Attachment 933307 Details for Bug 1135969 – Fix for RT#95940

[patch] Fix for RT#95940

0001-Avoid-Copy-On-Write-problems-with-Perl-5.20.patch (text/plain), 1.48 KB, created by Jitka Plesnikova on 2014-09-01 11:22:31 UTC

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Creator: Jitka Plesnikova

Created: 2014-09-01 11:22:31 UTC

Size: 1.48 KB

patch

obsolete

>>From 610a7fd5092921cc317d77eedf626b2c62ca4a38 Mon Sep 17 00:00:00 2001
>From: Niko Tyni <ntyni@debian.org>
>Date: Mon, 28 Jul 2014 00:15:11 +0300
>Subject: [PATCH] Avoid Copy-On-Write problems with Perl 5.20
>
>Quoting Dave Mitchell in https://rt.cpan.org/Public/Bug/Display.html?id=95940
>
>  After FC's commit, $buf gets marked as COW, since its a copy of a
>  COWable constant (the constant string "") and mmap() never unsets this
>  flag before stealing its buffer. So later on when it applies substr()
>  to $buf, the var is assumed to be COW and bad things happen to it.
>
>  The correct usage is still up for debate (see Leon's use case in
>  rt.perl.org tickets #116407 and #116925), but calling SvPV_force()
>  first would be a good first step (although that will cause the previous
>  contents of PVX() to leak). It might be better for Mmap.pm to call mmap()
>  with an undef value rather than assigning "" to it first.
>
>Bug: https://rt.cpan.org/Public/Bug/Display.html?id=95940
>Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=750226
>---
> Mmap.pm | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/Mmap.pm b/Mmap.pm
>index c3501b1..21925e9 100644
>--- a/Mmap.pm
>+++ b/Mmap.pm
>@@ -823,7 +823,7 @@ sub _set_options{
>     # mmap() isn't supposed to work on locked files, so unlock
>     $self->_unlock;
> 
>-    mmap($self->{_mmap}='',$size,$self->{_fh})
>+    mmap($self->{_mmap}=undef,$size,$self->{_fh})
>       or do{
> 	delete $self->{_mmap};
> 	croak "Can't mmap $self->{_filename}: $!";
>-- 
>2.0.1

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