That's a copy, which the OP doesn't want.

I think the problem in the original code is the use of SvPV_nolen instead of SvPVX. If XS is doing the right thing, it's returning a (new) buffer to an empty string, because the SV is still undefined and while its string has been allocated, it hasn't been initialized. This is the usual formula for creating a buffer, then passing the buffer to a C routine: 


        message_sv = newSV(83);
        SvPOK_on(message_sv);
        SvCUR_set(message_sv, 82);
        message = SvPVX(message_sv);
        ExpensiveGetString(row, col, message, 83);
        av_push(array, message_sv);

[download]
Ordinarily, one would null terminate with *SvEND(message_sv) = "\0", but I'm assuming that the null byte is the 83rd byte, so there's no need.
--
Marvin Humphrey
Rectangular Research ― http://www.rectangular.com

In reply to Re^2: XS efficient copy by creamygoodness
in thread XS efficient copy by TheDauthi

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