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/*
* The USB Monitor, inspired by Dave Harding's USBMon.
*
* This is the 's' or 'stat' reader which debugs usbmon itself.
* Note that this code blows through locks, so make sure that
* /dbg/usbmon/0s is well protected from non-root users.
*
*/
#include <linux/kernel.h>
#include <linux/usb.h>
#include <asm/uaccess.h>
#include "usb_mon.h"
#define STAT_BUF_SIZE 80
struct snap {
int slen;
char str[STAT_BUF_SIZE];
};
static int mon_stat_open(struct inode *inode, struct file *file)
{
struct mon_bus *mbus;
struct snap *sp;
if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
return -ENOMEM;
mbus = inode->i_private;
sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
"nreaders %d events %u text_lost %u\n",
mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
file->private_data = sp;
return 0;
}
static ssize_t mon_stat_read(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
struct snap *sp = file->private_data;
loff_t pos = *ppos;
int cnt;
if (pos < 0 || pos >= sp->slen)
return 0;
if (nbytes == 0)
return 0;
if ((cnt = sp->slen - pos) > nbytes)
cnt = nbytes;
if (copy_to_user(buf, sp->str + pos, cnt))
return -EFAULT;
*ppos = pos + cnt;
return cnt;
}
static int mon_stat_release(struct inode *inode, struct file *file)
{
return 0;
}
struct file_operations mon_fops_stat = {
.owner = THIS_MODULE,
.open = mon_stat_open,
.llseek = no_llseek,
.read = mon_stat_read,
/* .write = mon_stat_write, */
/* .poll = mon_stat_poll, */
/* .ioctl = mon_stat_ioctl, */
.release = mon_stat_release,
};
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