quine-global-labs/mirror-kde-plasma-desktop.git

/*
    SPDX-FileCopyrightText: 2025 Jeremy Whiting <jpwhiting@kde.org>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

#include "udevmatcher.h"

#include <cstring>
#include <libudev.h>

#include "logging.h"

static std::string kDevicePathKey = "DEVPATH";

// This function has one purpose, to translate udev devpaths into an id
// to get from something like /devices/virtual/misc/uhid/0005:18D1:9400.0005/hidraw/hidraw2
// to an id such as 0005:18D1:9400.005 for matching against the ids from hidapi.
std::string UDevMatcher::deviceToUdevId(const std::string &device_path)
{
    std::string devicePath;
    char sys_path[256];

    size_t lastSlash = device_path.find_last_of('/');

    std::string lastPart = device_path.substr(lastSlash + 1);

    if (lastPart.starts_with("hidraw")) {
        // hidrdaw devpaths end with hidrawX
        snprintf(sys_path, sizeof(sys_path), "/sys/class/hidraw/%s", lastPart.c_str());
    } else if (lastPart.starts_with("event")) {
        // input devpaths end with eventXY
        snprintf(sys_path, sizeof(sys_path), "/sys/class/input/%s", lastPart.c_str());
    } else {
        // Return empty if it doesn't match expected types
        return devicePath;
    }
    std::unique_ptr<struct udev, decltype(&udev_unref)> udev(udev_new(), &udev_unref);
    if (!udev) {
        return devicePath;
    }

    qCDebug(KCM_GAMECONTROLLER) << "Using sys path: " << sys_path;
    std::unique_ptr<struct udev_device, decltype(&udev_device_unref)> udevice(udev_device_new_from_syspath(udev.get(), sys_path), &udev_device_unref);

    if (!udevice) {
        return devicePath;
    }

    devicePath = udev_device_get_property_value(udevice.get(), kDevicePathKey.c_str());

    // Walk the devpath looking for the ID
    size_t slash = devicePath.find_last_of('/');

    qCDebug(KCM_GAMECONTROLLER) << "Looking for ID of " << devicePath;

    // If the bit after the last / is a digit, stop, we found it
    while (slash != std::string::npos && (slash + 1) < devicePath.length() && !std::isdigit(devicePath.at(slash + 1))) {
        // Remove the last bit
        devicePath = devicePath.substr(0, slash);

        slash = devicePath.find_last_of('/');

        qCDebug(KCM_GAMECONTROLLER) << "Last part isn't an id, moving up: " << devicePath;
    }

    // Now remove the prefix
    slash = devicePath.find_last_of('/');
    devicePath = devicePath.substr(slash + 1);

    return devicePath;
}