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From: eggert@twinsun.com (Paul Eggert)
Subject: Re: cvs 1.3 bugfix
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References: <RICH.93Mar3114046@omicron.Rice.edu> <SOMMERFELD.93Mar3180839@blatt.apollo.hp.com> <RICH.93Mar3233616@omicron.Rice.edu> <CGD.93Mar4170821@eden.CS.Berkeley.EDU> <blv0K2^8@twinsun.com> <RICH.93Mar6233047@omicron.Rice.edu>
Date: Sun, 7 Mar 1993 17:42:59 GMT
Lines: 30
rich@Rice.edu (Richard Murphey) writes:
>In article <blv0K2^8@twinsun.com> eggert@twinsun.com (Paul Eggert) writes:
> Posix 3.3.3.3 says that the sigismember macro must behave as follows.
> IF sigismember(N,S) completes successfully
> THEN it yields 1 if signal N is a member of the set S, 0 otherwise
> ELSE it yields -1 and sets errno
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>??? It says '...if an error is *detected*, a value of -1 is
>returned...' as you quoted below. Does 'is detected' mean the same
>thing as 'occurred' here?
It doesn't matter whether the error occurs, only whether it is detected.
(In this case, the ``error'' is sigismember(N,S) where N is out of range.)
There is some implementation freedom here, namely whether to detect the error.
If the error is detected, then sigismember must yield -1 and set errno;
otherwise, sigismember must yield the correct answer, which is 0 in this case.
>Why doesn't the standard use 'occurs' here as it does in other sections
>(e.g. 5.1.2.4) rather than 'is detected'?
In some places, Posix requires that errors *must* be detected. For example,
5.1.2.4 says that opendir() must detect and report EACCES-style errors.
(By ``report'' I mean ``yield -1 and set errno''.) But in other places,
Posix merely says that *if* an error is detected, *then* it must be reported.
This is the case for sigismember and EINVAL-style errors.