/// Pre-allocate storage for a range in a file
pubunsafefnposix_fallocate(fd:i32, offset: off_t, len: off_t)->Result<(), Errno>{let fd = fd asusize;let offset = offset asusize;let len = len asusize;syscall3(SYS_POSIX_FALLOCATE, fd, offset, len).map(drop)}