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

[Luiz Capitulino]

On Thu, 1 Nov 2012 11:22:13 -0500
Michael Roth <address@hidden> wrote:

> 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 <address@hidden>
> 
> Reviewed-by: Michael Roth <address@hidden>
> 
> 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)

Can this be a future improvement? I was also wondering if it would be good
to have GAOps instead of having global functions for win32 & posix.

> 
> > ---
> >  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
> > 
>