Re: [Qemu-devel] [PATCH 4/5] qemu-ga: win32: isolate virtio-serial specific code

[Michael Roth <mdroth@linux.vnet.ibm.com>]

On Wed, Oct 31, 2012 at 03:45:19PM -0200, Luiz Capitulino wrote:
> This commit prepares ga_channel_new(), ga_channel_read() and
> ga_channel_open() for isa-serial support.
> 
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>

Though I'm wondering if it'd be nicer to:

 1) Add a GAChannelOps struct with pointers for init/read/write/write_all
 2) Move all the method-specific init stuff from ga_channel_new() into
    method-specific init functions (which all use ga_channel_open() as
    a general helper function, or maybe roll the CreateFile() into the 
    init routines with the proper flags hard-coded
 3) Have ga_channel_new() simply hang the proper GAChannelOps* off of
    the GAChannel it create and then call GAChannel->ops->init(self)
 4) Make ga_channel_read/write/write_all(self) wrappers around
    GAChannel->ops->read/write/write_all(self)

> ---
>  qga/channel-win32.c | 75 ++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 42 insertions(+), 33 deletions(-)
> 
> diff --git a/qga/channel-win32.c b/qga/channel-win32.c
> index 8e259c3..c173270 100644
> --- a/qga/channel-win32.c
> +++ b/qga/channel-win32.c
> @@ -213,14 +213,20 @@ GIOStatus ga_channel_read(GAChannel *c, char *buf, size_t size, gsize *count)
>          return G_IO_STATUS_ERROR;
>      }
> 
> -    *count = to_read = MIN(size, rs->pending);
> -    if (to_read) {
> -        memcpy(buf, rs->buf + rs->cur, to_read);
> -        rs->cur += to_read;
> -        rs->pending -= to_read;
> -        status = G_IO_STATUS_NORMAL;
> -    } else {
> -        status = G_IO_STATUS_AGAIN;
> +    switch (c->method) {
> +    case GA_CHANNEL_VIRTIO_SERIAL:
> +        *count = to_read = MIN(size, rs->pending);
> +        if (to_read) {
> +            memcpy(buf, rs->buf + rs->cur, to_read);
> +            rs->cur += to_read;
> +            rs->pending -= to_read;
> +            status = G_IO_STATUS_NORMAL;
> +        } else {
> +            status = G_IO_STATUS_AGAIN;
> +        }
> +        break;
> +    default:
> +        abort(); /* impossible */
>      }
> 
>      return status;
> @@ -285,23 +291,11 @@ GIOStatus ga_channel_write_all(GAChannel *c, const char *buf, size_t size)
>      return status;
>  }
> 
> -static gboolean ga_channel_open(GAChannel *c, GAChannelMethod method,
> -                                const gchar *path)
> +static gboolean ga_channel_open(GAChannel *c, const gchar *path, int flags)
>  {
> -    if (!method == GA_CHANNEL_VIRTIO_SERIAL) {
> -        g_critical("unsupported communication method");
> -        return false;
> -    }
> -
>      c->handle = CreateFile(path, GENERIC_READ | GENERIC_WRITE, 0, NULL,
> -                           OPEN_EXISTING,
> -                           FILE_FLAG_NO_BUFFERING | FILE_FLAG_OVERLAPPED, NULL);
> -    if (c->handle == INVALID_HANDLE_VALUE) {
> -        g_critical("error opening path");
> -        return false;
> -    }
> -
> -    return true;
> +                           OPEN_EXISTING, FILE_FLAG_NO_BUFFERING | flags, NULL);
> +    return (c->handle == INVALID_HANDLE_VALUE) ? false : true;
>  }
> 
>  GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path,
> @@ -310,27 +304,42 @@ GAChannel *ga_channel_new(GAChannelMethod method, const gchar *path,
>      GAChannel *c = g_malloc0(sizeof(GAChannel));
>      SECURITY_ATTRIBUTES sec_attrs;
> 
> -    if (!ga_channel_open(c, method, path)) {
> -        g_critical("error opening channel");
> -        g_free(c);
> -        return NULL;
> +    switch (method) {
> +    case GA_CHANNEL_VIRTIO_SERIAL:
> +        if (!ga_channel_open(c, path, FILE_FLAG_OVERLAPPED)) {
> +            g_critical("error opening channel (path: %s)", path);
> +            goto out_err;
> +        }
> +
> +        sec_attrs.nLength = sizeof(SECURITY_ATTRIBUTES);
> +        sec_attrs.lpSecurityDescriptor = NULL;
> +        sec_attrs.bInheritHandle = false;
> +        c->rstate.ov.hEvent = CreateEvent(&sec_attrs, FALSE, FALSE, NULL);
> +        if (!c->rstate.ov.hEvent) {
> +            g_critical("can't create event");
> +            goto out_err;
> +        }
> +
> +        c->source = ga_channel_create_watch_ov(c);
> +        break;
> +    default:
> +        g_critical("unsupported communication method");
> +        goto out_err;
>      }
> 
>      c->cb = cb;
>      c->user_data = opaque;
>      c->method = method;
> 
> -    sec_attrs.nLength = sizeof(SECURITY_ATTRIBUTES);
> -    sec_attrs.lpSecurityDescriptor = NULL;
> -    sec_attrs.bInheritHandle = false;
> -
>      c->rstate.buf_size = QGA_READ_COUNT_DEFAULT;
>      c->rstate.buf = g_malloc(QGA_READ_COUNT_DEFAULT);
> -    c->rstate.ov.hEvent = CreateEvent(&sec_attrs, FALSE, FALSE, NULL);
> 
> -    c->source = ga_channel_create_watch_ov(c);
>      g_source_attach(c->source, NULL);
>      return c;
> +
> +out_err:
> +    g_free(c);
> +    return NULL;
>  }
> 
>  void ga_channel_free(GAChannel *c)
> -- 
> 1.7.12.315.g682ce8b
>