[CRIU] Re: [RFC 0/4] Lets try PB again

[Cyrill Gorcunov]

On Fri, Jul 06, 2012 at 04:21:25PM +0400, Pavel Emelyanov wrote:
> 
> Is there a way to unpack an object into a static buffer rather than
> allocating one dynamically?

Yes, previously I've been using 16K stack for that, I can bring it back ;)

+#define pbimg_write_obj(__fd, __object, __type, __get_packed_size, __pack)
+({
+	u8  ___buf[KILO(16)];
+	u32 ___size = __get_packed_size(__object);
+	int ___ret = -1;

that is from previous versions. If buffer is too small we will ge error.
But in most case 16K is more than enough ;)

> > +			fdinfo_entry__get_packed_size,
> > +			fdinfo_entry__pack);
> 
> I'd appreciate if this looked like
> 
> pc_write(fd, &e, fdinfo_entry);
> 
> where __get_packet_size and __pack are concatenated inside the macro

yeah, good point, will update

> > +#define pb_write(__fd, __obj_ptr, __get_pksize, __pack)				\
> > +({										\
> > +	u32 __size = __get_pksize(__obj_ptr);					\
> > +	u8 *__buf = xmalloc(__size);						\
> > +	int __ret = -1;								\
> > +										\
> > +	if (__buf) {								\
> > +		__pack(__obj_ptr, __buf);					\
> > +		__ret = write_img(__fd, &__size);				\
> > +		if (!__ret)							\
> > +			__ret = write_img_buf(__fd, __buf, __size);		\
> > +		xfree(__buf);							\
> > +	}									\
> > +										\
> > +	__ret;									\
> > +})
> 
> That's too big for a macro. Turn it into a macro + outlined function.

I've been trying, but the problem is that PB compiler generates pack/unpack
prototypes with argument typed and I can't use some abstract function which
has void* types as arguments, gcc complains. So I switched to macros.

	Cyrill