New subject: V7 ls -s option

25 May 2003

...
  From: Dennis Ritchie &lt;dmr(a)plan9.bell-labs.com&gt;
 To: tuhs(a)minnie.tuhs.org
 Subject: [TUHS] (no subject)
 Date: Fri, 23 May 2003 00:10:30 -0400

  The V7 ls(1) man page says that the -s option,
which prints total
blocks, includes any indirect blocks. 
 However, the V7 struct stat didn't have the
st_blocks member in the
 struct stat, and the code in ls.c uses 
  	long
	nblock(size)
	long size;
	{
		return((size+511)>>9);
	} 
 So, is this just a case of the man page being
mistaken? 
 Yes, it looks like a manual bug. Retrieving
 the true number of indirect blocks isn't possible
 from the 7th edition stat.  I'm not sure when (or by
 whom) the st_blocks member was added. 
Thanks for confirming this.  In fact, the V7 calculation is only
an approximation in another sense; a file with large holes could
generate too large a result.

System III doesn't have st_nblocks either.

...
   While I'm
at it, the V7 ls -a option only adds . and .. to the
 list; apparently all other dot files were printed by default.
 When did ls change such that -a applied to all dot files? 
 UCB or USL did this (I'm sure which first).
 Both tended to use more . files.

 	Dennis 
As already pointed out, earlier Research code only checked the
first character for being '.'; I later looked at the V6 ls.c.

The System III ls.c is essentially the V7 one, but with comments
added, and -l printing both owner and group, with -g and -o to
turn off group or owner from -l.  Also, support for FIFOs.

The nblock() calculation is considerably more complicated, and
would seem to actually get the number of indirect blocks. At
first glance, it looks though like a file with holes would
still confuse it.

Nothing like engaging in Software Archeology... :-)

Thanks,

Arnold

Re: [TUHS] V7 ls -s option