Re: [Qemu-devel] [PATCH] char: translate from QIOChannel error to errno

[Paolo Bonzini <pbonzini@redhat.com>]

On 11/03/2016 18:55, marcandre.lureau@redhat.com wrote:
> From: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> Caller of CharDriverState.chr* callback assume errno error conventions.
> Translate QIOChannel error to errno (this fixes potential EAGAIN
> regression, for ex if a vhost-user backend block, qemu_chr_fe_read_all()
> could get error -2 and not wait)
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  qemu-char.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/qemu-char.c b/qemu-char.c
> index ad11b75..4317388 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -2727,6 +2727,13 @@ static ssize_t tcp_chr_recv(CharDriverState *chr, char *buf, size_t len)
>                                       NULL);
>      }
>  
> +    if (ret == QIO_CHANNEL_ERR_BLOCK) {
> +        errno = EAGAIN;
> +        ret = -1;
> +    } else if (ret == -1) {
> +        errno = EIO;
> +    }
> +
>      if (msgfds_num) {
>          /* close and clean read_msgfds */
>          for (i = 0; i < s->read_msgfds_num; i++) {
> 

I can take this patch as it fixes a real regression, but could
QIOChannel just return negative errno?

Paolo