ReadFileScatter and WriteFileGather also require a handle for a file that's opened with FILE_FLAG_OVERLAPPED (asynchronous access; the file pointer is not updated) and FILE_FLAG_NO_BUFFERING (buffers must be a multiple of the physical sector size and aligned to the physical sector size). So Python wouldn't be able to use the C runtime's POSIX (low) I/O implementation. ISTM this requires resolving issue 12939, with support for overlapped I/O.
The need for asynchronous I/O (i.e. FILE_FLAG_OVERLAPPED) with ReadFileScatter() and WriteFileGather() makes them a poor fit for POSIX os.readv() and os.writev(), since we can't open the file with open() or os.open(). Python's socket module opens sockets in asynchronous mode, but ReadFileScatter() and WriteFileGather() don't support sockets, and there are socket-specific alternatives (e.g. WSASend with multiple buffers). If these Windows API functions are supported at all, I expect it will be in _winapi or _overlapped, and only if needed by the standard library. I'm changing the status of this enhancement request to pending, awaiting feedback from Марк and the core developers.
