--- posixmodule-orig.c  Wed Jul 01 10:35:00 2009
+++ posixmodule.c       Wed Jul 01 15:16:06 2009
@@ -122,6 +122,7 @@
 #else
 #ifdef _MSC_VER                /* Microsoft compiler */
 #define HAVE_GETCWD     1
+#define HAVE_GETPPID    1
 #define HAVE_SPAWNV    1
 #define HAVE_EXECV      1
 #define HAVE_PIPE       1
@@ -3889,15 +3890,59 @@
 
 #endif /* HAVE_SETPGRP */
 
+#ifdef MS_WINDOWS
+#include <tlhelp32.h>
+static PyObject*
+win32_getppid()
+{
+    HANDLE snapshot;
+    pid_t parentpid, mypid;
+    parentpid = (pid_t)-1;
+    
+    mypid = getpid();
+    snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
+    if (INVALID_HANDLE_VALUE != snapshot) {
+        BOOL have_record;
+        PROCESSENTRY32 pe;
+
+        pe.dwSize = sizeof(pe);
+        have_record = Process32First(snapshot, &pe);
+        while (have_record) {
+            if (mypid == (pid_t)pe.th32ProcessID) {
+                /* We could cache this value in a static variable. */
+                parentpid = pe.th32ParentProcessID;
+                break;
+            }
+
+            have_record = Process32Next(snapshot, &pe);
+        }
+
+        CloseHandle(snapshot);
+    }
+
+    if (-1 == parentpid) {
+        return win32_error("getppid", NULL);
+    }
+    
+    return PyLong_FromPid(parentpid);
+}
+#endif /*MS_WINDOWS*/
+
 #ifdef HAVE_GETPPID
 PyDoc_STRVAR(posix_getppid__doc__,
 "getppid() -> ppid\n\n\
-Return the parent's process id.");
+Return the parent's process id. On Windows systems a\n\
+WindowsError will be raised if the parent process id\n\
+can not be determined.");
 
 static PyObject *
 posix_getppid(PyObject *self, PyObject *noargs)
 {
+#ifdef MS_WINDOWS
+    return win32_getppid();
+#else
        return PyLong_FromPid(getppid());
+#endif
 }
 #endif
 
--- os-orig.rst Wed Jul 01 09:42:14 2009
+++ os.rst      Wed Jul 01 15:18:42 2009
@@ -171,7 +171,8 @@
 
    .. index:: single: process; id of parent
 
-   Return the parent's process id. Availability: Unix.
+   Return the parent's process id. On Windows, raises WindowsError if the
+   parent's process id can not be determined. Availability: Unix, Windows.
 
 
 .. function:: getuid()