From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <3FF2EA69.9030704@Princeton.EDU>
From: Martin Harriss <martin@Princeton.EDU>
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To: 9fans@cse.psu.edu
Subject: Re: [9fans] /sys/src/cmd/chmod.c
References: <20031231163240.Z25949@cackle.proxima.alt.za>
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Date: Wed, 31 Dec 2003 10:25:29 -0500
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Defensive programming?

Martin


Lucio De Re wrote:
> This struck me, looking at recent changes to chmod(1) which allow one
> to flag a file as "not to be included in nightly archives":
>
> 	for(; *s ; s++){
> 		switch(*s){
> 		case 'r':
> 			mode |= A(DMREAD); break;
> 		case 'w':
> 			mode |= A(DMWRITE); break;
> 		case 'x':
> 			mode |= A(DMEXEC); break;
> 		case 'a':
> 			mode |= DMAPPEND; break;
> 		case 'l':
> 			mode |= DMEXCL; break;
> 		case 't':
> 			mode |= DMTMP; break;
> 		default:
> 			return 0;
> 		}
> 	}
> 	if(*s != 0)
> 		return 0;
>
> I can't see how *s can be non-zero on exit from the for loop.  Is
> my C programming _so_ rusty?!
>
> ++L
>