[PATCH][AArch64] Add rawmemchr

[Wilco Dijkstra]

Alexander Cherepanov wrote:
>
> Is memchr on your arch guaranteed to work with an infinite size?

Yes it works fine. The AArch64 assembler functions have been carefully
written to avoid overflows on the size as well as end-pointer comparisons.

> In theory, it's guaranteed by C11 and POSIX (e.g. see
> http://open-std.org/jtc1/sc22/wg14/www/docs/n1533.htm ) but IIUC there
> is a sentiment in the glibc community that passing to a library function
> a size greater than the real size of an object is an error. (Would be
> glad to find out I misunderstood something here.)

The rawmemchr API is a bug by itself - it really is memchr with infinite size
(so using it is extremely risky), but making that explicit is by itself not an issue.

Wilco