support/jenkins/cat.py

#!/usr/bin/env python
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
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# See the License for the specific language governing permissions and
# limitations under the License.

"""
In the Apache Jenkins setup, the standard output and error file descriptors
are marked as non-blocking. As most programs do not correctly handle
`EAGAIN`, we pipe Jenkins scripts through this instead.

Example: ./support/jenkins/buildbot.sh | ./support/jenkins/cat.py
"""

import fcntl
import os
import sys

flags = fcntl.fcntl(sys.stdout, fcntl.F_GETFL)
fcntl.fcntl(sys.stdout, fcntl.F_SETFL, flags&~os.O_NONBLOCK)

while True:
    data = os.read(sys.stdin.fileno(), 1024)
    if not data:
        break

    os.write(sys.stdout.fileno(), data)