Core dump with "in memory" file
in [Perl]
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From: Frank Seitz on 4 Mar 2010 19:22 Hi! #!/usr/bin/perl use strict; use warnings; my $stderr; close STDERR; open STDERR,'>',\$stderr or die; warn "a\n"; $stderr =~ s/./xx/g; # eof $ ./test.pl Segmentation fault What is the problem? $ perl -v This is perl, v5.10.1 (*) built for i686-linux Frank -- Dipl.-Inform. Frank Seitz Anwendungen f�r Ihr Internet und Intranet Tel: 04103/180301; Fax: -02; Industriestr. 31, 22880 Wedel Blog: http://www.fseitz.de/blog XING-Profil: http://www.xing.com/profile/Frank_Seitz2
From: Ben Morrow on 4 Mar 2010 20:47 Quoth Frank Seitz <devnull4711(a)web.de>: > > #!/usr/bin/perl > > use strict; > use warnings; > > my $stderr; > close STDERR; > open STDERR,'>',\$stderr or die; > warn "a\n"; > $stderr =~ s/./xx/g; > > # eof > > $ ./test.pl > Segmentation fault > > What is the problem? > > $ perl -v > This is perl, v5.10.1 (*) built for i686-linux It's a bug in perl, but it appears to have been fixed in blead. The fix will be in 5.10.0, and probably in 5.10.2 if there ever is one (currently it's looking unlikely). Ben
From: C.DeRykus on 4 Mar 2010 21:03 On Mar 4, 4:22 pm, Frank Seitz <devnull4...(a)web.de> wrote: > Hi! > > #!/usr/bin/perl > > use strict; > use warnings; > > my $stderr; > close STDERR; > open STDERR,'>',\$stderr or die; > warn "a\n"; > $stderr =~ s/./xx/g; > > # eof > > $ ./test.pl > Segmentation fault > > What is the problem? > > $ perl -v > This is perl, v5.10.1 (*) built for i686-linux > A bug? The trailing \n appears to be problematic. Possible workaround: $stderr =~ s/[^\n]/xx/g; This is perl, v5.10.1 (*) built for MSWin32-x86-multi-thread -- Charles DeRykus
From: sln on 4 Mar 2010 21:56 On Fri, 05 Mar 2010 01:22:02 +0100, Frank Seitz <devnull4711(a)web.de> wrote: >Hi! > >#!/usr/bin/perl > >use strict; >use warnings; > >my $stderr; >close STDERR; >open STDERR,'>',\$stderr or die; >warn "a\n"; >$stderr =~ s/./xx/g; > ># eof > >$ ./test.pl >Segmentation fault > >What is the problem? > >$ perl -v >This is perl, v5.10.1 (*) built for i686-linux > >Frank If $stderr =~ s/./xx/sg; it seems to work. But, obviously some independent FILE buffering going on here, and its out of sync with the scalar buffer. Notice, even after $stderr is cleared of 'ab', ' b' shows back up after a FILE write: --------------------- use strict; use warnings; my $stderr; close STDERR; open STDERR,'>',\$stderr or die; print STDERR "ab"; print "length \$stderr = ",length($stderr), " '$stderr'\n"; print "tell (STDERR) = ", tell(STDERR),"\n"; print "\n"; $stderr = ''; print "length \$stderr = ",length($stderr), " '$stderr'\n"; print "\n"; print STDERR "ZSSS"; print "length \$stderr = ",length($stderr), " '$stderr'\n"; print "tell (STDERR) = ", tell(STDERR),"\n"; __END__ length $stderr = 2 'ab' tell (STDERR) = 2 length $stderr = 0 '' length $stderr = 6 ' bZSSS' tell (STDERR) = 6 -sln
From: Ben Morrow on 4 Mar 2010 21:50
Quoth "C.DeRykus" <derykus(a)gmail.com>: > On Mar 4, 4:22�pm, Frank Seitz <devnull4...(a)web.de> wrote: > > > > #!/usr/bin/perl > > > > use strict; > > use warnings; > > > > my $stderr; > > close STDERR; > > open STDERR,'>',\$stderr or die; > > warn "a\n"; > > $stderr =~ s/./xx/g; > > > > # eof > > > > $ ./test.pl > > Segmentation fault > > > > What is the problem? > > > > $ perl -v > > This is perl, v5.10.1 (*) built for i686-linux > > > > A bug? The trailing \n appears to be problematic. > > Possible workaround: > > $stderr =~ s/[^\n]/xx/g; > > This is perl, v5.10.1 (*) built for MSWin32-x86-multi-thread With 5.10.1 for i386-freebsd I can reproduce the bug without the newline, but only if I use a one-liner: ~% perl ioscseg ~% perl -e"$(<ioscseg)" Segmentation fault (core dumped) ~% The crash appears to be in the same place as before, so I presume it's just somewhat allocation-dependant. Ben |