diff -r d4ddc4978633 Lib/socket.py
--- a/Lib/socket.py	Thu Oct 14 10:08:56 2010 +0200
+++ b/Lib/socket.py	Thu Oct 14 12:29:12 2010 +0200
@@ -108,7 +108,7 @@ class socket(_socket.socket):
         if s.startswith("<socket object"):
             s = "<%s.%s%s%s" % (self.__class__.__module__,
                                 self.__class__.__name__,
-                                (self._closed and " [closed] ") or "",
+                                getattr(self, '_closed', False) and " [closed] " or "",
                                 s[7:])
         return s
 
diff -r d4ddc4978633 Lib/sysconfig.py
--- a/Lib/sysconfig.py	Thu Oct 14 10:08:56 2010 +0200
+++ b/Lib/sysconfig.py	Thu Oct 14 12:29:12 2010 +0200
@@ -333,7 +333,8 @@ def _init_posix(vars):
     # load the installed pyconfig.h:
     config_h = get_config_h_filename()
     try:
-        parse_config_h(open(config_h), vars)
+        with open(config_h) as f:
+            parse_config_h(f, vars)
     except IOError as e:
         msg = "invalid Python installation: unable to open %s" % config_h
         if hasattr(e, "strerror"):
diff -r d4ddc4978633 Modules/_io/bufferedio.c
--- a/Modules/_io/bufferedio.c	Thu Oct 14 10:08:56 2010 +0200
+++ b/Modules/_io/bufferedio.c	Thu Oct 14 12:29:12 2010 +0200
@@ -197,6 +197,7 @@ typedef struct {
     int detached;
     int readable;
     int writable;
+    int deallocating;
     
     /* True if this is a vanilla Buffered object (rather than a user derived
        class) *and* the raw stream is a vanilla FileIO object. */
@@ -342,6 +343,7 @@ typedef struct {
 static void
 buffered_dealloc(buffered *self)
 {
+    self->deallocating = 1;
     if (self->ok && _PyIOBase_finalize((PyObject *) self) < 0)
         return;
     _PyObject_GC_UNTRACK(self);
@@ -382,6 +384,23 @@ buffered_clear(buffered *self)
     return 0;
 }
 
+/* Because this can call arbitrary code, it shouldn't be called when
+   the refcount is 0 (that is, not directly from tp_dealloc unless
+   the refcount has been temporarily re-incremented). */
+PyObject *
+buffered_dealloc_warn(buffered *self, PyObject *source)
+{
+    if (self->ok && self->raw) {
+        PyObject *r;
+        r = PyObject_CallMethod(self->raw, "_dealloc_warn", "O", source);
+        if (r)
+            Py_DECREF(r);
+        else
+            PyErr_Clear();
+    }
+    Py_RETURN_NONE;
+}
+
 /*
  * _BufferedIOMixin methods
  * This is not a class, just a collection of methods that will be reused
@@ -435,6 +454,14 @@ buffered_close(buffered *self, PyObject 
         Py_INCREF(res);
         goto end;
     }
+
+    if (self->deallocating) {
+        PyObject *r = buffered_dealloc_warn(self, (PyObject *) self);
+        if (r)
+            Py_DECREF(r);
+        else
+            PyErr_Clear();
+    }
     /* flush() will most probably re-take the lock, so drop it first */
     LEAVE_BUFFERED(self)
     res = PyObject_CallMethodObjArgs((PyObject *)self, _PyIO_str_flush, NULL);
@@ -1461,6 +1488,7 @@ static PyMethodDef bufferedreader_method
     {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
     {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
     {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
+    {"_dealloc_warn", (PyCFunction)buffered_dealloc_warn, METH_O},
 
     {"read", (PyCFunction)buffered_read, METH_VARARGS},
     {"peek", (PyCFunction)buffered_peek, METH_VARARGS},
@@ -1843,6 +1871,7 @@ static PyMethodDef bufferedwriter_method
     {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
     {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
     {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
+    {"_dealloc_warn", (PyCFunction)buffered_dealloc_warn, METH_O},
 
     {"write", (PyCFunction)bufferedwriter_write, METH_VARARGS},
     {"truncate", (PyCFunction)buffered_truncate, METH_VARARGS},
@@ -2227,6 +2256,7 @@ static PyMethodDef bufferedrandom_method
     {"writable", (PyCFunction)buffered_writable, METH_NOARGS},
     {"fileno", (PyCFunction)buffered_fileno, METH_NOARGS},
     {"isatty", (PyCFunction)buffered_isatty, METH_NOARGS},
+    {"_dealloc_warn", (PyCFunction)buffered_dealloc_warn, METH_O},
 
     {"flush", (PyCFunction)buffered_flush, METH_NOARGS},
 
@@ -2296,4 +2326,3 @@ PyTypeObject PyBufferedRandom_Type = {
     0,                          /* tp_alloc */
     PyType_GenericNew,          /* tp_new */
 };
-
diff -r d4ddc4978633 Modules/_io/fileio.c
--- a/Modules/_io/fileio.c	Thu Oct 14 10:08:56 2010 +0200
+++ b/Modules/_io/fileio.c	Thu Oct 14 12:29:12 2010 +0200
@@ -2,6 +2,7 @@
 
 #define PY_SSIZE_T_CLEAN
 #include "Python.h"
+#include "structmember.h"
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
@@ -55,6 +56,7 @@ typedef struct {
     unsigned int writable : 1;
     signed int seekable : 2; /* -1 means unknown */
     unsigned int closefd : 1;
+    unsigned int deallocating: 1;
     PyObject *weakreflist;
     PyObject *dict;
 } fileio;
@@ -69,6 +71,23 @@ _PyFileIO_closed(PyObject *self)
     return ((fileio *)self)->fd < 0;
 }
 
+/* Because this can call arbitrary code, it shouldn't be called when
+   the refcount is 0 (that is, not directly from tp_dealloc unless
+   the refcount has been temporarily re-incremented). */
+static PyObject *
+fileio_dealloc_warn(fileio *self, PyObject *source)
+{
+    if (self->fd >= 0 && self->closefd) {
+        PyObject *exc, *val, *tb;
+        PyErr_Fetch(&exc, &val, &tb);
+        if (PyErr_WarnFormat(PyExc_RuntimeWarning, 1,
+                             "unclosed file %R", source))
+            PyErr_WriteUnraisable((PyObject *) self);
+        PyErr_Restore(exc, val, tb);
+    }
+    Py_RETURN_NONE;
+}
+
 static PyObject *
 portable_lseek(int fd, PyObject *posobj, int whence);
 
@@ -110,6 +129,13 @@ fileio_close(fileio *self)
         self->fd = -1;
         Py_RETURN_NONE;
     }
+    if (self->deallocating) {
+        PyObject *r = fileio_dealloc_warn(self, (PyObject *) self);
+        if (r)
+            Py_DECREF(r);
+        else
+            PyErr_Clear();
+    }
     errno = internal_close(self);
     if (errno < 0)
         return NULL;
@@ -398,6 +424,7 @@ fileio_clear(fileio *self)
 static void
 fileio_dealloc(fileio *self)
 {
+    self->deallocating = 1;
     if (_PyIOBase_finalize((PyObject *) self) < 0)
         return;
     _PyObject_GC_UNTRACK(self);
@@ -1007,6 +1034,7 @@ static PyMethodDef fileio_methods[] = {
     {"writable", (PyCFunction)fileio_writable, METH_NOARGS,      writable_doc},
     {"fileno",   (PyCFunction)fileio_fileno,   METH_NOARGS,      fileno_doc},
     {"isatty",   (PyCFunction)fileio_isatty,   METH_NOARGS,      isatty_doc},
+    {"_dealloc_warn", (PyCFunction)fileio_dealloc_warn, METH_O, NULL},
     {NULL,           NULL}             /* sentinel */
 };
 
diff -r d4ddc4978633 Modules/_io/textio.c
--- a/Modules/_io/textio.c	Thu Oct 14 10:08:56 2010 +0200
+++ b/Modules/_io/textio.c	Thu Oct 14 12:29:12 2010 +0200
@@ -658,6 +658,7 @@ typedef struct
     char writetranslate;
     char seekable;
     char telling;
+    char deallocating;
     /* Specialized encoding func (see below) */
     encodefunc_t encodefunc;
     /* Whether or not it's the start of the stream */
@@ -1094,6 +1095,7 @@ _textiowrapper_clear(textio *self)
 static void
 textiowrapper_dealloc(textio *self)
 {
+    self->deallocating = 1;
     if (_textiowrapper_clear(self) < 0)
         return;
     _PyObject_GC_UNTRACK(self);
@@ -2410,6 +2412,13 @@ textiowrapper_close(textio *self, PyObje
         Py_RETURN_NONE; /* stream already closed */
     }
     else {
+        if (self->deallocating) {
+            res = PyObject_CallMethod(self->buffer, "_dealloc_warn", "O", self);
+            if (res)
+                Py_DECREF(res);
+            else
+                PyErr_Clear();
+        }
         res = PyObject_CallMethod((PyObject *)self, "flush", NULL);
         if (res == NULL) {
             return NULL;
diff -r d4ddc4978633 Modules/socketmodule.c
--- a/Modules/socketmodule.c	Thu Oct 14 10:08:56 2010 +0200
+++ b/Modules/socketmodule.c	Thu Oct 14 12:29:12 2010 +0200
@@ -2910,8 +2910,18 @@ static PyMemberDef sock_memberlist[] = {
 static void
 sock_dealloc(PySocketSockObject *s)
 {
-    if (s->sock_fd != -1)
+    if (s->sock_fd != -1) {
+        PyObject *exc, *val, *tb;
+        Py_ssize_t old_refcount = Py_REFCNT(s);
+        Py_INCREF(s);
+        PyErr_Fetch(&exc, &val, &tb);
+        if (PyErr_WarnFormat(PyExc_RuntimeWarning, 1,
+                             "unclosed %R", s))
+            PyErr_WriteUnraisable((PyObject *) s);
+        PyErr_Restore(exc, val, tb);
         (void) SOCKETCLOSE(s->sock_fd);
+        Py_REFCNT(s) = old_refcount;
+    }
     Py_TYPE(s)->tp_free((PyObject *)s);
 }