Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket

[Paolo Bonzini <pbonzini@redhat.com>]

On 13/07/2015 10:13, pyssling@ludd.ltu.se wrote:
> Commit 812c1057 introduced HUP detection on unix and tcp sockets prior
> to a read in tcp_chr_read. This unfortunately broke CloudStack 4.2
> which relied on the old behaviour where data on a socket was readable
> even if a HUP was present.
> 
> On Linux a working solution seems to be to simply check the HUP after
> reading available data, while keeping the original behaviour for windows.
> 
> There is then a divergence in behaviour for the two platforms, but this
> seems better than breaking a whole software stack.

There is no need to do something special on Windows, I think.  You can
unconditionally check G_IO_HUP after reading.  One nit:

> -    if (size == 0) {
> +    if (size == 0 || (size < 0 && cond & G_IO_HUP)) {

Please put (cond & G_IO_HUP) within parentheses.

Please