exits, _exits, atexit, atexitdont, terminate - terminate process, process cleanup
void _exits(char *msg)
void exits(char *msg)
/* Alef only */
void _exits(byte *msg)
void exits(byte *msg)
void terminate(byte *msg)
Exits is the conventional way to terminate a process. _Exits is the underlying system
call. They can never return.
Msg conventionally includes a brief (maximum length ERRLEN) explanation of the reason for
exiting, or a null pointer or empty string to indicate normal termination. The string is
passed to the parent process, prefixed by the name and process id of the exiting process,
when the parent does a wait(2).
Before calling _exits with msg as an argument, exits calls in reverse order all the func-
tions recorded by atexit.
Atexit records fn as a function to be called by exits. It returns zero if it failed,
nonzero otherwise. A typical use is to register a cleanup routine for an I/O package. To
simplify programs that fork or share memory, exits only calls those atexit-registered
functions that were registered by the same process as that calling exits.
Calling atexit twice (or more) with the same function argument causes exits to invoke the
function twice (or more).
There is a limit to the number of exit functions that will be recorded; atexit returns 0
if that limit has been reached.
Atexitdont cancels a previous registration of an exit function.
In Alef, the system call _exits is the same, but its use is discouraged because the run-
time system needs to maintain consistency; terminate and exits are the recommended rou-
tines. Terminate is called automatically when a task or proc returns from its main func-
tion; it may also be called explicitly. In either case, it frees resources private to the
task (which may be the implicit main task within the proc) and terminates that task. If
that task is the last one in the proc, resources private to the proc are then freed. If
that proc is the last one in the program, it calls exits. Exits should only be called in
the last proc of a program; it calls any atexit functions (registered by any proc) and
then calls _exits.
In Alef, atexit and atexitdont behave the same as in C.