annotate hgext/convert/subversion.py @ 16511:ecd2fbe68b25 stable

convert/svn: make svn sink work with svn 1.7

"svn add file" now fails if "file" is already tracked. To filter them we have
to mirror the svn manifest in the sink.

Tested with svn 1.6.12 and 1.7.4.

# Subversion 1.4/1.5 Python API backend
#
# Copyright(C) 2007 Daniel Holth et al

import os, re, sys, tempfile, urllib, urllib2, xml.dom.minidom
import cPickle as pickle

from mercurial import strutil, scmutil, util, encoding
from mercurial.i18n import _

propertycache = util.propertycache

# Subversion stuff. Works best with very recent Python SVN bindings
# e.g. SVN 1.5 or backports. Thanks to the bzr folks for enhancing
# these bindings.

from cStringIO import StringIO

from common import NoRepo, MissingTool, commit, encodeargs, decodeargs
from common import commandline, converter_source, converter_sink, mapfile

try:
    from svn.core import SubversionException, Pool
    import svn
    import svn.client
    import svn.core
    import svn.ra
    import svn.delta
    import transport
    import warnings
    warnings.filterwarnings('ignore',
            module='svn.core',
            category=DeprecationWarning)

except ImportError:
    svn = None

class SvnPathNotFound(Exception):
    pass

def revsplit(rev):
    """Parse a revision string and return (uuid, path, revnum)."""
    url, revnum = rev.rsplit('@', 1)
    parts = url.split('/', 1)
    mod = ''
    if len(parts) > 1:
        mod = '/' + parts[1]
    return parts[0][4:], mod, int(revnum)

def quote(s):
    # As of svn 1.7, many svn calls expect "canonical" paths. In
    # theory, we should call svn.core.*canonicalize() on all paths
    # before passing them to the API.  Instead, we assume the base url
    # is canonical and copy the behaviour of svn URL encoding function
    # so we can extend it safely with new components. The "safe"
    # characters were taken from the "svn_uri__char_validity" table in
    # libsvn_subr/path.c.
    return urllib.quote(s, "!$&'()*+,-./:=@_~")

def geturl(path):
    try:
        return svn.client.url_from_path(svn.core.svn_path_canonicalize(path))
    except SubversionException:
        # svn.client.url_from_path() fails with local repositories
        pass
    if os.path.isdir(path):
        path = os.path.normpath(os.path.abspath(path))
        if os.name == 'nt':
            path = '/' + util.normpath(path)
        # Module URL is later compared with the repository URL returned
        # by svn API, which is UTF-8.
        path = encoding.tolocal(path)
        path = 'file://%s' % quote(path)
    return svn.core.svn_path_canonicalize(path)

def optrev(number):
    optrev = svn.core.svn_opt_revision_t()
    optrev.kind = svn.core.svn_opt_revision_number
    optrev.value.number = number
    return optrev

class changedpath(object):
    def __init__(self, p):
        self.copyfrom_path = p.copyfrom_path
        self.copyfrom_rev = p.copyfrom_rev
        self.action = p.action

def get_log_child(fp, url, paths, start, end, limit=0, discover_changed_paths=True,
                    strict_node_history=False):
    protocol = -1
    def receiver(orig_paths, revnum, author, date, message, pool):
        if orig_paths is not None:
            for k, v in orig_paths.iteritems():
                orig_paths[k] = changedpath(v)
        pickle.dump((orig_paths, revnum, author, date, message),
                    fp, protocol)

    try:
        # Use an ra of our own so that our parent can consume
        # our results without confusing the server.
        t = transport.SvnRaTransport(url=url)
        svn.ra.get_log(t.ra, paths, start, end, limit,
                       discover_changed_paths,
                       strict_node_history,
                       receiver)
    except IOError:
        # Caller may interrupt the iteration
        pickle.dump(None, fp, protocol)
    except Exception, inst:
        pickle.dump(str(inst), fp, protocol)
    else:
        pickle.dump(None, fp, protocol)
    fp.close()
    # With large history, cleanup process goes crazy and suddenly
    # consumes *huge* amount of memory. The output file being closed,
    # there is no need for clean termination.
    os._exit(0)

def debugsvnlog(ui, **opts):
    """Fetch SVN log in a subprocess and channel them back to parent to
    avoid memory collection issues.
    """
    util.setbinary(sys.stdin)
    util.setbinary(sys.stdout)
    args = decodeargs(sys.stdin.read())
    get_log_child(sys.stdout, *args)

class logstream(object):
    """Interruptible revision log iterator."""
    def __init__(self, stdout):
        self._stdout = stdout

    def __iter__(self):
        while True:
            try:
                entry = pickle.load(self._stdout)
            except EOFError:
                raise util.Abort(_('Mercurial failed to run itself, check'
                                   ' hg executable is in PATH'))
            try:
                orig_paths, revnum, author, date, message = entry
            except:
                if entry is None:
                    break
                raise util.Abort(_("log stream exception '%s'") % entry)
            yield entry

    def close(self):
        if self._stdout:
            self._stdout.close()
            self._stdout = None


# Check to see if the given path is a local Subversion repo. Verify this by
# looking for several svn-specific files and directories in the given
# directory.
def filecheck(ui, path, proto):
    for x in ('locks', 'hooks', 'format', 'db'):
        if not os.path.exists(os.path.join(path, x)):
            return False
    return True

# Check to see if a given path is the root of an svn repo over http. We verify
# this by requesting a version-controlled URL we know can't exist and looking
# for the svn-specific "not found" XML.
def httpcheck(ui, path, proto):
    try:
        opener = urllib2.build_opener()
        rsp = opener.open('%s://%s/!svn/ver/0/.svn' % (proto, path))
        data = rsp.read()
    except urllib2.HTTPError, inst:
        if inst.code != 404:
            # Except for 404 we cannot know for sure this is not an svn repo
            ui.warn(_('svn: cannot probe remote repository, assume it could '
                      'be a subversion repository. Use --source-type if you '
                      'know better.\n'))
            return True
        data = inst.fp.read()
    except:
        # Could be urllib2.URLError if the URL is invalid or anything else.
        return False
    return '<m:human-readable errcode="160013">' in data

protomap = {'http': httpcheck,
            'https': httpcheck,
            'file': filecheck,
            }
def issvnurl(ui, url):
    try:
        proto, path = url.split('://', 1)
        if proto == 'file':
            path = urllib.url2pathname(path)
    except ValueError:
        proto = 'file'
        path = os.path.abspath(url)
    if proto == 'file':
        path = util.pconvert(path)
    check = protomap.get(proto, lambda *args: False)
    while '/' in path:
        if check(ui, path, proto):
            return True
        path = path.rsplit('/', 1)[0]
    return False

# SVN conversion code stolen from bzr-svn and tailor
#
# Subversion looks like a versioned filesystem, branches structures
# are defined by conventions and not enforced by the tool. First,
# we define the potential branches (modules) as "trunk" and "branches"
# children directories. Revisions are then identified by their
# module and revision number (and a repository identifier).
#
# The revision graph is really a tree (or a forest). By default, a
# revision parent is the previous revision in the same module. If the
# module directory is copied/moved from another module then the
# revision is the module root and its parent the source revision in
# the parent module. A revision has at most one parent.
#
class svn_source(converter_source):
    def __init__(self, ui, url, rev=None):
        super(svn_source, self).__init__(ui, url, rev=rev)

        if not (url.startswith('svn://') or url.startswith('svn+ssh://') or
                (os.path.exists(url) and
                 os.path.exists(os.path.join(url, '.svn'))) or
                issvnurl(ui, url)):
            raise NoRepo(_("%s does not look like a Subversion repository")
                         % url)
        if svn is None:
            raise MissingTool(_('Could not load Subversion python bindings'))

        try:
            version = svn.core.SVN_VER_MAJOR, svn.core.SVN_VER_MINOR
            if version < (1, 4):
                raise MissingTool(_('Subversion python bindings %d.%d found, '
                                    '1.4 or later required') % version)
        except AttributeError:
            raise MissingTool(_('Subversion python bindings are too old, 1.4 '
                                'or later required'))

        self.lastrevs = {}

        latest = None
        try:
            # Support file://path@rev syntax. Useful e.g. to convert
            # deleted branches.
            at = url.rfind('@')
            if at >= 0:
                latest = int(url[at + 1:])
                url = url[:at]
        except ValueError:
            pass
        self.url = geturl(url)
        self.encoding = 'UTF-8' # Subversion is always nominal UTF-8
        try:
            self.transport = transport.SvnRaTransport(url=self.url)
            self.ra = self.transport.ra
            self.ctx = self.transport.client
            self.baseurl = svn.ra.get_repos_root(self.ra)
            # Module is either empty or a repository path starting with
            # a slash and not ending with a slash.
            self.module = urllib.unquote(self.url[len(self.baseurl):])
            self.prevmodule = None
            self.rootmodule = self.module
            self.commits = {}
            self.paths = {}
            self.uuid = svn.ra.get_uuid(self.ra)
        except SubversionException:
            ui.traceback()
            raise NoRepo(_("%s does not look like a Subversion repository")
                         % self.url)

        if rev:
            try:
                latest = int(rev)
            except ValueError:
                raise util.Abort(_('svn: revision %s is not an integer') % rev)

        self.trunkname = self.ui.config('convert', 'svn.trunk', 'trunk').strip('/')
        self.startrev = self.ui.config('convert', 'svn.startrev', default=0)
        try:
            self.startrev = int(self.startrev)
            if self.startrev < 0:
                self.startrev = 0
        except ValueError:
            raise util.Abort(_('svn: start revision %s is not an integer')
                             % self.startrev)

        try:
            self.head = self.latest(self.module, latest)
        except SvnPathNotFound:
            self.head = None
        if not self.head:
            raise util.Abort(_('no revision found in module %s')
                             % self.module)
        self.last_changed = self.revnum(self.head)

        self._changescache = None

        if os.path.exists(os.path.join(url, '.svn/entries')):
            self.wc = url
        else:
            self.wc = None
        self.convertfp = None

    def setrevmap(self, revmap):
        lastrevs = {}
        for revid in revmap.iterkeys():
            uuid, module, revnum = revsplit(revid)
            lastrevnum = lastrevs.setdefault(module, revnum)
            if revnum > lastrevnum:
                lastrevs[module] = revnum
        self.lastrevs = lastrevs

    def exists(self, path, optrev):
        try:
            svn.client.ls(self.url.rstrip('/') + '/' + quote(path),
                                 optrev, False, self.ctx)
            return True
        except SubversionException:
            return False

    def getheads(self):

        def isdir(path, revnum):
            kind = self._checkpath(path, revnum)
            return kind == svn.core.svn_node_dir

        def getcfgpath(name, rev):
            cfgpath = self.ui.config('convert', 'svn.' + name)
            if cfgpath is not None and cfgpath.strip() == '':
                return None
            path = (cfgpath or name).strip('/')
            if not self.exists(path, rev):
                if self.module.endswith(path) and name == 'trunk':
                    # we are converting from inside this directory
                    return None
                if cfgpath:
                    raise util.Abort(_('expected %s to be at %r, but not found')
                                 % (name, path))
                return None
            self.ui.note(_('found %s at %r\n') % (name, path))
            return path

        rev = optrev(self.last_changed)
        oldmodule = ''
        trunk = getcfgpath('trunk', rev)
        self.tags = getcfgpath('tags', rev)
        branches = getcfgpath('branches', rev)

        # If the project has a trunk or branches, we will extract heads
        # from them. We keep the project root otherwise.
        if trunk:
            oldmodule = self.module or ''
            self.module += '/' + trunk
            self.head = self.latest(self.module, self.last_changed)
            if not self.head:
                raise util.Abort(_('no revision found in module %s')
                                 % self.module)

        # First head in the list is the module's head
        self.heads = [self.head]
        if self.tags is not None:
            self.tags = '%s/%s' % (oldmodule , (self.tags or 'tags'))

        # Check if branches bring a few more heads to the list
        if branches:
            rpath = self.url.strip('/')
            branchnames = svn.client.ls(rpath + '/' + quote(branches),
                                        rev, False, self.ctx)
            for branch in branchnames.keys():
                module = '%s/%s/%s' % (oldmodule, branches, branch)
                if not isdir(module, self.last_changed):
                    continue
                brevid = self.latest(module, self.last_changed)
                if not brevid:
                    self.ui.note(_('ignoring empty branch %s\n') % branch)
                    continue
                self.ui.note(_('found branch %s at %d\n') %
                             (branch, self.revnum(brevid)))
                self.heads.append(brevid)

        if self.startrev and self.heads:
            if len(self.heads) > 1:
                raise util.Abort(_('svn: start revision is not supported '
                                   'with more than one branch'))
            revnum = self.revnum(self.heads[0])
            if revnum < self.startrev:
                raise util.Abort(
                    _('svn: no revision found after start revision %d')
                                 % self.startrev)

        return self.heads

    def getchanges(self, rev):
        if self._changescache and self._changescache[0] == rev:
            return self._changescache[1]
        self._changescache = None
        (paths, parents) = self.paths[rev]
        if parents:
            files, self.removed, copies = self.expandpaths(rev, paths, parents)
        else:
            # Perform a full checkout on roots
            uuid, module, revnum = revsplit(rev)
            entries = svn.client.ls(self.baseurl + quote(module),
                                    optrev(revnum), True, self.ctx)
            files = [n for n, e in entries.iteritems()
                     if e.kind == svn.core.svn_node_file]
            copies = {}
            self.removed = set()

        files.sort()
        files = zip(files, [rev] * len(files))

        # caller caches the result, so free it here to release memory
        del self.paths[rev]
        return (files, copies)

    def getchangedfiles(self, rev, i):
        changes = self.getchanges(rev)
        self._changescache = (rev, changes)
        return [f[0] for f in changes[0]]

    def getcommit(self, rev):
        if rev not in self.commits:
            uuid, module, revnum = revsplit(rev)
            self.module = module
            self.reparent(module)
            # We assume that:
            # - requests for revisions after "stop" come from the
            # revision graph backward traversal. Cache all of them
            # down to stop, they will be used eventually.
            # - requests for revisions before "stop" come to get
            # isolated branches parents. Just fetch what is needed.
            stop = self.lastrevs.get(module, 0)
            if revnum < stop:
                stop = revnum + 1
            self._fetch_revisions(revnum, stop)
            if rev not in self.commits:
                raise util.Abort(_('svn: revision %s not found') % revnum)
        commit = self.commits[rev]
        # caller caches the result, so free it here to release memory
        del self.commits[rev]
        return commit

    def gettags(self):
        tags = {}
        if self.tags is None:
            return tags

        # svn tags are just a convention, project branches left in a
        # 'tags' directory. There is no other relationship than
        # ancestry, which is expensive to discover and makes them hard
        # to update incrementally.  Worse, past revisions may be
        # referenced by tags far away in the future, requiring a deep
        # history traversal on every calculation.  Current code
        # performs a single backward traversal, tracking moves within
        # the tags directory (tag renaming) and recording a new tag
        # everytime a project is copied from outside the tags
        # directory. It also lists deleted tags, this behaviour may
        # change in the future.
        pendings = []
        tagspath = self.tags
        start = svn.ra.get_latest_revnum(self.ra)
        stream = self._getlog([self.tags], start, self.startrev)
        try:
            for entry in stream:
                origpaths, revnum, author, date, message = entry
                copies = [(e.copyfrom_path, e.copyfrom_rev, p) for p, e
                          in origpaths.iteritems() if e.copyfrom_path]
                # Apply moves/copies from more specific to general
                copies.sort(reverse=True)

                srctagspath = tagspath
                if copies and copies[-1][2] == tagspath:
                    # Track tags directory moves
                    srctagspath = copies.pop()[0]

                for source, sourcerev, dest in copies:
                    if not dest.startswith(tagspath + '/'):
                        continue
                    for tag in pendings:
                        if tag[0].startswith(dest):
                            tagpath = source + tag[0][len(dest):]
                            tag[:2] = [tagpath, sourcerev]
                            break
                    else:
                        pendings.append([source, sourcerev, dest])

                # Filter out tags with children coming from different
                # parts of the repository like:
                # /tags/tag.1 (from /trunk:10)
                # /tags/tag.1/foo (from /branches/foo:12)
                # Here/tags/tag.1 discarded as well as its children.
                # It happens with tools like cvs2svn. Such tags cannot
                # be represented in mercurial.
                addeds = dict((p, e.copyfrom_path) for p, e
                              in origpaths.iteritems()
                              if e.action == 'A' and e.copyfrom_path)
                badroots = set()
                for destroot in addeds:
                    for source, sourcerev, dest in pendings:
                        if (not dest.startswith(destroot + '/')
                            or source.startswith(addeds[destroot] + '/')):
                            continue
                        badroots.add(destroot)
                        break

                for badroot in badroots:
                    pendings = [p for p in pendings if p[2] != badroot
                                and not p[2].startswith(badroot + '/')]

                # Tell tag renamings from tag creations
                renamings = []
                for source, sourcerev, dest in pendings:
                    tagname = dest.split('/')[-1]
                    if source.startswith(srctagspath):
                        renamings.append([source, sourcerev, tagname])
                        continue
                    if tagname in tags:
                        # Keep the latest tag value
                        continue
                    # From revision may be fake, get one with changes
                    try:
                        tagid = self.latest(source, sourcerev)
                        if tagid and tagname not in tags:
                            tags[tagname] = tagid
                    except SvnPathNotFound:
                        # It happens when we are following directories
                        # we assumed were copied with their parents
                        # but were really created in the tag
                        # directory.
                        pass
                pendings = renamings
                tagspath = srctagspath
        finally:
            stream.close()
        return tags

    def converted(self, rev, destrev):
        if not self.wc:
            return
        if self.convertfp is None:
            self.convertfp = open(os.path.join(self.wc, '.svn', 'hg-shamap'),
                                  'a')
        self.convertfp.write('%s %d\n' % (destrev, self.revnum(rev)))
        self.convertfp.flush()

    def revid(self, revnum, module=None):
        return 'svn:%s%s@%s' % (self.uuid, module or self.module, revnum)

    def revnum(self, rev):
        return int(rev.split('@')[-1])

    def latest(self, path, stop=None):
        """Find the latest revid affecting path, up to stop revision
        number. If stop is None, default to repository latest
        revision. It may return a revision in a different module,
        since a branch may be moved without a change being
        reported. Return None if computed module does not belong to
        rootmodule subtree.
        """
        def findchanges(path, start, stop=None):
            stream = self._getlog([path], start, stop or 1)
            try:
                for entry in stream:
                    paths, revnum, author, date, message = entry
                    if stop is None and paths:
                        # We do not know the latest changed revision,
                        # keep the first one with changed paths.
                        break
                    if revnum <= stop:
                        break

                    for p in paths:
                        if (not path.startswith(p) or
                            not paths[p].copyfrom_path):
                            continue
                        newpath = paths[p].copyfrom_path + path[len(p):]
                        self.ui.debug("branch renamed from %s to %s at %d\n" %
                                      (path, newpath, revnum))
                        path = newpath
                        break
                if not paths:
                    revnum = None
                return revnum, path
            finally:
                stream.close()

        if not path.startswith(self.rootmodule):
            # Requests on foreign branches may be forbidden at server level
            self.ui.debug('ignoring foreign branch %r\n' % path)
            return None

        if stop is None:
            stop = svn.ra.get_latest_revnum(self.ra)
        try:
            prevmodule = self.reparent('')
            dirent = svn.ra.stat(self.ra, path.strip('/'), stop)
            self.reparent(prevmodule)
        except SubversionException:
            dirent = None
        if not dirent:
            raise SvnPathNotFound(_('%s not found up to revision %d')
                                  % (path, stop))

        # stat() gives us the previous revision on this line of
        # development, but it might be in *another module*. Fetch the
        # log and detect renames down to the latest revision.
        revnum, realpath = findchanges(path, stop, dirent.created_rev)
        if revnum is None:
            # Tools like svnsync can create empty revision, when
            # synchronizing only a subtree for instance. These empty
            # revisions created_rev still have their original values
            # despite all changes having disappeared and can be
            # returned by ra.stat(), at least when stating the root
            # module. In that case, do not trust created_rev and scan
            # the whole history.
            revnum, realpath = findchanges(path, stop)
            if revnum is None:
                self.ui.debug('ignoring empty branch %r\n' % realpath)
                return None

        if not realpath.startswith(self.rootmodule):
            self.ui.debug('ignoring foreign branch %r\n' % realpath)
            return None
        return self.revid(revnum, realpath)

    def reparent(self, module):
        """Reparent the svn transport and return the previous parent."""
        if self.prevmodule == module:
            return module
        svnurl = self.baseurl + quote(module)
        prevmodule = self.prevmodule
        if prevmodule is None:
            prevmodule = ''
        self.ui.debug("reparent to %s\n" % svnurl)
        svn.ra.reparent(self.ra, svnurl)
        self.prevmodule = module
        return prevmodule

    def expandpaths(self, rev, paths, parents):
        changed, removed = set(), set()
        copies = {}

        new_module, revnum = revsplit(rev)[1:]
        if new_module != self.module:
            self.module = new_module
            self.reparent(self.module)

        for i, (path, ent) in enumerate(paths):
            self.ui.progress(_('scanning paths'), i, item=path,
                             total=len(paths))
            entrypath = self.getrelpath(path)

            kind = self._checkpath(entrypath, revnum)
            if kind == svn.core.svn_node_file:
                changed.add(self.recode(entrypath))
                if not ent.copyfrom_path or not parents:
                    continue
                # Copy sources not in parent revisions cannot be
                # represented, ignore their origin for now
                pmodule, prevnum = revsplit(parents[0])[1:]
                if ent.copyfrom_rev < prevnum:
                    continue
                copyfrom_path = self.getrelpath(ent.copyfrom_path, pmodule)
                if not copyfrom_path:
                    continue
                self.ui.debug("copied to %s from %s@%s\n" %
                              (entrypath, copyfrom_path, ent.copyfrom_rev))
                copies[self.recode(entrypath)] = self.recode(copyfrom_path)
            elif kind == 0: # gone, but had better be a deleted *file*
                self.ui.debug("gone from %s\n" % ent.copyfrom_rev)
                pmodule, prevnum = revsplit(parents[0])[1:]
                parentpath = pmodule + "/" + entrypath
                fromkind = self._checkpath(entrypath, prevnum, pmodule)

                if fromkind == svn.core.svn_node_file:
                    removed.add(self.recode(entrypath))
                elif fromkind == svn.core.svn_node_dir:
                    oroot = parentpath.strip('/')
                    nroot = path.strip('/')
                    children = self._iterfiles(oroot, prevnum)
                    for childpath in children:
                        childpath = childpath.replace(oroot, nroot)
                        childpath = self.getrelpath("/" + childpath, pmodule)
                        if childpath:
                            removed.add(self.recode(childpath))
                else:
                    self.ui.debug('unknown path in revision %d: %s\n' % \
                                  (revnum, path))
            elif kind == svn.core.svn_node_dir:
                if ent.action == 'M':
                    # If the directory just had a prop change,
                    # then we shouldn't need to look for its children.
                    continue
                if ent.action == 'R' and parents:
                    # If a directory is replacing a file, mark the previous
                    # file as deleted
                    pmodule, prevnum = revsplit(parents[0])[1:]
                    pkind = self._checkpath(entrypath, prevnum, pmodule)
                    if pkind == svn.core.svn_node_file:
                        removed.add(self.recode(entrypath))
                    elif pkind == svn.core.svn_node_dir:
                        # We do not know what files were kept or removed,
                        # mark them all as changed.
                        for childpath in self._iterfiles(pmodule, prevnum):
                            childpath = self.getrelpath("/" + childpath)
                            if childpath:
                                changed.add(self.recode(childpath))

                for childpath in self._iterfiles(path, revnum):
                    childpath = self.getrelpath("/" + childpath)
                    if childpath:
                        changed.add(self.recode(childpath))

                # Handle directory copies
                if not ent.copyfrom_path or not parents:
                    continue
                # Copy sources not in parent revisions cannot be
                # represented, ignore their origin for now
                pmodule, prevnum = revsplit(parents[0])[1:]
                if ent.copyfrom_rev < prevnum:
                    continue
                copyfrompath = self.getrelpath(ent.copyfrom_path, pmodule)
                if not copyfrompath:
                    continue
                self.ui.debug("mark %s came from %s:%d\n"
                              % (path, copyfrompath, ent.copyfrom_rev))
                children = self._iterfiles(ent.copyfrom_path, ent.copyfrom_rev)
                for childpath in children:
                    childpath = self.getrelpath("/" + childpath, pmodule)
                    if not childpath:
                        continue
                    copytopath = path + childpath[len(copyfrompath):]
                    copytopath = self.getrelpath(copytopath)
                    copies[self.recode(copytopath)] = self.recode(childpath)

        self.ui.progress(_('scanning paths'), None)
        changed.update(removed)
        return (list(changed), removed, copies)

    def _fetch_revisions(self, from_revnum, to_revnum):
        if from_revnum < to_revnum:
            from_revnum, to_revnum = to_revnum, from_revnum

        self.child_cset = None

        def parselogentry(orig_paths, revnum, author, date, message):
            """Return the parsed commit object or None, and True if
            the revision is a branch root.
            """
            self.ui.debug("parsing revision %d (%d changes)\n" %
                          (revnum, len(orig_paths)))

            branched = False
            rev = self.revid(revnum)
            # branch log might return entries for a parent we already have

            if rev in self.commits or revnum < to_revnum:
                return None, branched

            parents = []
            # check whether this revision is the start of a branch or part
            # of a branch renaming
            orig_paths = sorted(orig_paths.iteritems())
            root_paths = [(p, e) for p, e in orig_paths
                          if self.module.startswith(p)]
            if root_paths:
                path, ent = root_paths[-1]
                if ent.copyfrom_path:
                    branched = True
                    newpath = ent.copyfrom_path + self.module[len(path):]
                    # ent.copyfrom_rev may not be the actual last revision
                    previd = self.latest(newpath, ent.copyfrom_rev)
                    if previd is not None:
                        prevmodule, prevnum = revsplit(previd)[1:]
                        if prevnum >= self.startrev:
                            parents = [previd]
                            self.ui.note(
                                _('found parent of branch %s at %d: %s\n') %
                                (self.module, prevnum, prevmodule))
                else:
                    self.ui.debug("no copyfrom path, don't know what to do.\n")

            paths = []
            # filter out unrelated paths
            for path, ent in orig_paths:
                if self.getrelpath(path) is None:
                    continue
                paths.append((path, ent))

            # Example SVN datetime. Includes microseconds.
            # ISO-8601 conformant
            # '2007-01-04T17:35:00.902377Z'
            date = util.parsedate(date[:19] + " UTC", ["%Y-%m-%dT%H:%M:%S"])

            log = message and self.recode(message) or ''
            author = author and self.recode(author) or ''
            try:
                branch = self.module.split("/")[-1]
                if branch == self.trunkname:
                    branch = None
            except IndexError:
                branch = None

            cset = commit(author=author,
                          date=util.datestr(date),
                          desc=log,
                          parents=parents,
                          branch=branch,
                          rev=rev)

            self.commits[rev] = cset
            # The parents list is *shared* among self.paths and the
            # commit object. Both will be updated below.
            self.paths[rev] = (paths, cset.parents)
            if self.child_cset and not self.child_cset.parents:
                self.child_cset.parents[:] = [rev]
            self.child_cset = cset
            return cset, branched

        self.ui.note(_('fetching revision log for "%s" from %d to %d\n') %
                     (self.module, from_revnum, to_revnum))

        try:
            firstcset = None
            lastonbranch = False
            stream = self._getlog([self.module], from_revnum, to_revnum)
            try:
                for entry in stream:
                    paths, revnum, author, date, message = entry
                    if revnum < self.startrev:
                        lastonbranch = True
                        break
                    if not paths:
                        self.ui.debug('revision %d has no entries\n' % revnum)
                        # If we ever leave the loop on an empty
                        # revision, do not try to get a parent branch
                        lastonbranch = lastonbranch or revnum == 0
                        continue
                    cset, lastonbranch = parselogentry(paths, revnum, author,
                                                       date, message)
                    if cset:
                        firstcset = cset
                    if lastonbranch:
                        break
            finally:
                stream.close()

            if not lastonbranch and firstcset and not firstcset.parents:
                # The first revision of the sequence (the last fetched one)
                # has invalid parents if not a branch root. Find the parent
                # revision now, if any.
                try:
                    firstrevnum = self.revnum(firstcset.rev)
                    if firstrevnum > 1:
                        latest = self.latest(self.module, firstrevnum - 1)
                        if latest:
                            firstcset.parents.append(latest)
                except SvnPathNotFound:
                    pass
        except SubversionException, (inst, num):
            if num == svn.core.SVN_ERR_FS_NO_SUCH_REVISION:
                raise util.Abort(_('svn: branch has no revision %s') % to_revnum)
            raise

    def getfile(self, file, rev):
        # TODO: ra.get_file transmits the whole file instead of diffs.
        if file in self.removed:
            raise IOError()
        mode = ''
        try:
            new_module, revnum = revsplit(rev)[1:]
            if self.module != new_module:
                self.module = new_module
                self.reparent(self.module)
            io = StringIO()
            info = svn.ra.get_file(self.ra, file, revnum, io)
            data = io.getvalue()
            # ra.get_files() seems to keep a reference on the input buffer
            # preventing collection. Release it explicitely.
            io.close()
            if isinstance(info, list):
                info = info[-1]
            mode = ("svn:executable" in info) and 'x' or ''
            mode = ("svn:special" in info) and 'l' or mode
        except SubversionException, e:
            notfound = (svn.core.SVN_ERR_FS_NOT_FOUND,
                svn.core.SVN_ERR_RA_DAV_PATH_NOT_FOUND)
            if e.apr_err in notfound: # File not found
                raise IOError()
            raise
        if mode == 'l':
            link_prefix = "link "
            if data.startswith(link_prefix):
                data = data[len(link_prefix):]
        return data, mode

    def _iterfiles(self, path, revnum):
        """Enumerate all files in path at revnum, recursively."""
        path = path.strip('/')
        pool = Pool()
        rpath = '/'.join([self.baseurl, quote(path)]).strip('/')
        entries = svn.client.ls(rpath, optrev(revnum), True, self.ctx, pool)
        if path:
            path += '/'
        return ((path + p) for p, e in entries.iteritems()
                if e.kind == svn.core.svn_node_file)

    def getrelpath(self, path, module=None):
        if module is None:
            module = self.module
        # Given the repository url of this wc, say
        #   "http://server/plone/CMFPlone/branches/Plone-2_0-branch"
        # extract the "entry" portion (a relative path) from what
        # svn log --xml says, ie
        #   "/CMFPlone/branches/Plone-2_0-branch/tests/PloneTestCase.py"
        # that is to say "tests/PloneTestCase.py"
        if path.startswith(module):
            relative = path.rstrip('/')[len(module):]
            if relative.startswith('/'):
                return relative[1:]
            elif relative == '':
                return relative

        # The path is outside our tracked tree...
        self.ui.debug('%r is not under %r, ignoring\n' % (path, module))
        return None

    def _checkpath(self, path, revnum, module=None):
        if module is not None:
            prevmodule = self.reparent('')
            path = module + '/' + path
        try:
            # ra.check_path does not like leading slashes very much, it leads
            # to PROPFIND subversion errors
            return svn.ra.check_path(self.ra, path.strip('/'), revnum)
        finally:
            if module is not None:
                self.reparent(prevmodule)

    def _getlog(self, paths, start, end, limit=0, discover_changed_paths=True,
                strict_node_history=False):
        # Normalize path names, svn >= 1.5 only wants paths relative to
        # supplied URL
        relpaths = []
        for p in paths:
            if not p.startswith('/'):
                p = self.module + '/' + p
            relpaths.append(p.strip('/'))
        args = [self.baseurl, relpaths, start, end, limit, discover_changed_paths,
                strict_node_history]
        arg = encodeargs(args)
        hgexe = util.hgexecutable()
        cmd = '%s debugsvnlog' % util.shellquote(hgexe)
        stdin, stdout = util.popen2(util.quotecommand(cmd))
        stdin.write(arg)
        try:
            stdin.close()
        except IOError:
            raise util.Abort(_('Mercurial failed to run itself, check'
                               ' hg executable is in PATH'))
        return logstream(stdout)

pre_revprop_change = '''#!/bin/sh

REPOS="$1"
REV="$2"
USER="$3"
PROPNAME="$4"
ACTION="$5"

if [ "$ACTION" = "M" -a "$PROPNAME" = "svn:log" ]; then exit 0; fi
if [ "$ACTION" = "A" -a "$PROPNAME" = "hg:convert-branch" ]; then exit 0; fi
if [ "$ACTION" = "A" -a "$PROPNAME" = "hg:convert-rev" ]; then exit 0; fi

echo "Changing prohibited revision property" >&2
exit 1
'''

class svn_sink(converter_sink, commandline):
    commit_re = re.compile(r'Committed revision (\d+).', re.M)
    uuid_re = re.compile(r'Repository UUID:\s*(\S+)', re.M)

    def prerun(self):
        if self.wc:
            os.chdir(self.wc)

    def postrun(self):
        if self.wc:
            os.chdir(self.cwd)

    def join(self, name):
        return os.path.join(self.wc, '.svn', name)

    def revmapfile(self):
        return self.join('hg-shamap')

    def authorfile(self):
        return self.join('hg-authormap')

    def __init__(self, ui, path):

        converter_sink.__init__(self, ui, path)
        commandline.__init__(self, ui, 'svn')
        self.delete = []
        self.setexec = []
        self.delexec = []
        self.copies = []
        self.wc = None
        self.cwd = os.getcwd()

        path = os.path.realpath(path)

        created = False
        if os.path.isfile(os.path.join(path, '.svn', 'entries')):
            self.wc = path
            self.run0('update')
        else:
            wcpath = os.path.join(os.getcwd(), os.path.basename(path) + '-wc')

            if os.path.isdir(os.path.dirname(path)):
                if not os.path.exists(os.path.join(path, 'db', 'fs-type')):
                    ui.status(_('initializing svn repository %r\n') %
                              os.path.basename(path))
                    commandline(ui, 'svnadmin').run0('create', path)
                    created = path
                path = util.normpath(path)
                if not path.startswith('/'):
                    path = '/' + path
                path = 'file://' + path

            ui.status(_('initializing svn working copy %r\n')
                      % os.path.basename(wcpath))
            self.run0('checkout', path, wcpath)

            self.wc = wcpath
        self.opener = scmutil.opener(self.wc)
        self.wopener = scmutil.opener(self.wc)
        self.childmap = mapfile(ui, self.join('hg-childmap'))
        self.is_exec = util.checkexec(self.wc) and util.isexec or None

        if created:
            hook = os.path.join(created, 'hooks', 'pre-revprop-change')
            fp = open(hook, 'w')
            fp.write(pre_revprop_change)
            fp.close()
            util.setflags(hook, False, True)

        output = self.run0('info')
        self.uuid = self.uuid_re.search(output).group(1).strip()

    def wjoin(self, *names):
        return os.path.join(self.wc, *names)

    @propertycache
    def manifest(self):
        # As of svn 1.7, the "add" command fails when receiving
        # already tracked entries, so we have to track and filter them
        # ourselves.
        m = set()
        output = self.run0('ls', recursive=True, xml=True)
        doc = xml.dom.minidom.parseString(output)
        for e in doc.getElementsByTagName('entry'):
            for n in e.childNodes:
                if n.nodeType != n.ELEMENT_NODE or n.tagName != 'name':
                    continue
                name = ''.join(c.data for c in n.childNodes
                               if c.nodeType == c.TEXT_NODE)
                # Entries are compared with names coming from
                # mercurial, so bytes with undefined encoding. Our
                # best bet is to assume they are in local
                # encoding. They will be passed to command line calls
                # later anyway, so they better be.
                m.add(encoding.tolocal(name.encode('utf-8')))
                break
        return m

    def putfile(self, filename, flags, data):
        if 'l' in flags:
            self.wopener.symlink(data, filename)
        else:
            try:
                if os.path.islink(self.wjoin(filename)):
                    os.unlink(filename)
            except OSError:
                pass
            self.wopener.write(filename, data)

            if self.is_exec:
                was_exec = self.is_exec(self.wjoin(filename))
            else:
                # On filesystems not supporting execute-bit, there is no way
                # to know if it is set but asking subversion. Setting it
                # systematically is just as expensive and much simpler.
                was_exec = 'x' not in flags

            util.setflags(self.wjoin(filename), False, 'x' in flags)
            if was_exec:
                if 'x' not in flags:
                    self.delexec.append(filename)
            else:
                if 'x' in flags:
                    self.setexec.append(filename)

    def _copyfile(self, source, dest):
        # SVN's copy command pukes if the destination file exists, but
        # our copyfile method expects to record a copy that has
        # already occurred.  Cross the semantic gap.
        wdest = self.wjoin(dest)
        exists = os.path.lexists(wdest)
        if exists:
            fd, tempname = tempfile.mkstemp(
                prefix='hg-copy-', dir=os.path.dirname(wdest))
            os.close(fd)
            os.unlink(tempname)
            os.rename(wdest, tempname)
        try:
            self.run0('copy', source, dest)
        finally:
            self.manifest.add(dest)
            if exists:
                try:
                    os.unlink(wdest)
                except OSError:
                    pass
                os.rename(tempname, wdest)

    def dirs_of(self, files):
        dirs = set()
        for f in files:
            if os.path.isdir(self.wjoin(f)):
                dirs.add(f)
            for i in strutil.rfindall(f, '/'):
                dirs.add(f[:i])
        return dirs

    def add_dirs(self, files):
        add_dirs = [d for d in sorted(self.dirs_of(files))
                    if d not in self.manifest]
        if add_dirs:
            self.manifest.update(add_dirs)
            self.xargs(add_dirs, 'add', non_recursive=True, quiet=True)
        return add_dirs

    def add_files(self, files):
        files = [f for f in files if f not in self.manifest]
        if files:
            self.manifest.update(files)
            self.xargs(files, 'add', quiet=True)
        return files

    def tidy_dirs(self, names):
        deleted = []
        for d in sorted(self.dirs_of(names), reverse=True):
            wd = self.wjoin(d)
            if os.listdir(wd) == '.svn':
                self.run0('delete', d)
                self.manifest.remove(d)
                deleted.append(d)
        return deleted

    def addchild(self, parent, child):
        self.childmap[parent] = child

    def revid(self, rev):
        return u"svn:%s@%s" % (self.uuid, rev)

    def putcommit(self, files, copies, parents, commit, source, revmap):
        for parent in parents:
            try:
                return self.revid(self.childmap[parent])
            except KeyError:
                pass

        # Apply changes to working copy
        for f, v in files:
            try:
                data, mode = source.getfile(f, v)
            except IOError:
                self.delete.append(f)
            else:
                self.putfile(f, mode, data)
                if f in copies:
                    self.copies.append([copies[f], f])
        files = [f[0] for f in files]

        entries = set(self.delete)
        files = frozenset(files)
        entries.update(self.add_dirs(files.difference(entries)))
        if self.copies:
            for s, d in self.copies:
                self._copyfile(s, d)
            self.copies = []
        if self.delete:
            self.xargs(self.delete, 'delete')
            for f in self.delete:
                self.manifest.remove(f)
            self.delete = []
        entries.update(self.add_files(files.difference(entries)))
        entries.update(self.tidy_dirs(entries))
        if self.delexec:
            self.xargs(self.delexec, 'propdel', 'svn:executable')
            self.delexec = []
        if self.setexec:
            self.xargs(self.setexec, 'propset', 'svn:executable', '*')
            self.setexec = []

        fd, messagefile = tempfile.mkstemp(prefix='hg-convert-')
        fp = os.fdopen(fd, 'w')
        fp.write(commit.desc)
        fp.close()
        try:
            output = self.run0('commit',
                               username=util.shortuser(commit.author),
                               file=messagefile,
                               encoding='utf-8')
            try:
                rev = self.commit_re.search(output).group(1)
            except AttributeError:
                if not files:
                    return parents[0]
                self.ui.warn(_('unexpected svn output:\n'))
                self.ui.warn(output)
                raise util.Abort(_('unable to cope with svn output'))
            if commit.rev:
                self.run('propset', 'hg:convert-rev', commit.rev,
                         revprop=True, revision=rev)
            if commit.branch and commit.branch != 'default':
                self.run('propset', 'hg:convert-branch', commit.branch,
                         revprop=True, revision=rev)
            for parent in parents:
                self.addchild(parent, rev)
            return self.revid(rev)
        finally:
            os.unlink(messagefile)

    def puttags(self, tags):
        self.ui.warn(_('writing Subversion tags is not yet implemented\n'))
        return None, None

    def hascommit(self, rev):
        # This is not correct as one can convert to an existing subversion
        # repository and childmap would not list all revisions. Too bad.
        if rev in self.childmap:
            return True
        raise util.Abort(_('splice map revision %s not found in subversion '
                           'child map (revision lookups are not implemented)')
                         % rev)