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1// SPDX-License-Identifier: GPL-2.0-only2/* Copyright (c) 2022 Benjamin Tissoires3 *4 * This is a pure HID-BPF example, and should be considered as such:5 * on the Etekcity Scroll 6E, the X and Y axes will be swapped and6 * inverted. On any other device... Not sure what this will do.7 *8 * This C main file is generic though. To adapt the code and test, users9 * must amend only the .bpf.c file, which this program will load any10 * eBPF program it finds.11 */12 13#include <assert.h>14#include <errno.h>15#include <fcntl.h>16#include <libgen.h>17#include <signal.h>18#include <stdbool.h>19#include <stdio.h>20#include <stdlib.h>21#include <string.h>22#include <sys/resource.h>23#include <unistd.h>24 25#include <linux/bpf.h>26#include <linux/errno.h>27 28#include <bpf/bpf.h>29#include <bpf/libbpf.h>30 31#include "hid_mouse.skel.h"32 33static bool running = true;34 35static void int_exit(int sig)36{37 running = false;38 exit(0);39}40 41static void usage(const char *prog)42{43 fprintf(stderr,44 "%s: %s /sys/bus/hid/devices/0BUS:0VID:0PID:00ID\n\n",45 __func__, prog);46 fprintf(stderr,47 "This program will upload and attach a HID-BPF program to the given device.\n"48 "On the Etekcity Scroll 6E, the X and Y axis will be inverted, but on any other\n"49 "device, chances are high that the device will not be working anymore\n\n"50 "consider this as a demo and adapt the eBPF program to your needs\n"51 "Hit Ctrl-C to unbind the program and reset the device\n");52}53 54static int get_hid_id(const char *path)55{56 const char *str_id, *dir;57 char uevent[1024];58 int fd;59 60 memset(uevent, 0, sizeof(uevent));61 snprintf(uevent, sizeof(uevent) - 1, "%s/uevent", path);62 63 fd = open(uevent, O_RDONLY | O_NONBLOCK);64 if (fd < 0)65 return -ENOENT;66 67 close(fd);68 69 dir = basename((char *)path);70 71 str_id = dir + sizeof("0003:0001:0A37.");72 return (int)strtol(str_id, NULL, 16);73}74 75int main(int argc, char **argv)76{77 struct hid_mouse *skel;78 struct bpf_link *link;79 int err;80 const char *optstr = "";81 const char *sysfs_path;82 int opt, hid_id;83 84 while ((opt = getopt(argc, argv, optstr)) != -1) {85 switch (opt) {86 default:87 usage(basename(argv[0]));88 return 1;89 }90 }91 92 if (optind == argc) {93 usage(basename(argv[0]));94 return 1;95 }96 97 sysfs_path = argv[optind];98 if (!sysfs_path) {99 perror("sysfs");100 return 1;101 }102 103 skel = hid_mouse__open();104 if (!skel) {105 fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__);106 return -1;107 }108 109 hid_id = get_hid_id(sysfs_path);110 111 if (hid_id < 0) {112 fprintf(stderr, "can not open HID device: %m\n");113 return 1;114 }115 skel->struct_ops.mouse_invert->hid_id = hid_id;116 117 err = hid_mouse__load(skel);118 if (err < 0) {119 fprintf(stderr, "can not load HID-BPF program: %m\n");120 return 1;121 }122 123 link = bpf_map__attach_struct_ops(skel->maps.mouse_invert);124 if (!link) {125 fprintf(stderr, "can not attach HID-BPF program: %m\n");126 return 1;127 }128 129 signal(SIGINT, int_exit);130 signal(SIGTERM, int_exit);131 132 while (running)133 sleep(1);134 135 hid_mouse__destroy(skel);136 137 return 0;138}139