Index: Modules/zlibmodule.c
===================================================================
--- Modules/zlibmodule.c	(revision 71045)
+++ Modules/zlibmodule.c	(working copy)
@@ -186,25 +186,34 @@
 }
 
 PyDoc_STRVAR(decompress__doc__,
-"decompress(string[, wbits[, bufsize]]) -- Return decompressed string.\n"
+"decompress(string[, wbits[, bufsize[, tail]]]) -- Return decompressed string.\n"
 "\n"
 "Optional arg wbits is the window buffer size.  Optional arg bufsize is\n"
-"the initial output buffer size.");
+"the initial output buffer size.  Optional arg tail, if True, will\n"
+"cause the return value to be a tuple, with the second element any\n"
+"unused data following the compressed part.");
 
 static PyObject *
-PyZlib_decompress(PyObject *self, PyObject *args)
+PyZlib_decompress(PyObject *self, PyObject *args, PyObject *kw)
 {
     PyObject *result_str;
     Byte *input;
     int length, err;
     int wsize=DEF_WBITS;
     Py_ssize_t r_strlen=DEFAULTALLOC;
+    PyObject *tailO = Py_False;
+    int tail = 0;
     z_stream zst;
+    char *keywords[] = {"string", "wbits", "bufsize", "tail", 0};
 
-    if (!PyArg_ParseTuple(args, "s#|in:decompress",
-			  &input, &length, &wsize, &r_strlen))
+    if (!PyArg_ParseTupleAndKeywords(args, kw, "s#|inO:decompress", keywords,
+			  &input, &length, &wsize, &r_strlen, &tailO))
 	return NULL;
-
+    if (tailO != Py_False) {
+	tail = PyObject_IsTrue(tailO);
+	if (tail < 0)
+	    return NULL;
+    }
     if (r_strlen <= 0)
 	r_strlen = 1;
 
@@ -279,6 +288,11 @@
     }
 
     _PyString_Resize(&result_str, zst.total_out);
+    if (result_str != NULL && tail) {
+	PyObject *tail = PyString_FromStringAndSize(
+		(char *)zst.next_in, zst.avail_in);
+	return Py_BuildValue("NN", result_str, tail);
+    }
     return result_str;
 
  error:
@@ -941,7 +955,7 @@
                     compressobj__doc__},
     {"crc32", (PyCFunction)PyZlib_crc32, METH_VARARGS,
               crc32__doc__},
-    {"decompress", (PyCFunction)PyZlib_decompress, METH_VARARGS,
+    {"decompress", (PyCFunction)PyZlib_decompress, METH_KEYWORDS,
                    decompress__doc__},
     {"decompressobj", (PyCFunction)PyZlib_decompressobj, METH_VARARGS,
                    decompressobj__doc__},