1 /* 2 * The USB Monitor, inspired by Dave Harding's USBMon. 3 * 4 * This is the 's' or 'stat' reader which debugs usbmon itself. 5 * Note that this code blows through locks, so make sure that 6 * /dbg/usbmon/0s is well protected from non-root users. 7 * 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/usb.h> 12 #include <asm/uaccess.h> 13 14 #include "usb_mon.h" 15 16 #define STAT_BUF_SIZE 80 17 18 struct snap { 19 int slen; 20 char str[STAT_BUF_SIZE]; 21 }; 22 23 static int mon_stat_open(struct inode *inode, struct file *file) 24 { 25 struct mon_bus *mbus; 26 struct snap *sp; 27 28 if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL) 29 return -ENOMEM; 30 31 mbus = inode->i_private; 32 33 sp->slen = snprintf(sp->str, STAT_BUF_SIZE, 34 "nreaders %d events %u text_lost %u\n", 35 mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost); 36 37 file->private_data = sp; 38 return 0; 39 } 40 41 static ssize_t mon_stat_read(struct file *file, char __user *buf, 42 size_t nbytes, loff_t *ppos) 43 { 44 struct snap *sp = file->private_data; 45 loff_t pos = *ppos; 46 int cnt; 47 48 if (pos < 0 || pos >= sp->slen) 49 return 0; 50 if (nbytes == 0) 51 return 0; 52 if ((cnt = sp->slen - pos) > nbytes) 53 cnt = nbytes; 54 if (copy_to_user(buf, sp->str + pos, cnt)) 55 return -EFAULT; 56 *ppos = pos + cnt; 57 return cnt; 58 } 59 60 static int mon_stat_release(struct inode *inode, struct file *file) 61 { 62 return 0; 63 } 64 65 const struct file_operations mon_fops_stat = { 66 .owner = THIS_MODULE, 67 .open = mon_stat_open, 68 .llseek = no_llseek, 69 .read = mon_stat_read, 70 /* .write = mon_stat_write, */ 71 /* .poll = mon_stat_poll, */ 72 /* .ioctl = mon_stat_ioctl, */ 73 .release = mon_stat_release, 74 }; 75