5.10.0 functionality change and segfault #9732
Comments
From @gbarrCreated by @gbarrI have not been able to track down the exact cause yet, but the following demonstrates $ cat test type(*DATA); $ /apps/perl-5.8.9/bin/perl test $ /apps/perl-5.10.0/bin/perl test When compiled with debugging, and assert fails Assertion ((buffer)->sv_flags & 0x00000400) failed: file "sv.c", line 1741 at test line 5. Perl Info |
From @nwc10On Mon, May 11, 2009 at 08:59:20PM -0700, Graham Barr wrote:
Yes, that's interesting. I think it has to be a bug in 5.8.9 and earlier that $ perl -MDevel::Peek -le 'print $]; $a = *STDIN{IO}; $b = *$a; print defined $b; print length $b' 0 How can something not be defined, yet stringify to "" without warning? Your testcase pinpoints the cause of the SEGV - it's an unexpected interaction void PERL_ARGS_ASSERT_GV_FULLNAME4; if (!hv) { and this call to it: SvFAKE_off(gv); assert(SvPOK(buffer)); The problem is that the "obvious" fix ends up with just a reversal of the Nicholas Clark |
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The RT System itself - Status changed from 'new' to 'open' |
From @gbarrOn May 12, 2009, at 3:12 PM, Nicholas Clark via RT wrote:
because you did not add -w to the command line adding -w I se the warning as far back as /apps/perl-5.4.5/bin/perl5.00405 Use of uninitialized value at -e line 1. However note that a Dump($b) is different in blead then 5.8.9 blead: SV = PVGV(0x89be768) at 0x89ad580 5.8.9: SV = PVGV(0x90caa3c) at 0x90b3b7c I have not followed closely enough to know if that dropping of magic Graham.
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From @nwc10On Tue, May 12, 2009 at 04:24:28PM -0500, Graham Barr wrote:
Totally intentional. 24+ bytes used per typeglob (hence per sub or method) http://perl5.git.perl.org/perl.git/commit/180488f8452e93d2afa0f62b189be1cc9ac6 Nicholas Clark |
From @gbarrOn May 12, 2009, at 5:41 PM, Nicholas Clark wrote:
Sure, OK. As I said I had not been following closely. I have done a little more digging It seems to me that the root of this issue is that gv_init(gv, 0, "", 0, 0); after this, in blead SvOK(gv) returns true, but in 5.8.9 SvOK(gv) is this is why defined($y) is true on 5.10.0 but false on 5.8.x and before While not a fix, because lib/Benchmark and op/tie fail, I put in a The result was that the following matches 5.8.x and before $ ./perl -wle '$x = *STDIN{IO}; $y = *$x; print "$x"; print "$y"' Graham. |
From @gbarrOn May 13, 2009, at 12:52 AM, Graham Barr wrote:
However, the following is still different $ perl5.8.9 -wle '$x = *STDERR{IO}; $y = *$x; print "$x"; print $ ./perl -wle '$x = *STDERR{IO}; $y = *$x; print "$x"; print Use of uninitialized value $y in string at -e line 1. So $y was undefined but still valid for use as a filehandle (time to seep) |
From @nwc10Dave notes: Fine in 5.8.8,5.8.9; assert fails in 5.10.0, maint, blead. Nick notes: I have some idea of what's going on here. |
From p5p@spam.wizbit.beBinary searches: There appears to be two changes: ----Program---- sub type { type(*DATA); ----Output of .../pPSPFBH/perl-5.9.3@27276/bin/perl---- ----EOF ($?='0')---- ----EOF ($?='0')---- http://public.activestate.com/cgi-bin/perlbrowse/p/27278 Remove get magic from typeglobs. This means that PVGVs holding ----Program---- sub type { type(*DATA); ----Output of .../pP16HNv/perl-5.9.3@27802/bin/perl---- ----EOF ($?='0')---- ----EOF ($?='11')---- http://public.activestate.com/cgi-bin/perlbrowse/p/27803 S_glob_2inpuv() did not check if lenp was NULL. Oops. (all perls compiled without -DDEBUGGING) |
From @iabynOn Wed, May 13, 2009 at 01:13:12AM -0500, Graham Barr wrote:
I've applied the following commit, which I hope makes for sensible commit 1809c94 fix for [perl #65582] anon globs segfaulting Affected files ... Differences ... Inline Patchdiff --git a/sv.c b/sv.c
index 063dd19..4e80e18 100644
--- a/sv.c
+++ b/sv.c
@@ -2986,11 +2986,17 @@ Perl_sv_2pv_flags(pTHX_ register SV *const sv, STRLEN *const lp, const I32 flags
gv_efullname3(buffer, gv, "*");
SvFLAGS(gv) |= wasfake;
- assert(SvPOK(buffer));
- if (lp) {
- *lp = SvCUR(buffer);
+ if (SvPOK(buffer)) {
+ if (lp) {
+ *lp = SvCUR(buffer);
+ }
+ return SvPVX(buffer);
+ }
+ else {
+ if (lp)
+ *lp = 0;
+ return (char *)"";
}
- return SvPVX(buffer);
}
if (lp)
diff --git a/t/op/gv.t b/t/op/gv.t
index 1b705ef..72787c4 100644
--- a/t/op/gv.t
+++ b/t/op/gv.t
@@ -12,7 +12,7 @@ BEGIN {
use warnings;
require './test.pl';
-plan( tests => 178 );
+plan( tests => 181 );
# type coersion on assignment
$foo = 'foo';
@@ -560,6 +560,27 @@ foreach my $type (qw(integer number string)) {
"with the correct error message");
}
+# RT #60954 anonymous glob should be defined, and not coredump when
+# stringified. The behaviours are:
+#
+# defined($glob) "$glob"
+# 5.8.8 false "" with uninit warning
+# 5.10.0 true (coredump)
+# 5.12.0 true ""
+
+{
+ my $io_ref = *STDOUT{IO};
+ my $glob = *$io_ref;
+ ok(defined $glob, "RT #60954 anon glob should be defined");
+
+ my $warn = '';
+ local $SIG{__WARN__} = sub { $warn = $_[0] };
+ use warnings;
+ my $str = "$glob";
+ is($warn, '', "RT #60954 anon glob stringification shouln't warn");
+ is($str, '', "RT #60954 anon glob stringification should be empty");
+}
+
__END__
Perl
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-- Red sky at night - gerroff my land! |
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@iabyn - Status changed from 'open' to 'resolved' |
Migrated from rt.perl.org#65582 (status was 'resolved')
Searchable as RT65582$
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