diff --git Python-2.6.4/Python/import.c Python-2.6.4/Python/import.c

--- Python-2.6.4/Python/import.c

+++ Python-2.6.4/Python/import.c

@@ -868,8 +868,9 @@

 /* Write a compiled module to a file, placing the time of last

    modification of its source into the header.

-   Errors are ignored, if a write error occurs an attempt is made to

-   remove the file. */

+   Write to a temporary file first so that creating the file is atomic.

+   Errors are ignored, if a write/unlink/rename error occurs an attempt

+   is made to remove the temporary file. */

 static void

 write_compiled_module(PyCodeObject *co, char *cpathname, struct stat *srcstat)

@@ -882,11 +883,21 @@

     mode_t mode = srcstat->st_mode & ~S_IXUSR & ~S_IXGRP & ~S_IXOTH;

 #endif

-    fp = open_exclusive(cpathname, mode);

+    char *tmppathname;

+

+    /* the temporary file is called cpathname + ".tmp" */

+    if ((tmppathname = PyMem_Malloc(strlen(cpathname) + strlen(".tmp") + 1))

+        == NULL) {

+        return;

+    }

+    sprintf (tmppathname, "%s.tmp", cpathname);

+    fp = open_exclusive(tmppathname, mode);

+

     if (fp == NULL) {

         if (Py_VerboseFlag)

             PySys_WriteStderr(

-                "# can't create %s\n", cpathname);

+                "# can't create %s\n", tmppathname);

+        PyMem_Free(tmppathname);

         return;

     }

     PyMarshal_WriteLongToFile(pyc_magic, fp, Py_MARSHAL_VERSION);

@@ -895,10 +906,11 @@

     PyMarshal_WriteObjectToFile((PyObject *)co, fp, Py_MARSHAL_VERSION);

     if (fflush(fp) != 0 || ferror(fp)) {

         if (Py_VerboseFlag)

-            PySys_WriteStderr("# can't write %s\n", cpathname);

+            PySys_WriteStderr("# can't write %s\n", tmppathname);

         /* Don't keep partial file */

         fclose(fp);

-        (void) unlink(cpathname);

+        (void) unlink(tmppathname);

+        PyMem_Free(tmppathname);

         return;

     }

     /* Now write the true mtime */

@@ -907,8 +919,29 @@

     PyMarshal_WriteLongToFile((long)mtime, fp, Py_MARSHAL_VERSION);

     fflush(fp);

     fclose(fp);

+    /* Delete the old compiled file, if exists */

+    if (unlink (cpathname)) {

+        if ((errno != ENOENT)) {

+            /* the file exists but could not be deleted */

+            if (Py_VerboseFlag)

+                PySys_WriteStderr("# can't unlink %s\n", cpathname);

+            (void) unlink(tmppathname);

+            PyMem_Free(tmppathname);

+            return;

+        }

+    }

+    /* rename the tmp file to the real file name */

+    if (rename (tmppathname, cpathname)) {

+        if (Py_VerboseFlag)

+            PySys_WriteStderr(

+                "# can't rename %s to %s\n", tmppathname, cpathname);

+        (void) unlink(tmppathname);

+        PyMem_Free(tmppathname);

+        return;

+    }

     if (Py_VerboseFlag)

         PySys_WriteStderr("# wrote %s\n", cpathname);

+    PyMem_Free(tmppathname);

 }

 static void