问题
I've got a RFID USB device that registers as a HID device (A USB Keyboard more or less).
I'm looking for a way to capture this input, and block/filter it before it hits the normal keyboard event handler (and outputs the 10 digit RFID code to the console).
I would of course have to exclusively capture just this device, and leave the real keyboard input alone (or pass it along).
My initial idea was to block the device in UDEV (So the usbhid/event/kbd kernel module didn't bind to it) and write my own basic driver for this device - but I don't know where to begin, or if that'll even work.
What would be great (and I'm not sure if such a thing can be done) - is if I write a event-filter module that can sit in-line with the event driver and capture (then filter) the appropriate input from the RFID unit, but let everything else pass through. I imagine such a module wouldn't require much code, and would be the most practical.
Help?
[EDIT: I should add that Xorg is NOT installed - console only]
cat /proc/bus/input:
I: Bus=0003 Vendor=0419 Product=0912 Version=0100
N: Name="NewRoad Sem. NewRoad System PS2 Interface"
P: Phys=usb-0000:00:1d.3-2/input0
S: Sysfs=/devices/pci0000:00/0000:00:1d.3/usb5/5-2/5-2:1.0/input/input20
U: Uniq=
H: Handlers=sysrq kbd mouse0 event3
B: PROP=0
B: EV=120017
B: KEY=70000 0 0 e080ffdf01cfffff fffffffffffffffe
B: REL=103
B: MSC=10
B: LED=1f
More info:
lsusb -d 0419:0912 -v
Bus 005 Device 019: ID 0419:0912 Samsung Info. Systems America, Inc.
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x0419 Samsung Info. Systems America, Inc.
idProduct 0x0912
bcdDevice 0.01
iManufacturer 1 NewRoad Sem.
iProduct 2 NewRoad System PS2 Interface
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 34
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 4
bmAttributes 0xa0
(Bus Powered)
Remote Wakeup
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 1 Boot Interface Subclass
bInterfaceProtocol 1 Keyboard
iInterface 5
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.00
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 119
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 10
Device Status: 0x0000
(Bus Powered)
回答1:
So I whipped up a proof-of-concept app according to that post I found here
It does exactly what I require - just though I'd share my solution anyway.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <dirent.h>
#include <linux/input.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/select.h>
#include <sys/time.h>
#include <termios.h>
#include <signal.h>
int main(int argc, char* argv[])
{
struct input_event ev[64];
int fevdev = -1;
int result = 0;
int size = sizeof(struct input_event);
int rd;
int value;
char name[256] = "Unknown";
char *device = "/dev/input/event3";
fevdev = open(device, O_RDONLY);
if (fevdev == -1) {
printf("Failed to open event device.\n");
exit(1);
}
result = ioctl(fevdev, EVIOCGNAME(sizeof(name)), name);
printf ("Reading From : %s (%s)\n", device, name);
printf("Getting exclusive access: ");
result = ioctl(fevdev, EVIOCGRAB, 1);
printf("%s\n", (result == 0) ? "SUCCESS" : "FAILURE");
while (1)
{
if ((rd = read(fevdev, ev, size * 64)) < size) {
break;
}
value = ev[0].value;
if (value != ' ' && ev[1].value == 1 && ev[1].type == 1) {
printf ("Code[%d]\n", (ev[1].code));
}
}
printf("Exiting.\n");
result = ioctl(fevdev, EVIOCGRAB, 1);
close(fevdev);
return 0;
}
回答2:
You can use EVIOCGRAB ioctl on an event device to capture it exclusively.
回答3:
Ungrabbing requires a "false" value parameter, as below:
result = ioctl(fevdev, EVIOCGRAB, 0);
来源:https://stackoverflow.com/questions/7668872/need-to-intercept-hid-keyboard-events-and-then-block-them