Function write 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn write(
    fildes: c_int,
    buf: *const c_void,
    nbyte: size_t,
) -> ssize_t

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/write.html.

Attempts to write nbyte bytes from the buffer pointed to by buf to the file associated with the open file descriptor, fildes.

When successful, returns a non-negative number indicating the number of bytes actually written to the file associated with fildes. Upon failure, returns -1.