1 files changed, 38 insertions, 4 deletions
diff --git a/swiftclient/utils.py b/swiftclient/utils.py
index 9d94b6b..0abaed6 100644
--- a/swiftclient/utils.py
+++ b/swiftclient/utils.py
@@ -202,27 +202,36 @@ class LengthWrapper(object):
     def __init__(self, readable, length, md5=False):
         """
         :param readable: The filelike object to read from.
-        :param length: The maximum amount of content to that can be read from
+        :param length: The maximum amount of content that can be read from
                        the filelike object before it is simulated to be
                        empty.
         :param md5: Flag to enable calculating the MD5 of the content
                     as it is read.
         """
-        self.md5sum = hashlib.md5() if md5 else NoopMD5()
+        self._md5 = md5
+        self._reset_md5()
         self._length = self._remaining = length
         self._readable = readable
+        self._can_reset = all(hasattr(readable, attr)
+                              for attr in ('seek', 'tell'))
+        if self._can_reset:
+            self._start = readable.tell()
 
     def __len__(self):
         return self._length
 
+    def _reset_md5(self):
+        self.md5sum = hashlib.md5() if self._md5 else NoopMD5()
+
     def get_md5sum(self):
         return self.md5sum.hexdigest()
 
-    def read(self, *args, **kwargs):
+    def read(self, size=-1):
         if self._remaining <= 0:
             return ''
 
-        chunk = self._readable.read(*args, **kwargs)[:self._remaining]
+        to_read = self._remaining if size < 0 else min(size, self._remaining)
+        chunk = self._readable.read(to_read)
         self._remaining -= len(chunk)
 
         try:
@@ -232,6 +241,21 @@ class LengthWrapper(object):
 
         return chunk
 
+    @property
+    def reset(self):
+        if self._can_reset:
+            return self._reset
+        raise AttributeError("%r object has no attribute 'reset'" %
+                             type(self).__name__)
+
+    def _reset(self, *args, **kwargs):
+        if not self._can_reset:
+            raise TypeError('%r object cannot be reset; needs both seek and '
+                            'tell methods' % type(self._readable).__name__)
+        self._readable.seek(self._start)
+        self._reset_md5()
+        self._remaining = self._length
+
 
 def iter_wrapper(iterable):
     for chunk in iterable:
@@ -240,3 +264,13 @@ def iter_wrapper(iterable):
             # causing the server to close the connection
             continue
         yield chunk
+
+
+def n_at_a_time(seq, n):
+    for i in range(0, len(seq), n):
+        yield seq[i:i + n]
+
+
+def n_groups(seq, n):
+    items_per_group = ((len(seq) - 1) // n) + 1
+    return n_at_a_time(seq, items_per_group)