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From: dan%bbncd@sri-unix.UUCP
Newsgroups: net.unix-wizards
Subject: Re: setexit()
Message-ID: <12826@sri-arpa.UUCP>
Date: Thu, 20-Oct-83 17:32:39 EDT
Article-I.D.: sri-arpa.12826
Posted: Thu Oct 20 17:32:39 1983
Date-Received: Tue, 25-Oct-83 02:46:56 EDT
Lines: 19

From:  Dan Franklin <dan@bbncd>

setexit() and reset() were the crude V6 primitives that were later generalized
to setjmp and longjmp.  They take no arguments, and can be simulated with

    #include <setjmp.h>
    jmp_buf label;
    
    #define setexit()  setjmp(label)
    #define reset() longjmp(label, 0)

at the beginning of any program using them.  In other words, setexit() was like
setjmp of a built-in fixed "jmp_buf"; reset() was like a longjmp to that
"jmp_buf".  Unlike setjmp(), however, you could not find out from the return
value of setexit() whether you were setting it up or returning from a reset()
(in standard V6, that is; we changed ours to return nonzero on reset(), and
probably other people did the same thing).

	Dan Franklin (dan@bbn-unix)