Add edit_file support

Following what the Perl API does, the edit_file
method is implemented to fetch an existing and
new URL from the tracker, DAV MOVE from one to
the other and then pass back a mutable file.

Upon closing the file, a length of `-1` is
supplied to avoid having to keep an accurate
internal counter in LargeHTTPFile.

pymogile/client.py

@@ -9,6 +9,8 @@
 from pymogile.backend import Backend
 from pymogile.exceptions import MogileFSError
 from pymogile.file import NormalHTTPFile, LargeHTTPFile
+from urlparse import urlparse
+import httplib
 
 
 class Client(object):
@@ -121,7 +123,31 @@ def edit_file(self, key, overwrite=False):
     By default, the file contents are preserved on open, but you may specify the overwrite option to zero the file first.
     The seek position is at the beginning of the file, but you may seek to the end to append.
     """
-    raise NotImplementedError()
+    params = {'domain': self.domain,
+              'key': key}
+    res = self.backend.do_request('edit_file', params)
+    if not res:
+      return None
+    # {'newpath': 'http://.../0000000594.fid', 'devid': '1', 'oldpath': 'http://.../0000000593.fid', 'fid': '594', 'class': '0'}
+
+    bits = urlparse(res['oldpath'])
+
+    c = httplib.HTTPConnection(bits.netloc)
+    c.request('MOVE', bits.path, headers={'Destination': res['newpath']})
+    cres = c.getresponse()
+    if cres.status != 201:
+      return None
+
+    main_devid, main_path, cls = res['devid'], res['newpath'], res['class']
+
+    return LargeHTTPFile(mg=self,
+                         fid=res['fid'],
+                         path=main_path,
+                         devid=main_devid,
+                         cls=cls,
+                         key=key,
+                         overwrite=overwrite,
+                         mutate_file=True)
 
   def read_file(self, key):
     """

pymogile/file.py

@@ -127,6 +127,7 @@ def __init__(self,
                key=None, 
                readonly=False, 
                create_close_arg=None, 
+               mutate_file=False,
                **kwds):
 
     super(LargeHTTPFile, self).__init__(mg, fid, key, cls, create_close_arg)
@@ -162,6 +163,8 @@ def __init__(self,
     self._pos = 0
     self._eof = 0
 
+    self.mutate_file = mutate_file
+
   def read(self, n= -1):
     if self._is_closed:
       return False
@@ -226,7 +229,7 @@ def close(self):
                    'fid': self.fid,
                    'devid': self.devid,
                    'domain': self.mg.domain,
-                   'size': self.length,
+                   'size': self.mutate_file and -1 or self.length,
                    'key': self.key,
                    'path': self.path,
                  }

tests/test_client.py

@@ -241,22 +241,22 @@ def test_mkcol(self):
       self.assertTrue(paths)
 
 
-#  def test_edit_file(self): 
-#    cl = Client(TEST_NS, HOSTS)
-#    key = 'test_file_%s_%s' % (random.random(), time.time())
-#
-#    cl.store_content(key, "SPAM")
-#    assert cl.get_paths(key)
-#    assert cl.get_file_data(key) == "SPAM"
-#
-#    fp = cl.edit_file(key)
-#    assert fp
-#    fp.write("s")
-#    fp.seek(2)
-#    fp.write("a")
-#    fp.close()
-#
-#    assert cl.get_file_data(key) == "sPaM"
+  def test_edit_file(self):
+    cl = Client(TEST_NS, HOSTS)
+    key = 'test_file_%s_%s' % (random.random(), time.time())
+
+    cl.store_content(key, "SPAM")
+    self.assertTrue(cl.get_paths(key))
+    self.assertEqual("SPAM", cl.get_file_data(key))
+
+    fp = cl.edit_file(key)
+    self.assertTrue(fp)
+    fp.write("s")
+    fp.seek(2)
+    fp.write("a")
+    fp.close()
+
+    self.assertEqual("sPaM", cl.get_file_data(key))
 
   def test_file_like_object(self): 
     client = Client(TEST_NS, HOSTS)