bug#23073: wc reports wrong byte counts when using '--from-files0=-'

[William R. Fraser]

Looks good :)

On Mon, Dec 19, 2016 at 11:00 AM, Pádraig Brady <address@hidden> wrote:

> On 21/03/16 15:16, Pádraig Brady wrote:
> > On 21/03/16 00:59, William R. Fraser wrote:
> >> When wc gets its list of files by reading from stdin, using the argument
> >> '--from-files0=-', it reuses the same fstatus struct for each file.
> >>
> >> The problem is that the 'wc' function checks the 'failed' member of this
> >> struct and if it is <=0, it skips doing fstat on the file. The main loop
> >> doesn't reset this value between files, so only the first file has fstat
> >> done on it.
> >>
> >> This can result in the 'wc' function seeking past the end of
> >> subsequent files and then over-reporting their byte counts.
> >>
> >> See the attached patch, which resets the fstatus struct in between files
> >> when reading the file list from stdin.
> >
> > Ouch. This seems to be since v7.0-96-gc2e56e0
> > It would also mean there would be a lot of redundant reading
> > if the initial file was significantly smaller than any other file.
> >
> > $ truncate -s1G wc.big
> > $ touch wc.small
> > $ printf '%s\0' wc.big wc.small | wc -c --files0-from=-
> > 1073741824 wc.big
> > 1073741760 wc.small
> > 2147483584 total
>
> Sorry for the delay.
> I didn't go far enough back in my TODO list so missed this.
> Proposed patch attached.
>
> thanks,
> Pádraig
>
>


-- 
Bill Fraser { http://www.codewise.org/wrf }
<http://www.cs.uic.edu/%7Ewfraser/>