[RedirectStream] Supress unwanted stdout or stderr output from external librarys #hack #stdout #stderr

redirect_stream.py

# taken from https://github.com/bulletphysics/bullet3/issues/3131

import ctypes
import sys
import os


class RedirectStream(object):
    @staticmethod
    def _flush_c_stream(stream):
        streamname = stream.name[1:-1]
        libc = ctypes.CDLL(None)
        libc.fflush(ctypes.c_void_p.in_dll(libc, streamname))

    def __init__(self, stream=sys.stdout, file=os.devnull):
        self.stream = stream
        self.file = file

    def __enter__(self):
        self.stream.flush()  # ensures python stream unaffected
        self.fd = open(self.file, "w+")
        self.dup_stream = os.dup(self.stream.fileno())
        os.dup2(self.fd.fileno(), self.stream.fileno())  # replaces stream

    def __exit__(self, type, value, traceback):
        RedirectStream._flush_c_stream(self.stream)  # empty C stream buffer
        os.dup2(self.dup_stream, self.stream.fileno())  # restores stream
        os.close(self.dup_stream)
        self.fd.close()