Re: [Qemu-devel] [PATCH 2/5] Add SCM_RIGHTS support to unix socket character devices

[Avi Kivity <avi@redhat.com>]

On 07/08/2009 05:57 PM, Mark McLoughlin wrote:
> If a file descriptor is passed via a message with SCM_RIGHTS ancillary
> data on a unix socket, store the file descriptor for use in the
> chr_read() handler. Close the file descriptor if it was not used.
>
> The qemu_chr_get_msgfd() API provides access to the passed descriptor.
>
> Signed-off-by: Mark McLoughlin<markmc@redhat.com>
> ---
>   qemu-char.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   qemu-char.h |    2 ++
>   2 files changed, 52 insertions(+), 0 deletions(-)
>
> diff --git a/qemu-char.c b/qemu-char.c
> index e0d7220..f06a614 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -168,6 +168,11 @@ void qemu_chr_read(CharDriverState *s, uint8_t *buf, int len)
>       s->chr_read(s->handler_opaque, buf, len);
>   }
>
> +int qemu_chr_get_msgfd(CharDriverState *s)
> +{
> +    return s->get_msgfd ? s->get_msgfd(s) : -1;
> +}
> +
>   void qemu_chr_accept_input(CharDriverState *s)
>   {
>       if (s->chr_accept_input)
> @@ -1832,6 +1837,7 @@ typedef struct {
>       int do_telnetopt;
>       int do_nodelay;
>       int is_unix;
> +    int msgfd;
>   } TCPCharDriver;
>    

SCM_RIGHTS messages can contain multiple fds, and multiple messages can 
arrive.  I think you need to queue fds here in case the client sends two 
getfd commands back-to-back and does buffering.


-- 
error compiling committee.c: too many arguments to function