[PATCH] Reimplement aligned_alloc

[Brian Inglis]

>> On 19/05/2020 11:52, Szabolcs Nagy wrote:
>>> - Failed to set errno on error.

> The 05/19/2020 19:41, Sebastian Huber wrote:
>> why should aligned_alloc() set errno on error?

On 2020-05-20 02:54, Szabolcs Nagy wrote:
> iso c allows standard api calls to set errno
> (except not to 0) but usually does not specify
> error conditions, however posix does and
> requires allocation functions to set errno
> to ENOMEM on failure.
> 
> posix is not yet aligned with c11 so there is
> no errno specification for aligned_alloc but
> that does not mean newlib should make it
> deliberately inconsistent with other allocation
> functions, users will try to use perror or
> strerror when calls fail that may internally
> use aligned_alloc and expect reasonable error
> message.

IEC 9899-2011[2012] specifies no errno values for any of the 7.22.3 Memory
management functions, and under Annex J.1 Unspecified behaviour and J.2
Undefined behaviour, omits aligned_alloc from issues of related functions, but
under J.2 specifies as a portability issue only:

-- The alignment requested of the aligned_alloc function is not valid or not
supported by the implementation, or the size requested is not an integral
multiple of the alignment (7.22.3.1).

POSIX posix_memalign specifies errno = EINVAL for this case and errno = ENOMEM
for the OoM case.

It seems more useful to set errno to POSIX compatible values when returning a
NULL pointer than attempt nasal demon emission.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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