Re: [Qemu-trivial] [Qemu-devel] [PATCH 1/1] Do not hang on full PTY

[Don Slutz <dslutz@verizon.com>]

On 12/29/14 18:41, Peter Maydell wrote:
> On 29 December 2014 at 20:27, Don Slutz <dslutz@verizon.com> wrote:
>> I was not sure on this being trivial also, but it looked like it could
>> be to me.  The uses of this FD all looked that they handle non-blocking.
> Does g_io_channel_read_chars() definitely return G_IO_STATUS_NORMAL
> (and not, say, G_IO_STATUS_AGAIN) for an attempted read on a non-blocking
> fd with no data?

The only time I know of to get here in that state, is when the other end 
disconnects.
Normally pty_chr_read will only be called when there is at least 1 
character to read or
a state change.

>   Otherwise pty_chr_read() is going to call
> pty_chr_state(chr, 0) which I think means "the other end has hung up"
> and will take the fd out of the main loop's poll set.

Yes, that is correct.  But it only happens when the other end disconnects.
pty_chr_timer() also is involved here, so on a reconnect, the polling is 
re-enabled.

    -Don Slutz

>
> thanks
> -- PMM