[TUHS] V7 ls -s option

[Greg 'groggy' Lehey]

On Tuesday, 27 May 2003 at 15:26:24 +0300, Aharon Robbins wrote:
> The V7 ls.c code:
>
>>>>> 	long
>>>>>	nblock(size)
>>>>>	long size;
>>>>>	{
>>>>>		return((size+511)>>9);
>>>>>	}
>>>>
>
> I wrote:
>
>>> In fact, the V7 calculation is only
>>> an approximation in another sense; a file with large holes could
>>> generate too large a result.
>
> Greg wrote:
>
>> A block is a block.  If it's allocated, it's all there (at least in
>> the Seventh Edition).  It doesn't make any difference that some of the
>> space in the block may not represent valid data.
>
> You're missing my point.  Consider a C program along these lines:
>
> 	int main(void)
> 	{
> 		int fd = creat("/some/file", 0600);
>
> 		lseek(fd, 123456789L, 0);	/* absolute seek */
> 		write(fd, "x", 1);
> 		close(fd);
> 	}
>
> After running this program, the `/some/file' file now looks rather
> large. But it only has one block allocated to it.  However, the V7
> nblock() function computes a number somewhat larger than one.

Yes, I missed your point.  Sorry.  This is what comes of shooting off
my mouth before reading the code.

Greg
--
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