pid.c

Linux内核编程模块的简单实现

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <linux/sched.h>


#define MAX_LENGTH 64

static struct proc_dir_entry *pid_entry;

static char pid_buffer[MAX_LENGTH];
static unsigned long pid_buffer_size = 0;
static char pid[MAX_LENGTH] = { "1" };

module_param_string (pid, pid, MAX_LENGTH, 0644);
MODULE_LICENSE ("GPL");

static int
pid_write (struct file *file,
	   const char *buffer, unsigned long count, void *data)
{

  struct task_struct *_process;
  pid_buffer_size = count;

  if (pid_buffer_size > MAX_LENGTH)
    pid_buffer_size = MAX_LENGTH;


  if (copy_from_user (pid_buffer, buffer, pid_buffer_size))
    return -EFAULT;

  for_each_process (_process)
  {
    char _tmp[MAX_LENGTH];
    sprintf (_tmp, "%d\n", _process->pid);
    if (!strcmp (_tmp, pid_buffer))
      printk ("<1>  The EXE file is: %20s \n", _process->comm);

  }
  return pid_buffer_size;
}

static int
pid_read (char *buffer,
	  char **buffer_location,
	  off_t offset, int buffer_length, int *eof, void *data)
{
  if (offset > 0)
    return 0;
  memcpy (buffer, pid_buffer, pid_buffer_size);
  return pid_buffer_size;
}

static int __init
pid_init (void)
{
  struct task_struct *_process;
  pid_entry = create_proc_entry ("pid", 0666, &proc_root);

  if (!pid_entry)
    {
      remove_proc_entry ("pid",&proc_root);
      printk (KERN_ALERT " \"/proc/pid\" created failed  ^_^ \n");
      return -ENOMEM;
    }

  pid_entry->read_proc = pid_read;
  pid_entry->write_proc = pid_write;
  pid_entry->owner = THIS_MODULE;
  pid_entry->uid = 0;
  pid_entry->gid = 0;
  pid_entry->size = 0;

  printk ("<1> create \"/proc/pid\" SUCCESSFULLY.\n");


  for_each_process (_process)
  {
    char _temp[MAX_LENGTH];
    sprintf (_temp, "%d", _process->pid);
    if (strcmp (_temp, pid) == 0)
      printk ("<1> EXE file is: %20s \n ", _process->comm);

  }
  return 0;

}




static void
pid_exit (void)
{

  remove_proc_entry ("pid", &proc_root);
  printk ("<1> Exit.\n");

}

module_init (pid_init);
module_exit (pid_exit);