The comment and the code that rejects size==0, or doesn't, are copied
below. Konstantin Belousov is the last person to have touched most of
it, and can better explain its meaning than I.
Doug Moore
/*
* Enforce the constraints.
* Mapping of length 0 is only allowed for old binaries.
* Anonymous mapping shall specify -1 as filedescriptor and
* zero position for new code. Be nice to ancient a.out
* binaries and correct pos for anonymous mapping, since old
* ld.so sometimes issues anonymous map requests with non-zero
* pos.
*/
if (!SV_CURPROC_FLAG(SV_AOUT)) {
if ((size == 0 && curproc->p_osrel >= P_OSREL_MAP_ANON) ||
((flags & MAP_ANON) != 0 && (fd != -1 || pos != 0)))
return (EINVAL);
} else {
if ((flags & MAP_ANON) != 0)
pos = 0;
}
On 6/10/19 9:27 AM, Shawn Webb wrote:
> Sounds good! I think the manpage still might still need a change
> to match the current behavior, or perhaps matching something similar
> to that vm_mmap.c comment. But that comment brings another question:
> what's the definition of "old binaries"? a.out?
>
> Thanks,
>
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