捕获HID键盘事件 [英] Capture HID keyboard event

问题描述

以下代码仅适用于一个输入设备.不幸的是，我需要捕获大约12种不同的HID设备(RFID读取器)，所以我想知道是否有人知道如何使代码适用于12种不同的输入?

The code below works fine for only one input device. Unfortunately I need to capture about 12 different HID devices (RFID readers), so I would like to know if does anyone know how to adapt the code to work with 12 different inputs?

#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;
}

推荐答案

为每个设备调用 open()，然后使用 select()(或(e)poll())一起监视所有文件描述符，这样您就可以检测到哪些设备具有可用的数据，然后可以在任何给定时刻进行 read().

Call open() for each device, and then use select() (or (e)poll()) to monitor all of the file descriptors together so you can detect which devices have data available to then be read() from at any given moment.

更新:例如:

struct event_device
{
    char *device;
    int fd;
};

int main(int argc, char* argv[])
{
    struct input_event ev[64];
    int numevents;
    int result = 0;
    int size = sizeof(struct input_event);
    int rd;
    char name[256];
    char* device[12];
    event_device evdevs[12], *evdev;
    int numevdevs = 0;
    fd_set fds;
    int maxfd;

    device[0] = "/dev/input/event3";
    device[1] = "/dev/input/event4";
    // and so on...

    for (int i = 0; i < 12; ++i) {
        evdev = &evdevs[numevdevs];

        evdev->device = device[i];
        evdev->fd = open(evdev->device, O_RDONLY);
        if (evdev->fd == -1) {
            printf("Failed to open event device: %s.\n", evdev->device);
            continue;
        }
        ++numevdevs;

        memset(name, 0, sizeof(name));
        result = ioctl(evdev->fd, EVIOCGNAME(sizeof(name)), name);
        printf ("Reading From : %s (%s)\n", evdev->device, name);

        printf("Getting exclusive access: ");
        result = ioctl(evdev->fd, EVIOCGRAB, 1);
        printf("%s\n", (result == 0) ? "SUCCESS" : "FAILURE");
    }

    if (numevdevs == 0) {
        exit(1);
    }

    while (1)
    {
        FD_ZERO(&fds);
        maxfd = -1;

        for (int i = 0; i < numevdevs; ++i) {
            evdev = &evdevs[i];
            FD_SET(evdev->fd, &fds);
            if (maxfd < evdev->fd) maxfd = evdev->fd;
        }

        result = select(maxfd+1, &fds, NULL, NULL, NULL);
        if (result == -1) {
            break;        
        }

        for (int i = 0; i < numevdevs; ++i) {
            evdev = &evdevs[i];

            if (!FD_ISSET(evdev->fd, &fds)) {
                continue;
            }

            if ((rd = read(evdev->fd, ev, size * 64)) < size) {
                continue;
            }

            numevents = rd / size;
            for (int j = 0; j < numevents; ++j) {
                printf ("%s: Type[%d] Code[%d] Value[%d]\n", evdev->device, ev[j].type, ev[j].code, ev[j].value);
            }
        }
    }

    printf("Exiting.\n");

    for (int i = 0; i < numevdevs; ++i) {
        evdev = &evdevs[i];
        result = ioctl(evdev->fd, EVIOCGRAB, 0);
        close(evdev->);
    }

    return 0;
}

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