Path: utzoo!attcan!uunet!samsung!uakari.primate.wisc.edu!bin
From: bin@primate.wisc.edu (Brain in Neutral)
Newsgroups: comp.sys.mips
Subject: Signal return value?
Message-ID: <1568@uakari.primate.wisc.edu>
Date: 8 Feb 90 16:40:08 GMT
Organization: UW-Madison Primate Center
Lines: 53


For the signal() system call in RISC/os 4, there are multiple versions.
The BSD man page indicates that the handler function returns int:

SIGNAL(3C-BSD)      RISC/os Reference Manual       SIGNAL(3C-BSD)
SYNOPSIS
     #include <signal.h>

     (*signal(sig, func))()
     int (*func)();

NOTES  (MIPS)
     The handler routine can be declared:

         handler(sig, code, scp)
         int sig, code;
         struct sigcontext *scp;

That's fine, and consistent.
----------------------------------------------------------------------------

On the other hand, one SYSV man page indicates that the function returns
void, but then the example declaration is that of a function that returns
int.  Which is it?

SIGNAL(2-SysV)      RISC/os Reference Manual       SIGNAL(2-SysV)
SYNOPSIS
     #include <signal.h>

     void (*signal (sig, func))()
     int sig;
     void (*func)();

NOTES  (MIPS)
     The handler routine can be declared:

         handler(sig, code, scp)
         int sig, code;
         struct sigcontext *scp;

Even more confusing, there is a SIGNAL(3-SysV) man page, which says:

     (*signal(sig, func))()
     int (*func)();

which is the same as SIGNAL(3C-BSD), but different than SIGNAL(3-SysV)!

I seek enlightenment...

Paul DuBois
Internet:	dubois@primate.wisc.edu
UUCP:		rhesus!dubois
FAX:		608/263-4031