Index: _test_ftp_sync.py
===================================================================
--- _test_ftp_sync.py (revision 676:cc436d273369)
+++ _test_ftp_sync.py (revision 679:f4405b7674a3)
@@ -32,3 +32,31 @@
 # $Id$
 
+import os
+import shutil
+import sys
+import unittest
 
+TEST_ROOT = "/home/schwa/sd/python/ftputil"
+sys.path.insert(0, os.path.dirname(TEST_ROOT))
+
+from ftputil import ftp_sync
+
+
+class TestLocalToLocal(unittest.TestCase):
+    def setUp(self):
+        target_dir = os.path.join(TEST_ROOT, "test_target")
+        shutil.rmtree(target_dir)
+        os.mkdir(target_dir)
+
+    def test_sync_empty_dir(self):
+        source = ftp_sync.LocalHost()
+        target = ftp_sync.LocalHost()
+        syncer = ftp_sync.Syncer(source, target)
+        source_dir = os.path.join(TEST_ROOT, "test_empty")
+        target_dir = os.path.join(TEST_ROOT, "test_target")
+        syncer.sync(source_dir, target_dir)
+
+
+if __name__ == '__main__':
+    unittest.main()
+
Index: ftp_sync.py
===================================================================
--- ftp_sync.py (revision 674:3f97934659f9)
+++ ftp_sync.py (revision 679:f4405b7674a3)
@@ -32,2 +32,113 @@
 # $Id$
 
+"""
+Tools for syncing combinations of local and remote directories.
+
+*** WARNING: This is an unfinished in-development version!
+"""
+
+# Sync combinations:
+# - remote -> local (download)
+# - local -> remote (upload)
+# - remote -> remote
+# - local -> local (perhaps implicitly possible due to design, but not targeted)
+
+import os
+import shutil
+
+from ftputil import FTPHost
+import ftp_error
+
+__all__ = ['FTPHost', 'LocalHost', 'Syncer']
+
+
+# 64 KB
+CHUNK_SIZE = 64*1024
+
+
+class LocalHost(object):
+    def open(self, path, mode):
+        """
+        Return a Python file object for file name `path`, opened in
+        mode `mode`.
+        """
+        # this is the built-in `open` function, not `os.open`!
+        return open(path, mode)
+
+    def __getattr__(self, attr):
+        return getattr(os, attr)
+
+
+class Syncer(object):
+    def __init__(self, source, target):
+        """
+        Init the `FTPSyncer` instance.
+        
+        Each of `source` and `target` is either an `FTPHost` or a
+        `LocalHost` object. The source and target directories, resp.
+        have to be set with the `chdir` command before passing them
+        in. The semantics is so that the items under the source
+        directory will show up under the target directory after the
+        synchronization (unless there's an error).
+        """
+        self._source = source
+        self._target = target
+
+    def _mkdir(self, target_dir):
+        """
+        Try to create the target directory `target_dir`. If it already
+        exists, don't do anything. If the directory is present but
+        it's actually a file, raise a `SyncError`.
+        """
+        #TODO handle setting of target mtime according to source mtime
+        #  (beware of rootdir anomalies; try to handle them as well)
+        print "Making", target_dir
+        if self._target.path.isfile(target_dir):
+            raise ftp_error.SyncError("target dir '%s' is actually a file" %
+                                      target_dir)
+        if not self._target.path.isdir(target_dir):
+            self._target.mkdir(target_dir)
+
+    def _sync_file(self, source_file, target_file):
+        #TODO handle `IOError`s
+        #TODO handle conditional copy
+        #TODO handle setting of target mtime according to source mtime
+        #  (beware of rootdir anomalies; try to handle them as well)
+        print "Syncing", source_file, "->", target_file
+        source = self._source.open(source_file, "rb")
+        try:
+            target = self._target.open(target_file, "wb")
+            try:
+                shutil.copyfileobj(source, target, length=CHUNK_SIZE)
+            finally:
+                target.close()
+        finally:
+            source.close()
+
+    def sync(self, source_dir, target_dir):
+        """
+        Synchronize the source and the target by updating the target
+        to match the source as far as possible.
+
+        Current limitations:
+        - _don't_ delete items which are on the target path but not on the
+          source path
+        - files are always copied, the modification timestamps are not
+          compared
+        - all files are copied in binary mode, never in ASCII/text mode
+        - incomplete error handling
+        """
+        source_dir = self._source.path.abspath(source_dir)
+        target_dir = self._target.path.abspath(target_dir)
+        self._mkdir(target_dir)
+        for dirpath, dirnames, filenames in self._source.walk(source_dir):
+            for dirname in dirnames:
+                inner_source_dir = self._source.path.join(dirpath, dirname)
+                inner_target_dir = inner_source_dir.replace(source_dir,
+                                                            target_dir, 1)
+                self._mkdir(inner_target_dir)
+            for filename in filenames:
+                source_file = self._source.path.join(dirpath, filename)
+                target_file = source_file.replace(source_dir, target_dir, 1)
+                self._sync_file(source_file, target_file)
+