avoid unnecessary close of original FDs

test.py

@@ -2,7 +2,10 @@
 from __future__ import print_function
 
 import io
+import os
+from tempfile import TemporaryFile
 import time
+
 import mock
 
 from wurlitzer import (
@@ -73,7 +76,7 @@ def test_sys_pipes():
     with mock.patch('sys.stdout', stdout), mock.patch('sys.stderr', stderr), sys_pipes():
         printf(u"Hellø")
         printf_err(u"Hi, stdérr")
-    
+
     assert stdout.getvalue() == u"Hellø\n"
     assert stderr.getvalue() == u"Hi, stdérr\n"
 
@@ -89,3 +92,24 @@ def test_redirect_everything():
     assert stderr.getvalue() == u"Hi, stdérr\n"
 
 
+def count_fds():
+    """utility for counting file descriptors"""
+    proc_fds = '/proc/{}/fd'.format(os.getpid())
+    if os.path.isdir(proc_fds):
+        return len(proc_fds)
+    else:
+        # this is an approximate count,
+        # but it should at least be stable if we aren't leaking
+        with TemporaryFile() as tf:
+            return tf.fileno()
+
+
+def test_fd_leak():
+    base_count = count_fds()
+    with pipes():
+        print('ok')
+    assert count_fds() == base_count
+    for i in range(10):
+        with pipes():
+            print('ok')
+        assert count_fds() == base_count

wurlitzer.py

@@ -191,7 +191,7 @@ def forwarder():
         self.thread = threading.Thread(target=forwarder)
         self.thread.daemon = True
         self.thread.start()
-        
+
         return self.handle
 
     def __exit__(self, exc_type, exc_value, traceback):
@@ -202,9 +202,7 @@ def __exit__(self, exc_type, exc_value, traceback):
         os.write(self._control_w, b'\1')
         self.thread.join()
         os.close(self._control_w)
-        for real_fd in self._real_fds.values():
-            os.close(real_fd)
-
+
         # restore original state
         for name, real_fd in self._real_fds.items():
             save_fd = self._save_fds[name]
@@ -217,12 +215,12 @@ def __exit__(self, exc_type, exc_value, traceback):
 @contextmanager
 def pipes(stdout=PIPE, stderr=PIPE, encoding=_default_encoding):
     """Capture C-level stdout/stderr in a context manager.
-    
+
     The return value for the context manager is (stdout, stderr).
-    
+
     Examples
     --------
-    
+
     >>> with capture() as (stdout, stderr):
     ...     printf("C-level stdout")
     ... output = stdout.read()