Merge pull request #812 from hathawsh/master

Fixed logfile output to special files like /dev/stdout on Python 3.

Author: mnaberez

supervisor/loggers.py

@@ -138,9 +138,22 @@ class FileHandler(Handler):
     """File handler which supports reopening of logs.
     """
 
-    def __init__(self, filename, mode="a"):
+    def __init__(self, filename, mode='a'):
         Handler.__init__(self)
-        self.stream = open(filename, mode)
+
+        try:
+            self.stream = open(filename, mode)
+        except OSError as e:
+            if mode == 'a' and e.errno == errno.ESPIPE:
+                # Python 3 can't open special files like
+                # /dev/stdout in 'a' mode due to an implicit seek call
+                # that fails with ESPIPE. Retry in 'w' mode.
+                # See: http://bugs.python.org/issue27805
+                mode = 'w'
+                self.stream = open(filename, mode)
+            else:
+                raise
+
         self.baseFilename = filename
         self.mode = mode
 

supervisor/tests/test_loggers.py

@@ -220,6 +220,22 @@ def test_emit_error(self):
         self.assertTrue(dummy_stderr.written.endswith('OSError\n'),
                         dummy_stderr.written)
 
+if os.path.exists('/dev/stdout'):
+    StdoutTestsBase = FileHandlerTests
+else:
+    # Skip the stdout tests on platforms that don't have /dev/stdout.
+    StdoutTestsBase = object
+
+class StdoutTests(StdoutTestsBase):
+    def test_ctor_with_dev_stdout(self):
+        handler = self._makeOne('/dev/stdout')
+        # Modes 'w' and 'a' have the same semantics when applied to
+        # character device files and fifos.
+        self.assertTrue(handler.mode in ['w', 'a'], handler.mode)
+        self.assertEqual(handler.baseFilename, '/dev/stdout')
+        self.assertEqual(handler.stream.name, '/dev/stdout')
+        handler.close()
+
 class RotatingFileHandlerTests(FileHandlerTests):
 
     def _getTargetClass(self):