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struct file_operations { struct module *owner; loff_t (*llseek) (struct file *, loff_t, int); ssize_t (*read) (struct file *, char __user *, size_t, loff_t *); ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t); ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t); ssize_t (*read_iter) (struct kiocb *, struct iov_iter *); ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); unsigned int (*poll) (struct file *, struct poll_table_struct *); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); int (*mmap) (struct file *, struct vm_area_struct *); int (*mremap)(struct file *, struct vm_area_struct *); int (*open) (struct inode *, struct file *); int (*flush) (struct file *, fl_owner_t id); int (*release) (struct inode *, struct file *); int (*fsync) (struct file *, loff_t, loff_t, int datasync); int (*aio_fsync) (struct kiocb *, int datasync); int (*fasync) (int, struct file *, int); int (*lock) (struct file *, int, struct file_lock *); ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int); unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); int (*check_flags)(int); int (*flock) (struct file *, int, struct file_lock *); ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int); ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int); int (*setlease)(struct file *, long, struct file_lock **, void **); long (*fallocate)(struct file *file, int mode, loff_t offset, loff_t len); void (*show_fdinfo)(struct seq_file *m, struct file *f);#ifndef CONFIG_MMU unsigned (*mmap_capabilities)(struct file *);#endif}; #includeint ioctl(int d, int request, ...);long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
ioctl(fd, IOCGREG, &my_msg); ret = copy_from_user(&msg, \ (struct msg __user *)arg, sizeof(my_msg)); if (ret) return -EFAULT; msg->data = read_reg(msg->addr); ret = copy_to_user((struct msg __user *)arg, \ &msg, sizeof(my_msg));
3. 函数功能 1. 数据传输 内核->用户 // 大小由cmd 中 的第三个数值决定, 地址 为 unsigned long 参数,应该传个指针. 用户->内核 2. 命令交互 由cmd 的第二个数值和第一个数值决定4. 魔数打包_IO (魔数， 基数);_IOR (魔数， 基数， 变量型)_IOW (魔数， 基数， 变量型)_IOWR (魔数， 基数，变量型 )#include ""_IO(type,nr)_IOR(type,nr,size)_IOW(type,nr,size)_IOWR(type,nr,size)6.魔数拆包#include " "_IOC_DIR(nr) // 这个是解压 读写属性 的 , R W RW_IOC_TYPE(nr)_IOC_NR(nr)_IOC_SIZE(nr)6. 返回值 返回0 正确Usually, on success zero is returned. A few ioctl() requests use the return value as an output parameter and return a nonnegative value on success. On error, -1 is returned, and errno is set appropriately. errno 怎么设置??
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