diff -r e1be927146df Lib/zipfile.py
--- a/Lib/zipfile.py	Sat Dec 13 05:02:20 2008 +0100
+++ b/Lib/zipfile.py	Sat Dec 13 20:31:35 2008 +0100
@@ -2,7 +2,12 @@
 Read and write ZIP files.
 """
 import struct, os, time, sys, shutil
-import binascii, cStringIO
+import binascii
+
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
 
 try:
     import zlib # We may need its compression method
@@ -451,7 +456,8 @@ class ZipExtFile:
         self.decrypter = decrypt
         self.bytes_read = 0L
         self.rawbuffer = ''
-        self.readbuffer = ''
+        self.readbuffer = StringIO()
+        self.readbufferlength = 0
         self.linebuffer = ''
         self.eof = False
         self.univ_newlines = False
@@ -468,7 +474,7 @@ class ZipExtFile:
         # read from compressed files in 64k blocks
         self.compreadsize = 64*1024
         if self.compress_type == ZIP_DEFLATED:
-            self.dc = zlib.decompressobj(-15)
+            self.dc = zlib.decompressobj(-zlib.MAX_WBITS)
 
     def set_univ_newlines(self, univ_newlines):
         self.univ_newlines = univ_newlines
@@ -578,10 +584,10 @@ class ZipExtFile:
 
         if size is not None and size >= 0:
             if self.compress_type == ZIP_STORED:
-                lr = len(self.readbuffer)
+                lr = self.readbufferlength - self.readbuffer.tell()
                 bytesToRead = min(bytesToRead, size - lr)
             elif self.compress_type == ZIP_DEFLATED:
-                if len(self.readbuffer) > size:
+                if self.readbufferlength - self.readbuffer.tell() > size:
                     # the user has requested fewer bytes than we've already
                     # pulled through the decompressor; don't read any more
                     bytesToRead = 0
@@ -603,7 +609,6 @@ class ZipExtFile:
             # handle contents of raw buffer
             if self.rawbuffer:
                 newdata = self.rawbuffer
-                self.rawbuffer = ''
 
                 # decrypt new data if we were given an object to handle that
                 if newdata and self.decrypter is not None:
@@ -620,20 +625,16 @@ class ZipExtFile:
                         newdata += self.dc.flush()
                         # prevent decompressor from being used again
                         self.dc = None
+                else:
+                    self.rawbuffer = ''
 
-                self.readbuffer += newdata
-
+                newdata = self.readbuffer.read() + newdata
+                # reallocate a new StringIO in order to avoid memory growth
+                self.readbuffer = StringIO(newdata)
+                self.readbufferlength = len(newdata)
 
         # return what the user asked for
-        if size is None or len(self.readbuffer) <= size:
-            bytes = self.readbuffer
-            self.readbuffer = ''
-        else:
-            bytes = self.readbuffer[:size]
-            self.readbuffer = self.readbuffer[size:]
-
-        return bytes
-
+        return self.readbuffer.read(size or -1)
 
 class ZipFile:
     """ Class with methods to open, read, write, close, list zip files.
@@ -747,7 +748,7 @@ class ZipFile:
         self.start_dir = offset_cd + concat
         fp.seek(self.start_dir, 0)
         data = fp.read(size_cd)
-        fp = cStringIO.StringIO(data)
+        fp = StringIO(data)
         total = 0
         while total < size_cd:
             centdir = fp.read(sizeCentralDir)
@@ -1347,18 +1348,7 @@ def main(args = None):
 
         zf = ZipFile(args[1], 'r')
         out = args[2]
-        for path in zf.namelist():
-            if path.startswith('./'):
-                tgt = os.path.join(out, path[2:])
-            else:
-                tgt = os.path.join(out, path)
-
-            tgtdir = os.path.dirname(tgt)
-            if not os.path.exists(tgtdir):
-                os.makedirs(tgtdir)
-            fp = open(tgt, 'wb')
-            fp.write(zf.read(path))
-            fp.close()
+        zf.extractall(out)
         zf.close()
 
     elif args[0] == '-c':