# HG changeset patch
# Parent ca54c27a9045c655ef1ad9ce248f02eb00137476
diff -r ca54c27a9045 -r ba8c5a38f856 Modules/_io/fileio.c
--- a/Modules/_io/fileio.c	Tue Aug 21 14:54:22 2012 +0100
+++ b/Modules/_io/fileio.c	Wed Aug 22 11:05:33 2012 +0100
@@ -615,10 +615,6 @@
     if (!_PyVerify_fd(self->fd))
         return PyErr_SetFromErrno(PyExc_IOError);
 
-    result = PyBytes_FromStringAndSize(NULL, SMALLCHUNK);
-    if (result == NULL)
-        return NULL;
-
 #ifdef HAVE_FSTAT
 #if defined(MS_WIN64) || defined(MS_WINDOWS)
     pos = _lseeki64(self->fd, 0L, SEEK_CUR);
@@ -629,13 +625,21 @@
         end = st.st_size;
     else
         end = (Py_off_t)-1;
+    if (end <= 0)
 #endif
+    {
+        _Py_IDENTIFIER(readall);
+        return _PyObject_CallMethodId((PyObject*)&PyRawIOBase_Type,
+                                      &PyId_readall, "O", self);
+    }
+
+#ifdef HAVE_FSTAT
+    result = PyBytes_FromStringAndSize(NULL, SMALLCHUNK);
+    if (result == NULL)
+        return NULL;
+
     while (1) {
-#ifdef HAVE_FSTAT
         newsize = new_buffersize(self, total, pos, end);
-#else
-        newsize = new_buffersize(self, total);
-#endif
         if (newsize > PY_SSIZE_T_MAX || newsize <= 0) {
             PyErr_SetString(PyExc_OverflowError,
                 "unbounded read returned more bytes "
@@ -681,9 +685,7 @@
             return NULL;
         }
         total += n;
-#ifdef HAVE_FSTAT
         pos += n;
-#endif
     }
 
     if (PyBytes_GET_SIZE(result) > total) {
@@ -694,6 +696,7 @@
         }
     }
     return result;
+#endif
 }
 
 static PyObject *