Ports / other userland often needs such an implementation to function.
Lets expose `AK::timing_safe_compare` under the same name used used in
OpenBSD / FreeBSD / Solaris and other projects.
These POSIX APIs are defined as mapping directly to
`strrchr` and `strchr` respectively.
These are needed for the latest version of the stress-ng port,
and also give us better POSIX compliance.
This fixes at least half of our LibC includes in the kernel. The source
of truth for errno codes and their description strings now lives in
Kernel/API/POSIX/errno.h as an enumeration, which LibC includes.
This implements the XSI-compliant version of strerror_r() - as opposed
to the GNU-specific variant.
The function explicitly saves errno so as to not accidentally change it
with one of the calls to other functions.
According to POSIX.1 all error codes have to be distinct - with
the exception for EAGAIN and EWOULDBLOCK. Other libcs including
eglibc and newlib define EWOULDBLOCK as an alias for EAGAIN and
some software including OpenTTD expect this behavior.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
I dont know why we do a fast path in the Kernel, but not in Userspace
Also simplified the byte explosion in memset to "explode_byte"
it even seemed so, that we missed the highest byte when memseting something
