Explicitly closing STDOUT at end of script on Windows fails always

[qikdauie]

Explicitly closing STDOUT at end of script on Windows fails always

[shawnlaffan]

Thanks @sisyphus

@qikdauie - Some other approaches are given at https://www.perl.com/article/45/2013/10/27/How-to-redirect-and-restore-STDOUT/

[shawnlaffan]

I don't think this is a strawberry perl issue per se. The script is opening its own file handle called STDOUT, which overrides or conflicts with the existing STDOUT, and which then causes issues when the close is called.

I assume this is the full script? https://github.com/dot-asm/cryptogams/blob/master/ppc/aesp8-ppc.pl

Changing the script to use a lexical file handle and printing to that might fix things. (A general update to use lexical variables, strict and warnings would also be useful).

This should only need changes at four locations to use a lexical file handle, print to that file handle and then close it.

#L67
open my $stdout, "| $^X $xlate $flavour ".shift || die "can't call $xlate: $!";
# L3777
print {$stdout} ".byte\t",join(',',map (sprintf("0x%02x",$_),@bytes)),"\n";
#L3798
print {$stdout} print $_,"\n";
#L3801
close $stdout;

If you want to ensure all prints are flushed immediately then you can set local $|=1 near the top of the script before any print statements.

[sisyphus]

This is still an open Issue on github for anyone interested:
Perl/perl5#4106

Cheers,
Rob

[shawnlaffan]

@qikdauie - good to hear you have it working now.

The underlying issue is a perl one, as noted by @sisyphus in #46 (comment) , although it is not specific to Strawberry perl.

However it is easily avoided by using lexical file handles directly rather than making changes to global file handles such as STDOUT. Lexical file handles have been available since Perl version 5.6, released more than 20 years ago. Ideally the scripts would be updated in their repo.

[qikdauie]

Hey @shawnlaffan, thanks for such a quick response. Yes, this is the script in question.
Oh, I didn't realize that the STDOUT in this script was not the canonical STDOUT...
I've never really used Perl before, so let me digest what you're suggesting and make these changes. Again, thank you for your assistance.

[qikdauie]

Okay I just made the changes to aesp8-ppc.pl that you suggested @shawnlaffan. The script was able to complete after the changes. One other script failed afterwards, boringssl/src/crypto/fipsmodules/modes/asm/ghashp8-pcc.pl. I applied the same changes to this script, which then passed through as well.
Both of these scripts utilize xlate pipes.
So, is this pointing towards an issue with Perl + xlate pipe + typeglob filehandles?

[shawnlaffan]

Issue resolved, so closing.