466 lines
11 KiB
C
466 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* UHID Example
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*
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* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
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*
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* The code may be used by anyone for any purpose,
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* and can serve as a starting point for developing
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* applications using uhid.
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*/
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/*
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* UHID Example
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* This example emulates a basic 3 buttons mouse with wheel over UHID. Run this
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* program as root and then use the following keys to control the mouse:
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* q: Quit the application
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* 1: Toggle left button (down, up, ...)
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* 2: Toggle right button
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* 3: Toggle middle button
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* a: Move mouse left
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* d: Move mouse right
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* w: Move mouse up
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* s: Move mouse down
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* r: Move wheel up
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* f: Move wheel down
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*
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* Additionally to 3 button mouse, 3 keyboard LEDs are also supported (LED_NUML,
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* LED_CAPSL and LED_SCROLLL). The device doesn't generate any related keyboard
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* events, though. You need to manually write the EV_LED/LED_XY/1 activation
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* input event to the evdev device to see it being sent to this device.
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*
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* If uhid is not available as /dev/uhid, then you can pass a different path as
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* first argument.
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* If <linux/uhid.h> is not installed in /usr, then compile this with:
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* gcc -o ./uhid_test -Wall -I./include ./samples/uhid/uhid-example.c
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* And ignore the warning about kernel headers. However, it is recommended to
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* use the installed uhid.h if available.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <termios.h>
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#include <unistd.h>
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#include <linux/uhid.h>
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/*
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* HID Report Desciptor
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* We emulate a basic 3 button mouse with wheel and 3 keyboard LEDs. This is
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* the report-descriptor as the kernel will parse it:
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*
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* INPUT(1)[INPUT]
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* Field(0)
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* Physical(GenericDesktop.Pointer)
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* Application(GenericDesktop.Mouse)
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* Usage(3)
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* Button.0001
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* Button.0002
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* Button.0003
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* Logical Minimum(0)
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* Logical Maximum(1)
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* Report Size(1)
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* Report Count(3)
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* Report Offset(0)
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* Flags( Variable Absolute )
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* Field(1)
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* Physical(GenericDesktop.Pointer)
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* Application(GenericDesktop.Mouse)
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* Usage(3)
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* GenericDesktop.X
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* GenericDesktop.Y
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* GenericDesktop.Wheel
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* Logical Minimum(-128)
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* Logical Maximum(127)
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* Report Size(8)
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* Report Count(3)
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* Report Offset(8)
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* Flags( Variable Relative )
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* OUTPUT(2)[OUTPUT]
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* Field(0)
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* Application(GenericDesktop.Keyboard)
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* Usage(3)
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* LED.NumLock
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* LED.CapsLock
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* LED.ScrollLock
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* Logical Minimum(0)
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* Logical Maximum(1)
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* Report Size(1)
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* Report Count(3)
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* Report Offset(0)
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* Flags( Variable Absolute )
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*
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* This is the mapping that we expect:
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* Button.0001 ---> Key.LeftBtn
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* Button.0002 ---> Key.RightBtn
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* Button.0003 ---> Key.MiddleBtn
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* GenericDesktop.X ---> Relative.X
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* GenericDesktop.Y ---> Relative.Y
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* GenericDesktop.Wheel ---> Relative.Wheel
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* LED.NumLock ---> LED.NumLock
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* LED.CapsLock ---> LED.CapsLock
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* LED.ScrollLock ---> LED.ScrollLock
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*
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* This information can be verified by reading /sys/kernel/debug/hid/<dev>/rdesc
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* This file should print the same information as showed above.
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*/
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static unsigned char rdesc[] = {
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x02, /* USAGE (Mouse) */
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0xa1, 0x01, /* COLLECTION (Application) */
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0x09, 0x01, /* USAGE (Pointer) */
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0xa1, 0x00, /* COLLECTION (Physical) */
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0x85, 0x01, /* REPORT_ID (1) */
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0x05, 0x09, /* USAGE_PAGE (Button) */
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0x19, 0x01, /* USAGE_MINIMUM (Button 1) */
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0x29, 0x03, /* USAGE_MAXIMUM (Button 3) */
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0x15, 0x00, /* LOGICAL_MINIMUM (0) */
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0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
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0x95, 0x03, /* REPORT_COUNT (3) */
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0x75, 0x01, /* REPORT_SIZE (1) */
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0x81, 0x02, /* INPUT (Data,Var,Abs) */
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0x95, 0x01, /* REPORT_COUNT (1) */
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0x75, 0x05, /* REPORT_SIZE (5) */
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0x81, 0x01, /* INPUT (Cnst,Var,Abs) */
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x30, /* USAGE (X) */
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0x09, 0x31, /* USAGE (Y) */
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0x09, 0x38, /* USAGE (WHEEL) */
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0x15, 0x81, /* LOGICAL_MINIMUM (-127) */
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0x25, 0x7f, /* LOGICAL_MAXIMUM (127) */
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0x75, 0x08, /* REPORT_SIZE (8) */
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0x95, 0x03, /* REPORT_COUNT (3) */
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0x81, 0x06, /* INPUT (Data,Var,Rel) */
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0xc0, /* END_COLLECTION */
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0xc0, /* END_COLLECTION */
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0x05, 0x01, /* USAGE_PAGE (Generic Desktop) */
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0x09, 0x06, /* USAGE (Keyboard) */
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0xa1, 0x01, /* COLLECTION (Application) */
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0x85, 0x02, /* REPORT_ID (2) */
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0x05, 0x08, /* USAGE_PAGE (Led) */
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0x19, 0x01, /* USAGE_MINIMUM (1) */
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0x29, 0x03, /* USAGE_MAXIMUM (3) */
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0x15, 0x00, /* LOGICAL_MINIMUM (0) */
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0x25, 0x01, /* LOGICAL_MAXIMUM (1) */
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0x95, 0x03, /* REPORT_COUNT (3) */
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0x75, 0x01, /* REPORT_SIZE (1) */
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0x91, 0x02, /* Output (Data,Var,Abs) */
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0x95, 0x01, /* REPORT_COUNT (1) */
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0x75, 0x05, /* REPORT_SIZE (5) */
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0x91, 0x01, /* Output (Cnst,Var,Abs) */
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0xc0, /* END_COLLECTION */
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};
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static int uhid_write(int fd, const struct uhid_event *ev)
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{
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ssize_t ret;
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ret = write(fd, ev, sizeof(*ev));
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if (ret < 0) {
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fprintf(stderr, "Cannot write to uhid: %m\n");
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return -errno;
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} else if (ret != sizeof(*ev)) {
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fprintf(stderr, "Wrong size written to uhid: %ld != %lu\n",
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ret, sizeof(ev));
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return -EFAULT;
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} else {
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return 0;
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}
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}
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static int create(int fd)
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{
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struct uhid_event ev;
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memset(&ev, 0, sizeof(ev));
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ev.type = UHID_CREATE;
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strcpy((char*)ev.u.create.name, "test-uhid-device");
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ev.u.create.rd_data = rdesc;
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ev.u.create.rd_size = sizeof(rdesc);
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ev.u.create.bus = BUS_USB;
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ev.u.create.vendor = 0x15d9;
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ev.u.create.product = 0x0a37;
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ev.u.create.version = 0;
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ev.u.create.country = 0;
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return uhid_write(fd, &ev);
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}
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static void destroy(int fd)
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{
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struct uhid_event ev;
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memset(&ev, 0, sizeof(ev));
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ev.type = UHID_DESTROY;
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uhid_write(fd, &ev);
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}
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/* This parses raw output reports sent by the kernel to the device. A normal
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* uhid program shouldn't do this but instead just forward the raw report.
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* However, for ducomentational purposes, we try to detect LED events here and
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* print debug messages for it. */
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static void handle_output(struct uhid_event *ev)
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{
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/* LED messages are adverised via OUTPUT reports; ignore the rest */
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if (ev->u.output.rtype != UHID_OUTPUT_REPORT)
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return;
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/* LED reports have length 2 bytes */
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if (ev->u.output.size != 2)
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return;
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/* first byte is report-id which is 0x02 for LEDs in our rdesc */
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if (ev->u.output.data[0] != 0x2)
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return;
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/* print flags payload */
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fprintf(stderr, "LED output report received with flags %x\n",
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ev->u.output.data[1]);
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}
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static int event(int fd)
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{
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struct uhid_event ev;
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ssize_t ret;
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memset(&ev, 0, sizeof(ev));
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ret = read(fd, &ev, sizeof(ev));
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if (ret == 0) {
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fprintf(stderr, "Read HUP on uhid-cdev\n");
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return -EFAULT;
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} else if (ret < 0) {
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fprintf(stderr, "Cannot read uhid-cdev: %m\n");
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return -errno;
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} else if (ret != sizeof(ev)) {
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fprintf(stderr, "Invalid size read from uhid-dev: %ld != %lu\n",
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ret, sizeof(ev));
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return -EFAULT;
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}
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switch (ev.type) {
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case UHID_START:
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fprintf(stderr, "UHID_START from uhid-dev\n");
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break;
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case UHID_STOP:
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fprintf(stderr, "UHID_STOP from uhid-dev\n");
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break;
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case UHID_OPEN:
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fprintf(stderr, "UHID_OPEN from uhid-dev\n");
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break;
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case UHID_CLOSE:
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fprintf(stderr, "UHID_CLOSE from uhid-dev\n");
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break;
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case UHID_OUTPUT:
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fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");
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handle_output(&ev);
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break;
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case UHID_OUTPUT_EV:
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fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
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break;
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default:
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fprintf(stderr, "Invalid event from uhid-dev: %u\n", ev.type);
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}
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return 0;
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}
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static bool btn1_down;
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static bool btn2_down;
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static bool btn3_down;
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static signed char abs_hor;
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static signed char abs_ver;
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static signed char wheel;
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static int send_event(int fd)
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{
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struct uhid_event ev;
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memset(&ev, 0, sizeof(ev));
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ev.type = UHID_INPUT;
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ev.u.input.size = 5;
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ev.u.input.data[0] = 0x1;
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if (btn1_down)
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ev.u.input.data[1] |= 0x1;
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if (btn2_down)
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ev.u.input.data[1] |= 0x2;
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if (btn3_down)
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ev.u.input.data[1] |= 0x4;
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ev.u.input.data[2] = abs_hor;
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ev.u.input.data[3] = abs_ver;
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ev.u.input.data[4] = wheel;
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return uhid_write(fd, &ev);
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}
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static int keyboard(int fd)
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{
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char buf[128];
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ssize_t ret, i;
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ret = read(STDIN_FILENO, buf, sizeof(buf));
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if (ret == 0) {
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fprintf(stderr, "Read HUP on stdin\n");
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return -EFAULT;
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} else if (ret < 0) {
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fprintf(stderr, "Cannot read stdin: %m\n");
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return -errno;
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}
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for (i = 0; i < ret; ++i) {
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switch (buf[i]) {
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case '1':
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btn1_down = !btn1_down;
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ret = send_event(fd);
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if (ret)
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return ret;
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break;
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case '2':
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btn2_down = !btn2_down;
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ret = send_event(fd);
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if (ret)
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return ret;
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break;
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case '3':
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btn3_down = !btn3_down;
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ret = send_event(fd);
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if (ret)
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return ret;
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break;
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case 'a':
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abs_hor = -20;
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ret = send_event(fd);
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abs_hor = 0;
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if (ret)
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return ret;
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break;
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case 'd':
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abs_hor = 20;
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ret = send_event(fd);
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abs_hor = 0;
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if (ret)
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return ret;
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break;
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case 'w':
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abs_ver = -20;
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ret = send_event(fd);
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abs_ver = 0;
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if (ret)
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return ret;
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break;
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case 's':
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abs_ver = 20;
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ret = send_event(fd);
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abs_ver = 0;
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if (ret)
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return ret;
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break;
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case 'r':
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wheel = 1;
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ret = send_event(fd);
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wheel = 0;
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if (ret)
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return ret;
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break;
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case 'f':
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wheel = -1;
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ret = send_event(fd);
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wheel = 0;
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if (ret)
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return ret;
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break;
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case 'q':
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return -ECANCELED;
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default:
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fprintf(stderr, "Invalid input: %c\n", buf[i]);
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}
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}
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return 0;
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}
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int main(int argc, char **argv)
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{
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int fd;
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const char *path = "/dev/uhid";
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struct pollfd pfds[2];
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int ret;
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struct termios state;
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ret = tcgetattr(STDIN_FILENO, &state);
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if (ret) {
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fprintf(stderr, "Cannot get tty state\n");
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} else {
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state.c_lflag &= ~ICANON;
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state.c_cc[VMIN] = 1;
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ret = tcsetattr(STDIN_FILENO, TCSANOW, &state);
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if (ret)
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fprintf(stderr, "Cannot set tty state\n");
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}
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if (argc >= 2) {
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if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
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fprintf(stderr, "Usage: %s [%s]\n", argv[0], path);
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return EXIT_SUCCESS;
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} else {
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path = argv[1];
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}
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}
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fprintf(stderr, "Open uhid-cdev %s\n", path);
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fd = open(path, O_RDWR | O_CLOEXEC);
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if (fd < 0) {
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fprintf(stderr, "Cannot open uhid-cdev %s: %m\n", path);
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return EXIT_FAILURE;
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}
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fprintf(stderr, "Create uhid device\n");
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ret = create(fd);
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if (ret) {
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close(fd);
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return EXIT_FAILURE;
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}
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pfds[0].fd = STDIN_FILENO;
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pfds[0].events = POLLIN;
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pfds[1].fd = fd;
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pfds[1].events = POLLIN;
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fprintf(stderr, "Press 'q' to quit...\n");
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while (1) {
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ret = poll(pfds, 2, -1);
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if (ret < 0) {
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fprintf(stderr, "Cannot poll for fds: %m\n");
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break;
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}
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if (pfds[0].revents & POLLHUP) {
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fprintf(stderr, "Received HUP on stdin\n");
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break;
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}
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if (pfds[1].revents & POLLHUP) {
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fprintf(stderr, "Received HUP on uhid-cdev\n");
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break;
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}
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if (pfds[0].revents & POLLIN) {
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ret = keyboard(fd);
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if (ret)
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break;
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}
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if (pfds[1].revents & POLLIN) {
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ret = event(fd);
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if (ret)
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break;
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}
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}
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fprintf(stderr, "Destroy uhid device\n");
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destroy(fd);
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return EXIT_SUCCESS;
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}
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