SYS_COPYFD Create a copy of a file handle
SYS_FDCTL Modify flags of a file descriptor
SYS_READ Read from an open file
+SYS_READAT Read from an open file (with offset)
SYS_WRITE Write to an open file
+SYS_WRITEAT Write to an open file (with offset)
SYS_IOCTL Perform an IOCtl Call
SYS_SEEK Seek to a new position in the file
SYS_READDIR Read from an open directory