filedes

    The descriptor of a file that must be open for writing.

 length

    The new length of the file, in bytes. The off_t data type is
    either a 32-bit or 64-bit integer. The 64-bit interface allows
    for file sizes greater than 2 GB, and can be selected at compile
    time by defining the _LARGEFILE feature-test macro as follows:

    CC/DEFINE=_LARGEFILE