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Postings from December 2000
Nick Ing-Simmons <nik@tiuk.ti.com> writes:
>B. When I fix A in Tk sources it core dumps in a manner which suggests
> something has done heap-overrun.
Debugging this I discovered a "feature" of sv_utf8_upgrade:
void
Perl_sv_utf8_upgrade(pTHX_ register SV *sv)
{
char *s, *t;
bool hibit;
if (!sv || !SvPOK(sv) || SvUTF8(sv))
return;
/* This function could be much more efficient if we had a FLAG in SVs
* to signal if there are any hibit chars in the PV.
*/
for (s = t = SvPVX(sv), hibit = FALSE; t < SvEND(sv) && !hibit; t++)
if (*t & 0x80)
hibit = TRUE;
if (hibit) {
STRLEN len = SvCUR(sv) + 1; /* Plus the \0 */
SvPVX(sv) = (char*)bytes_to_utf8((U8*)s, &len);
SvCUR(sv) = len - 1;
SvLEN(sv) = len; /* No longer know the real size. */
SvUTF8_on(sv);
Safefree(s); /* No longer using what was there before. */
}
}
Tk wants UTF8 so every time it sees an SV without SvUTF8 it calls
upgrade. Code above then scans it sees it is all ASCII and exits.
A few C statements later we do it again, and again, and ...
Is there any reason NOT to turn on SvUTF8 once we have established
that it is valid UTF8 - even if only because it has no high bit chars?
Should perl do this or should Tk do it ?
--
Nick Ing-Simmons <nik@tiuk.ti.com>
Via, but not speaking for: Texas Instruments Ltd.
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