27 May
2003
27 May
'03
6:26 p.m.
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.
Thanks,
Arnold