[PATCH] coreutils tac (was: coreutils tac)

[Tito]

On Friday 28 December 2007 16:39:27 Natanael Copa wrote:
> On Tue, 2007-12-25 at 15:48 +0000, Denys Vlasenko wrote:
> > On Tuesday 25 December 2007 08:45, Natanael Copa wrote:
> > > Hi,
> > >
> > > Seems like someone posted a tac applet some time ago:
> > > http://www.uclibc.org/lists/busybox/2003-July/008813.html
> > >
> > > It looks like tac is needed for shorewall. Is there interest for an
> > > updated patch of tac?
> > 
> > Why not.
> 
> Attatched.
> 
> > > Do you think its acceptable to make a tempfile when stdin is used, as in
> > > the patch above?
> > 
> > You can try to do it in memory... or control it with command-line switch.
> 
> GNU coreutils's tac uses tempfile. Seems like the most reasonable
> choice.
> 
> I took the patch from
> http://www.uclibc.org/lists/busybox/2003-July/008813.html and adapted it
> to current libbb (some name changes since 2003). Then I modified the
> tac.c to reduce size. Here is the bloatcheck for my changes.
> 
> function                                             old     new   delta
> concat_tmpdir_file                                     -     102    +102
> static.template                                        4       -      -4
> static.tempdir                                         4       -      -4
> .rodata                                             9426    9412     -14
> tac_main                                             447     431     -16
> mktemp_main                                          212     179     -33
> tac_file                                             187       -    -187
> ------------------------------------------------------------------------------
> (add/remove: 1/3 grow/shrink: 0/3 up/down: 102/-258)         Total: -156
> bytes
>    text    data     bss     dec     hex filename
>   86428    1501    4484   92413   168fd busybox_old
>   86280    1497    4480   92257   16861 busybox_unstripped
> 
> 
> A few notes:
> * I introduced a new libbb func: concat_tmpdir_file(), which will
> concatenate getenv("TMPDIR") or "/tmp" with given filename. This was to
> avoid duplicate code with mktemp applet.
> 
> * Old patch copied any file that fstat() reported as not regular file to
> temp file. My patch will try mmap all files and copy to tempfile if mmap
> fails. So if there are any non regular files that still are mmap'able
> those will not  be copied. I dont know if it makes any difference in
> real life (probably not).
> 
> * applet is marked as NOFORK.
> 
> > --
> > vda
> 
> -nc
> 

Hi,
just for fun I've created an alternative version of tac
using only linked lists in memory. Probably the size
is smaller but I haven't checked it yet as I
would like to hear first the opinion of the list
members about it. For the same reason i haven't
attached a patch but only a drop in replacement
of tac.c.
Hints, critics, improvements and correction
are always welcome!!!


Ciao,
Tito

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