[ python-Bugs-1177468 ] random.py/os.urandom robustness

[SourceForge.net]

Bugs item #1177468, was opened at 2005-04-05 18:03
Message generated for change (Tracker Item Submitted) made by Item Submitter
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1177468&group_id=5470

Category: Python Library
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Fazal Majid (majid)
Assigned to: Nobody/Anonymous (nobody)
Summary: random.py/os.urandom robustness

Initial Comment:
Python 2.4.1 now uses os.urandom() to seed the random
number generator. This is mostly an improvement, but
can lead to subtle regression bugs.

os.urandom() will open /dev/urandom on demand, e.g.
when random.Random.seed() is called, and keep it alive
as os._urandomfd.

It is standard programming practice for a daemon
process to close file descriptors it has inherited from
its parent process, and if it closes the file
descriptor corresponding to os._urandomfd, the os
module is blissfully unaware and the next time
os.urandom() is called, it will try to read from a
closed file descriptor (or worse, a new one opened
since), with unpredictable results.

My recommendation would be to make os.urandom() open
/dev/urandom each time and not keep a persistent file
descripto. This will be slightly slower, but more
robust. I am not sure how I feel about a standard
library function steal a file descriptor slot forever,
specially when os.urandom() is probably going to be
called only once in the lifetime of a program, when the
random module is seeded.


----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1177468&group_id=5470