NAME
        Read -- Read bytes of data from a file

    SYNOPSIS
        actualLength = Read( file, buffer, length )
        D0                   D1    D2      D3

        long read(bptr, void *, long)

    FUNCTION
        Data can be copied using a combination of Read() and write().
        Read() reads bytes of information from an opened file (represented
        here by the argument 'file') into the buffer given. The argument
        'length' is the length of the buffer given.

        The value returned is the length of the information actually read.
        So, when 'actualLength' is greater than zero, the value of
        'actualLength' is the the number of characters read. Usually Read
        will try to fill up your buffer before returning. A value of zero
        means that end-of-file has been reached. Errors are indicated by a
        value of -1.

        Note: this is an unbuffered routine (the request is passed directly
        to the filesystem.)  Buffered I/O is more efficient for small
        reads and writes; see fgetc().

    INPUTS
        file - BCPL pointer to a file handle
        buffer - pointer to buffer
        length - integer

    RESULTS
        actualLength - integer

    SEE ALSO
        open(), close(), write(), seek(), fgetc()