New submission from Ian Wienand <[email protected]>:
Hi,
Lib/random.py has a fallback if os.urandom() returns NotImplementedError
---
from os import urandom as _urandom
...
def seed(self, a=None):
if a is None:
try:
a = long(_hexlify(_urandom(16)), 16)
except NotImplementedError:
import time
a = long(time.time() * 256) # use fractional seconds
---
In 2.6, this is indeed what happens in Lib/os.py where "import urandom from os"
gets [2]:
---
if not _exists("urandom"):
def urandom(n):
...
try:
_urandomfd = open("/dev/urandom", O_RDONLY)
except (OSError, IOError):
raise NotImplementedError("/dev/urandom (or equivalent) not found")
---
however, in 2.7, things have shuffled around as a result of issue Issue #13703
and now _PyOS_URandom will return an OSError if it can't find /dev/urandom [3].
This means if you "import random" without "/dev/urandom" available it crashes
trying to seed
I'm not sure if this is intentional? One easy solution would be to catch
OSError in random.py and fall back then too
[1] http://hg.python.org/cpython/file/70274d53c1dd/Python/random.c#l227
[2] http://hg.python.org/cpython/file/9f8771e09052/Lib/os.py#l746
[3] http://hg.python.org/cpython/file/70274d53c1dd/Lib/random.py#l111
----------
components: Library (Lib)
messages: 165340
nosy: iwienand
priority: normal
severity: normal
status: open
title: OSError with "import random" when /dev/urandom doesn't exist (regression
from 2.6)
versions: Python 2.7
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Python tracker <[email protected]>
<http://bugs.python.org/issue15340>
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