文件锁

int
lock_reg( int fd, int cmd, int type, off_t offset, int whence, off_t len )
{
    struct flock lock;

    lock.l_type = type;
    lock.l_start = offset;
    lock.l_whence = whence;
    lock.l_len = len;

    return( fcntl( fd, cmd, &lock ) );
}