[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] [PATCH] safe{read, write}: Don't lie on nonblocking FD



On Wed, Jan 16, 2013 at 07:27:46PM +0100, Michal Privoznik wrote:
> Currently, whenever somebody calls saferead() on nonblocking FD
> (safewrite() is totally interchangeable for purpose of this
> message) he might get wrong return value. For instance, in the
> first iteration some data is read. The number of bytes read is
> stored into local variable 'nread'. However, in next iterations
> we can get -1 from read() with errno == EAGAIN, in which case the
> -1 is returned despite fact some data has already been read. So
> the caller gets confused.
> 
> Moreover, the comment just above the functions says, they act
> like regular read() with nicer handling of EINTR. Well, they
> don't now.

I think that it is correct that these APIs return -1 on EAGAIN.
These APIs should *not* be used on non-blocking FDs.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]