Patch #934711: Expose platform-specific entropy.

Lib/os.py

@@ -656,3 +656,24 @@ try:
                      _make_statvfs_result)
 except NameError: # statvfs_result may not exist
     pass
+
+if not _exists("urandom"):
+    _urandomfd = None   
+    def urandom(n):
+        """urandom(n) -> str
+ 
+        Return a string of n random bytes suitable for cryptographic use.
+
+        """    
+        global _urandomfd
+        if not _urandomfd:
+            try:
+                _urandomfd = open("/dev/urandom", O_RDONLY)         
+            except:
+                _urandomfd = NotImplementedError
+        if _urandomfd is NotImplementedError:
+            raise NotImplementedError("/dev/urandom (or equivalent) not found")
+        bytes = ""
+        while len(bytes) < n:
+            bytes += read(_urandomfd, n - len(bytes))
+        return bytes