That's during extraction though. There's no way to reliably decompress a ZIP without reading the Central Directory first. While scanning for the Local File Head

That's during extraction though. There's no way to reliably decompress a ZIP without reading the Central Directory first. While scanning for the Local File Headers works for most files, it's not guaranteed to be correct since it may not match what's in the Central Directory. Also as you point out it doesn't work when the file length is not in the LFH. Streaming zip creation is well supported by the format though.