The function dio_seek() is used
to change the file position of the file with descriptor resource. The parameter whence specifies how the
position pos should be
interpreted:
SEEK_CUR - Specifies that
pos is a count of characters from the current
file position. This count may be positive or negative
SEEK_END - Specifies that
pos is a count of characters from the end of the
file. A negative count specifies a position within the
current extent of the file; a positive count specifies a
position past the current end. If you set the position
past the current end, and actually write data, you will
extend the file with zeros up to that position