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电梯直达

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发表于 2009-10-30 09:20 |只看该作者 |倒序浏览

内核与应用层交互的方式都有哪几种,最好是能够有代码实例。
我先抛砖引玉了。
proc文件系统实现内核与应用层的交互。下面是代码，基于2.6.24.4内核。
#include <linux/spinlock.h>
#include <linux/version.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_layer7.h>
#include <linux/ctype.h>
#include <linux/proc_fs.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("LTW <tingw.liu@gmail.com>");
MODULE_DESCRIPTION("interaction with proc file");
//static struct nf_hook_ops procfile;
static int procnum=20;

static struct proc_dir_entry* father;

/*unsigned int procfile_func(unsigned int hooknum,struct sk_buff *skb,const struct net_device *in,const struct net_device *out,int(*okfn)(struct sk_buff*))
{
printk(KERN_ALERT "OK\n");
return NF_ACCEPT;
}*/

static int my_atoi(const char *s)
{
int val = 0;

for (;; s++) {
switch (*s) {
case '0'...'9':
val = 10*val+(*s-'0');
break;
default:
return val;
}
}
}
/* write out num_packets to userland. */
static int procfile_read_proc(char* page, char ** start, off_t off, int count,int* eof, void * data)
{
if(procnum>99)
printk(KERN_ALERT "procnum is too big\n");
page[0] = procnum/10 + '0';
page[1] = procnum%10 + '0';
page[2] = '\n';
page[3] = '\0';

*eof=1;

return 3;
}

/* Read in num_packets from userland */
static int procfile_write_proc(struct file* file, const char* buffer,
unsigned long count, void *data)
{
char * foo = kmalloc(count, GFP_ATOMIC);

if(!foo){
return count;
}

if(copy_from_user(foo, buffer, count)) {
return -EFAULT;
}

procnum= my_atoi(foo);
kfree (foo);
if(procnum > 99) {
printk(KERN_ALERT "procnum can't be > 99.\n");
procnum = 99;
} else if(procnum < 1) {
printk(KERN_ALERT "procnum can't be < 1.\n");
procnum = 1;
}

return count;
}

static void procfile_cleanup_proc(void)
{
remove_proc_entry("procfile",father);
remove_proc_entry("procdir",init_net.proc_net);
}

static int procfile_init_proc(void)
{
struct proc_dir_entry* entry;
father=proc_mkdir("procdir",init_net.proc_net);
entry = create_proc_entry("procfile", 0644,father);
entry->read_proc = procfile_read_proc;
entry->write_proc = procfile_write_proc;
return 1;
}

static int __init procfile_init(void)
{
printk(KERN_ALERT "procfile init\n");
return procfile_init_proc();
}
static void __exit procfile_exit(void)
{
procfile_cleanup_proc();
printk(KERN_ALERT "procfile exit\n");
}
module_init(procfile_init);
module_exit(procfile_exit);