Re: How do I make the garbage collector throw an exception when it fails to auto-close a filehandle?

In Linux:

PolettiX:~# dd if=/dev/zero of=testfile bs=1024 count=1024
1024+0 records in
1024+0 records out
1048576 bytes transferred in 0.019164 seconds (54715967 bytes/sec)
PolettiX:~# 
PolettiX:~# 
PolettiX:~# mkfs.ext2 testfile
mke2fs 1.37 (21-Mar-2005)
testfile is not a block special device.
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
128 inodes, 1024 blocks
51 blocks (4.98%) reserved for the super user
First data block=1
1 block group
8192 blocks per group, 8192 fragments per group
128 inodes per group

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 27 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
PolettiX:~# 
PolettiX:~# 
PolettiX:~# mount testfile -o loop /mnt
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Now you have a filesystem that will be easy to fill up:

#!/usr/bin/perl
use strict;
use warnings;
use Fatal qw( open close );

chdir '/mnt';
{
   open my $fh, '>', 'prova.dat';
   print {$fh} "ciao\n" for 1 .. 1000000;
   # close $fh;
}

print {*STDERR} "should be closed here!\n";
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In my system, the final string on STDERR gets printed when the close above is commented; uncommenting the close triggers the fatal error:

Can't close(GLOB(0x814cd4c)): No space left on device at (eval 2) line
+ 3
        main::__ANON__('GLOB(0x814cd4c)') called at ./prova.pl line 13
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Flavio
perl -ple'$_=reverse' <<<ti.xittelop@oivalf

Don't fool yourself.

Comment on Re: How do I make the garbage collector throw an exception when it fails to auto-close a filehandle? Select or Download Code

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Re^2: How do I make the garbage collector throw an exception when it fails to auto-close a filehandle? by Aristotle (Chancellor) on Jan 13, 2007 at 23:51 UTC
In my system, the final string on `STDERR` gets printed when the `close` above is commented; uncommenting the close triggers the fatal error: And that’s exactly the point: when you have an explicit close, you can make it throw an exception; when you omit the close, the error is silent. But I want to omit the close and still get an exception. Fatal won’t help me there. Thanks for the pointer about the loop device though! All I can say in retrospect is, d’uh. However, Linux has an easier way, mentioned by Zaxo in the old thread from gaal: there’s a `/dev/full` device where writing always fails with ENOSPC. Makeshifts last the longest.	[reply]
Re^3: How do I make the garbage collector throw an exception when it fails to auto-close a filehandle? by polettix (Vicar) on Jan 14, 2007 at 01:01 UTC
Oh, I misunderstood that you didn't know for sure about Fatal's behaviour: In the simplest case, `use Fatal qw( :void close );` would work for this, but I strongly doubt it, and in any case I can’t think of a good way to purposefully trigger a close failure in order to test it. And yes... the loop device rocks :) Flavio perl -ple'$_=reverse' <<<ti.xittelop@oivalf Don't fool yourself.	[reply] [d/l]
Re^3: How do I make the garbage collector throw an exception when it fails to auto-close a filehandle? by BrowserUk (Patriarch) on Jan 14, 2007 at 00:01 UTC
Won't the /dev/full device fail when you try to write to it long before you get to close it? Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]
Re^4: How do I make the garbage collector throw an exception when it fails to auto-close a filehandle? by Aristotle (Chancellor) on Jan 14, 2007 at 01:32 UTC
No… $ perl -MFatal=open,close,syswrite -e'open $fh,">/dev/full"; syswrite $fh, 1; close $fh' Can't syswrite(GLOB(0x8130c24), 1): No space left on device at (eval 3) line 3 main::__ANON__('GLOB(0x8130c24)') called at -e line 1 $ perl -MFatal=open,close -e'open $fh,">/dev/full"; print { $fh } 1 or die "$!\n"; close $fh' Can't close(GLOB(0x8130c24)): No space left on device at (eval 2) line 3 main::__ANON__('GLOB(0x8130c24)') called at -e line 1 … not with buffered I/O. Makeshifts last the longest.	[reply]