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Date: Sun, 20 Nov 2005 20:56:05 +0000
From: Brian Candler <B.Candler@pobox.com>
To: Giorgos Keramidas <keramida@hellug.gr>
Message-ID: <20051120205605.GB19791@uk.tiscali.com>
References: <20051116161540.GB4383@uk.tiscali.com>
	<437F7E22.5050800@freebsd.org> <20051120193416.GB1599@flame.pc>
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Cc: Tim Kientzle <kientzle@freebsd.org>, freebsd-current@freebsd.org
Subject: Re: Order of files with 'cp'
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On Sun, Nov 20, 2005 at 09:34:16PM +0200, Giorgos Keramidas wrote:
> qsort() can be 'stable' enough for our purposes if the comparison
> function uses something like this:
> 
>     int
>     compare_int32_t(void *pa, void *pb)
>     {
>         int32_t a, b;
> 
>         assert(pa != NULL && pb != NULL);
>         a = *((int32_t *)pa);
>         b = *((int32_t *)pb);
> 
>         if (a < b && pa != pb)
>             return 1;
>         if (a > b && pa != pb)
>             return -1;
>         return 0;
>     }

Care to explain??

For one thing, I don't think qsort() will ever call its comparison function
with two equal pointers, as that would be a point(er)less thing to do.
Therefore, I can't see why you are testing for pa != pb, since this
condition will always be true. (Also, a < b could never be true if pa == pb).

Secondly, mastercmp() doesn't compare integers, it compares FTS structures.
The comparison function just compares whether one item is a directory and
the other a file. How would you have mastercmp() work instead?

Regards,

Brian.