[python-daemon-Bugs][315090] Redirecting `sys.stdout` fails when `sys.stdout` is not a real stream

Sat Jun 20 10:45:05 UTC 2015

python-daemon-Bugs item #315090, was opened at 2015-06-20 10:45 by Torfus Polymorphus
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https://alioth.debian.org/tracker/?func=detail&atid=413098&aid=315090&group_id=100328

Status: Open
Priority: 3
Submitted By: Torfus Polymorphus (torf-guest)
Assigned to: Nobody (None)
Summary: Redirecting `sys.stdout` fails when `sys.stdout` is not a real stream 

Initial Comment:
A feature of many Python testing frameworks (e.g. nose) is to capture output to STDOUT (the captured output is only displayed if a test fails). Usually, this is accomplished by replacing `sys.stdout` with another file-like object, e.g. a `cStringIO.StringIO` instance. However, this breaks DaemonContext, since DaemonContext tries to access `sys.stdout.fileno` in `redirect_stream` -- the capturing objects usually don't have a `fileno` attribute:

  File "/home/torf/projects/coba/venv/local/lib/python2.7/site-packages/daemon/daemon.py", line 380, in __enter__
    self.open()
  File "/home/torf/projects/coba/venv/local/lib/python2.7/site-packages/daemon/daemon.py", line 367, in open
    redirect_stream(sys.stdin, self.stdin)
  File "/home/torf/projects/coba/venv/local/lib/python2.7/site-packages/daemon/daemon.py", line 845, in redirect_stream
    os.dup2(target_fd, system_stream.fileno())
AttributeError: 'cStringIO.StringIO' object has no attribute 'fileno'

In my opinion, DaemonContext should handle this situation gracefully.

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