[perl #113982] Reopening filehandles can clobber PerlIO layers

On Wed Jul 04 07:59:23 2012, dmcbride@cpan.org wrote:
> The following code has two surprises.
> 
> a) the layers for STDOUT are different for input vs output.
> b) the layers for STDOUT's output are missing the utf8 layer after
>    the reopening.  (They're missing for $fh, too.)
> 
> (Thanks to #perl for pointing me to PerlIO and that the layers can
> be different, and to leont on #p5p for pointing me to re-opening
>    issues.)

I found this lovely explanation in do_openn (doio.c:597):

    /* Eeek - FIXME !!!
     * If this is a standard handle we discard all the layer stuff
     * and just dup the fd into whatever was on the handle before !
     */

This has been there since 2001 (e99cca91) :-(

Leon

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via perlbug:  queue: perl5 status: open
https://rt.perl.org:443/rt3/Ticket/Display.html?id=113982

• [perl #113982] Reopening filehandles can clobber PerlIO layers by Leon Timmermans via RT