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Postings from January 2012
On Thu, Jan 26, 2012 at 05:25:56PM -0800, Yitzchak Scott-Thoennes wrote:
> open(FH, "<", undef) triggers special behavior to open a temporary file
> (at least with perlio) that is documented as only applying to +> and +<.
>
> To keep open(FH, "<", $hash{typoedkey}) from quietly succeeding, this
> should at least trigger a warning (and the doc be updated to not be mode
> specific).
I think that a comprehensive fix should be possible. Note that XS can tell
the difference:
$ ./perl -Ilib -MDevel::Peek -e 'Dump undef'
SV = NULL(0x0) at 0x1003aa990
REFCNT = 2147483621
FLAGS = (READONLY)
$ ./perl -Ilib -MDevel::Peek -e 'Dump $a'
SV = NULL(0x0) at 0x100812b90
REFCNT = 1
FLAGS = ()
$ ./perl -Ilib -MDevel::Peek -e 'Dump $hash{typoedkey}'
SV = PVLV(0x100818a00) at 0x100802ed0
REFCNT = 1
FLAGS = (TEMP,GMG,SMG)
IV = 0
NV = 0
PV = 0
MAGIC = 0x100509040
MG_VIRTUAL = &PL_vtbl_defelem
MG_TYPE = PERL_MAGIC_defelem(y)
MG_FLAGS = 0x02
REFCOUNTED
MG_OBJ = 0x100803110
SV = PV(0x100801070) at 0x100803110
REFCNT = 1
FLAGS = (POK,pPOK)
PV = 0x100501b50 "typoedkey"\0
CUR = 9
LEN = 16
TYPE = y
TARGOFF = 0
TARGLEN = 1
TARG = 0x100812ae8
FLAGS = 0
SV = PVHV(0x100807ea0) at 0x100812ae8
REFCNT = 2
FLAGS = (SHAREKEYS)
ARRAY = 0x0
KEYS = 0
FILL = 0
MAX = 7
RITER = -1
EITER = 0x0
Quite a big difference.
And that the case of a simple undefined variable is already spotted:
$ ./perl -e 'open $fh, "<", $a or die'
Died at -e line 1.
$ ./perl -e 'open $fh, "<", $hash{typoedkey} or die'
So I think that there's something more subtly amis here, probably due to
how and when the magic is executed for hash keys passed to subroutines.
Nicholas Clark
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