hgext/transplant.py

lock: fixed race condition in trylock/testlock (issue3506)

Suppose the following scenario:

1. Process A takes the lock (e.g. on commit).
2. Process B wants to grab the lock. Since lock file exists
   the exception is raised. In the catch block the testlock
   function is called.
3. Process A releases the lock.
4. Process B tries to read the lock file as a part of testlock
   function. This results in OSError (ENOENT) and since we're
   not inside the exception handler function this is propagated
   and aborts the whole operation.

To fix this we now check in testlock function whether lock file
actually exists and if not (i.e. if readlock fails) we just return.

# Patch transplanting extension for Mercurial
#
# Copyright 2006, 2007 Brendan Cully <[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.

'''command to transplant changesets from another branch

This extension allows you to transplant patches from another branch.

Transplanted patches are recorded in .hg/transplant/transplants, as a
map from a changeset hash to its hash in the source repository.
'''

from mercurial.i18n import _
import os, tempfile
from mercurial.node import short
from mercurial import bundlerepo, hg, merge, match
from mercurial import patch, revlog, scmutil, util, error, cmdutil
from mercurial import revset, templatekw

class TransplantError(error.Abort):
    pass

cmdtable = {}
command = cmdutil.command(cmdtable)
testedwith = 'internal'

class transplantentry(object):
    def __init__(self, lnode, rnode):
        self.lnode = lnode
        self.rnode = rnode

class transplants(object):
    def __init__(self, path=None, transplantfile=None, opener=None):
        self.path = path
        self.transplantfile = transplantfile
        self.opener = opener

        if not opener:
            self.opener = scmutil.opener(self.path)
        self.transplants = {}
        self.dirty = False
        self.read()

    def read(self):
        abspath = os.path.join(self.path, self.transplantfile)
        if self.transplantfile and os.path.exists(abspath):
            for line in self.opener.read(self.transplantfile).splitlines():
                lnode, rnode = map(revlog.bin, line.split(':'))
                list = self.transplants.setdefault(rnode, [])
                list.append(transplantentry(lnode, rnode))

    def write(self):
        if self.dirty and self.transplantfile:
            if not os.path.isdir(self.path):
                os.mkdir(self.path)
            fp = self.opener(self.transplantfile, 'w')
            for list in self.transplants.itervalues():
                for t in list:
                    l, r = map(revlog.hex, (t.lnode, t.rnode))
                    fp.write(l + ':' + r + '\n')
            fp.close()
        self.dirty = False

    def get(self, rnode):
        return self.transplants.get(rnode) or []

    def set(self, lnode, rnode):
        list = self.transplants.setdefault(rnode, [])
        list.append(transplantentry(lnode, rnode))
        self.dirty = True

    def remove(self, transplant):
        list = self.transplants.get(transplant.rnode)
        if list:
            del list[list.index(transplant)]
            self.dirty = True

class transplanter(object):
    def __init__(self, ui, repo):
        self.ui = ui
        self.path = repo.join('transplant')
        self.opener = scmutil.opener(self.path)
        self.transplants = transplants(self.path, 'transplants',
                                       opener=self.opener)
        self.editor = None

    def applied(self, repo, node, parent):
        '''returns True if a node is already an ancestor of parent
        or is parent or has already been transplanted'''
        if hasnode(repo, parent):
            parentrev = repo.changelog.rev(parent)
        if hasnode(repo, node):
            rev = repo.changelog.rev(node)
            reachable = repo.changelog.incancestors([parentrev], rev)
            if rev in reachable:
                return True
        for t in self.transplants.get(node):
            # it might have been stripped
            if not hasnode(repo, t.lnode):
                self.transplants.remove(t)
                return False
            lnoderev = repo.changelog.rev(t.lnode)
            if lnoderev in repo.changelog.incancestors([parentrev], lnoderev):
                return True
        return False

    def apply(self, repo, source, revmap, merges, opts={}):
        '''apply the revisions in revmap one by one in revision order'''
        revs = sorted(revmap)
        p1, p2 = repo.dirstate.parents()
        pulls = []
        diffopts = patch.diffopts(self.ui, opts)
        diffopts.git = True

        lock = wlock = tr = None
        try:
            wlock = repo.wlock()
            lock = repo.lock()
            tr = repo.transaction('transplant')
            for rev in revs:
                node = revmap[rev]
                revstr = '%s:%s' % (rev, short(node))

                if self.applied(repo, node, p1):
                    self.ui.warn(_('skipping already applied revision %s\n') %
                                 revstr)
                    continue

                parents = source.changelog.parents(node)
                if not (opts.get('filter') or opts.get('log')):
                    # If the changeset parent is the same as the
                    # wdir's parent, just pull it.
                    if parents[0] == p1:
                        pulls.append(node)
                        p1 = node
                        continue
                    if pulls:
                        if source != repo:
                            repo.pull(source.peer(), heads=pulls)
                        merge.update(repo, pulls[-1], False, False, None)
                        p1, p2 = repo.dirstate.parents()
                        pulls = []

                domerge = False
                if node in merges:
                    # pulling all the merge revs at once would mean we
                    # couldn't transplant after the latest even if
                    # transplants before them fail.
                    domerge = True
                    if not hasnode(repo, node):
                        repo.pull(source, heads=[node])

                skipmerge = False
                if parents[1] != revlog.nullid:
                    if not opts.get('parent'):
                        self.ui.note(_('skipping merge changeset %s:%s\n')
                                     % (rev, short(node)))
                        skipmerge = True
                    else:
                        parent = source.lookup(opts['parent'])
                        if parent not in parents:
                            raise util.Abort(_('%s is not a parent of %s') %
                                             (short(parent), short(node)))
                else:
                    parent = parents[0]

                if skipmerge:
                    patchfile = None
                else:
                    fd, patchfile = tempfile.mkstemp(prefix='hg-transplant-')
                    fp = os.fdopen(fd, 'w')
                    gen = patch.diff(source, parent, node, opts=diffopts)
                    for chunk in gen:
                        fp.write(chunk)
                    fp.close()

                del revmap[rev]
                if patchfile or domerge:
                    try:
                        try:
                            n = self.applyone(repo, node,
                                              source.changelog.read(node),
                                              patchfile, merge=domerge,
                                              log=opts.get('log'),
                                              filter=opts.get('filter'))
                        except TransplantError:
                            # Do not rollback, it is up to the user to
                            # fix the merge or cancel everything
                            tr.close()
                            raise
                        if n and domerge:
                            self.ui.status(_('%s merged at %s\n') % (revstr,
                                      short(n)))
                        elif n:
                            self.ui.status(_('%s transplanted to %s\n')
                                           % (short(node),
                                              short(n)))
                    finally:
                        if patchfile:
                            os.unlink(patchfile)
            tr.close()
            if pulls:
                repo.pull(source.peer(), heads=pulls)
                merge.update(repo, pulls[-1], False, False, None)
        finally:
            self.saveseries(revmap, merges)
            self.transplants.write()
            if tr:
                tr.release()
            lock.release()
            wlock.release()

    def filter(self, filter, node, changelog, patchfile):
        '''arbitrarily rewrite changeset before applying it'''

        self.ui.status(_('filtering %s\n') % patchfile)
        user, date, msg = (changelog[1], changelog[2], changelog[4])
        fd, headerfile = tempfile.mkstemp(prefix='hg-transplant-')
        fp = os.fdopen(fd, 'w')
        fp.write("# HG changeset patch\n")
        fp.write("# User %s\n" % user)
        fp.write("# Date %d %d\n" % date)
        fp.write(msg + '\n')
        fp.close()

        try:
            util.system('%s %s %s' % (filter, util.shellquote(headerfile),
                                   util.shellquote(patchfile)),
                        environ={'HGUSER': changelog[1],
                                 'HGREVISION': revlog.hex(node),
                                 },
                        onerr=util.Abort, errprefix=_('filter failed'),
                        out=self.ui.fout)
            user, date, msg = self.parselog(file(headerfile))[1:4]
        finally:
            os.unlink(headerfile)

        return (user, date, msg)

    def applyone(self, repo, node, cl, patchfile, merge=False, log=False,
                 filter=None):
        '''apply the patch in patchfile to the repository as a transplant'''
        (manifest, user, (time, timezone), files, message) = cl[:5]
        date = "%d %d" % (time, timezone)
        extra = {'transplant_source': node}
        if filter:
            (user, date, message) = self.filter(filter, node, cl, patchfile)

        if log:
            # we don't translate messages inserted into commits
            message += '\n(transplanted from %s)' % revlog.hex(node)

        self.ui.status(_('applying %s\n') % short(node))
        self.ui.note('%s %s\n%s\n' % (user, date, message))

        if not patchfile and not merge:
            raise util.Abort(_('can only omit patchfile if merging'))
        if patchfile:
            try:
                files = set()
                patch.patch(self.ui, repo, patchfile, files=files, eolmode=None)
                files = list(files)
            except Exception, inst:
                seriespath = os.path.join(self.path, 'series')
                if os.path.exists(seriespath):
                    os.unlink(seriespath)
                p1 = repo.dirstate.p1()
                p2 = node
                self.log(user, date, message, p1, p2, merge=merge)
                self.ui.write(str(inst) + '\n')
                raise TransplantError(_('fix up the merge and run '
                                        'hg transplant --continue'))
        else:
            files = None
        if merge:
            p1, p2 = repo.dirstate.parents()
            repo.setparents(p1, node)
            m = match.always(repo.root, '')
        else:
            m = match.exact(repo.root, '', files)

        n = repo.commit(message, user, date, extra=extra, match=m,
                        editor=self.editor)
        if not n:
            self.ui.warn(_('skipping emptied changeset %s\n') % short(node))
            return None
        if not merge:
            self.transplants.set(n, node)

        return n

    def resume(self, repo, source, opts=None):
        '''recover last transaction and apply remaining changesets'''
        if os.path.exists(os.path.join(self.path, 'journal')):
            n, node = self.recover(repo)
            self.ui.status(_('%s transplanted as %s\n') % (short(node),
                                                           short(n)))
        seriespath = os.path.join(self.path, 'series')
        if not os.path.exists(seriespath):
            self.transplants.write()
            return
        nodes, merges = self.readseries()
        revmap = {}
        for n in nodes:
            revmap[source.changelog.rev(n)] = n
        os.unlink(seriespath)

        self.apply(repo, source, revmap, merges, opts)

    def recover(self, repo):
        '''commit working directory using journal metadata'''
        node, user, date, message, parents = self.readlog()
        merge = False

        if not user or not date or not message or not parents[0]:
            raise util.Abort(_('transplant log file is corrupt'))

        parent = parents[0]
        if len(parents) > 1:
            if opts.get('parent'):
                parent = source.lookup(opts['parent'])
                if parent not in parents:
                    raise util.Abort(_('%s is not a parent of %s') %
                                     (short(parent), short(node)))
            else:
                merge = True

        extra = {'transplant_source': node}
        wlock = repo.wlock()
        try:
            p1, p2 = repo.dirstate.parents()
            if p1 != parent:
                raise util.Abort(
                    _('working dir not at transplant parent %s') %
                                 revlog.hex(parent))
            if merge:
                repo.setparents(p1, parents[1])
            n = repo.commit(message, user, date, extra=extra,
                            editor=self.editor)
            if not n:
                raise util.Abort(_('commit failed'))
            if not merge:
                self.transplants.set(n, node)
            self.unlog()

            return n, node
        finally:
            wlock.release()

    def readseries(self):
        nodes = []
        merges = []
        cur = nodes
        for line in self.opener.read('series').splitlines():
            if line.startswith('# Merges'):
                cur = merges
                continue
            cur.append(revlog.bin(line))

        return (nodes, merges)

    def saveseries(self, revmap, merges):
        if not revmap:
            return

        if not os.path.isdir(self.path):
            os.mkdir(self.path)
        series = self.opener('series', 'w')
        for rev in sorted(revmap):
            series.write(revlog.hex(revmap[rev]) + '\n')
        if merges:
            series.write('# Merges\n')
            for m in merges:
                series.write(revlog.hex(m) + '\n')
        series.close()

    def parselog(self, fp):
        parents = []
        message = []
        node = revlog.nullid
        inmsg = False
        user = None
        date = None
        for line in fp.read().splitlines():
            if inmsg:
                message.append(line)
            elif line.startswith('# User '):
                user = line[7:]
            elif line.startswith('# Date '):
                date = line[7:]
            elif line.startswith('# Node ID '):
                node = revlog.bin(line[10:])
            elif line.startswith('# Parent '):
                parents.append(revlog.bin(line[9:]))
            elif not line.startswith('# '):
                inmsg = True
                message.append(line)
        if None in (user, date):
            raise util.Abort(_("filter corrupted changeset (no user or date)"))
        return (node, user, date, '\n'.join(message), parents)

    def log(self, user, date, message, p1, p2, merge=False):
        '''journal changelog metadata for later recover'''

        if not os.path.isdir(self.path):
            os.mkdir(self.path)
        fp = self.opener('journal', 'w')
        fp.write('# User %s\n' % user)
        fp.write('# Date %s\n' % date)
        fp.write('# Node ID %s\n' % revlog.hex(p2))
        fp.write('# Parent ' + revlog.hex(p1) + '\n')
        if merge:
            fp.write('# Parent ' + revlog.hex(p2) + '\n')
        fp.write(message.rstrip() + '\n')
        fp.close()

    def readlog(self):
        return self.parselog(self.opener('journal'))

    def unlog(self):
        '''remove changelog journal'''
        absdst = os.path.join(self.path, 'journal')
        if os.path.exists(absdst):
            os.unlink(absdst)

    def transplantfilter(self, repo, source, root):
        def matchfn(node):
            if self.applied(repo, node, root):
                return False
            if source.changelog.parents(node)[1] != revlog.nullid:
                return False
            extra = source.changelog.read(node)[5]
            cnode = extra.get('transplant_source')
            if cnode and self.applied(repo, cnode, root):
                return False
            return True

        return matchfn

def hasnode(repo, node):
    try:
        return repo.changelog.rev(node) is not None
    except error.RevlogError:
        return False

def browserevs(ui, repo, nodes, opts):
    '''interactively transplant changesets'''
    def browsehelp(ui):
        ui.write(_('y: transplant this changeset\n'
                   'n: skip this changeset\n'
                   'm: merge at this changeset\n'
                   'p: show patch\n'
                   'c: commit selected changesets\n'
                   'q: cancel transplant\n'
                   '?: show this help\n'))

    displayer = cmdutil.show_changeset(ui, repo, opts)
    transplants = []
    merges = []
    for node in nodes:
        displayer.show(repo[node])
        action = None
        while not action:
            action = ui.prompt(_('apply changeset? [ynmpcq?]:'))
            if action == '?':
                browsehelp(ui)
                action = None
            elif action == 'p':
                parent = repo.changelog.parents(node)[0]
                for chunk in patch.diff(repo, parent, node):
                    ui.write(chunk)
                action = None
            elif action not in ('y', 'n', 'm', 'c', 'q'):
                ui.write(_('no such option\n'))
                action = None
        if action == 'y':
            transplants.append(node)
        elif action == 'm':
            merges.append(node)
        elif action == 'c':
            break
        elif action == 'q':
            transplants = ()
            merges = ()
            break
    displayer.close()
    return (transplants, merges)

@command('transplant',
    [('s', 'source', '', _('pull patches from REPO'), _('REPO')),
    ('b', 'branch', [],
     _('pull patches from branch BRANCH'), _('BRANCH')),
    ('a', 'all', None, _('pull all changesets up to BRANCH')),
    ('p', 'prune', [], _('skip over REV'), _('REV')),
    ('m', 'merge', [], _('merge at REV'), _('REV')),
    ('', 'parent', '',
     _('parent to choose when transplanting merge'), _('REV')),
    ('e', 'edit', False, _('invoke editor on commit messages')),
    ('', 'log', None, _('append transplant info to log message')),
    ('c', 'continue', None, _('continue last transplant session '
                              'after repair')),
    ('', 'filter', '',
     _('filter changesets through command'), _('CMD'))],
    _('hg transplant [-s REPO] [-b BRANCH [-a]] [-p REV] '
      '[-m REV] [REV]...'))
def transplant(ui, repo, *revs, **opts):
    '''transplant changesets from another branch

    Selected changesets will be applied on top of the current working
    directory with the log of the original changeset. The changesets
    are copied and will thus appear twice in the history. Use the
    rebase extension instead if you want to move a whole branch of
    unpublished changesets.

    If --log is specified, log messages will have a comment appended
    of the form::

      (transplanted from CHANGESETHASH)

    You can rewrite the changelog message with the --filter option.
    Its argument will be invoked with the current changelog message as
    $1 and the patch as $2.

    If --source/-s is specified, selects changesets from the named
    repository. If --branch/-b is specified, selects changesets from
    the branch holding the named revision, up to that revision. If
    --all/-a is specified, all changesets on the branch will be
    transplanted, otherwise you will be prompted to select the
    changesets you want.

    :hg:`transplant --branch REV --all` will transplant the
    selected branch (up to the named revision) onto your current
    working directory.

    You can optionally mark selected transplanted changesets as merge
    changesets. You will not be prompted to transplant any ancestors
    of a merged transplant, and you can merge descendants of them
    normally instead of transplanting them.

    Merge changesets may be transplanted directly by specifying the
    proper parent changeset by calling :hg:`transplant --parent`.

    If no merges or revisions are provided, :hg:`transplant` will
    start an interactive changeset browser.

    If a changeset application fails, you can fix the merge by hand
    and then resume where you left off by calling :hg:`transplant
    --continue/-c`.
    '''
    def incwalk(repo, csets, match=util.always):
        for node in csets:
            if match(node):
                yield node

    def transplantwalk(repo, root, branches, match=util.always):
        if not branches:
            branches = repo.heads()
        ancestors = []
        for branch in branches:
            ancestors.append(repo.changelog.ancestor(root, branch))
        for node in repo.changelog.nodesbetween(ancestors, branches)[0]:
            if match(node):
                yield node

    def checkopts(opts, revs):
        if opts.get('continue'):
            if opts.get('branch') or opts.get('all') or opts.get('merge'):
                raise util.Abort(_('--continue is incompatible with '
                                   'branch, all or merge'))
            return
        if not (opts.get('source') or revs or
                opts.get('merge') or opts.get('branch')):
            raise util.Abort(_('no source URL, branch tag or revision '
                               'list provided'))
        if opts.get('all'):
            if not opts.get('branch'):
                raise util.Abort(_('--all requires a branch revision'))
            if revs:
                raise util.Abort(_('--all is incompatible with a '
                                   'revision list'))

    checkopts(opts, revs)

    if not opts.get('log'):
        opts['log'] = ui.config('transplant', 'log')
    if not opts.get('filter'):
        opts['filter'] = ui.config('transplant', 'filter')

    tp = transplanter(ui, repo)
    if opts.get('edit'):
        tp.editor = cmdutil.commitforceeditor

    p1, p2 = repo.dirstate.parents()
    if len(repo) > 0 and p1 == revlog.nullid:
        raise util.Abort(_('no revision checked out'))
    if not opts.get('continue'):
        if p2 != revlog.nullid:
            raise util.Abort(_('outstanding uncommitted merges'))
        m, a, r, d = repo.status()[:4]
        if m or a or r or d:
            raise util.Abort(_('outstanding local changes'))

    sourcerepo = opts.get('source')
    if sourcerepo:
        peer = hg.peer(ui, opts, ui.expandpath(sourcerepo))
        branches = map(peer.lookup, opts.get('branch', ()))
        source, csets, cleanupfn = bundlerepo.getremotechanges(ui, repo, peer,
                                    onlyheads=branches, force=True)
    else:
        source = repo
        branches = map(source.lookup, opts.get('branch', ()))
        cleanupfn = None

    try:
        if opts.get('continue'):
            tp.resume(repo, source, opts)
            return

        tf = tp.transplantfilter(repo, source, p1)
        if opts.get('prune'):
            prune = [source.lookup(r)
                     for r in scmutil.revrange(source, opts.get('prune'))]
            matchfn = lambda x: tf(x) and x not in prune
        else:
            matchfn = tf
        merges = map(source.lookup, opts.get('merge', ()))
        revmap = {}
        if revs:
            for r in scmutil.revrange(source, revs):
                revmap[int(r)] = source.lookup(r)
        elif opts.get('all') or not merges:
            if source != repo:
                alltransplants = incwalk(source, csets, match=matchfn)
            else:
                alltransplants = transplantwalk(source, p1, branches,
                                                match=matchfn)
            if opts.get('all'):
                revs = alltransplants
            else:
                revs, newmerges = browserevs(ui, source, alltransplants, opts)
                merges.extend(newmerges)
            for r in revs:
                revmap[source.changelog.rev(r)] = r
        for r in merges:
            revmap[source.changelog.rev(r)] = r

        tp.apply(repo, source, revmap, merges, opts)
    finally:
        if cleanupfn:
            cleanupfn()

def revsettransplanted(repo, subset, x):
    """``transplanted([set])``
    Transplanted changesets in set, or all transplanted changesets.
    """
    if x:
        s = revset.getset(repo, subset, x)
    else:
        s = subset
    return [r for r in s if repo[r].extra().get('transplant_source')]

def kwtransplanted(repo, ctx, **args):
    """:transplanted: String. The node identifier of the transplanted
    changeset if any."""
    n = ctx.extra().get('transplant_source')
    return n and revlog.hex(n) or ''

def extsetup(ui):
    revset.symbols['transplanted'] = revsettransplanted
    templatekw.keywords['transplanted'] = kwtransplanted

# tell hggettext to extract docstrings from these functions:
i18nfunctions = [revsettransplanted, kwtransplanted]