/* Copyright (c) 2017-2018, Feral Interactive All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Feral Interactive nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef CLIENT_GAMEMODE_H #define CLIENT_GAMEMODE_H /* * GameMode supports the following client functions * Requests are refcounted in the daemon * * int gamemode_request_start() - Request gamemode starts * 0 if the request was sent successfully * -1 if the request failed * * int gamemode_request_end() - Request gamemode ends * 0 if the request was sent successfully * -1 if the request failed * * int gamemode_query_status() - Query the current status of gamemode * 0 if gamemode is inactive * 1 if gamemode is active * 2 if gamemode is active and this client is registered * -1 if the query failed * * const char* gamemode_error_string() - Get an error string * returns a string describing any of the above errors */ #include #include #include #include #include #include #include static char internal_gamemode_client_error_string[512] = { 0 }; /** * Load libgamemode dynamically to dislodge us from most dependencies. * This allows clients to link and/or use this regardless of runtime. * See SDL2 for an example of the reasoning behind this in terms of * dynamic versioning as well. */ static volatile int internal_libgamemode_loaded = 1; /* Typedefs for the functions to load */ typedef int (*internal_gamemode_request_start)(void); typedef int (*internal_gamemode_request_end)(void); typedef int (*internal_gamemode_query_status)(void); typedef const char *(*internal_gamemode_error_string)(void); /* Storage for functors */ static internal_gamemode_request_start REAL_internal_gamemode_request_start = NULL; static internal_gamemode_request_end REAL_internal_gamemode_request_end = NULL; static internal_gamemode_query_status REAL_internal_gamemode_query_status = NULL; static internal_gamemode_error_string REAL_internal_gamemode_error_string = NULL; /** * Internal helper to perform the symbol binding safely. * * Returns 0 on success and -1 on failure */ __attribute__((always_inline)) static inline int internal_bind_libgamemode_symbol(void *handle, const char *name, void **out_func, size_t func_size) { void *symbol_lookup = NULL; char *dl_error = NULL; /* Safely look up the symbol */ symbol_lookup = dlsym(handle, name); dl_error = dlerror(); if (dl_error || !symbol_lookup) { snprintf(internal_gamemode_client_error_string, sizeof(internal_gamemode_client_error_string), "dlsym failed - %s", dl_error); return -1; } /* Have the symbol correctly, copy it to make it usable */ memcpy(out_func, &symbol_lookup, func_size); return 0; } /** * Loads libgamemode and needed functions * * Returns 0 on success and -1 on failure */ __attribute__((always_inline)) static inline int internal_load_libgamemode(void) { /* We start at 1, 0 is a success and -1 is a fail */ if (internal_libgamemode_loaded != 1) { return internal_libgamemode_loaded; } /* Anonymous struct type to define our bindings */ struct binding { const char *name; void **functor; size_t func_size; bool required; } bindings[] = { { "real_gamemode_request_start", (void **)&REAL_internal_gamemode_request_start, sizeof(REAL_internal_gamemode_request_start), true }, { "real_gamemode_request_end", (void **)&REAL_internal_gamemode_request_end, sizeof(REAL_internal_gamemode_request_end), true }, { "real_gamemode_query_status", (void **)&REAL_internal_gamemode_query_status, sizeof(REAL_internal_gamemode_query_status), false }, { "real_gamemode_error_string", (void **)&REAL_internal_gamemode_error_string, sizeof(REAL_internal_gamemode_error_string), true }, }; void *libgamemode = NULL; /* Try and load libgamemode */ libgamemode = dlopen("libgamemode.so.0", RTLD_NOW); if (!libgamemode) { /* Attempt to load unversioned library for compatibility with older * versions (as of writing, there are no ABI changes between the two - * this may need to change if ever ABI-breaking changes are made) */ libgamemode = dlopen("libgamemode.so", RTLD_NOW); if (!libgamemode) { snprintf(internal_gamemode_client_error_string, sizeof(internal_gamemode_client_error_string), "dlopen failed - %s", dlerror()); internal_libgamemode_loaded = -1; return -1; } } /* Attempt to bind all symbols */ for (size_t i = 0; i < sizeof(bindings) / sizeof(bindings[0]); i++) { struct binding *binder = &bindings[i]; if (internal_bind_libgamemode_symbol(libgamemode, binder->name, binder->functor, binder->func_size) != 0 && binder->required) { internal_libgamemode_loaded = -1; return -1; }; } /* Success */ internal_libgamemode_loaded = 0; return 0; } /** * Redirect to the real libgamemode */ __attribute__((always_inline)) static inline const char *gamemode_error_string(void) { /* If we fail to load the system gamemode, or we have an error string already, return our error * string instead of diverting to the system version */ if (internal_load_libgamemode() < 0 || internal_gamemode_client_error_string[0] != '\0') { return internal_gamemode_client_error_string; } return REAL_internal_gamemode_error_string(); } /** * Redirect to the real libgamemod * Allow automatically requesting game mode * Also prints errors as they happen. */ #ifdef GAMEMODE_AUTO __attribute__((constructor)) #else __attribute__((always_inline)) static inline #endif int gamemode_request_start(void) { /* Need to load gamemode */ if (internal_load_libgamemode() < 0) { #ifdef GAMEMODE_AUTO fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string()); #endif return -1; } if (REAL_internal_gamemode_request_start() < 0) { #ifdef GAMEMODE_AUTO fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string()); #endif return -1; } return 0; } /* Redirect to the real libgamemode */ #ifdef GAMEMODE_AUTO __attribute__((destructor)) #else __attribute__((always_inline)) static inline #endif int gamemode_request_end(void) { /* Need to load gamemode */ if (internal_load_libgamemode() < 0) { #ifdef GAMEMODE_AUTO fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string()); #endif return -1; } if (REAL_internal_gamemode_request_end() < 0) { #ifdef GAMEMODE_AUTO fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string()); #endif return -1; } return 0; } /* Redirect to the real libgamemode */ __attribute__((always_inline)) static inline int gamemode_query_status(void) { /* Need to load gamemode */ if (internal_load_libgamemode() < 0) { return -1; } if (REAL_internal_gamemode_query_status == NULL) { snprintf(internal_gamemode_client_error_string, sizeof(internal_gamemode_client_error_string), "gamemode_query_status missing (older host?)"); return -1; } return REAL_internal_gamemode_query_status(); } #endif // CLIENT_GAMEMODE_H