glfw/src/linux_joystick.c

//========================================================================
// GLFW 3.3 Linux - www.glfw.org
//------------------------------------------------------------------------
// Copyright (c) 2002-2006 Marcus Geelnard
// Copyright (c) 2006-2016 Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================

#include "internal.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/inotify.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define TEST_BIT(bit, arr) (arr[(bit) / 8] & (1 << ((bit) % 8)))

static void handleKeyEvent(_GLFWjoystick* js, int code, int value)
{
    int jid = js - _glfw.joysticks;
    int button = js->linjs.keyMap[code];

    _glfwInputJoystickButton(jid, button, value ? 1 : 0);
}

static void handleAbsEvent(_GLFWjoystick* js, int code, int value)
{
    int jid = js - _glfw.joysticks;
    int index = js->linjs.absMap[code];

    if (code >= ABS_HAT0X && code <= ABS_HAT3Y)
    {
        static const char stateMap[3][3] =
        {
            {GLFW_HAT_CENTERED, GLFW_HAT_UP,       GLFW_HAT_DOWN},
            {GLFW_HAT_LEFT,     GLFW_HAT_LEFT_UP,  GLFW_HAT_LEFT_DOWN},
            {GLFW_HAT_RIGHT,    GLFW_HAT_RIGHT_UP, GLFW_HAT_RIGHT_DOWN},
        };

        int hat = (code - ABS_HAT0X) / 2;
        int axis = (code - ABS_HAT0X) % 2;
        int *state = js->linjs.hats[hat];

        // Looking at several input drivers, it seems all hat events use
        // -1 for left / up, 0 for centered and 1 for right / down
        if (value == 0)
            state[axis] = 0;
        else if (value < 0)
            state[axis] = 1;
        else if (value > 0)
            state[axis] = 2;

        _glfwInputJoystickHat(jid, index, stateMap[state[0]][state[1]]);
    }
    else
    {
        struct input_absinfo *info = &js->linjs.absInfo[code];
        int range = info->maximum - info->minimum;
        float normalized = value;

        if (range != 0)
        {
            // Normalize from 0.0 -> 1.0
            normalized = (normalized - info->minimum) / range;
            // Normalize from -1.0 -> 1.0
            normalized = normalized * 2.0f - 1.0f;
        }

        _glfwInputJoystickAxis(jid, index, normalized);
    }
}

static void pollJoystick(_GLFWjoystick* js)
{
    int i;

    for (i = 0;  i < ABS_CNT;  i++)
    {
        if (js->linjs.absMap[i] < 0)
            continue;

        struct input_absinfo *info = &js->linjs.absInfo[i];

        if (ioctl(js->linjs.fd, EVIOCGABS(i), info) < 0)
            continue;

        handleAbsEvent(js, i, info->value);
    }
}

// Attempt to open the specified joystick device
//
static GLFWbool openJoystickDevice(const char* path)
{
    int jid, fd, i;
    char name[256] = "";
    char evBits[(EV_CNT + 7) / 8] = {0};
    char keyBits[(KEY_CNT + 7) / 8] = {0};
    char absBits[(ABS_CNT + 7) / 8] = {0};
    int axisCount = 0;
    int buttonCount = 0;
    int hatCount = 0;
    _GLFWjoystickLinux linjs = {0};
    _GLFWjoystick* js = NULL;

    for (jid = 0;  jid <= GLFW_JOYSTICK_LAST;  jid++)
    {
        if (!_glfw.joysticks[jid].present)
            continue;
        if (strcmp(_glfw.joysticks[jid].linjs.path, path) == 0)
            return GLFW_FALSE;
    }

    fd = open(path, O_RDONLY | O_NONBLOCK);
    if (fd == -1)
        return GLFW_FALSE;

    // Ensure this device supports the events expected of a joystick
    if (ioctl(fd, EVIOCGBIT(0, sizeof(evBits)), evBits) < 0 ||
        ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(keyBits)), keyBits) < 0 ||
        ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(absBits)), absBits) < 0 ||
        !TEST_BIT(EV_KEY, evBits) || !TEST_BIT(EV_ABS, evBits))
    {
        close(fd);
        return GLFW_FALSE;
    }

    if (ioctl(fd, EVIOCGNAME(sizeof(name)), name) < 0)
        strncpy(name, "Unknown", sizeof(name));

    for (i = BTN_MISC;  i < KEY_CNT;  i++)
    {
        if (!TEST_BIT(i, keyBits))
            continue;

        linjs.keyMap[i] = buttonCount++;
    }

    for (i = 0;  i < ABS_CNT;  i++)
    {
        linjs.absMap[i] = -1;
        if (!TEST_BIT(i, absBits))
            continue;

        if (i >= ABS_HAT0X && i <= ABS_HAT3Y)
        {
            linjs.absMap[i] = hatCount++;

            // Skip the Y axis
            i++;
        }
        else
        {
            if (ioctl(fd, EVIOCGABS(i), &linjs.absInfo[i]) < 0)
                continue;

            linjs.absMap[i] = axisCount++;
        }
    }

    js = _glfwAllocJoystick(name, axisCount, buttonCount, hatCount);
    if (!js)
    {
        close(fd);
        return GLFW_FALSE;
    }

    linjs.fd = fd;
    strncpy(linjs.path, path, sizeof(linjs.path));
    memcpy(&js->linjs, &linjs, sizeof(linjs));

    // Set initial values for absolute axes
    pollJoystick(js);

    _glfwInputJoystick(_GLFW_JOYSTICK_ID(js), GLFW_CONNECTED);
    return GLFW_TRUE;
}

// Frees all resources associated with the specified joystick
//
static void closeJoystick(_GLFWjoystick* js)
{
    close(js->linjs.fd);
    _glfwFreeJoystick(js);
    _glfwInputJoystick(_GLFW_JOYSTICK_ID(js), GLFW_DISCONNECTED);
}

// Lexically compare joysticks by name; used by qsort
//
static int compareJoysticks(const void* fp, const void* sp)
{
    const _GLFWjoystick* fj = fp;
    const _GLFWjoystick* sj = sp;
    return strcmp(fj->linjs.path, sj->linjs.path);
}


//////////////////////////////////////////////////////////////////////////
//////                       GLFW internal API                      //////
//////////////////////////////////////////////////////////////////////////

// Initialize joystick interface
//
GLFWbool _glfwInitJoysticksLinux(void)
{
    DIR* dir;
    int count = 0;
    const char* dirname = "/dev/input";

    _glfw.linjs.inotify = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
    if (_glfw.linjs.inotify == -1)
    {
        _glfwInputError(GLFW_PLATFORM_ERROR,
                        "Linux: Failed to initialize inotify: %s",
                        strerror(errno));
        return GLFW_FALSE;
    }

    // HACK: Register for IN_ATTRIB as well to get notified when udev is done
    //       This works well in practice but the true way is libudev

    _glfw.linjs.watch = inotify_add_watch(_glfw.linjs.inotify,
                                          dirname,
                                          IN_CREATE | IN_ATTRIB | IN_DELETE);
    if (_glfw.linjs.watch == -1)
    {
        _glfwInputError(GLFW_PLATFORM_ERROR,
                        "Linux: Failed to watch for joystick connections in %s: %s",
                        dirname,
                        strerror(errno));
        // Continue without device connection notifications
    }

    if (regcomp(&_glfw.linjs.regex, "^event[0-9]\\+$", 0) != 0)
    {
        _glfwInputError(GLFW_PLATFORM_ERROR, "Linux: Failed to compile regex");
        return GLFW_FALSE;
    }

    dir = opendir(dirname);
    if (dir)
    {
        struct dirent* entry;

        while ((entry = readdir(dir)))
        {
            regmatch_t match;

            if (regexec(&_glfw.linjs.regex, entry->d_name, 1, &match, 0) != 0)
                continue;

            const size_t length = strlen(dirname) + strlen(entry->d_name) + 1;
            char* path = calloc(length + 1, 1);

            snprintf(path, length + 1, "%s/%s", dirname, entry->d_name);

            if (openJoystickDevice(path))
                count++;

            free(path);
        }

        closedir(dir);
    }
    else
    {
        _glfwInputError(GLFW_PLATFORM_ERROR,
                        "Linux: Failed to open joystick device directory %s: %s",
                        dirname,
                        strerror(errno));
        // Continue with no joysticks detected
    }

    qsort(_glfw.joysticks, count, sizeof(_GLFWjoystick), compareJoysticks);
    return GLFW_TRUE;
}

// Close all opened joystick handles
//
void _glfwTerminateJoysticksLinux(void)
{
    int jid;

    for (jid = 0;  jid <= GLFW_JOYSTICK_LAST;  jid++)
    {
        _GLFWjoystick* js = _glfw.joysticks + jid;
        if (js->present)
            closeJoystick(js);
    }

    regfree(&_glfw.linjs.regex);

    if (_glfw.linjs.inotify > 0)
    {
        if (_glfw.linjs.watch > 0)
            inotify_rm_watch(_glfw.linjs.inotify, _glfw.linjs.watch);

        close(_glfw.linjs.inotify);
    }
}

void _glfwDetectJoystickConnectionLinux(void)
{
    ssize_t offset = 0;
    char buffer[16384];

    const ssize_t size = read(_glfw.linjs.inotify, buffer, sizeof(buffer));

    while (size > offset)
    {
        regmatch_t match;
        const struct inotify_event* e = (struct inotify_event*) (buffer + offset);

        if (regexec(&_glfw.linjs.regex, e->name, 1, &match, 0) == 0)
        {
            char path[20];
            snprintf(path, sizeof(path), "/dev/input/%s", e->name);

            if (e->mask & (IN_CREATE | IN_ATTRIB))
                openJoystickDevice(path);
            else if (e->mask & IN_DELETE)
            {
                int jid;

                for (jid = 0;  jid <= GLFW_JOYSTICK_LAST;  jid++)
                {
                    if (strcmp(_glfw.joysticks[jid].linjs.path, path) == 0)
                    {
                        closeJoystick(_glfw.joysticks + jid);
                        break;
                    }
                }
            }
        }

        offset += sizeof(struct inotify_event) + e->len;
    }
}


//////////////////////////////////////////////////////////////////////////
//////                       GLFW platform API                      //////
//////////////////////////////////////////////////////////////////////////

int _glfwPlatformPollJoystick(int jid, int mode)
{
    _GLFWjoystick* js = _glfw.joysticks + jid;

    // Read all queued events (non-blocking)
    for (;;)
    {
        struct input_event e;

        errno = 0;
        if (read(js->linjs.fd, &e, sizeof(e)) < 0)
        {
            // Reset the joystick slot if the device was disconnected
            if (errno == ENODEV)
                closeJoystick(js);

            break;
        }

        if (e.type == EV_KEY)
            handleKeyEvent(js, e.code, e.value);
        else if (e.type == EV_ABS)
            handleAbsEvent(js, e.code, e.value);
        else if (e.type == EV_SYN && e.code == SYN_DROPPED)
            // Refresh axes
            pollJoystick(js);
    }

    return js->present;
}