evdevpp/evdev.hpp

#pragma once

#include <fcntl.h>
#include <libevdev/libevdev.h>
#include <unistd.h>

#include <phosphor-logging/elog-errors.hpp>
#include <phosphor-logging/elog.hpp>
#include <phosphor-logging/lg2.hpp>
#include <xyz/openbmc_project/Common/error.hpp>

#include <memory>
#include <string>
#include <tuple>

namespace evdevpp
{
namespace evdev
{

using EvDevPtr = libevdev*;

namespace details
{

/** @brief unique_ptr functor to release an evdev reference. */
struct EvDevDeleter
{
    void operator()(libevdev* ptr) const
    {
        deleter(ptr);
    }

    decltype(&libevdev_free) deleter = libevdev_free;
};

/* @brief Alias evdev to a unique_ptr type for auto-release. */
using EvDev = std::unique_ptr<libevdev, EvDevDeleter>;

} // namespace details

/** @class EvDev
 *  @brief Provides C++ bindings to the libevdev C API.
 */
class EvDev
{
  private:
    using InternalFailure =
        sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;

  public:
    /* Define all of the basic class operations:
     *     Not allowed:
     *         - Default constructor to avoid nullptrs.
     *         - Copy operations due to internal unique_ptr.
     *     Allowed:
     *         - Move operations.
     *         - Destructor.
     */
    EvDev() = delete;
    EvDev(const EvDev&) = delete;
    EvDev& operator=(const EvDev&) = delete;
    EvDev(EvDev&&) = default;
    EvDev& operator=(EvDev&&) = default;
    ~EvDev() = default;

    /** @brief Conversion constructor from evdev. */
    explicit EvDev(EvDevPtr ptr) : evdev(ptr) {}

    /** @brief Get the current event state. */
    auto fetch(unsigned int type, unsigned int code)
    {
        int val;
        auto rc = libevdev_fetch_event_value(evdev.get(), type, code, &val);
        if (!rc)
        {
            lg2::error(
                "Error in call to libevdev_fetch_event_value, Type={TYPE}, Code={CODE}",
                "TYPE", type, "CODE", code);
            phosphor::logging::elog<InternalFailure>();
        }

        return val;
    }

    /** @brief Get the next event. */
    auto next()
    {
        struct input_event ev;
        while (true)
        {
            auto rc = libevdev_next_event(evdev.get(),
                                          LIBEVDEV_READ_FLAG_NORMAL, &ev);
            if (rc < 0)
            {
                lg2::error("Error in call to libevdev_next_event, RC={RC}",
                           "RC", rc);
                phosphor::logging::elog<InternalFailure>();
            }

            if (ev.type == EV_SYN && ev.code == SYN_REPORT)
                continue;

            break;
        }
        return std::make_tuple(ev.type, ev.code, ev.value);
    }

  private:
    EvDevPtr get()
    {
        return evdev.get();
    }

    details::EvDev evdev;
};

inline auto newFromFD(int fd)
{
    using InternalFailure =
        sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;

    EvDevPtr dev = nullptr;
    auto rc = libevdev_new_from_fd(fd, &dev);

    if (rc)
    {
        lg2::error("Error in call to libevdev_new_from_fd, RC={RC}, FD={FD}",
                   "RC", rc, "FD", fd);
        phosphor::logging::elog<InternalFailure>();
    }

    return EvDev(dev);
}
} // namespace evdev
} // namespace evdevpp