Store an ngx_fd_t within the void *

[Igor Sysoev]

On Fri, Apr 30, 2010 at 01:07:32PM +0200, Grzegorz Nosek wrote:

> On Fri, Apr 30, 2010 at 03:02:04PM +0400, Peter Leonov wrote:
> > Hi devels,
> > 
> > Wanna store the value of ngx_fd_t in the void * variable (on the SpiderMonkey “private” field).
> > Am doing the following trick to avoid the warning “cast to pointer from integer of different size”:
> > 
> > #if (NGX_PTR_SIZE == 8)
> > #define FD_TO_PTR(fd)  ((void *) (uint64_t) fd)
> > #elif (NGX_PTR_SIZE == 4)
> > #define FD_TO_PTR(fd)  ((void *) (uint32_t) fd)
> > #else
> > #warning can't determine the proper fd to pointer conversion
> > #define FD_TO_PTR(fd)  ((void *) fd)
> > #endif
> > 
> > and somewhere in the code:
> > void *private = FD_TO_PTR(fd);
> > 
> > Is all this legal?
> 
> I'd say uintptr_t is a better alternative. It's an unsigned integer type
> equal in size to void*. However, I'm not sure it's available on all
> platforms and whether Nginx emulates one if not found.
> 
> There's also intptr_t, which is the signed counterpart.

uintptr_t is certainly better and nginx tries to emulate it.


-- 
Igor Sysoev
http://sysoev.ru/en/