diff -r 9725ddcd37e6 Doc/library/os.rst
--- a/Doc/library/os.rst	Sun Jun 24 11:57:07 2012 +0200
+++ b/Doc/library/os.rst	Sun Jun 24 12:17:33 2012 +0200
@@ -1629,6 +1629,9 @@ features:
    included in ``pathconf_names``, an :exc:`OSError` is raised with
    :const:`errno.EINVAL` for the error number.
 
+   This function can support :ref:`specifying an open file descriptor
+   <path_fd>`.
+
    Availability: Unix.
 
 
diff -r 9725ddcd37e6 Lib/os.py
--- a/Lib/os.py	Sun Jun 24 11:57:07 2012 +0200
+++ b/Lib/os.py	Sun Jun 24 12:17:33 2012 +0200
@@ -174,6 +174,7 @@ if _exists("_have_functions"):
     _set.add(stat) # fstat always works
     _add("HAVE_FUTIMENS",   "utime")
     _add("HAVE_FUTIMES",    "utime")
+    _add("HAVE_FPATHCONF",  "pathconf")
     if _exists("statvfs") and _exists("fstatvfs"): # mac os x10.3
         _add("HAVE_FSTATVFS", "statvfs")
     supports_fd = _set
diff -r 9725ddcd37e6 Modules/posixmodule.c
--- a/Modules/posixmodule.c	Sun Jun 24 11:57:07 2012 +0200
+++ b/Modules/posixmodule.c	Sun Jun 24 12:17:33 2012 +0200
@@ -9219,31 +9219,45 @@ posix_fpathconf(PyObject *self, PyObject
 PyDoc_STRVAR(posix_pathconf__doc__,
 "pathconf(path, name) -> integer\n\n\
 Return the configuration limit name for the file or directory path.\n\
-If there is no limit, return -1.");
-
-static PyObject *
-posix_pathconf(PyObject *self, PyObject *args)
-{
+If there is no limit, return -1.\n\
+On some platforms, path may also be specified as an open file descriptor.\n\
+  If this functionality is unavailable, using it raises an exception.");
+
+static PyObject *
+posix_pathconf(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    path_t path;
     PyObject *result = NULL;
     int name;
-    char *path;
-
-    if (PyArg_ParseTuple(args, "sO&:pathconf", &path,
-                         conv_path_confname, &name)) {
+    static char *keywords[] = {"path", "name", NULL};
+
+    memset(&path, 0, sizeof(path));
+#ifdef HAVE_FPATHCONF
+    path.allow_fd = 1;
+#endif
+    if (PyArg_ParseTupleAndKeywords(args, kwargs, "O&O&:pathconf", keywords,
+                                    path_converter, &path,
+                                    conv_path_confname, &name)) {
     long limit;
 
     errno = 0;
-    limit = pathconf(path, name);
+#ifdef HAVE_FPATHCONF
+    if (path.fd != -1)
+        limit = fpathconf(path.fd, name);
+    else
+#endif
+        limit = pathconf(path.narrow, name);
     if (limit == -1 && errno != 0) {
         if (errno == EINVAL)
             /* could be a path or name problem */
             posix_error();
         else
-            posix_error_with_filename(path);
+            result = path_error("pathconf", &path);
     }
     else
         result = PyLong_FromLong(limit);
     }
+    path_cleanup(&path);
     return result;
 }
 #endif
@@ -11149,7 +11163,9 @@ static PyMethodDef posix_methods[] = {
     {"fpathconf",       posix_fpathconf, METH_VARARGS, posix_fpathconf__doc__},
 #endif
 #ifdef HAVE_PATHCONF
-    {"pathconf",        posix_pathconf, METH_VARARGS, posix_pathconf__doc__},
+    {"pathconf",        (PyCFunction)posix_pathconf,
+                        METH_VARARGS | METH_KEYWORDS,
+                        posix_pathconf__doc__},
 #endif
     {"abort",           posix_abort, METH_NOARGS, posix_abort__doc__},
 #ifdef MS_WINDOWS
@@ -11741,6 +11757,10 @@ static char *have_functions[] = {
     "HAVE_FDOPENDIR",
 #endif
 
+#ifdef HAVE_FPATHCONF
+    "HAVE_FPATHCONF",
+#endif
+
 #ifdef HAVE_FSTATAT
     "HAVE_FSTATAT",
 #endif