  1#include <linux/module.h>
  2#include <linux/kernel.h>
  3#include <linux/init.h>
  4#include <linux/cdev.h>
  5#include <linux/device.h>
  6#include <linux/fs.h>
  7#include <linux/uaccess.h>
  8
  9#define MAX_DEV 2
 10
 11static int dev_major = 0;
 12static struct class *lx_class = NULL;
 13static struct cdev cdev;
 14
 15static ssize_t lx_read(struct file *, char __user *, size_t, loff_t *);
 16static ssize_t lx_write(struct file *, const char __user *, size_t, loff_t *);
 17
 18static struct file_operations fops = {
 19  .owner = THIS_MODULE,
 20  .read = lx_read,
 21  .write = lx_write,
 22};
 23
 24static struct nuke {
 25  struct cdev cdev;
 26} devs[MAX_DEV];
 27
 28static int __init lx_init(void) {
 29  dev_t dev;
 30  int i;
 31
 32  // allocate device range
 33  alloc_chrdev_region(&dev, 0, 1, "nuke");
 34
 35  // create device major number
 36  dev_major = MAJOR(dev);
 37
 38  // create class
 39  lx_class = class_create(THIS_MODULE, "nuke");
 40
 41  for (i = 0; i < MAX_DEV; i++) {
 42    // register device
 43    cdev_init(&devs[i].cdev, &fops);
 44    cdev.owner = THIS_MODULE;
 45    cdev_add(&devs[i].cdev, MKDEV(dev_major, i), 1);
 46    device_create(lx_class, NULL, MKDEV(dev_major, i), NULL, "nuke%d", i);
 47  }
 48  return 0;    
 49}
 50
 51static void __exit lx_exit(void) {
 52  device_destroy(lx_class, MKDEV(dev_major, 0));
 53  class_unregister(lx_class);
 54  class_destroy(lx_class);
 55  unregister_chrdev_region(MKDEV(dev_major, 0), MINORMASK);
 56}
 57
 58static ssize_t lx_read(struct file *file, char __user *buf, size_t count, loff_t *offset) {
 59  if (*offset != 0) {
 60    return 0;
 61  } else {
 62    uint8_t *data = "This is dangerous!\n";
 63    size_t datalen = strlen(data);
 64    if (count > datalen) {
 65      count = datalen;
 66    }
 67    if (copy_to_user(buf, data, count)) {
 68      return -EFAULT;
 69    }
 70    *offset += count;
 71    return count;
 72  }
 73}
 74
 75static ssize_t lx_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) {
 76  char databuf[4] = "\0\0\0\0";
 77  if (count > 4) {
 78    count = 4;
 79  }
 80
 81  copy_from_user(databuf, buf, count);
 82  if (strncmp(databuf, "\x01\x14\x05\x14", 4) == 0) {
 83    const char *EXPLODE[] = {
 84      "    ⠀⠀⠀⠀⠀⠀⠀⠀⣀⣠⣀⣀⠀⠀⣀⣤⣤⣄⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀",
 85      "    ⠀⠀⠀⣀⣠⣤⣤⣾⣿⣿⣿⣿⣷⣾⣿⣿⣿⣿⣿⣶⣿⣿⣿⣶⣤⡀⠀⠀⠀⠀",
 86      "    ⠀⢠⣾⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⠀⠀⠀⠀",
 87      "    ⠀⢸⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣶⡀⠀",
 88      "    ⠀⢀⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡇⠀",
 89      "    ⠀⢸⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⠿⠟⠁⠀",
 90      "    ⠀⠀⠻⢿⡿⢿⣿⣿⣿⣿⠟⠛⠛⠋⣀⣀⠙⠻⠿⠿⠋⠻⢿⣿⣿⠟⠀⠀⠀⠀",
 91      "    ⠀⠀⠀⠀⠀⠀⠈⠉⣉⣠⣴⣷⣶⣿⣿⣿⣿⣶⣶⣶⣾⣶⠀⠀⠀⠀⠀⠀⠀⠀",
 92      "    ⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠋⠈⠛⠿⠟⠉⠻⠿⠋⠉⠛⠁⠀⠀⠀⠀⠀⠀⠀⠀",
 93      "    ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣶⣷⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀",
 94      "    ⠀⠀⠀⠀⠀⠀⢀⣀⣠⣤⣤⣤⣤⣶⣿⣿⣷⣦⣤⣤⣤⣤⣀⣀⠀⠀⠀⠀⠀⠀",
 95      "    ⠀⠀⠀⠀⢰⣿⠛⠉⠉⠁⠀⠀⠀⢸⣿⣿⣧⠀⠀⠀⠀⠉⠉⠙⢻⣷⠀⠀⠀⠀",
 96      "    ⠀⠀⠀⠀⠀⠙⠻⠷⠶⣶⣤⣤⣤⣿⣿⣿⣿⣦⣤⣤⣴⡶⠶⠟⠛⠁⠀⠀⠀⠀",
 97      "    ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣴⣿⣿⣿⣿⣿⣿⣷⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀",
 98      "    ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠒⠛⠛⠛⠛⠛⠛⠛⠛⠛⠛⠓⠀⠀⠀⠀⠀⠀⠀⠀⠀",
 99    };
100    int i;
101
102    for (i = 0; i < sizeof(EXPLODE) / sizeof(EXPLODE[0]); i++) {
103      printk("\033[01;31m%s\033[0m\n", EXPLODE[i]);
104    }
105  } else {
106    printk("nuke: incorrect secret, cannot lanuch.\n");
107  }
108  return count;
109}
110
111module_init(lx_init);
112module_exit(lx_exit);
113MODULE_LICENSE("GPL");
114MODULE_AUTHOR("jyy");
27. 设备驱动程序与文件系统¶

Take-away Messages¶

课后习题/编程作业¶

1. 阅读材料¶
