Good but ... mk-origtargz Allow more files to be deleted than can fit inside argv (`getconf ARG_MAX`)

[Osamu Aoki]

Hi,

On Tue, Jan 23, 2018 at 03:58:11PM +0100, Mattia Rizzolo wrote:
> On Tue, Jan 23, 2018 at 10:58:53PM +0900, Osamu Aoki wrote:
> > This looks a reasonable patch.  But I don't know why you chose
> > 16384=0x400 as the max figure.
...  (It's ARG_MAX is in BYTEs but ...) 

> Jan 13 21:39:31 <jamessan[m]>   infinity0: why a magic number in the mk-origtargz patch?
> Jan 13 21:43:10 <mapreri>       (instead of running a getconf and getting the value and use it, I suppose)
> Jan 13 21:45:38 <mapreri>       (and then doing some computation to turn number in something usable)
> Jan 13 21:50:07 <infinity0>     jamessan[m]: it's `getconf ARG_MAX` / 128 which i felt was a reasonable path length for source filenames
> Jan 13 21:50:33 <infinity0>     and worked in practise for me (larger values like 30000 broke)
> Jan 13 21:56:52 <mapreri>       infinity0: yes, but why not detecting it at runtime (and a comment explaining why 128 is better than NAME_MAX=255)
> Jan 13 21:57:09 <infinity0>     because it would involve more perl code
> 
> 
> So I agree.  Please don't merge that as it is until somebody does what's
> written here ↑.

Maybe before discussing technical solutions, we should know what issues
we are addressing by this modification.  Is there a real cases which you
need to have this patch?

I don't know perl at all but in rough idea in perl/python mix pseudo
code:

# suppose @args has all the filename paths

$max = `getconf ARG_MAX`;
$file = shift;
while #args > 0
    $cmdline =  "command ";
    while (total_length($cmdline) + len($file) -2 < $max) {
        $cmdline = $cmdline . " " . $file;
        $file = shift;
    }
    if ("command " != $cmdline ) {
        shell_out_code($cmdline);
    } else {
        error_message;
    }

Then it is guaranteed to be within ARG_MAX. But is these such case?

Osamu




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> regards,
>                         Mattia Rizzolo
> 
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