Merge pull request #54237 from dwoz/dup2

Do not dup2 things without fileno

salt/utils/process.py

@@ -6,6 +6,7 @@ Functions for daemonizing and otherwise modifying running processes
 # Import python libs
 from __future__ import absolute_import, with_statement, print_function, unicode_literals
 import copy
+import io
 import os
 import sys
 import time
@@ -102,12 +103,32 @@ def daemonize(redirect_out=True):
         with salt.utils.files.fopen('/dev/null', 'r+') as dev_null:
             # Redirect python stdin/out/err
             # and the os stdin/out/err which can be different
-            os.dup2(dev_null.fileno(), sys.stdin.fileno())
-            os.dup2(dev_null.fileno(), sys.stdout.fileno())
-            os.dup2(dev_null.fileno(), sys.stderr.fileno())
-            os.dup2(dev_null.fileno(), 0)
-            os.dup2(dev_null.fileno(), 1)
-            os.dup2(dev_null.fileno(), 2)
+            dup2(dev_null, sys.stdin)
+            dup2(dev_null, sys.stdout)
+            dup2(dev_null, sys.stderr)
+            dup2(dev_null, 0)
+            dup2(dev_null, 1)
+            dup2(dev_null, 2)
+
+
+def dup2(file1, file2):
+    if isinstance(file1, int):
+        fno1 = file1
+    else:
+        try:
+            fno1 = file1.fileno()
+        except io.UnsupportedOperation:
+            log.warn('Unsupported operation on file: %r', file1)
+            return
+    if isinstance(file2, int):
+        fno2 = file2
+    else:
+        try:
+            fno2 = file2.fileno()
+        except io.UnsupportedOperation:
+            log.warn('Unsupported operation on file: %r', file2)
+            return
+    os.dup2(fno1, fno2)
 
 
 def daemonize_if(opts):

tests/unit/utils/test_process.py

@@ -2,6 +2,7 @@
 
 # Import python libs
 from __future__ import absolute_import, print_function, unicode_literals
+import io
 import os
 import sys
 import time
@@ -399,3 +400,19 @@ class TestSignalHandlingMultiprocessingProcess(TestCase):
             evt.set()
             proc2.join(30)
             proc.join(30)
+
+
+class TestDup2(TestCase):
+
+    def test_dup2_no_fileno(self):
+        'The dup2 method does not fail on streams without fileno support'
+        f1 = io.StringIO("some initial text data")
+        f2 = io.StringIO("some initial other text data")
+        with self.assertRaises(io.UnsupportedOperation):
+            f1.fileno()
+        with patch('os.dup2') as dup_mock:
+            try:
+                salt.utils.process.dup2(f1, f2)
+            except io.UnsupportedOperation:
+                assert False, 'io.UnsupportedOperation was raised'
+        assert not dup_mock.called