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From: muller@sdccsu3.UUCP (Keith Muller)
Newsgroups: net.news.b,net.bugs.4bsd
Subject: Re: alarm() bug in 4.2
Message-ID: <2049@sdccsu3.UUCP>
Date: Tue, 17-Jul-84 02:37:54 EDT
Article-I.D.: sdccsu3.2049
Posted: Tue Jul 17 02:37:54 1984
Date-Received: Fri, 13-Jul-84 03:28:07 EDT
References: <282@voder.UUCP>
Organization: U.C. San Diego, Computer Center
Lines: 20

> Fortunately, there is an easy workaround; change the previous code
> to read:
>
>	for (...) {
>		oldmask = sigblock(1<<SIGALRM);
>		...
>		sigblock(oldmask);
>	}

This won't work, this will block off SIGTERM not SIGALRM. Sigblock()
requires that to block off signal i the i-th bit in the mask must
be set. (The bits are numbered from 1 to n). So that line must read:

		oldmask = sigblock(1 << (SIGALRM - 1));

Note this easily confused with select()'s mask which does NOT need to
have 1 subtracted since descriptors are numbered from 0 to n.

		Keith Muller
		UCSD Computer Center