FAQ 5.16 Is there a leak/bug in glob()?

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5.16: Is there a leak/bug in glob()?


Due to the current implementation on some operating systems, when you
use the glob() function or its angle-bracket alias in a scalar context,
you may cause a memory leak and/or unpredictable behavior. It's best
therefore to use glob() only in list context.



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Re: FAQ 5.16 Is there a leak/bug in glob()?

> 5.16: Is there a leak/bug in glob()?
>
>
> Due to the current implementation on some operating systems, when you
> use the glob() function or its angle-bracket alias in a scalar context,
> you may cause a memory leak and/or unpredictable behavior. It's best
> therefore to use glob() only in list context.

It's still buggy in list context, see below. I filed this bug to p5p
weeks ago.

This works fine:

#! /bin/perl
$"=','; print join ',', glob "aaaa{@{[q{01}..q{05}]}}cccc"
__END__

aaaa01cccc,aaaa02cccc,aaaa03cccc,aaaa04cccc,aaaa05cccc


After make the range bigger enough, the bug occurs:

#! /bin/perl
$"=','; print join ',', glob "aaaa{@{[q{001}..q{999}]}}cccc"
__END__
aaaa

-Todd

Re: FAQ 5.16 Is there a leak/bug in glob()?

In article
<5fe6496b-8de5-4806-a106-8a42603b4d20@d21g2000prf.googlegroups.com>,
Todd wrote:

> > 5.16: Is there a leak/bug in glob()?
> >
> >
> > Due to the current implementation on some operating systems, when you
> > use the glob() function or its angle-bracket alias in a scalar context,
> > you may cause a memory leak and/or unpredictable behavior. It's best
> > therefore to use glob() only in list context.
>
> It's still buggy in list context, see below. I filed this bug to p5p
> weeks ago.
>
> This works fine:
>
> #! /bin/perl
> $"=','; print join ',', glob "aaaa{@{[q{01}..q{05}]}}cccc"
> __END__
>
> aaaa01cccc,aaaa02cccc,aaaa03cccc,aaaa04cccc,aaaa05cccc

> After make the range bigger enough, the bug occurs:
>
> #! /bin/perl
> $"=','; print join ',', glob "aaaa{@{[q{001}..q{999}]}}cccc"
> __END__
> aaaa

This has already been explained, I think. It's a MAXPATHLEN limitation
that perl takes from your system.

http://groups.google.com/group/perl.perl5.porters/browse_thr ead/thread/2
40e1011be62ec5d/7e1b6958749ec3a9?lnk=st&q=glob+todd+perl#7e1 b6958749ec3a
9

These ranges work:

perl -le '$"=q|,|; print glob "aaaa{@{[q{000}..q{253}]}}cccc"'
perl -le '$"=q|,|; print glob "aaaa{@{[q{500}..q{753}]}}cccc"'

That is, until I shift the window, which doesn't work:

perl -le '$"=q|,|; print glob "aaaa{@{[q{1500}..q{753}]}}cccc"'

Then I try printing the length of the values I get back from glob. On
my machine, going past the upper bounds just gives back 'aaa'.

perl -le '$"=","; print length join "", glob
"aaaa{@{[q{000}..q{253}]}}cccc"'
2286
$ perl -le '$"=q|,|; print length join "", glob
"aaaa{@{[q{1000}..q{1202}]}}cccc"'
2233

It's not related to strictly related to total length though, because
shortening it doesn't let me extend the range that much (by one!):

perl -le '$"=q|,|; print length join "", glob
"a{@{[q{1000}..q{1203}]}}c"'
1224
perl -le '$"=q|,|; print length join "", glob
"a{@{[q{1000}..q{1204}]}}c"'
1