Patch #934711: Expose platform-specific entropy.

2 files changed, 32 insertions, 0 deletions

diff --git a/Lib/os.py b/Lib/os.py
index 5b79981..86b3566 100644
--- a/Lib/os.py
+++ b/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
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 22cd112..a9668aa 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -343,6 +343,16 @@ class DevNullTests (unittest.TestCase):
         self.assertEqual(f.read(), '')
         f.close()
 
+class URandomTests (unittest.TestCase):
+    def test_urandom(self):
+        try:
+            self.assertEqual(len(os.urandom(1)), 1)
+            self.assertEqual(len(os.urandom(10)), 10)
+            self.assertEqual(len(os.urandom(100)), 100)
+            self.assertEqual(len(os.urandom(1000)), 1000)
+        except NotImplementedError:
+            pass
+
 def test_main():
     test_support.run_unittest(
         TemporaryFileTests,
@@ -351,6 +361,7 @@ def test_main():
         WalkTests,
         MakedirTests,
         DevNullTests,
+        URandomTests	
     )
 
 if __name__ == "__main__":