bug#7357: csplit: memory exhausted when using stdout / pipe instead of a file

[Pádraig Brady]

On 10/11/10 17:42, Jim Meyering wrote:
> Pádraig Brady wrote:
> 
>> On 10/11/10 17:27, Jim Meyering wrote:
>>> That looks fine except that there were some problems
>>> (sorry, don't remember details off hand)
>>> with tests using that "yes|..." idiom, so I converted
>>> them all to use other means.
>>
>> [snip]
>>
>>> As far as I'm concerned, using require-perl is fine.
>>> Take your pick, or even leave it using yes|head for now.
>>> It's no big deal if the test fails on some fringe system.
>>
>> I'll take the later.
>> It would be nice to know what the weird issue was :)
> 
> yes [sic]
> 
> I dug it up:
> 
>   http://git.sv.gnu.org/cgit/coreutils.git/commit/?id=cf0fa2d930de1609
> 
>     Use seq, not `yes' to generate link target.
>     Otherwise, on systems (DJGPP) that emulate pipes using files,
>     this test would never complete, waiting for `yes' to terminate.
> 
> diff --git a/tests/du/slink b/tests/du/slink
> -  name=`yes|tr '\n' y|head -c$len`
> +  name=`seq 1 $len|tr -c x y |head -c$len`

Interesting, thanks.

> Is DJGPP still relevant?
> The last update of http://www.delorie.com/djgpp/ was in 2003.
> Now, I'm tempted to leave your seq|head pipe there,
> just to see if anyone notices.

OK I'll apply as is, and if it's ever an issue,
we can test with a variation of:

# yes never terminates with the file based
# pipe emulation in DJGPP
require_pipes_() {
  timeout 10 yes | head -n1 > /dev/null ||
    skip_test_ "Emulated pipes unsupported"
}

cheers,
Pádraig.