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Postings from October 2003
Gisle Aas <gisle@ActiveState.com> writes: > >The following invariant should always hold if SvPOK(sv): > > - SvCUR(sv) < SvLEN(sv) Unless SvLEN(sv) == 0 > - *SvEND(sv) == '\0' > >The perl core ensures that Experience with Tk says that is not always true, it is mostly true, and I can't give a core case where it isn't true, but it has happened. I seem to recall magcial $1 used to point into the original/saved PV and not be copied to add the NUL. The SvLEN(sv) == 0 case (SvPV is owned by someone else) is made considerably less useful if code expects terminating '\0' - the alien SvPV may not have that property, but doing a new malloc and a mega-byte copy just to add the '\0' is a pain. There are very few spots in the core which _need_ the NUL > >> After all, null-termination itself is moot w/ UTF-(16|32)(BE|LE)?. > >True, but when they are stuffed in perl strings they should still be >made safe for external APIs that expect NUL-termination. Ah, but if external API is has a 32-bit wchar_t and expects NUL-termination then perl must ensure that all SvPVs have FOUR trailing 0 octets... (Been burnt here with rendering "wide" strings...)Thread Previous | Thread Next