Re: [Qemu-devel] [PATCH 3/5] Add getfd and closefd monitor commands

[Mark McLoughlin]

On Wed, 2009-07-08 at 18:26 +0300, Avi Kivity wrote:
> On 07/08/2009 05:57 PM, Mark McLoughlin wrote:
> > Add monitor commands to support passing file descriptors via
> > SCM_RIGHTS.
> >
> > getfd assigns the passed file descriptor a name for use with other
> > monitor commands.
> >
> > closefd allows passed file descriptors to be closed. If a monitor
> > command actually uses a named file descriptor, closefd will not be
> > required.
> >
> >
> >    
> 
> > @@ -70,6 +70,14 @@ typedef struct mon_cmd_t {
> >       const char *help;
> >   } mon_cmd_t;
> >
> > +/* file descriptors passed via SCM_RIGHTS */
> > +typedef struct mon_fd_t mon_fd_t;
> > +struct mon_fd_t {
> > +    char *name;
> > +    int fd;
> > +    LIST_ENTRY(mon_fd_t) next;
> > +};
> > +
> >    
> 
> The _t namespace is reserved by posix and not used for structures in 
> qemu anyway.  I see there's precedent a few lines above but let's not 
> introduce new violations.

Bah, where there's a number of different styles used in a code base, and
where there's no guidelines in CODING_STYLE, I tend to stick with the
style of the code I'm editing. And, in this case, the closest structure
definition used this style.

> > +
> > +    fd = dup(fd);
> >    
> 
> Why?

Because it gets closed again after the chr_read() handler finishes. I
guess we could make qemu_chr_get_msgfd() pass ownership of the fd to the
caller.

Cheers,
Mark.