Issue 3708: os.urandom(1.1): infinite loop

Calling os.urandom(1 + float(x)) ends in a infinite loop due to a naive
condition check:

while len(bytes) < n:
    bytes += read(_urandomfd, n - len(bytes))

Trivial patch attached.

i'll fix this and add a unit test.

better patch with tests attached, no explicit int conversion is done.

i also wrapped the use of the fd returned by open with a try: finally:
to avoid any chance of a leak and renamed the bytes variable to bs to
match whats in py3k and avoid overriding the builtin type.

The explicit int() conversion looked saner to me, rather than passing a
float argument to read().
By the way, is there a reason this code still uses os.open rather than
the builtin io.open?

if i did 

 n = int(n)

that would change the API to allow bytes/unicode to be passed in which
is not something i want.  i don't even like that it allows floats.

by not doing the int conversion at all, a DeprecationWarning is raised
by the read() about the argument being a float which I figure it not a
bad thing given that the API really should only accept ints...

fwiw, daniel's patch would still cause this deprecation warning from
read so I guess using while len(bs) < int(n): isn't that bad either. 
but it would allow a string such as '0' to be passed in as an argument
without an exception...

Gregory,
IMHO your patch is better in all aspects.

Regarding my patch, the API wouldn't change at all, as the source reads:
        while len(bytes) < int(n):
            bytes += read(_urandomfd, n - len(bytes))

So "n - len(bytes)" restricts the API to what it was before. But it
would call int() for each loop iteration :/

@Pitrou: My patch still passed the float to read (to keep the current
behavior, warning included), but if doing that can be considered a bug,
let's get rid of the DeprecationWarning by passing an int.

Le jeudi 28 août 2008 à 19:30 +0000, Gregory P. Smith a écrit :
> if i did 
> 
>  n = int(n)
> 
> that would change the API to allow bytes/unicode to be passed in which
> is not something i want.

Ok, I hadn't thought about that. You convinced me.

The patch looks fine to me as well.

committed to trunk r66142

Gregory, could you merge this into py3k, please?

Apparently this isn't an issue in py3k, so no worries! :)

It seems to me that test case will fail on windows and vms platforms.
The case contain os.urandom(1.1) but in posixmodule.c for urandon
functions (windows and vms) exits:
  PyArg_ParseTuple(args, "i:urandom", &howMany))

./python.exe -c 'import os; print "%s" %(os.urandom(1.9))' =>
-c:1: DeprecationWarning: integer argument expected, got float