在linux核心中讀寫檔案2

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1，核心代碼

#include <linux/kernel.h>#include <linux/init.h>#include <linux/types.h>#include <linux/spinlock.h>#include <linux/blkdev.h>#include <linux/module.h>  #include <linux/fs.h>  #include <linux/errno.h>  #include <linux/mm.h>  #include <linux/cdev.h>  #include <linux/sched.h>#define IO_CMD_LEN      1024  #define CHAR_DEV_NAME   "klog"typedef struct {    int file_id; //todo    int rw_pos;  //todo    int cmd_type;    int buff_len;    char io_buff[IO_CMD_LEN - 16];}KLOG_CMD_INFO;#if 1struct file *klog_fp = NULL;loff_t klog_pos = 0;static int user_cmd_proc(char *user_cmd, char *out_str){    KLOG_CMD_INFO *klog_cmd = (KLOG_CMD_INFO *)user_cmd;    KLOG_CMD_INFO *klog_ack = (KLOG_CMD_INFO *)out_str;        if(klog_cmd->cmd_type == 1) { //open file        if (klog_fp != NULL)  filp_close(klog_fp, NULL);                    klog_fp = filp_open(klog_cmd->io_buff, O_RDWR | O_CREAT | O_TRUNC, 0644);        if (IS_ERR(klog_fp)){            printk("filp_open error \n");            return -1;        }        klog_pos = 0;        sprintf(klog_ack->io_buff, "filp_open ok\n");    }        if(klog_cmd->cmd_type == 2) { //write file        mm_segment_t old_fs;        old_fs = get_fs();        set_fs(KERNEL_DS); //to check why        klog_pos += vfs_write(klog_fp, klog_cmd->io_buff, klog_cmd->buff_len, &klog_pos);        set_fs(old_fs);        sprintf(klog_ack->io_buff, "vfs_write ok\n");    }    if(klog_cmd->cmd_type == 3) { //close file        filp_close(klog_fp, NULL);        klog_fp = NULL;        sprintf(klog_ack->io_buff, "filp_close ok\n");    }        return 0;}#endif#if 1  int mem_open(struct inode *inode, struct file *filp)  {      return 0;   }    int mem_release(struct inode *inode, struct file *filp)  {      return 0;  }  char user_cmd[IO_CMD_LEN] = {0};char out_str[IO_CMD_LEN] = {0};int mem_ioctl( struct file *file, unsigned int cmd, unsigned long arg){        printk("mem_ioctl: %d \n", cmd);            if(copy_from_user(user_cmd,  (int *)arg, IO_CMD_LEN))         return -EFAULT;        user_cmd_proc(user_cmd, out_str);        if(copy_to_user( (int *)arg, out_str, IO_CMD_LEN))         return -EFAULT;    return 0;}static int mem_major = 0;struct class *pclass = NULL;  struct cdev my_dev;   static const struct file_operations mem_fops =  {      .owner = THIS_MODULE,      .unlocked_ioctl = mem_ioctl,    .open = mem_open,      .release = mem_release,  };  static int memdev_init(void)  {      int result;      dev_t devno = MKDEV(mem_major, 0);      if (mem_major) { /* 靜態申請裝置號*/          result = register_chrdev_region(devno, 2, CHAR_DEV_NAME);      } else { /* 動態分配裝置號 */          result = alloc_chrdev_region(&devno, 0, 2, CHAR_DEV_NAME);          mem_major = MAJOR(devno);      }       if (result < 0)  {          printk("alloc_chrdev failed!\n");          return result;      }      cdev_init(&my_dev, &mem_fops);      my_dev.owner = THIS_MODULE;      my_dev.ops = &mem_fops;      cdev_add(&my_dev, MKDEV(mem_major, 0), 2);   /*裝置數2*/      pclass = class_create(THIS_MODULE, CHAR_DEV_NAME);      if (IS_ERR(pclass))  {          printk("class_create failed!\n");          goto failed;      }      device_create(pclass, NULL, devno, NULL, CHAR_DEV_NAME);      return 0;  failed:       cdev_del(&my_dev);    unregister_chrdev_region(devno, 1);      return result;  }    static void memdev_exit(void)  {      device_destroy(pclass, MKDEV(mem_major, 0));      class_destroy(pclass);        cdev_del(&my_dev);    unregister_chrdev_region(MKDEV(mem_major, 0), 2); }  #endif  MODULE_AUTHOR("derek yi");  MODULE_LICENSE("GPL");    module_init(memdev_init);  module_exit(memdev_exit);  

 

 

2，測試代碼

#include <stdio.h>  #include <fcntl.h>  #include <stdlib.h>  #include <string.h>  #include <sys/types.h>  #include <sys/stat.h>#include <unistd.h>#include <sys/ioctl.h>#include <fcntl.h>#include <errno.h>#include <signal.h>#include <sys/syscall.h>#define IO_CMD_LEN      1024  typedef struct {    int file_id; //todo    int rw_pos;  //todo    int cmd_type;    int buff_len;    char io_buff[IO_CMD_LEN - 16];}KLOG_CMD_INFO;KLOG_CMD_INFO cmd_info;int main(){    int fd;    int ret = 0;    fd = open("/dev/klog", O_RDWR);    if( fd < 0 ) {        printf("open memdev WRONG！\n");        return 0;    }    sprintf(cmd_info.io_buff, "/home/derek/klog.txt");    cmd_info.cmd_type = 1;    ret = ioctl(fd, 0, &cmd_info);    printf("open: ret=%d rdata:%s\n", ret, cmd_info.io_buff);    for(int i = 0; i < 10; i++) {        sprintf(cmd_info.io_buff, "%d: ==============================\n", i);        cmd_info.buff_len = strlen(cmd_info.io_buff);        cmd_info.cmd_type = 2;        ret = ioctl(fd, 0, &cmd_info);        printf("read: ret=%d rdata:%s\n", ret, cmd_info.io_buff);    }    cmd_info.cmd_type = 3;    ret = ioctl(fd, 0, &cmd_info);    printf("close: ret=%d rdata:%s\n", ret, cmd_info.io_buff);       close(fd);    return 0;}

 

在linux核心中讀寫檔案2