[FFmpeg-devel] [PATCH] Make av_get_random_seed not block when waiting for more entropy

[Martin Storsjö]

On Tue, 29 Jun 2010, Martin Storsj? wrote:

> On Tue, 29 Jun 2010, M?ns Rullg?rd wrote:
> 
> > Martin Storsj? <martin at martin.st> writes:
> > 
> > > On Tue, 29 Jun 2010, M?ns Rullg?rd wrote:
> > >
> > >> This will still block if urandom isn't available.  How about this?
> > >
> > >> From cb60e983c550c2bdffc5fc07075336fb7c465fe9 Mon Sep 17 00:00:00 2001
> > >> From: Mans Rullgard <mans at mansr.com>
> > >> Date: Tue, 29 Jun 2010 14:22:51 +0100
> > >> Subject: [PATCH] Make av_get_random_seed() non-blocking
> > >> 
> > >> Attempt to read from /dev/urandom and /dev/random with O_NONBLOCK set.
> > >> If neither succeeds, proceed with fallbacks.
> > >
> > > In general, this looks like an even better alternative. Neither fcntl, 
> > > F_SETFL, F_GETFL nor O_NONBLOCK are available on windows, though, so they 
> > > need to be hidden within some kind of ifdef.
> > 
> > Cygwin should have them, mingw might not.
> > 
> > Do /dev/[u]random exist on cygwin/mingw?
> 
> Don't know about cygwin, but mingw won't have them at least, since it's 
> almost plain win32.

Would the cleanest fix be to check for fcntl and/or O_NONBLOCK in 
configure, and just keep the nonblock setting line within ifdef? That 
ought to work correctly on both cygwin and mingw.

// Martin