Index: Lib/gzip.py
===================================================================
--- Lib/gzip.py	(revision 76872)
+++ Lib/gzip.py	(working copy)
@@ -97,8 +97,12 @@
             self.mode = READ
             # Set flag indicating start of a new member
             self._new_member = True
+            # Buffer data read from gzip file. extrastart is offset in
+            # stream where buffer starts. extrasize is number of
+            # bytes remaining in buffer from current stream position.
             self.extrabuf = ""
             self.extrasize = 0
+            self.extrastart = 0
             self.name = filename
             # Starts small, scales exponentially
             self.min_readsize = 100
@@ -204,12 +208,28 @@
 
         if self.fileobj is None:
             raise ValueError, "write() on closed GzipFile object"
+
+        # Convert data type if called by io.BufferedWriter.
+        if type(data) is memoryview:
+            data = data.tobytes()
+
         if len(data) > 0:
             self.size = self.size + len(data)
             self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
             self.fileobj.write( self.compress.compress(data) )
             self.offset += len(data)
 
+        return len(data)
+
+    def readinto(self, b):
+        """Read up to len(b) bytes into b.
+
+        Returns number of bytes read (0 for EOF).
+        """        
+        chunk = self.read(len(b))
+        b[: len(chunk)] = chunk
+        return len(chunk)
+
     def read(self, size=-1):
         if self.mode != READ:
             import errno
@@ -235,15 +255,14 @@
                 if size > self.extrasize:
                     size = self.extrasize
 
-        chunk = self.extrabuf[:size]
-        self.extrabuf = self.extrabuf[size:]
+        offset = self.offset - self.extrastart
+        chunk = self.extrabuf[offset: offset + size]
         self.extrasize = self.extrasize - size
 
         self.offset += size
         return chunk
 
     def _unread(self, buf):
-        self.extrabuf = buf + self.extrabuf
         self.extrasize = len(buf) + self.extrasize
         self.offset -= len(buf)
 
@@ -299,8 +318,10 @@
 
     def _add_read_data(self, data):
         self.crc = zlib.crc32(data, self.crc) & 0xffffffffL
-        self.extrabuf = self.extrabuf + data
+        offset = self.offset - self.extrastart
+        self.extrabuf = self.extrabuf[offset:] + data
         self.extrasize = self.extrasize + len(data)
+        self.extrastart = self.offset
         self.size = self.size + len(data)
 
     def _read_eof(self):
@@ -318,6 +339,10 @@
         elif isize != (self.size & 0xffffffffL):
             raise IOError, "Incorrect length of data produced"
 
+    @property
+    def closed(self):
+        return self.fileobj is None
+
     def close(self):
         if self.fileobj is None:
             return
@@ -371,8 +396,18 @@
         self._new_member = True
         self.extrabuf = ""
         self.extrasize = 0
+        self.extrastart = 0
         self.offset = 0
 
+    def readable(self):
+        return self.mode == READ
+
+    def writable(self):
+        return self.mode == WRITE
+
+    def seekable(self):
+        return True
+
     def seek(self, offset, whence=0):
         if whence:
             if whence == 1:
@@ -395,8 +430,18 @@
                 self.read(1024)
             self.read(count % 1024)
 
+        return self.offset
+
     def readline(self, size=-1):
         if size < 0:
+            # Shortcut common case - newline found in buffer.
+            offset = self.offset - self.extrastart
+            i = self.extrabuf.find('\n', offset) + 1
+            if i > 0:
+                self.extrasize -= i - offset
+                self.offset += i - offset
+                return self.extrabuf[offset: i]
+
             size = sys.maxint
             readsize = self.min_readsize
         else:
Index: Lib/test/test_gzip.py
===================================================================
--- Lib/test/test_gzip.py	(revision 76872)
+++ Lib/test/test_gzip.py	(working copy)
@@ -5,6 +5,7 @@
 import unittest
 from test import test_support
 import os
+import io
 import struct
 gzip = test_support.import_module('gzip')
 
@@ -80,7 +81,14 @@
         zgfile.close()
         self.assertEquals(contents, 'a'*201)
 
+    def test_buffered_reader_7471(self):
+        self.test_write()
 
+        f = gzip.GzipFile(self.filename, 'rb')
+        r = io.BufferedReader(f)
+        lines = [line for line in r]
+        r.close() 
+    
     def test_readline(self):
         self.test_write()
         # Try .readline() with varying line lengths