Re: Can't open($newfh, $mode_layers, '&' . fileno($fh))

Looks like there's two issues here. One is that in the three-arg form of open, the '&' character goes at the end of the second argument, not the beginning of the third one. The proper syntax would be open($fd2, '+>>&', $fn); Your code as is opens a file called &3 with $fd2 pointing to it. The other is that, based on a quick test here, it seems that you cannot specify PerlIO layers when opening a filehandle this way. But binmode should be able to help with that.

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Re^2: Can't open($newfh, $mode_layers, '&' . fileno($fh)) by renodino (Curate) on Feb 10, 2006 at 21:51 UTC
OK, thnx for the pointers wrt '&' placement. However, testing binmode() seems to do some odd things; if I apply the layers of the original to the dup'ed handle, the layers stack, rather than replace: `use PerlIO; my $fd; open($fd, '+>>:raw', 'somefile.data') \|\| die $!; my $layers = ':' . join(':', PerlIO::get_layers($fd)); print "$layers\n"; # # this doesn't complain, but the layers aren't being properly applied # my $fd3; open($fd3, "+>>&", fileno($fd)) \|\| die $!; binmode $fd3, $layers; print join(',', PerlIO::get_layers($fd3)), "\n";` [download] results in "unix,crlf,unix" as the reported layers for $fd3. I guess its possible scan and apply layers - but how do I remove them ? I tried using just "binmode $fd3;", and that still reports unix,crlf... And I'm still left in limbo wrt getting handle access modes on Win32...is there any Win32API solution to that ?	[reply] [d/l]

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Re^2: Can't open($newfh, $mode_layers, '&' . fileno($fh))
by renodino (Curate) on Feb 10, 2006 at 21:51 UTC

However, testing binmode() seems to do some odd things; if I apply the layers of the original to the dup'ed handle, the layers stack, rather than replace:

use PerlIO;

my $fd;
open($fd, '+>>:raw', 'somefile.data') || die $!;

my $layers = ':' . join(':', PerlIO::get_layers($fd));

print "$layers\n";

#
# this doesn't complain, but the layers aren't being properly applied
#
my $fd3;
open($fd3, "+>>&", fileno($fd)) || die $!;
binmode $fd3, $layers;

print join(',', PerlIO::get_layers($fd3)), "\n";
[download]

And I'm still left in limbo wrt getting handle access modes on Win32...is there any Win32API solution to that ?

[reply]
[d/l]