-- Errno - Provide direct access from Ada to that asinine C language integer value of the same name.
-- Written in 2023 by Prince Trippy <programmer@verisimilitudes.net>.

-- To the extent possible under law, the author(s) have dedicated all copyright and related and
-- neighboring rights to this software to the public domain worldwide.
-- This software is distributed without any warranty.

-- You should have received a copy of the CC0 Public Domain Dedication along with this software.
-- If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.

-- This program does so little that it can't help but adhere to the requirements of Ada 1995, alone.
with Interfaces.C;

-- That errno is exposed only to the C language, since it's implemented as a text replacement macro.
-- I'm wholly unwilling to write any C language code to expose it, however, as its scope would grow.
-- I skulked, to find an identical function used in its implementations, using only different names.
-- For GNU, and one compatible system library, the function is appropriately named __errno_location.
-- For other systems I've found the name used to be either __errno or __error and so note such here.
-- I'm not certain how the C convention interacts with the access return value type, but I care not.
-- I could've used the System package and its address type, but that's overkill, and always will be.
-- This code will be changed whenever porting, so anything greater is wasted effort and naught more.
function Errno return Interfaces.C.Int is
   function True_Errno return access Interfaces.C.Int;
   pragma Import(Convention => C, Entity => True_Errno, External_Name => "__errno_location");
begin
   return True_Errno.all;
end Errno;
.