用于键盘的不合适的ioctl（EVIOCGRAB）＆＃39;设备

Question

我正在尝试从以下github source.调试evmuxd工具（具有切换支持的物理键盘多路复用器）我安装了bluez库并成功编译了源代码。但是，当我尝试按手册页运行时，我会收到以下错误：

sudo evmuxd /dev/input/event7
Could not grab keyboard for exclusive use: Inappropriate ioctl for device

从下面的代码中，您可以看到ioctl (fd, EVIOCGRAB, 1)返回错误

#include <linux/input.h>
#include <linux/uinput.h>

#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>

#define UINPUT "/dev/uinput"

static int
open_uinput (const char *name)
{
    int fd;
    struct uinput_user_dev dev = { 0, };
    int i;

    fd = open (UINPUT, O_WRONLY | O_NDELAY);
    if (fd == -1) {
        perror (UINPUT);
        return -1;
    }

    if (ioctl(fd, UI_SET_EVBIT, EV_KEY) == -1) {
        perror ("Could not enable key events");
        goto fail;
    }

    for (i = 0; i < KEY_CNT; i++) {
        if (ioctl(fd, UI_SET_KEYBIT, i) == -1) {
            perror ("Could not enable a key event");
            goto fail;
        }
    }

    if (ioctl(fd, UI_SET_EVBIT, EV_REP) == -1) {
        perror ("Could not enable autorepeat events");
        goto fail;
    }

    strncpy (dev.name, name, UINPUT_MAX_NAME_SIZE);
    dev.id.bustype = BUS_VIRTUAL;
    dev.id.vendor  = 0x0666;
    dev.id.product = 0x8086;
    dev.id.version = 1;

    if (write (fd, &dev, sizeof (dev)) != sizeof (dev)) {
        perror (UINPUT);
        goto fail;
    }

    if (ioctl(fd, UI_DEV_CREATE) == -1) {
        perror ("Could not create the virtual keyboard");
        goto fail;
    }

    return fd;
fail:
    close (fd);
    return -1;
}

static int
open_input (char *dev)
{
    int version;
    int features;
    int fd;
    int norepeat[2] = { 0, 0 };

    fd = open (dev, O_RDWR);
    if (fd == -1) {
        perror (dev);
        return -1;
    }

    if (ioctl (fd, EVIOCGVERSION, &version) == -1) {
        perror ("Could not read input protocol version");
        goto fail;
    }
    if (version >> 16 != EV_VERSION >> 16) {
        fprintf (stderr, "Bad input subsystem version");
        goto fail;
    }

    if (ioctl (fd, EVIOCGBIT(0, EV_MAX), &features) == -1) {
        perror ("Could query device for supported features");
        goto fail;
    }
    if (!(features & EV_KEY)) {
        fprintf (stderr, "Device not capable of producing key press event.");
        goto fail;
    }

    if (ioctl (fd, EVIOCGRAB, 1) == -1) {
        perror ("Could not grab keyboard for exclusive use");
        goto fail;
    }

    if (ioctl (fd, EVIOCSREP, norepeat) == -1) {
        perror ("Could not disable autorepeat");
        goto fail;
    }

    return fd;
fail:
    close (fd);
    return -1;
}

int
main (int argc, char *argv[])
{
    int uinput[2], input;
    struct input_event event;
    int active = 0;
    int switching = 0;

    if (argc != 2) {
        fprintf (stderr, "Usage: %s /dev/input/event<n>\n", argv[0]);
        return 1;
    }

    input = open_input (argv[1]);
    if (input == -1)
        return 1;

    uinput[0] = open_uinput ("evmuxd primary");
    if (uinput[0] == -1)
        return 1;

    uinput[1] = open_uinput ("evmuxd secondary");
    if (uinput[1] == -1)
        return 1;

    while (1) {
        switch (read (input, &event, sizeof(event))) {
        case -1:
            perror ("Error reading from event device");
            return 1;
        case sizeof(event):
            break;
        default:
            fprintf (stderr, "Short read from the event device.\n");
            return 1;
        }

        switch (write (uinput[active], &event, sizeof(event))) {
        case -1:
            perror ("Error forwarding the event");
            return 1;
        case sizeof(event):
            break;
        default:
            fprintf (stderr, "Short write forwarding the event.\n");
            return 1;
        }

        if (event.type == EV_KEY
            && event.code == KEY_SCROLLLOCK
            && event.value == 0) {
            switching = 1;
        }
        if (event.type == EV_SYN && switching) {
            switching = 0;
            active = !active;
        }
    }

    return 0;
}

那么问题是什么以及如何解决它？