what does wait(2) really do with status?

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2 total messages Started by David Sherman Tue, 08 Jan 1985 03:54

Author: David Sherman
Date: Tue, 08 Jan 1985 03:54

12 lines
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According to the manual for wait(2), the argument supplied
is a pointer to int (that is, "int *status"). The manual goes
on to talk about its "high byte" and "low byte", obviously
a throwback to the PDP-11. Anyone know whether status should
be declared pointer to short, or what?

Dave Sherman
The Law Society of Upper Canada
Toronto
-- 
{utzoo pesnta nrcaero utcs}!lsuc!dave
{allegra decvax ihnp4 linus}!utcsrgv!lsuc!dave

Re: what does wait(2) really do with status?

Author: Danny
Date: Tue, 08 Jan 1985 16:09

31 lines
1522 bytes

David Sherman writes:
    >According to the manual for wait(2), the argument supplied
    >is a pointer to int (that is, "int *status"). The manual goes
    >on to talk about its "high byte" and "low byte", obviously
    >a throwback to the PDP-11. Anyone know whether status should
    >be declared pointer to short, or what?

    This is the way I've done it, it's simple, it requires no
masking/shifting, etc.

/*
 *      Structure of return from wait() system call
 *      Note:  This is probably machine dependent
 */
struct status {
        char    dummy1; /* dummy char # 1 */
        char    dummy2; /* dummy char # 2 */
        char    ret;    /* Exit code from process */
        char    pstat;  /* Signal process died with (if any) */
};

    The note above is correct, it is very machine-dependant.  The
VAX version reverses pstat and ret, and defines them first in the
struct (I think).

    Anyway, try it out...

                                        Danny
-- 
				Daniel S. Cox
				({gatech|akgua}!itm!danny)

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