view hgext/convert/subversion.py @ 6858:8f256bf98219

Add support for multiple possible bisect results (issue1228, issue1182)

The real reason for both issue is that bisect can not handle cases where there
are multiple possibilities for the result.

Example (from issue1228):
rev 0 -> good
rev 1 -> skipped
rev 2 -> skipped
rev 3 -> skipped
rev 4 -> bad

Note that this patch does not only fix the reported Assertion Error but also
the problem of a non converging bisect:

hg init
for i in `seq 3`; do echo $i > $i; hg add $i; hg ci -m$i; done
hg bisect -b 2
hg bisect -g 0
hg bisect -s

From this state on, you can:
 a) mark as bad forever (non converging!)
 b) mark as good to get an inconsistent state
 c) skip for the Assertion Error

Minor description and code edits by pmezard.

# Subversion 1.4/1.5 Python API backend
#
# Copyright(C) 2007 Daniel Holth et al
#
# Configuration options:
#
# convert.svn.trunk
#   Relative path to the trunk (default: "trunk")
# convert.svn.branches
#   Relative path to tree of branches (default: "branches")
# convert.svn.tags
#   Relative path to tree of tags (default: "tags")
#
# Set these in a hgrc, or on the command line as follows:
#
#   hg convert --config convert.svn.trunk=wackoname [...]

import locale
import os
import re
import sys
import cPickle as pickle
import tempfile

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

# 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, commit, converter_source, encodeargs, decodeargs
from common import commandline, 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
except ImportError:
    pass

def geturl(path):
    try:
        return svn.client.url_from_path(svn.core.svn_path_canonicalize(path))
    except SubversionException:
        pass
    if os.path.isdir(path):
        path = os.path.normpath(os.path.abspath(path))
        if os.name == 'nt':
            path = '/' + util.normpath(path)
        return 'file://%s' % path
    return 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 SubversionException, (inst, num):
        pickle.dump(num, fp, protocol)
    except IOError:
        # Caller may interrupt the iteration
        pickle.dump(None, 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.set_binary(sys.stdin)
    util.set_binary(sys.stdout)
    args = decodeargs(sys.stdin.read())
    get_log_child(sys.stdout, *args)

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

    def __iter__(self):
        while True:
            entry = pickle.load(self._stdout)
            try:
                orig_paths, revnum, author, date, message = entry
            except:
                if entry is None:
                    break
                raise SubversionException("child raised exception", entry)
            yield entry

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

# 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)

        try:
            SubversionException
        except NameError:
            raise NoRepo('Subversion python bindings could not be loaded')

        self.encoding = locale.getpreferredencoding()
        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, e:
            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.base = 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 = self.url[len(self.base):]
            self.prevmodule = None
            self.rootmodule = self.module
            self.commits = {}
            self.paths = {}
            self.uuid = svn.ra.get_uuid(self.ra).decode(self.encoding)
        except SubversionException, e:
            ui.print_exc()
            raise NoRepo("%s does not look like a Subversion repo" % self.url)

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

        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.get_blacklist()
        except IOError, e:
            pass

        self.head = self.latest(self.module, latest)
        if not self.head:
            raise util.Abort(_('no revision found in module %s') %
                             self.module.encode(self.encoding))
        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 = self.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('/') + '/' + path,
                                 optrev, False, self.ctx)
            return True
        except SubversionException, err:
            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 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.encode(self.encoding))

        # 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 + '/' + 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.encode(self.encoding))
                    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 '
                                   '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 getfile(self, file, rev):
        data, mode = self._getfile(file, rev)
        self.modecache[(file, rev)] = mode
        return data

    def getmode(self, file, rev):
        return self.modecache[(file, rev)]

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

        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 = self.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)
        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)
        try:
            for entry in self._getlog([self.tags], start, self.startrev):
                origpaths, revnum, author, date, message = entry
                copies = [(e.copyfrom_path, e.copyfrom_rev, p) for p, e
                          in origpaths.iteritems() if e.copyfrom_path]
                copies.sort()
                # Apply moves/copies from more specific to general
                copies.reverse()

                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.split('/')[-1]])

                # Tell tag renamings from tag creations
                remainings = []
                for source, sourcerev, tagname in pendings:
                    if source.startswith(srctagspath):
                        remainings.append([source, sourcerev, tagname])
                        continue
                    # From revision may be fake, get one with changes
                    tagid = self.latest(source, sourcerev)
                    if tagid:
                        tags[tagname] = tagid
                pendings = remainings
                tagspath = srctagspath

        except SubversionException, (inst, num):
            self.ui.note('no tags found at revision %d\n' % start)
        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()

    # -- helper functions --

    def revid(self, revnum, module=None):
        if not module:
            module = self.module
        return u"svn:%s%s@%s" % (self.uuid, module.decode(self.encoding),
                                 revnum)

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

    def revsplit(self, rev):
        url, revnum = rev.encode(self.encoding).split('@', 1)
        revnum = int(revnum)
        parts = url.split('/', 1)
        uuid = parts.pop(0)[4:]
        mod = ''
        if parts:
            mod = '/' + parts[0]
        return uuid, mod, revnum

    def latest(self, path, stop=0):
        """Find the latest revid affecting path, up to stop. 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.
        """
        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 not stop:
            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 util.Abort('%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.
        stream = self._getlog([path], stop, dirent.created_rev)
        try:
            for entry in stream:
                paths, revnum, author, date, message = entry
                if revnum <= dirent.created_rev:
                    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
        finally:
            stream.close()

        if not path.startswith(self.rootmodule):
            self.ui.debug(_('ignoring foreign branch %r\n') % path)
            return None
        return self.revid(dirent.created_rev, path)

    def get_blacklist(self):
        """Avoid certain revision numbers.
        It is not uncommon for two nearby revisions to cancel each other
        out, e.g. 'I copied trunk into a subdirectory of itself instead
        of making a branch'. The converted repository is significantly
        smaller if we ignore such revisions."""
        self.blacklist = util.set()
        blacklist = self.blacklist
        for line in file("blacklist.txt", "r"):
            if not line.startswith("#"):
                try:
                    svn_rev = int(line.strip())
                    blacklist.add(svn_rev)
                except ValueError, e:
                    pass # not an integer or a comment

    def is_blacklisted(self, svn_rev):
        return svn_rev in self.blacklist

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

    def expandpaths(self, rev, paths, parents):
        entries = []
        copyfrom = {} # Map of entrypath, revision for finding source of deleted revisions.
        copies = {}

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

        for path, ent in paths:
            entrypath = self.getrelpath(path)
            entry = entrypath.decode(self.encoding)

            kind = self._checkpath(entrypath, revnum)
            if kind == svn.core.svn_node_file:
                entries.append(self.recode(entry))
                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 = self.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(entry)] = 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)

                # if a branch is created but entries are removed in the same
                # changeset, get the right fromrev
                # parents cannot be empty here, you cannot remove things from
                # a root revision.
                uuid, old_module, fromrev = self.revsplit(parents[0])

                basepath = old_module + "/" + self.getrelpath(path)
                entrypath = basepath

                def lookup_parts(p):
                    rc = None
                    parts = p.split("/")
                    for i in range(len(parts)):
                        part = "/".join(parts[:i])
                        info = part, copyfrom.get(part, None)
                        if info[1] is not None:
                            self.ui.debug("Found parent directory %s\n" % info[1])
                            rc = info
                    return rc

                self.ui.debug("base, entry %s %s\n" % (basepath, entrypath))

                frompath, froment = lookup_parts(entrypath) or (None, revnum - 1)

                # need to remove fragment from lookup_parts and replace with copyfrom_path
                if frompath is not None:
                    self.ui.debug("munge-o-matic\n")
                    self.ui.debug(entrypath + '\n')
                    self.ui.debug(entrypath[len(frompath):] + '\n')
                    entrypath = froment.copyfrom_path + entrypath[len(frompath):]
                    fromrev = froment.copyfrom_rev
                    self.ui.debug("Info: %s %s %s %s\n" % (frompath, froment, ent, entrypath))

                # We can avoid the reparent calls if the module has not changed
                # but it probably does not worth the pain.
                prevmodule = self.reparent('')
                fromkind = svn.ra.check_path(self.ra, entrypath.strip('/'), fromrev)
                self.reparent(prevmodule)

                if fromkind == svn.core.svn_node_file:   # a deleted file
                    entries.append(self.recode(entry))
                elif fromkind == svn.core.svn_node_dir:
                    # print "Deleted/moved non-file:", revnum, path, ent
                    # children = self._find_children(path, revnum - 1)
                    # print "find children %s@%d from %d action %s" % (path, revnum, ent.copyfrom_rev, ent.action)
                    # Sometimes this is tricky. For example: in
                    # The Subversion Repository revision 6940 a dir
                    # was copied and one of its files was deleted
                    # from the new location in the same commit. This
                    # code can't deal with that yet.
                    if ent.action == 'C':
                        children = self._find_children(path, fromrev)
                    else:
                        oroot = entrypath.strip('/')
                        nroot = path.strip('/')
                        children = self._find_children(oroot, fromrev)
                        children = [s.replace(oroot,nroot) for s in children]
                    # Mark all [files, not directories] as deleted.
                    for child in children:
                        # Can we move a child directory and its
                        # parent in the same commit? (probably can). Could
                        # cause problems if instead of revnum -1,
                        # we have to look in (copyfrom_path, revnum - 1)
                        entrypath = self.getrelpath("/" + child, module=old_module)
                        if entrypath:
                            entry = self.recode(entrypath.decode(self.encoding))
                            if entry in copies:
                                # deleted file within a copy
                                del copies[entry]
                            else:
                                entries.append(entry)
                else:
                    self.ui.debug('unknown path in revision %d: %s\n' % \
                                  (revnum, path))
            elif kind == svn.core.svn_node_dir:
                # Should probably synthesize normal file entries
                # and handle as above to clean up copy/rename handling.

                # If the directory just had a prop change,
                # then we shouldn't need to look for its children.
                if ent.action == 'M':
                    continue

                # Also this could create duplicate entries. Not sure
                # whether this will matter. Maybe should make entries a set.
                # print "Changed directory", revnum, path, ent.action, ent.copyfrom_path, ent.copyfrom_rev
                # This will fail if a directory was copied
                # from another branch and then some of its files
                # were deleted in the same transaction.
                children = self._find_children(path, revnum)
                children.sort()
                for child in children:
                    # Can we move a child directory and its
                    # parent in the same commit? (probably can). Could
                    # cause problems if instead of revnum -1,
                    # we have to look in (copyfrom_path, revnum - 1)
                    entrypath = self.getrelpath("/" + child)
                    # print child, self.module, entrypath
                    if entrypath:
                        # Need to filter out directories here...
                        kind = self._checkpath(entrypath, revnum)
                        if kind != svn.core.svn_node_dir:
                            entries.append(self.recode(entrypath))

                # Copies here (must copy all from source)
                # Probably not a real problem for us if
                # source does not exist
                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 = self.revsplit(parents[0])[1:]
                if ent.copyfrom_rev < prevnum:
                    continue
                copyfrompath = ent.copyfrom_path.decode(self.encoding)
                copyfrompath = self.getrelpath(copyfrompath, pmodule)
                if not copyfrompath:
                    continue
                copyfrom[path] = ent
                self.ui.debug("mark %s came from %s:%d\n"
                              % (path, copyfrompath, ent.copyfrom_rev))
                children = self._find_children(ent.copyfrom_path, ent.copyfrom_rev)
                children.sort()
                for child in children:
                    entrypath = self.getrelpath("/" + child, pmodule)
                    if not entrypath:
                        continue
                    entry = entrypath.decode(self.encoding)
                    copytopath = path + entry[len(copyfrompath):]
                    copytopath = self.getrelpath(copytopath)
                    copies[self.recode(copytopath)] = self.recode(entry, pmodule)

        return (util.unique(entries), 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 isdescendantof(parent, child):
            if not child or not parent or not child.startswith(parent):
                return False
            subpath = child[len(parent):]
            return len(subpath) > 1 and subpath[0] == '/'

        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 = orig_paths.items()
            orig_paths.sort()
            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:
                    # If dir was moved while one of its file was removed
                    # the log may look like:
                    # A /dir   (from /dir:x)
                    # A /dir/a (from /dir/a:y)
                    # A /dir/b (from /dir/b:z)
                    # ...
                    # for all remaining children.
                    # Let's take the highest child element from rev as source.
                    copies = [(p,e) for p,e in orig_paths[:-1]
                          if isdescendantof(ent.copyfrom_path, e.copyfrom_path)]
                    fromrev = max([e.copyfrom_rev for p,e in copies] + [ent.copyfrom_rev])
                    branched = True
                    newpath = ent.copyfrom_path + self.module[len(path):]
                    # ent.copyfrom_rev may not be the actual last revision
                    previd = self.latest(newpath, fromrev)
                    if previd is not None:
                        prevmodule, prevnum = self.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 == 'trunk':
                    branch = ''
            except IndexError:
                branch = None

            cset = commit(author=author,
                          date=util.datestr(date),
                          desc=log,
                          parents=parents,
                          branch=branch,
                          rev=rev.encode('utf-8'))

            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 self.is_blacklisted(revnum):
                        self.ui.note('skipping blacklisted revision %d\n'
                                     % revnum)
                        continue
                    if paths is None:
                        self.ui.debug('revision %d has no entries\n' % revnum)
                        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 util.Abort:
                    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):
        io = StringIO()
        # TODO: ra.get_file transmits the whole file instead of diffs.
        mode = ''
        try:
            new_module, revnum = self.revsplit(rev)[1:]
            if self.module != new_module:
                self.module = new_module
                self.reparent(self.module)
            info = svn.ra.get_file(self.ra, file, revnum, io)
            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
        data = io.getvalue()
        if mode == 'l':
            link_prefix = "link "
            if data.startswith(link_prefix):
                data = data[len(link_prefix):]
        return data, mode

    def _find_children(self, path, revnum):
        path = path.strip('/')
        pool = Pool()
        rpath = '/'.join([self.base, path]).strip('/')
        return ['%s/%s' % (path, x) for x in svn.client.ls(rpath, optrev(revnum), True, self.ctx, pool).keys()]

    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):
        # 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)

    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.base, relpaths, start, end, limit, discover_changed_paths,
                strict_node_history]
        arg = encodeargs(args)
        hgexe = util.hgexecutable()
        cmd = '%s debugsvnlog' % util.shellquote(hgexe)
        stdin, stdout = os.popen2(cmd, 'b')
        stdin.write(arg)
        stdin.close()
        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)

    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 repo %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 wc %r\n') % os.path.basename(wcpath))
            self.run0('checkout', path, wcpath)

            self.wc = wcpath
        self.opener = util.opener(self.wc)
        self.wopener = util.opener(self.wc)
        self.childmap = mapfile(ui, self.join('hg-childmap'))
        self.is_exec = util.checkexec(self.wc) and util.is_exec 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.set_flags(hook, "x")

        xport = transport.SvnRaTransport(url=geturl(path))
        self.uuid = svn.ra.get_uuid(xport.ra)

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

    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(filename, 'w').write(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.set_flags(self.wjoin(filename), flags)
            if was_exec:
                if 'x' not in flags:
                    self.delexec.append(filename)
            else:
                if 'x' in flags:
                    self.setexec.append(filename)

    def delfile(self, name):
        self.delete.append(name)

    def copyfile(self, source, dest):
        self.copies.append([source, dest])

    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.exists(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:
            if exists:
                try:
                    os.unlink(wdest)
                except OSError:
                    pass
                os.rename(tempname, wdest)

    def dirs_of(self, files):
        dirs = util.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 self.dirs_of(files)
                    if not os.path.exists(self.wjoin(d, '.svn', 'entries'))]
        if add_dirs:
            add_dirs.sort()
            self.xargs(add_dirs, 'add', non_recursive=True, quiet=True)
        return add_dirs

    def add_files(self, files):
        if files:
            self.xargs(files, 'add', quiet=True)
        return files

    def tidy_dirs(self, names):
        dirs = list(self.dirs_of(names))
        dirs.sort()
        dirs.reverse()
        deleted = []
        for d in dirs:
            wd = self.wjoin(d)
            if os.listdir(wd) == '.svn':
                self.run0('delete', 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, parents, commit):
        for parent in parents:
            try:
                return self.revid(self.childmap[parent])
            except KeyError:
                pass
        entries = util.set(self.delete)
        files = util.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')
            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:
                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(_('XXX TAGS NOT IMPLEMENTED YET\n'))