udev camera iteration

gistfile1.txt

void find_device()
{

    struct udev* udev = udev_new();
    if (!udev)
    {
        setError(Error("Unable to create udev reference.", EIO));
        return device_list;
    }

    /* Create a list of the devices in the 'video4linux' subsystem. */
    struct udev_enumerate* enumerate = udev_enumerate_new(udev);
    udev_enumerate_add_match_subsystem(enumerate, "video4linux");
    udev_enumerate_scan_devices(enumerate);
    struct udev_list_entry* devices = udev_enumerate_get_list_entry(enumerate);
    struct udev_list_entry* dev_list_entry;

    udev_list_entry_foreach(dev_list_entry, devices)
    {
        const char* path;
        char needed_path[100];

        /* Get the filename of the /sys entry for the device
           and create a udev_device object (dev) representing it */
        path = udev_list_entry_get_name(dev_list_entry);
        struct udev_device* dev = udev_device_new_from_syspath(udev, path);

        /* The device pointed to by dev contains information about
           the hidraw device. In order to get information about the
           USB device, get the parent device with the
           subsystem/devtype pair of "usb"/"usb_device". This will
           be several levels up the tree, but the function will find
           it.*/

        /* we need to copy the devnode (/dev/videoX) before the path
           is changed to the path of the usb device behind it (/sys/class/....) */
        strcpy(needed_path, udev_device_get_devnode(dev));

        struct udev_device* parent_device = udev_device_get_parent_with_subsystem_devtype(dev, "usb", "usb_device");

        if (!parent_device)
        {
            setError(Error("udev_device_get_parent_with_subsystem_devtype failed", EIO));
            return device_list;
        }

        /* From here, we can call get_sysattr_value() for each file
           in the device's /sys entry. The strings passed into these
           functions (idProduct, idVendor, serial, etc.) correspond
           directly to the files in the directory which represents
           the USB device. Note that USB strings are Unicode, UCS2
           encoded, but the strings returned from
           udev_device_get_sysattr_value() are UTF-8 encoded. */

        // TODO: no hard coded numbers find more general approach
        // only use TIS devices
        static const char* TCAM_VENDOR_ID_STRING = "199e";

        if (strcmp(udev_device_get_sysattr_value(parent_device, "idVendor"), TCAM_VENDOR_ID_STRING) == 0)
        {

            if (udev_device_get_sysattr_value(parent_device, "serial") != NULL)
              // compare for your serial here!

        }

        udev_device_unref(dev);
    }

    /* Free the enumerator object */
    udev_enumerate_unref(enumerate);

    udev_unref(udev);
}