From f6a6e8f98997f421a3cc6193a8ebd88b7389cb67 Mon Sep 17 00:00:00 2001
From: Stefan Tatschner <stefan.tatschner@aisec.fraunhofer.de>
Date: Tue, 13 Aug 2024 11:49:42 +0200
Subject: [PATCH] fix(hr): Handle BrokenPipeError according to official
 recommendations

https://docs.python.org/3/library/signal.html#note-on-sigpipe
---
 src/hr/__init__.py     | 14 ++++++++++++--
 tests/bats/100-hr.bats |  4 ++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/hr/__init__.py b/src/hr/__init__.py
index 6eae8c269..e8001d843 100644
--- a/src/hr/__init__.py
+++ b/src/hr/__init__.py
@@ -3,6 +3,8 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import argparse
+import os
+import signal
 import sys
 from itertools import islice
 from pathlib import Path
@@ -89,8 +91,16 @@ def main() -> None:
         print(f"invalid file format: {e}", file=sys.stderr)
         sys.exit(1)
     # BrokenPipeError appears when stuff is piped to | head.
-    except (KeyboardInterrupt, BrokenPipeError):
-        pass
+    # This is not an error for hr.
+    except BrokenPipeError:
+        # https://docs.python.org/3/library/signal.html#note-on-sigpipe
+        # Python flushes standard streams on exit; redirect remaining output
+        # to devnull to avoid another BrokenPipeError at shutdown.
+        devnull = os.open(os.devnull, os.O_WRONLY)
+        os.dup2(devnull, sys.stdout.fileno())
+        sys.exit(0)
+    except KeyboardInterrupt:
+        sys.exit(128 + signal.SIGINT)
 
 
 if __name__ == "__main__":
diff --git a/tests/bats/100-hr.bats b/tests/bats/100-hr.bats
index 53fe31da5..c2fa663e1 100644
--- a/tests/bats/100-hr.bats
+++ b/tests/bats/100-hr.bats
@@ -29,6 +29,10 @@
 	run -1 bash -c "echo 'invalid json' | hr -"
 }
 
+@test "pipe to head and handle SIGPIPE" {
+	hr "$BATS_TEST_DIRNAME/testfiles/log-01.json.zst" | head
+}
+
 @test "filter priority" {
 	local additional_line
 	additional_line='{"module": "foo", "data": "I am the line!", "host": "kronos", "datetime":"2020-04-23T15:21:50.620310", "priority": 5, "version": 2}'