private DataBuffer getBuffer(int index) throws IOException {
		// if databufferIdTable is null, index must be null.  let it throw null pointer in this case.
		int bufferId =
			(dataBufferIdTable == null && index == 0) ? firstBufferId : dataBufferIdTable[index];
		if (bufferId < 0) {
			DataBuffer buf = bufferMgr.createBuffer();
			initializeAllocatedBuffer(index, buf);
			addBuffer(index, buf);
			return buf;
		}
		return bufferMgr.getBuffer(bufferId);
	}
Get a data buffer.
@param index index of within buffer chain
@return requested data buffer.
@throws IOException thrown if an IO error occurs
Ghidra/Framework/DB/src/main/java/db/ChainedBuffer.java