src/core/linux/SDL_dbus.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.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 "../../SDL_internal.h"
#include "SDL_dbus.h"

#if !SDL_THREADS_DISABLED
#include <sys/time.h>
#include <sys/resource.h>
#endif

#if SDL_USE_LIBDBUS
/* we never link directly to libdbus. */
#include "SDL_loadso.h"
static const char *dbus_library = "libdbus-1.so.3";
static void *dbus_handle = NULL;
static unsigned int screensaver_cookie = 0;
static SDL_DBusContext dbus;

static int
LoadDBUSSyms(void)
{
    #define SDL_DBUS_SYM2(x, y) \
        if (!(dbus.x = SDL_LoadFunction(dbus_handle, #y))) return -1
        
    #define SDL_DBUS_SYM(x) \
        SDL_DBUS_SYM2(x, dbus_##x)

    SDL_DBUS_SYM(bus_get_private);
    SDL_DBUS_SYM(bus_register);
    SDL_DBUS_SYM(bus_add_match);
    SDL_DBUS_SYM(connection_open_private);
    SDL_DBUS_SYM(connection_set_exit_on_disconnect);
    SDL_DBUS_SYM(connection_get_is_connected);
    SDL_DBUS_SYM(connection_add_filter);
    SDL_DBUS_SYM(connection_try_register_object_path);
    SDL_DBUS_SYM(connection_send);
    SDL_DBUS_SYM(connection_send_with_reply_and_block);
    SDL_DBUS_SYM(connection_close);
    SDL_DBUS_SYM(connection_unref);
    SDL_DBUS_SYM(connection_flush);
    SDL_DBUS_SYM(connection_read_write);
    SDL_DBUS_SYM(connection_dispatch);
    SDL_DBUS_SYM(message_is_signal);
    SDL_DBUS_SYM(message_new_method_call);
    SDL_DBUS_SYM(message_append_args);
    SDL_DBUS_SYM(message_append_args_valist);
    SDL_DBUS_SYM(message_get_args);
    SDL_DBUS_SYM(message_get_args_valist);
    SDL_DBUS_SYM(message_iter_init);
    SDL_DBUS_SYM(message_iter_next);
    SDL_DBUS_SYM(message_iter_get_basic);
    SDL_DBUS_SYM(message_iter_get_arg_type);
    SDL_DBUS_SYM(message_iter_recurse);
    SDL_DBUS_SYM(message_unref);
    SDL_DBUS_SYM(error_init);
    SDL_DBUS_SYM(error_is_set);
    SDL_DBUS_SYM(error_free);
    SDL_DBUS_SYM(get_local_machine_id);
    SDL_DBUS_SYM(free);
    SDL_DBUS_SYM(free_string_array);
    SDL_DBUS_SYM(shutdown);

    #undef SDL_DBUS_SYM
    #undef SDL_DBUS_SYM2

    return 0;
}

static void
UnloadDBUSLibrary(void)
{
    if (dbus_handle != NULL) {
        SDL_UnloadObject(dbus_handle);
        dbus_handle = NULL;
    }
}

static int
LoadDBUSLibrary(void)
{
    int retval = 0;
    if (dbus_handle == NULL) {
        dbus_handle = SDL_LoadObject(dbus_library);
        if (dbus_handle == NULL) {
            retval = -1;
            /* Don't call SDL_SetError(): SDL_LoadObject already did. */
        } else {
            retval = LoadDBUSSyms();
            if (retval < 0) {
                UnloadDBUSLibrary();
            }
        }
    }

    return retval;
}

void
SDL_DBus_Init(void)
{
    if (!dbus.session_conn && LoadDBUSLibrary() != -1) {
        DBusError err;
        dbus.error_init(&err);
        dbus.session_conn = dbus.bus_get_private(DBUS_BUS_SESSION, &err);
        if (!dbus.error_is_set(&err)) {
            dbus.system_conn = dbus.bus_get_private(DBUS_BUS_SYSTEM, &err);
        }
        if (dbus.error_is_set(&err)) {
            dbus.error_free(&err);
            SDL_DBus_Quit();
            return;  /* oh well */
        }
        dbus.connection_set_exit_on_disconnect(dbus.system_conn, 0);
        dbus.connection_set_exit_on_disconnect(dbus.session_conn, 0);
    }
}

void
SDL_DBus_Quit(void)
{
    if (dbus.system_conn) {
        dbus.connection_close(dbus.system_conn);
        dbus.connection_unref(dbus.system_conn);
    }
    if (dbus.session_conn) {
        dbus.connection_close(dbus.session_conn);
        dbus.connection_unref(dbus.session_conn);
    }
/* Don't do this - bug 3950
   dbus_shutdown() is a debug feature which closes all global resources in the dbus library. Calling this should be done by the app, not a library, because if there are multiple users of dbus in the process then SDL could shut it down even though another part is using it.
*/
#if 0
    if (dbus.shutdown) {
        dbus.shutdown();
    }
#endif
    SDL_zero(dbus);
    UnloadDBUSLibrary();
}

SDL_DBusContext *
SDL_DBus_GetContext(void)
{
    if(!dbus_handle || !dbus.session_conn){
        SDL_DBus_Init();
    }
    
    if(dbus_handle && dbus.session_conn){
        return &dbus;
    } else {
        return NULL;
    }
}

static SDL_bool
SDL_DBus_CallMethodInternal(DBusConnection *conn, const char *node, const char *path, const char *interface, const char *method, va_list ap)
{
    SDL_bool retval = SDL_FALSE;

    if (conn) {
        DBusMessage *msg = dbus.message_new_method_call(node, path, interface, method);
        if (msg) {
            int firstarg;
            va_list ap_reply;
            va_copy(ap_reply, ap);  /* copy the arg list so we don't compete with D-Bus for it */
            firstarg = va_arg(ap, int);
            if ((firstarg == DBUS_TYPE_INVALID) || dbus.message_append_args_valist(msg, firstarg, ap)) {
                DBusMessage *reply = dbus.connection_send_with_reply_and_block(conn, msg, 300, NULL);
                if (reply) {
                    /* skip any input args, get to output args. */
                    while ((firstarg = va_arg(ap_reply, int)) != DBUS_TYPE_INVALID) {
                        /* we assume D-Bus already validated all this. */
                        { void *dumpptr = va_arg(ap_reply, void*); (void) dumpptr; }
                        if (firstarg == DBUS_TYPE_ARRAY) {
                            { const int dumpint = va_arg(ap_reply, int); (void) dumpint; }
                        }
                    }
                    firstarg = va_arg(ap_reply, int);
                    if ((firstarg == DBUS_TYPE_INVALID) || dbus.message_get_args_valist(reply, NULL, firstarg, ap_reply)) {
                        retval = SDL_TRUE;
                    }
                    dbus.message_unref(reply);
                }
            }
            va_end(ap_reply);
            dbus.message_unref(msg);
        }
    }

    return retval;
}

SDL_bool
SDL_DBus_CallMethodOnConnection(DBusConnection *conn, const char *node, const char *path, const char *interface, const char *method, ...)
{
    SDL_bool retval;
    va_list ap;
    va_start(ap, method);
    retval = SDL_DBus_CallMethodInternal(conn, node, path, interface, method, ap);
    va_end(ap);
    return retval;
}

SDL_bool
SDL_DBus_CallMethod(const char *node, const char *path, const char *interface, const char *method, ...)
{
    SDL_bool retval;
    va_list ap;
    va_start(ap, method);
    retval = SDL_DBus_CallMethodInternal(dbus.session_conn, node, path, interface, method, ap);
    va_end(ap);
    return retval;
}

static SDL_bool
SDL_DBus_CallVoidMethodInternal(DBusConnection *conn, const char *node, const char *path, const char *interface, const char *method, va_list ap)
{
    SDL_bool retval = SDL_FALSE;

    if (conn) {
        DBusMessage *msg = dbus.message_new_method_call(node, path, interface, method);
        if (msg) {
            int firstarg = va_arg(ap, int);
            if ((firstarg == DBUS_TYPE_INVALID) || dbus.message_append_args_valist(msg, firstarg, ap)) {
                if (dbus.connection_send(conn, msg, NULL)) {
                    dbus.connection_flush(conn);
                    retval = SDL_TRUE;
                }
            }

            dbus.message_unref(msg);
        }
    }

    return retval;
}

SDL_bool
SDL_DBus_CallVoidMethodOnConnection(DBusConnection *conn, const char *node, const char *path, const char *interface, const char *method, ...)
{
    SDL_bool retval;
    va_list ap;
    va_start(ap, method);
    retval = SDL_DBus_CallVoidMethodInternal(conn, node, path, interface, method, ap);
    va_end(ap);
    return retval;
}

SDL_bool
SDL_DBus_CallVoidMethod(const char *node, const char *path, const char *interface, const char *method, ...)
{
    SDL_bool retval;
    va_list ap;
    va_start(ap, method);
    retval = SDL_DBus_CallVoidMethodInternal(dbus.session_conn, node, path, interface, method, ap);
    va_end(ap);
    return retval;
}

SDL_bool
SDL_DBus_QueryPropertyOnConnection(DBusConnection *conn, const char *node, const char *path, const char *interface, const char *property, const int expectedtype, void *result)
{
    SDL_bool retval = SDL_FALSE;

    if (conn) {
        DBusMessage *msg = dbus.message_new_method_call(node, path, "org.freedesktop.DBus.Properties", "Get");
        if (msg) {
            if (dbus.message_append_args(msg, DBUS_TYPE_STRING, &interface, DBUS_TYPE_STRING, &property, DBUS_TYPE_INVALID)) {
                DBusMessage *reply = dbus.connection_send_with_reply_and_block(conn, msg, 300, NULL);
                if (reply) {
                    DBusMessageIter iter, sub;
                    dbus.message_iter_init(reply, &iter);
                    if (dbus.message_iter_get_arg_type(&iter) == DBUS_TYPE_VARIANT) {
                        dbus.message_iter_recurse(&iter, &sub);
                        if (dbus.message_iter_get_arg_type(&sub) == expectedtype) {
                            dbus.message_iter_get_basic(&sub, result);
                            retval = SDL_TRUE;
                        }
                    }
                    dbus.message_unref(reply);
                }
            }
            dbus.message_unref(msg);
        }
    }

    return retval;
}

SDL_bool
SDL_DBus_QueryProperty(const char *node, const char *path, const char *interface, const char *property, const int expectedtype, void *result)
{
    return SDL_DBus_QueryPropertyOnConnection(dbus.session_conn, node, path, interface, property, expectedtype, result);
}


void
SDL_DBus_ScreensaverTickle(void)
{
    SDL_DBus_CallVoidMethod("org.gnome.ScreenSaver", "/org/gnome/ScreenSaver", "org.gnome.ScreenSaver", "SimulateUserActivity", DBUS_TYPE_INVALID);
}

SDL_bool
SDL_DBus_ScreensaverInhibit(SDL_bool inhibit)
{
    if ( (inhibit && (screensaver_cookie != 0)) || (!inhibit && (screensaver_cookie == 0)) ) {
        return SDL_TRUE;
    } else {
        const char *node = "org.freedesktop.ScreenSaver";
        const char *path = "/org/freedesktop/ScreenSaver";
        const char *interface = "org.freedesktop.ScreenSaver";

        if (inhibit) {
            const char *app = "My SDL application";
            const char *reason = "Playing a game";
            if (!SDL_DBus_CallMethod(node, path, interface, "Inhibit",
                    DBUS_TYPE_STRING, &app, DBUS_TYPE_STRING, &reason, DBUS_TYPE_INVALID,
                    DBUS_TYPE_UINT32, &screensaver_cookie, DBUS_TYPE_INVALID)) {
                return SDL_FALSE;
            }
            return (screensaver_cookie != 0) ? SDL_TRUE : SDL_FALSE;
        } else {
            if (!SDL_DBus_CallVoidMethod(node, path, interface, "UnInhibit", DBUS_TYPE_UINT32, &screensaver_cookie, DBUS_TYPE_INVALID)) {
                return SDL_FALSE;
            }
            screensaver_cookie = 0;
        }
    }

    return SDL_TRUE;
}

#if !SDL_THREADS_DISABLED
/* d-bus queries to org.freedesktop.RealtimeKit1. */
#define RTKIT_DBUS_NODE "org.freedesktop.RealtimeKit1"
#define RTKIT_DBUS_PATH "/org/freedesktop/RealtimeKit1"
#define RTKIT_DBUS_INTERFACE "org.freedesktop.RealtimeKit1"

static pthread_once_t rtkit_initialize_once = PTHREAD_ONCE_INIT;
static Sint32 rtkit_min_nice_level = -20;

static void
rtkit_initialize()
{
    SDL_DBusContext *dbus = SDL_DBus_GetContext();

    /* Try getting minimum nice level: this is often greater than PRIO_MIN (-20). */
    if (!dbus || !SDL_DBus_QueryPropertyOnConnection(dbus->system_conn, RTKIT_DBUS_NODE, RTKIT_DBUS_PATH, RTKIT_DBUS_INTERFACE, "MinNiceLevel",
                                            DBUS_TYPE_INT32, &rtkit_min_nice_level)) {
        rtkit_min_nice_level = -20;
    }
}

static SDL_bool
rtkit_setpriority(pid_t thread, int nice_level)
{
    Uint64 ui64 = (Uint64)thread;
    Sint32 si32 = (Sint32)nice_level;
    SDL_DBusContext *dbus = SDL_DBus_GetContext();

    pthread_once(&rtkit_initialize_once, rtkit_initialize);

    if (si32 < rtkit_min_nice_level)
        si32 = rtkit_min_nice_level;

    if (!dbus || !SDL_DBus_CallMethodOnConnection(dbus->system_conn,
            RTKIT_DBUS_NODE, RTKIT_DBUS_PATH, RTKIT_DBUS_INTERFACE, "MakeThreadHighPriority",
            DBUS_TYPE_UINT64, &ui64, DBUS_TYPE_INT32, &si32, DBUS_TYPE_INVALID,
            DBUS_TYPE_INVALID)) {
        return SDL_FALSE;
    }
    return SDL_TRUE;
}
#endif

#endif

/* this is a public symbol, so it has to exist even if threads are disabled. */
int
SDL_LinuxSetThreadPriority(Sint64 threadID, int priority)
{
#if SDL_THREADS_DISABLED
    return SDL_Unsupported();
#else
    if (setpriority(PRIO_PROCESS, (id_t)threadID, priority) == 0) {
        return 0;
    }

#if SDL_USE_LIBDBUS
    /* Note that this fails if you're trying to set high priority
       and you don't have root permission. BUT DON'T RUN AS ROOT!

       You can grant the ability to increase thread priority by
       running the following command on your application binary:
          sudo setcap 'cap_sys_nice=eip' <application>

       Let's try setting priority with RealtimeKit...

       README and sample code at: http://git.0pointer.net/rtkit.git
    */
    if (rtkit_setpriority((pid_t)threadID, priority)) {
        return 0;
    }
#endif

    return SDL_SetError("setpriority() failed");
#endif
}

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