargs)

    def __delitem__(self, key):
        self._clean = False
        return dict.__delitem__(self, key)

    def recordchange(self, tr):
        """record that bookmarks have been changed in a transaction

        The transaction is then responsible for updating the file content."""
        tr.addfilegenerator('bookmarks', ('bookmarks',), self._write,
                            location='plain')
        tr.hookargs['bookmark_moved'] = '1'

    def _writerepo(self, repo):
        """Factored out for extensibility"""
        rbm = repo._bookmarks
        if rbm.active not in self:
            rbm.active = None
            rbm._writeactive()

        with repo.wlock():
            file_ = repo.vfs('bookmarks', 'w', atomictemp=True,
                             checkambig=True)
            try:
                self._write(file_)
            except: # re-raises
                file_.discard()
                raise
            finally:
                file_.close()

    def _writeactive(self):
        if self._aclean:
            return
        with self._repo.wlock():
            if self._active is not None:
                f = self._repo.vfs('bookmarks.current', 'w', atomictemp=True,
                                   checkambig=True)
                try:
                    f.write(encoding.fromlocal(self._active))
                finally:
                    f.close()
            else:
                self._repo.vfs.tryunlink('bookmarks.current')
        self._aclean = True

    def _write(self, fp):
        for name, node in self.iteritems():
            fp.write("%s %s\n" % (hex(node), encoding.fromlocal(name)))
        self._clean = True
        self._repo.invalidatevolatilesets()

    def expandname(self, bname):
        if bname == '.':
            if self.active:
                return self.active
            else:
                raise error.Abort(_("no active bookmark"))
        return bname

    def checkconflict(self, mark, force=False, target=None):
        """check repo for a potential clash of mark with an existing bookmark,
        branch, or hash

        If target is supplied, then check that we are moving the bookmark
        forward.

        If force is supplied, then forcibly move the bookmark to a new commit
        regardless if it is a move forward.
        """
        cur = self._repo.changectx('.').node()
        if mark in self and not force:
            if target:
                if self[mark] == target and target == cur:
                    # re-activating a bookmark
                    return
                rev = self._repo[target].rev()
                anc = self._repo.changelog.ancestors([rev])
                bmctx = self._repo[self[mark]]
                divs = [self._repo[b].node() for b in self
                        if b.split('@', 1)[0] == mark.split('@', 1)[0]]

                # allow resolving a single divergent bookmark even if moving
                # the bookmark across branches when a revision is specified
                # that contains a divergent bookmark
                if bmctx.rev() not in anc and target in divs:
                    deletedivergent(self._repo, [target], mark)
                    return

                deletefrom = [b for b in divs
                              if self._repo[b].rev() in anc or b == target]
                deletedivergent(self._repo, deletefrom, mark)
                if validdest(self._repo, bmctx, self._repo[target]):
                    self._repo.ui.status(
                        _("moving bookmark '%s' forward from %s\n") %
                        (mark, short(bmctx.node())))
                    return
            raise error.Abort(_("bookmark '%s' already exists "
                                "(use -f to force)") % mark)
        if ((mark in self._repo.branchmap() or
             mark == self._repo.dirstate.branch()) and not force):
            raise error.Abort(
                _("a bookmark cannot have the name of an existing branch"))
        if len(mark) > 3 and not force:
            try:
                shadowhash = (mark in self._repo)
            except error.LookupError:  # ambiguous identifier
                shadowhash = False
            if shadowhash:
                self._repo.ui.warn(
                    _("bookmark %s matches a changeset hash\n"
                      "(did you leave a -r out of an 'hg bookmark' "
                      "command?)\n")
                    % mark)

def _readactive(repo, marks):
    """
    Get the active bookmark. We can have an active bookmark that updates
    itself as we commit. This function returns the name of that bookmark.
    It is stored in .hg/bookmarks.current
    """
    mark = None
    try:
        file = repo.vfs('bookmarks.current')
    except IOError as inst:
        if inst.errno != errno.ENOENT:
            raise
        return None
    try:
        # No readline() in osutil.posixfile, reading everything is
        # cheap.
        # Note that it's possible for readlines() here to raise
        # IOError, since we might be reading the active mark over
        # static-http which only tries to load the file when we try
        # to read from it.
        mark = encoding.tolocal((file.readlines() or [''])[0])
        if mark == '' or mark not in marks:
            mark = None
    except IOError as inst:
        if inst.errno != errno.ENOENT:
            raise
        return None
    finally:
        file.close()
    return mark

def activate(repo, mark):
    """
    Set the given bookmark to be 'active', meaning that this bookmark will
    follow new commits that are made.
    The name is recorded in .hg/bookmarks.current
    """
    repo._bookmarks.active = mark
    repo._bookmarks._writeactive()

def deactivate(repo):
    """
    Unset the active bookmark in this repository.
    """
    repo._bookmarks.active = None
    repo._bookmarks._writeactive()

def isactivewdirparent(repo):
    """
    Tell whether the 'active' bookmark (the one that follows new commits)
    points to one of the parents of the current working directory (wdir).

    While this is normally the case, it can on occasion be false; for example,
    immediately after a pull, the active bookmark can be moved to point
    to a place different than the wdir. This is solved by running `hg update`.
    """
    mark = repo._activebookmark
    marks = repo._bookmarks
    parents = [p.node() for p in repo[None].parents()]
    return (mark in marks and marks[mark] in parents)

def deletedivergent(repo, deletefrom, bm):
    '''Delete divergent versions of bm on nodes in deletefrom.

    Return True if at least one bookmark was deleted, False otherwise.'''
    deleted = False
    marks = repo._bookmarks
    divergent = [b for b in marks if b.split('@', 1)[0] == bm.split('@', 1)[0]]
    for mark in divergent:
        if mark == '@' or '@' not in mark:
            # can't be divergent by definition
            continue
        if mark and marks[mark] in deletefrom:
            if mark != bm:
                del marks[mark]
                deleted = True
    return deleted

def headsforactive(repo):
    """Given a repo with an active bookmark, return divergent bookmark nodes.

    Args:
      repo: A repository with an active bookmark.

    Returns:
      A list of binary node ids that is the full list of other
      revisions with bookmarks divergent from the active bookmark. If
      there were no divergent bookmarks, then this list will contain
      only one entry.
    """
    if not repo._activebookmark:
        raise ValueError(
            'headsforactive() only makes sense with an active bookmark')
    name = repo._activebookmark.split('@', 1)[0]
    heads = []
    for mark, n in repo._bookmarks.iteritems():
        if mark.split('@', 1)[0] == name:
            heads.append(n)
    return heads

def calculateupdate(ui, repo, checkout):
    '''Return a tuple (targetrev, movemarkfrom) indicating the rev to
    check out and where to move the active bookmark from, if needed.'''
    movemarkfrom = None
    if checkout is None:
        activemark = repo._activebookmark
        if isactivewdirparent(repo):
            movemarkfrom = repo['.'].node()
        elif activemark:
            ui.status(_("updating to active bookmark %s\n") % activemark)
            checkout = activemark
    return (checkout, movemarkfrom)

def update(repo, parents, node):
    deletefrom = parents
    marks = repo._bookmarks
    update = False
    active = marks.active
    if not active:
        return False

    if marks[active] in parents:
        new = repo[node]
        divs = [repo[b] for b in marks
                if b.split('@', 1)[0] == active.split('@', 1)[0]]
        anc = repo.changelog.ancestors([new.rev()])
        deletefrom = [b.node() for b in divs if b.rev() in anc or b == new]
        if validdest(repo, repo[marks[active]], new):
            marks[active] = new.node()
            update = True

    if deletedivergent(repo, deletefrom, active):
        update = True

    if update:
        lock = tr = None
        try:
            lock = repo.lock()
            tr = repo.transaction('bookmark')
            marks.recordchange(tr)
            tr.close()
        finally:
            lockmod.release(tr, lock)
    return update

def listbinbookmarks(repo):
    # We may try to list bookmarks on a repo type that does not
    # support it (e.g., statichttprepository).
    marks = getattr(repo, '_bookmarks', {})

    hasnode = repo.changelog.hasnode
    for k, v in marks.iteritems():
        # don't expose local divergent bookmarks
        if hasnode(v) and ('@' not in k or k.endswith('@')):
            yield k, v

def listbookmarks(repo):
    d = {}
    for book, node in listbinbookmarks(repo):
        d[book] = hex(node)
    return d

def pushbookmark(repo, key, old, new):
    w = l = tr = None
    try:
        w = repo.wlock()
        l = repo.lock()
        tr = repo.transaction('bookmarks')
        marks = repo._bookmarks
        existing = hex(marks.get(key, ''))
        if existing != old and existing != new:
            return False
        if new == '':
            del marks[key]
        else:
            if new not in repo:
                return False
            marks[key] = repo[new].node()
        marks.recordchange(tr)
        tr.close()
        return True
    finally:
        lockmod.release(tr, l, w)

def comparebookmarks(repo, srcmarks, dstmarks, targets=None):
    '''Compare bookmarks between srcmarks and dstmarks

    This returns tuple "(addsrc, adddst, advsrc, advdst, diverge,
    differ, invalid)", each are list of bookmarks below:

    :addsrc:  added on src side (removed on dst side, perhaps)
    :adddst:  added on dst side (removed on src side, perhaps)
    :advsrc:  advanced on src side
    :advdst:  advanced on dst side
    :diverge: diverge
    :differ:  changed, but changeset referred on src is unknown on dst
    :invalid: unknown on both side
    :same:    same on both side

    Each elements of lists in result tuple is tuple "(bookmark name,
    changeset ID on source side, changeset ID on destination
    side)". Each changeset IDs are 40 hexadecimal digit string or
    None.

    Changeset IDs of tuples in "addsrc", "adddst", "differ" or
     "invalid" list may be unknown for repo.

    If "targets" is specified, only bookmarks listed in it are
    examined.
    '''

    if targets:
        bset = set(targets)
    else:
        srcmarkset = set(srcmarks)
        dstmarkset = set(dstmarks)
        bset = srcmarkset | dstmarkset

    results = ([], [], [], [], [], [], [], [])
    addsrc = results[0].append
    adddst = results[1].append
    advsrc = results[2].append
    advdst = results[3].append
    diverge = results[4].append
    differ = results[5].append
    invalid = results[6].append
    same = results[7].append

    for b in sorted(bset):
        if b not in srcmarks:
            if b in dstmarks:
                adddst((b, None, dstmarks[b]))
            else:
                invalid((b, None, None))
        elif b not in dstmarks:
            addsrc((b, srcmarks[b], None))
        else:
            scid = srcmarks[b]
            dcid = dstmarks[b]
            if scid == dcid:
                same((b, scid, dcid))
            elif scid in repo and dcid in repo:
                sctx = repo[scid]
                dctx = repo[dcid]
                if sctx.rev() < dctx.rev():
                    if validdest(repo, sctx, dctx):
                        advdst((b, scid, dcid))
                    else:
                        diverge((b, scid, dcid))
                else:
                    if validdest(repo, dctx, sctx):
                        advsrc((b, scid, dcid))
                    else:
                        diverge((b, scid, dcid))
            else:
                # it is too expensive to examine in detail, in this case
                differ((b, scid, dcid))

    return results

def _diverge(ui, b, path, localmarks, remotenode):
    '''Return appropriate diverged bookmark for specified ``path``

    This returns None, if it is failed to assign any divergent
    bookmark name.

    This reuses already existing one with "@number" suffix, if it
    refers ``remotenode``.
    '''
    if b == '@':
        b = ''
    # try to use an @pathalias suffix
    # if an @pathalias already exists, we overwrite (update) it
    if path.startswith("file:"):
        path = util.url(path).path
    for p, u in ui.configitems("paths"):
        if u.startswith("file:"):
            u = util.url(u).path
        if path == u:
            return '%s@%s' % (b, p)

    # assign a unique "@number" suffix newly
    for x in range(1, 100):
        n = '%s@%d' % (b, x)
        if n not in localmarks or localmarks[n] == remotenode:
            return n

    return None

def unhexlifybookmarks(marks):
    binremotemarks = {}
    for name, node in marks.items():
        binremotemarks[name] = bin(node)
    return binremotemarks

def updatefromremote(ui, repo, remotemarks, path, trfunc, explicit=()):
    ui.debug("checking for updated bookmarks\n")
    localmarks = repo._bookmarks
    (addsrc, adddst, advsrc, advdst, diverge, differ, invalid, same
    ) = comparebookmarks(repo, remotemarks, localmarks)

    status = ui.status
    warn = ui.warn
    if ui.configbool('ui', 'quietbookmarkmove', False):
        status = warn = ui.debug

    explicit = set(explicit)
    changed = []
    for b, scid, dcid in addsrc:
        if scid in repo: # add remote bookmarks for changes we already have
            changed.append((b, scid, status,
                            _("adding remote bookmark %s\n") % (b)))
        elif b in explicit:
            explicit.remove(b)
            ui.warn(_("remote bookmark %s points to locally missing %s\n")
                    % (b, hex(scid)[:12]))

    for b, scid, dcid in advsrc:
        changed.append((b, scid, status,
                        _("updating bookmark %s\n") % (b)))
    # remove normal movement from explicit set
    explicit.difference_update(d[0] for d in changed)

    for b, scid, dcid in diverge:
        if b in explicit:
            explicit.discard(b)
            changed.append((b, scid, status,
                            _("importing bookmark %s\n") % (b)))
        else:
            db = _diverge(ui, b, path, localmarks, scid)
            if db:
                changed.append((db, scid, warn,
                                _("divergent bookmark %s stored as %s\n") %
                                (b, db)))
            else:
                warn(_("warning: failed to assign numbered name "
                       "to divergent bookmark %s\n") % (b))
    for b, scid, dcid in adddst + advdst:
        if b in explicit:
            explicit.discard(b)
            changed.append((b, scid, status,
                            _("importing bookmark %s\n") % (b)))
    for b, scid, dcid in differ:
        if b in explicit:
            explicit.remove(b)
            ui.warn(_("remote bookmark %s points to locally missing %s\n")
                    % (b, hex(scid)[:12]))

    if changed:
        tr = trfunc()
        for b, node, writer, msg in sorted(changed):
            localmarks[b] = node
            writer(msg)
        localmarks.recordchange(tr)

def incoming(ui, repo, other):
    '''Show bookmarks incoming from other to repo
    '''
    ui.status(_("searching for changed bookmarks\n"))

    remotemarks = unhexlifybookmarks(other.listkeys('bookmarks'))
    r = comparebookmarks(repo, remotemarks, repo._bookmarks)
    addsrc, adddst, advsrc, advdst, diverge, differ, invalid, same = r

    incomings = []
    if ui.debugflag:
        getid = lambda id: id
    else:
        getid = lambda id: id[:12]
    if ui.verbose:
        def add(b, id, st):
            incomings.append("   %-25s %s %s\n" % (b, getid(id), st))
    else:
        def add(b, id, st):
            incomings.append("   %-25s %s\n" % (b, getid(id)))
    for b, scid, dcid in addsrc:
        # i18n: "added" refers to a bookmark
        add(b, hex(scid), _('added'))
    for b, scid, dcid in advsrc:
        # i18n: "advanced" refers to a bookmark
        add(b, hex(scid), _('advanced'))
    for b, scid, dcid in diverge:
        # i18n: "diverged" refers to a bookmark
        add(b, hex(scid), _('diverged'))
    for b, scid, dcid in differ:
        # i18n: "changed" refers to a bookmark
        add(b, hex(scid), _('changed'))

    if not incomings:
        ui.status(_("no changed bookmarks found\n"))
        return 1

    for s in sorted(incomings):
        ui.write(s)

    return 0

def outgoing(ui, repo, other):
    '''Show bookmarks outgoing from repo to other
    '''
    ui.status(_("searching for changed bookmarks\n"))

    remotemarks = unhexlifybookmarks(other.listkeys('bookmarks'))
    r = comparebookmarks(repo, repo._bookmarks, remotemarks)
    addsrc, adddst, advsrc, advdst, diverge, differ, invalid, same = r

    outgoings = []
    if ui.debugflag:
        getid = lambda id: id
    else:
        getid = lambda id: id[:12]
    if ui.verbose:
        def add(b, id, st):
            outgoings.append("   %-25s %s %s\n" % (b, getid(id), st))
    else:
        def add(b, id, st):
            outgoings.append("   %-25s %s\n" % (b, getid(id)))
    for b, scid, dcid in addsrc:
        # i18n: "added refers to a bookmark
        add(b, hex(scid), _('added'))
    for b, scid, dcid in adddst:
        # i18n: "deleted" refers to a bookmark
        add(b, ' ' * 40, _('deleted'))
    for b, scid, dcid in advsrc:
        # i18n: "advanced" refers to a bookmark
        add(b, hex(scid), _('advanced'))
    for b, scid, dcid in diverge:
        # i18n: "diverged" refers to a bookmark
        add(b, hex(scid), _('diverged'))
    for b, scid, dcid in differ:
        # i18n: "changed" refers to a bookmark
        add(b, hex(scid), _('changed'))

    if not outgoings:
        ui.status(_("no changed bookmarks found\n"))
        return 1

    for s in sorted(outgoings):
        ui.write(s)

    return 0

def summary(repo, other):
    '''Compare bookmarks between repo and other for "hg summary" output

    This returns "(# of incoming, # of outgoing)" tuple.
    '''
    remotemarks = unhexlifybookmarks(other.listkeys('bookmarks'))
    r = comparebookmarks(repo, remotemarks, repo._bookmarks)
    addsrc, adddst, advsrc, advdst, diverge, differ, invalid, same = r
    return (len(addsrc), len(adddst))

def validdest(repo, old, new):
    """Is the new bookmark destination a valid update from the old one"""
    repo = repo.unfiltered()
    if old == new:
        # Old == new -> nothing to update.
        return False
    elif not old:
        # old is nullrev, anything is valid.
        # (new != nullrev has been excluded by the previous check)
        return True
    elif repo.obsstore:
        return new.node() in obsutil.foreground(repo, [old.node()])
    else:
        # still an independent clause as it is lazier (and therefore faster)
        return old.descendant(new)

def checkformat(repo, mark):
    """return a valid version of a potential bookmark name

    Raises an abort error if the bookmark name is not valid.
    """
    mark = mark.strip()
    if not mark:
        raise error.Abort(_("bookmark names cannot consist entirely of "
                            "whitespace"))
    scmutil.checknewlabel(repo, mark, 'bookmark')
    return mark

def delete(repo, tr, names):
    """remove a mark from the bookmark store

    Raises an abort error if mark does not exist.
    """
    marks = repo._bookmarks
    for mark in names:
        if mark not in marks:
            raise error.Abort(_("bookmark '%s' does not exist") % mark)
        if mark == repo._activebookmark:
            deactivate(repo)
        del marks[mark]
    marks.recordchange(tr)

def rename(repo, tr, old, new, force=False, inactive=False):
    """rename a bookmark from old to new

    If force is specified, then the new name can overwrite an existing
    bookmark.

    If inactive is specified, then do not activate the new bookmark.

    Raises an abort error if old is not in the bookmark store.
    """
    marks = repo._bookmarks
    mark = checkformat(repo, new)
    if old not in marks:
        raise error.Abort(_("bookmark '%s' does not exist") % old)
    marks.checkconflict(mark, force)
    marks[mark] = marks[old]
    if repo._activebookmark == old and not inactive:
        activate(repo, mark)
    del marks[old]
    marks.recordchange(tr)

def addbookmarks(repo, tr, names, rev=None, force=False, inactive=False):
    """add a list of bookmarks

    If force is specified, then the new name can overwrite an existing
    bookmark.

    If inactive is specified, then do not activate any bookmark. Otherwise, the
    first bookmark is activated.

    Raises an abort error if old is not in the bookmark store.
    """
    marks = repo._bookmarks
    cur = repo.changectx('.').node()
    newact = None
    for mark in names:
        mark = checkformat(repo, mark)
        if newact is None:
            newact = mark
        if inactive and mark == repo._activebookmark:
            deactivate(repo)
            return
        tgt = cur
        if rev:
            tgt = scmutil.revsingle(repo, rev).node()
        marks.checkconflict(mark, force, tgt)
        marks[mark] = tgt
    if not inactive and cur == marks[newact] and not rev:
        activate(repo, newact)
    elif cur != tgt and newact == repo._activebookmark:
        deactivate(repo)
    marks.recordchange(tr)

def _printbookmarks(ui, repo, bmarks, **opts):
    """private method to print bookmarks

    Provides a way for extensions to control how bookmarks are printed (e.g.
    prepend or postpend names)
    """
    opts = pycompat.byteskwargs(opts)
    fm = ui.formatter('bookmarks', opts)
    hexfn = fm.hexfunc
    if len(bmarks) == 0 and fm.isplain():
        ui.status(_("no bookmarks set\n"))
    for bmark, (n, prefix, label) in sorted(bmarks.iteritems()):
        fm.startitem()
        if not ui.quiet:
            fm.plain(' %s ' % prefix, label=label)
        fm.write('bookmark', '%s', bmark, label=label)
        pad = " " * (25 - encoding.colwidth(bmark))
        fm.condwrite(not ui.quiet, 'rev node', pad + ' %d:%s',
                     repo.changelog.rev(n), hexfn(n), label=label)
        fm.data(active=(activebookmarklabel in label))
        fm.plain('\n')
    fm.end()

def printbookmarks(ui, repo, **opts):
    """print bookmarks to a formatter

    Provides a way for extensions to control how bookmarks are printed.
    """
    marks = repo._bookmarks
    bmarks = {}
    for bmark, n in sorted(marks.iteritems()):
        active = repo._activebookmark
        if bmark == active:
            prefix, label = '*', activebookmarklabel
        else:
            prefix, label = ' ', ''

        bmarks[bmark] = (n, prefix, label)
    _printbookmarks(ui, repo, bmarks, **opts)