Re: [Qemu-devel] [PATCH 5/5] qemu-ga: win32: add isa-serial support

[Michael Roth]

On Wed, Oct 31, 2012 at 03:45:20PM -0200, Luiz Capitulino wrote:
> It's implemented by opening the serial port in "non-blocking" mode
> and using the GSourceFuncs API in the following way:
> 
>  o prepare(): issue a read request. If something has been read, it's
>               stored in rs->buf and rs->pending will store the number
>                         of bytes read. If there wasn't any bytes available, we
>                         set the timeout to 500 ms and return
> 
>  o check():   returns true if prepare() was able to read anything,
>               otherwise return false
> 
>  o finalize(): does nothing
> 
> At dispatch() time we simply copy the bytes read to the buffer passed
> to ga_channel_read().
> 
> Signed-off-by: Luiz Capitulino <address@hidden>
> ---
>  qga/channel-win32.c | 87 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 87 insertions(+)
> 
> diff --git a/qga/channel-win32.c b/qga/channel-win32.c
> index c173270..887fe5f 100644
> --- a/qga/channel-win32.c
> +++ b/qga/channel-win32.c
> @@ -179,6 +179,46 @@ static gboolean ga_channel_dispatch_ov(GSource *source, 
> GSourceFunc unused,
>      return success;
>  }
> 
> +static gboolean ga_channel_prepare(GSource *source, gint *timeout_ms)
> +{
> +    GAWatch *watch = (GAWatch *)source;
> +    GAChannel *c = (GAChannel *)watch->channel;
> +    GAChannelReadState *rs = &c->rstate;
> +    DWORD count_read = 0;
> +    bool success;
> +
> +    success = ReadFile(c->handle, rs->buf, rs->buf_size, &count_read, NULL);
> +    if (success) {
> +        if (count_read == 0) {
> +            *timeout_ms = 500;
> +            return false;
> +        }
> +        rs->pending = count_read;
> +        return true;
> +    }
> +
> +    return false;
> +}
> +
> +static gboolean ga_channel_check(GSource *source)
> +{
> +    GAWatch *watch = (GAWatch *)source;
> +    GAChannel *c = (GAChannel *)watch->channel;
> +    GAChannelReadState *rs = &c->rstate;
> +
> +    return !!rs->pending;
> +}
> +
> +static gboolean ga_channel_dispatch(GSource *source, GSourceFunc unused,
> +                                    gpointer user_data)
> +{
> +    GAWatch *watch = (GAWatch *)source;
> +    GAChannel *c = (GAChannel *)watch->channel;
> +
> +    g_assert(c->cb);
> +    return c->cb(0, c->user_data);
> +}
> +
>  static void ga_channel_finalize_ov(GSource *source)
>  {
>      g_debug("finalize");
> @@ -203,6 +243,30 @@ static GSource *ga_channel_create_watch_ov(GAChannel *c)
>      return source;
>  }
> 
> +static void ga_channel_finalize(GSource *source)
> +{
> +    g_debug("finalize");
> +}
> +
> +GSourceFuncs ga_channel_watch_funcs = {
> +    ga_channel_prepare,
> +    ga_channel_check,
> +    ga_channel_dispatch,
> +    ga_channel_finalize
> +};
> +
> +static GSource *ga_channel_create_watch(GAChannel *c)
> +{
> +    GSource *source = g_source_new(&ga_channel_watch_funcs, sizeof(GAWatch));
> +    GAWatch *watch = (GAWatch *)source;
> +
> +    watch->channel = c;
> +    watch->pollfd.fd = -1;
> +    g_source_add_poll(source, &watch->pollfd);
> +
> +    return source;
> +}
> +
>  GIOStatus ga_channel_read(GAChannel *c, char *buf, size_t size, gsize *count)
>  {
>      GAChannelReadState *rs = &c->rstate;
> @@ -225,6 +289,12 @@ GIOStatus ga_channel_read(GAChannel *c, char *buf, 
> size_t size, gsize *count)
>              status = G_IO_STATUS_AGAIN;
>          }
>          break;
> +    case GA_CHANNEL_ISA_SERIAL:
> +        memcpy(buf, rs->buf, rs->pending);

Do we really want to ignore size? Seems like we can overrun their buffer
if it's smaller than ours. You can use rs->start to track the number of
bytes theyve read so far and offset from that in prepare()

> +        *count = rs->pending;
> +        rs->pending = 0;
> +        status = G_IO_STATUS_NORMAL;
> +        break;
>      default:
>          abort(); /* impossible */
>      }
> @@ -303,6 +373,7 @@ GAChannel *ga_channel_new(GAChannelMethod method, const 
> gchar *path,
>  {
>      GAChannel *c = g_malloc0(sizeof(GAChannel));
>      SECURITY_ATTRIBUTES sec_attrs;
> +    COMMTIMEOUTS timeouts;
> 
>      switch (method) {
>      case GA_CHANNEL_VIRTIO_SERIAL:
> @@ -322,6 +393,22 @@ GAChannel *ga_channel_new(GAChannelMethod method, const 
> gchar *path,
> 
>          c->source = ga_channel_create_watch_ov(c);
>          break;
> +    case GA_CHANNEL_ISA_SERIAL:
> +        if (!ga_channel_open(c, path, 0)) {
> +            g_critical("error opening channel (path: %s)", path);
> +            goto out_err;
> +        }
> +
> +        /* non-blocking I/O */
> +        memset(&timeouts, 0, sizeof(timeouts));
> +        timeouts.ReadIntervalTimeout = MAXDWORD;
> +        if (!SetCommTimeouts(c->handle, &timeouts)) {
> +            CloseHandle(c->handle);
> +            goto out_err;
> +        }
> +
> +        c->source = ga_channel_create_watch(c);
> +        break;
>      default:
>          g_critical("unsupported communication method");
>          goto out_err;
> -- 
> 1.7.12.315.g682ce8b
> 
>