wait() function survey

[Ben Lindstrom]

On Sat, 26 Aug 2000, Damien Miller wrote:

> On Fri, 25 Aug 2000, Ben Lindstrom wrote:
> 
> > 
> > In serverloop.c we have two wait() lines.
> > 
> > POSIX defines wait() was "pid_t wait(int *status)".  However older BSD
> > systems could have "int wait(union wait *statusp)" as it's defines.
> > 
> > I'm interested to see how many platforms OpenSSH is ported requires the
> > latter define.
> > 
> > I know NeXT does.  
> 
> What is the definition of the union? Is it a fatal error or just a
> warning if the (int*) version is used?
> 
It's just a warning if (int*) is used.  The reason why I've not looked to
closely at it until recently.

As for the definition of "unit wait" .. <cough> Massively different.
Another nasty thing that NeXT did (unless you defined -posix and use the
libposix.a library.. Maybe I should beg for libposix.a code from Apple
in BSD licensing form =).

As tempting as it is just to implement wait() based on wait4() like
OpenBSD.. wait4() uses the same union structure.  Which makes my
waitpid() implement also incorrect (since I was not closely look at
structure differences. <sigh>)

union wait      {
        int     w_status;               /* used in syscall */
        /*
         * Terminated process status.
         */
        struct {
#if     __BIG_ENDIAN__
                unsigned short  w_PAD16;
                unsigned        w_Retcode:8;   /* exit code if w_termsig==0 */
                unsigned        w_Coredump:1;  /* core dump indicator */
                unsigned        w_Termsig:7;   /* termination signal */
#else   __BIG_ENDIAN__
                unsigned short  w_Termsig:7;   /* termination signal */
                unsigned short  w_Coredump:1;  /* core dump indicator */
                unsigned short  w_Retcode:8;   /* exit code if
w_termsig==0 */
#endif  __BIG_ENDIAN__
        } w_T;
        /*
         * Stopped process status.  Returned
         * only for traced children unless requested
         * with the WUNTRACED option bit.
         */
        struct {
#if     __BIG_ENDIAN__
                unsigned short  w_PAD16;
                unsigned        w_Stopsig:8;    /* signal that stopped us*/
                unsigned        w_Stopval:8;    /* == W_STOPPED if stopped*/
#else   __BIG_ENDIAN__
                unsigned short  w_Stopval:8;    /* == W_STOPPED if stopped*/
                unsigned short  w_Stopsig:8;    /* signal that stopped us*/
#endif  __BIG_ENDIAN__
        } w_S;
};