SQL logon - check user profile and password

Logon.sql

-- Check the user profile and password 
-- This also showcase how to integrate the C code directly into your UDTF
-- You need my IFS_WRITE UDTF found elsewhere at my gist
--
-- Simply paste this gist into ACS SQL and step through the example.
--
-- It is a cool example how far you can go with SQL: Have fun - 
-- (C) Niels Liisberg 2021
--
-- This gist is distributed on an "as is" basis, without warranties 
-- or conditions of any kind, either express or implied.
----------------------------------------------------------------------------------------------
call qusrsys.ifs_write('/tmp/main.c' , '
{
    #include "QSYSINC/H/QSYGETPH"
    QSYGETPH ( 
          MAIN.USR_ID    
        , MAIN.USR_PASSWORD                
        , MAIN.HAND    
        , MAIN.ERR                 
        , MAIN.USR_PASSWORD_LEN        
        , MAIN.USR_CCSID
    );  
} 
');

create or replace function qusrsys.logon (
    user_id char(10),
    user_password varchar(128) ccsid 1208
) 
returns varchar (256)
set option output=*print, commit=*none, dbgview = *source --list
main:begin
    declare usr_id char(10); 
    declare usr_password_len int;
    declare usr_password char(128) ccsid 1208;
    declare usr_ccsid int;
    declare err char(256); 
    declare hand  char(12); 
    
    set err = x'000000ff00000000'; 
    set usr_id = user_id; 
    set usr_password_len = length(user_password);
    set usr_password = user_password;
    set usr_ccsid = 1208;
    include '/tmp/main.c';
    return substring( err , 9);
end;

-- unit test 
values ( 
   qusrsys.logon ('DEMO' , 'demo2')
)