当前位置: 首页 >> 程序设计 >> 内核模块编程-实现简单的类似ps命令

内核模块编程-实现简单的类似ps命令

作者：mq110 来源：chinaunix 发表时间：2006-07-14 浏览次数：字号：大 中 小

内核模块创建在proc文件系统上建立_ps文件.遍例进程内核链表task_struct.将遍例结果存入缓冲区.影射到/proc/_ps文件中.用户态的程序去读取这个文件.打印显示当前进程的的pid,ppid 和进程名.

CODE:

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

MODULE_LICENSE("GPL");
MODULE_AUTHOR("mq110");

static int ps_read(char *page, char **start, off_t offset,int count, int *eof, void *data)
{
static char buf[1024*8]={0};
char tmp[128];
struct task_struct *p;

if(offset >0)
      return 0;
memset(buf,0,sizeof(buf));
read_lock(&tasklist_lock);
for_each_process(p) //遍例内核进程链表.
{
      sprintf(tmp,"%d\t\t%d\t\t\t%s\n",p->pid,p->parent->pid,p->comm);
      strcat(buf,tmp);
      memset(tmp,0,sizeof(tmp));
}
read_unlock(&tasklist_lock);
*start=buf;
return strlen(buf);
}

static __init int ps_init(void)
{
struct proc_dir_entry *entry;

entry = create_proc_entry("_ps", 0444, &proc_root);  //建立/proc/_ps文件.
if(entry == 0)
{
      printk(KERN_ERR "create_proc_entry failed!\n");
      return -1;
}
entry->mode = S_IFREG | 0444;
entry->size = 0;
entry->read_proc = ps_read;
return 0;
}
static __exit void ps_cleanup(void)
{
remove_proc_entry("_ps", &proc_root);
}

module_init(ps_init);
module_exit(ps_cleanup);

以下是Makefile. TARGET改名成程序名就OK了.

CODE:

[Copy to clipboard]

TARGET = 006
obj-m := $(TARGET).o
KERNELDIR=/lib/modules/`uname -r`/build
PWD=`pwd`

default :
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

install :
insmod $(TARGET).ko
uninstall :
rmmod $(TARGET).ko

clean :
rm -rf *.o *.mod.c *.ko

以下是用户态程序:

CODE:

[Copy to clipboard]

#include <stdio.h>
#include <error.h>

int main()
{
FILE *fp;
char buf[1024];

fp=fopen("/proc/_ps","r");
if(fp==NULL)
{
      perror("fopen");
      return -1;
}
printf("pid\t\tppid\t\t\tcommand\n");
while(!feof(fp))
{
      if(fgets(buf,sizeof(buf),fp)!=NULL)
         printf("%s",buf);
}
fclose(fp);
return 0;
}

make ;make install 之后编译用户态程序.
执行结果:
[root@Firewall 006]# ./likeps
pid          ppid                   command
1             0                      init
2             1                      migration/0
3             1                      ksoftirqd/0
4             1                      watchdog/0
5             1                      migration/1
6             1                      ksoftirqd/1
7             1                      watchdog/1
8             1                      migration/2
9             1                      ksoftirqd/2
10             1                      watchdog/2
11             1                      migration/3
12             1                      ksoftirqd/3
13             1                      watchdog/3
14             1                      events/0
15             1                      events/1
16             1                      events/2
17             1                      events/3
18             1                      khelper
19             1                      kthread
24             19                   kacpid
100          19                   kblockd/0
101          19                   kblockd/1
102          19                   kblockd/2
103          19                   kblockd/3
106          19                   khubd
197          19                   pdflush
198          19                   pdflush
199          1                      kswapd0
200          19                   aio/0
201          19                   aio/1
202          19                   aio/2
203          19                   aio/3
288          19                   kseriod
392          1                      kjournald
1224          1                      udevd
1941          1                      kjournald
1944          1                      kjournald
1967          1                      kjournald
2820          1                      syslogd
2824          1                      klogd
2840          1                      sshd
2852          1                      vsftpd
2862          1                      gpm
2882          1                      atd
3184          1                      mingetty
3185          1                      mingetty
3186          1                      mingetty
3187          1                      mingetty
3188          1                      mingetty
3189          1                      mingetty
6819          1                      mysqld_safe
6846          6819                   mysqld
7475          1                      smbd
7476          7475                   smbd
7480          1                      nmbd
19400          2840                   sshd
19404          19400                bash

责任编辑 webmaster

相关链接