Add support for automatically skipping over fifo files

2 files changed, 24 insertions, 0 deletions

diff --git a/isort/main.py b/isort/main.py
index 5d48f84c..b9b86687 100644
--- a/isort/main.py
+++ b/isort/main.py
@@ -4,6 +4,7 @@ import functools
 import glob
 import os
 import re
+import stat
 import sys
 from pathlib import Path
 from typing import Any, Dict, Iterable, Iterator, List, MutableMapping, Optional, Sequence
@@ -45,6 +46,12 @@ def is_python_file(path: str) -> bool:
         return False
 
     try:
+        if stat.S_ISFIFO(os.stat(path).st_mode):
+            return False
+    except OSError:
+        pass
+
+    try:
         with open(path, "rb") as fp:
             line = fp.readline(100)
     except OSError:
diff --git a/tests/test_main.py b/tests/test_main.py
new file mode 100644
index 00000000..b3e50b54
--- /dev/null
+++ b/tests/test_main.py
@@ -0,0 +1,17 @@
+import os
+from isort import main
+
+
+def test_is_python_file(tmpdir):
+    assert main.is_python_file("file.py")
+    assert main.is_python_file("file.pyi")
+    assert main.is_python_file("file.pyx")
+    assert not main.is_python_file("file.pyc")
+    assert not main.is_python_file("file.txt")
+
+    fifo_file = os.path.join(tmpdir, "fifo_file")
+    os.mkfifo(fifo_file)
+    assert not main.is_python_file(fifo_file)
+
+
+