Re: GET_BYTES() macro, doing a bounds check and a memcpy()?

[Francois-Xavier Le Bail <devel.fx.lebail () orange fr>]

On 03/05/2019 19:08, Guy Harris wrote:

> Should we have a function
>
>       static inline void
>       get_bytes(netdissect_options *ndo, u_char *dst, const u_char *p, size_t len)
>       {
>               if (!ND_TCHECK_LEN(p, len))
>                       longjmp(ndo->ndo_truncated, 1);
>               UNALIGNED_MEMCPY(dst, p, len);
>       }
>
> and a macro
>
>       #define GET_BYTES(p, len) get_bytes(ndo, (const u_char *)(p), len)
>
> (it uses UNALIGNED_MEMCPY() to handle cases where the compiler "helpfully" optimizes the copy under the assumption 
> that the source is aligned on a 2-byte or 4-byte boundary, on a platform such as a SPARC-based machine where 
> misaligned loads/stores cause a trap or, worse, some ARM-based machines where unaligned access isn't enabled).

Agreed.
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