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From: chris@umcp-cs.UUCP
Newsgroups: net.unix-wizards
Subject: Re: what's the opinion on "sigrestartable()"?
Message-ID: <6637@umcp-cs.UUCP>
Date: Fri, 20-Apr-84 15:59:06 EST
Article-I.D.: umcp-cs.6637
Posted: Fri Apr 20 15:59:06 1984
Date-Received: Sun, 22-Apr-84 08:40:02 EST
References: <798@eosp1.UUCP>
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 28

I'd rather have the kernel look at the return value from the called
routine, to decide whether to restart system calls or not.  Then you
can have two C libraries, "-l4.1" and the default.  -l4.1 would have
a signal system call that looks something like

	static int (*_sigtraps[32])();

	static
	_signal (sig, pc, and whatever else goes here) {
		(*_sigtraps[sig]) (sig, pc, and ...);
		return EINTR;	/* just an example, who knows that
				   the "right" values would be */
	}

	signal (sig, d) int (*d)(); {
		_sigtraps[sig] = d;
		_signal (sig, _signal);
	}

This would mean that compiling with the "4.1 compatibility library"
would get you the old behaviour, while using the standard library
would give you your choice.

Libraries are a very good way to do backward compatibility!
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci (301) 454-7690
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