No if w > bufw, this check triggers:

		if (w > bufw) {
			write = (u8 *)tmpTexBufRearrange.data();
			finalBuf = tmpTexBufRearrange.data();
		} else ...

and the rearrange is from RAM to tmpTexBufArrange, assuming we change it to not do the mentioned copy first.

But if you swap bufw and w, then indeed, it is in place, my bad.