Fix broken pipe error when piping into programs using the CLI.

CHANGELOG.rst

@@ -10,6 +10,8 @@ Changelog
 version 1.0.1-dev
 -----------------
 + Update included zlib-ng distribution to 2.3.3.
++ Fix BrokenPipeError when piping ``python -m isal.igzip`` into ``head``,
+  ``less`` or similar programs.
 + Fix ``gzip_ng_threaded`` writers that waited forever when writing to the
   underlying file failed, for example, because the disk was full. A later call
   to ``write()``, ``flush()``, or ``close()`` raises the error. After an error,

src/zlib_ng/gzip_ng.py

@@ -304,6 +304,9 @@ def main():
     READ_BUFFER_SIZE = args.buffer_size
     try:
         shutil.copyfileobj(in_file, out_file, args.buffer_size)
+    except BrokenPipeError:
+        # Do not throw errors when a pipe to head or less closes.
+        pass
     finally:
         if in_file is not sys.stdin.buffer:
             in_file.close()

tests/test_gzip_ng.py

@@ -15,6 +15,7 @@
 import re
 import shutil
 import struct
+import subprocess
 import sys
 import tempfile
 import zlib
@@ -496,3 +497,14 @@ def test_adverserial_header():
                 gzip_file.read()
     finally:
         os.remove(tmpfile.name)
+
+
+@pytest.mark.skipif(sys.platform != "linux", reason="bash required")
+def test_no_broken_pipe():
+    subprocess.run(
+        [
+            "bash", "-c", "-e", "-o", "pipefail",
+            f"{sys.executable} -m zlib_ng.gzip_ng -cd {TEST_FILE} | head -n 10"
+        ],
+        check=True
+    )