Messages in this thread | | | Date | Sat, 15 Jan 2005 20:58:43 -0800 | From | Matt Mackall <> | Subject | Re: short read from /dev/urandom |
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On Sat, Jan 15, 2005 at 07:58:23PM -0800, Ulrich Drepper wrote: > Matt Mackall wrote: > >_Neither_ case mentions signals and the "and will return as many bytes > >as requested" is clearly just a restatement of "does not have this > >limit". Whoever copied this comment to the manpage was a bit sloppy > >and dropped the first clause rather than the second: > > It still means the documented API says there are no short reads.
I maintain that it's ambiguous. And read(2) makes it clear that short reads can happen any time, any where. Further, your interpretation makes for a nonsensical API as it implies being uninterruptible for arbitrary lengths of time.
Changing the longstanding, sensible code to match a silly and highly non-standard interpretation of the documentation doesn't fix the problem in apps either. Presumably they'll still be running on kernels older than 2.6.11 and I believe most *BSDs have /dev/urandom as well.
> >So anyone doing a read() can expect a short read regardless of the fd > >and is quite clear that reads can be interrupted by signals. "It is > >not an error". Ever. > > Of course are signal interruptions wrong if the signal uses SA_RESTART.
That's a separate problem. I'll take a look at fixing that.
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