twn_textures.c: support for .so rodata inference

src/game_object/twn_linux_game_object.c

@@ -0,0 +1,149 @@
+#include "twn_game_object_c.h"
+#include "twn_engine_context_c.h"
+
+#include <x-watcher.h>
+#include <SDL2/SDL.h>
+
+#include <dlfcn.h>
+
+
+#define GAME_OBJECT_PATH "./libgame.so"
+#define MODIFIED_TICKS_MERGED 10
+
+
+static void (*game_tick_callback)(void);
+static void (*game_end_callback)(void);
+
+static x_watcher *watcher;
+static void *handle = NULL;
+
+static uint64_t last_tick_modified;
+static bool loaded_after_modification = true;
+static SDL_mutex *lock;
+
+
+static void load_game_object(void) {
+    /* needs to be closed otherwise symbols aren't resolved again */
+    if (handle) {
+        dlclose(handle);
+        handle = NULL;
+        game_tick_callback = NULL;
+        game_end_callback = NULL;
+    }
+
+    void *new_handle = dlopen(GAME_OBJECT_PATH, RTLD_LAZY);
+    if (!new_handle) {
+        log_critical("Hot Reload Error: Cannot open game code shared object (%s)", dlerror());
+        goto ERR_OPENING_SO;
+    }
+
+#pragma GCC diagnostic push 
+#pragma GCC diagnostic ignored "-Wpedantic"
+
+    game_tick_callback = (void (*)(void))dlsym(new_handle, "game_tick");
+    if (!game_tick_callback) {
+        CRY("Hot Reload Error", "game_tick_callback() symbol wasn't found");
+        goto ERR_GETTING_PROC;
+    }
+
+    game_end_callback = (void (*)(void))dlsym(new_handle, "game_end");
+    if (!game_end_callback) {
+        CRY("Hot Reload Error", "game_end_callback() symbol wasn't found");
+        goto ERR_GETTING_PROC;
+    }
+
+#pragma GCC diagnostic pop
+
+    handle = new_handle;
+
+    if (ctx.game.tick_count != 0)
+        log_info("Game object was reloaded\n");
+
+    return;
+
+ERR_GETTING_PROC:
+    dlclose(new_handle);
+    game_tick_callback = NULL;
+    game_end_callback = NULL;
+
+ERR_OPENING_SO:
+    SDL_UnlockMutex(lock);
+
+}
+
+static void watcher_callback(XWATCHER_FILE_EVENT event,
+                             const char *path,
+                             int context,
+                             void *data)
+{
+    (void)context;
+    (void)path;
+    (void)data;
+
+    switch(event) {
+        case XWATCHER_FILE_MODIFIED:
+            SDL_LockMutex(lock);
+            last_tick_modified = ctx.game.tick_count;
+            loaded_after_modification = false;
+            SDL_UnlockMutex(lock);
+            break;
+
+        default:
+            break;
+    }
+}
+
+
+void game_object_load(void) {
+    watcher = xWatcher_create();
+
+    xWatcher_reference dir;
+    dir.path = GAME_OBJECT_PATH;
+    dir.callback_func = watcher_callback;
+
+    xWatcher_appendFile(watcher, &dir);
+    xWatcher_start(watcher);
+
+    lock = SDL_CreateMutex();
+    load_game_object();
+}
+
+
+void game_object_unload(void) {
+    game_end_callback();
+    xWatcher_destroy(watcher);
+    watcher = NULL;
+    dlclose(handle);
+    handle = NULL;
+    game_tick_callback = NULL;
+    game_end_callback = NULL;
+    SDL_DestroyMutex(lock);
+}
+
+
+bool game_object_try_reloading(void) {
+    bool result = false;
+
+    /* only load the modified library after some time, as compilers make a lot of modifications */
+    SDL_LockMutex(lock);
+    if (ctx.game.tick_count - last_tick_modified > MODIFIED_TICKS_MERGED &&
+            !loaded_after_modification) {
+        load_game_object();
+        loaded_after_modification = true;
+        result = true;
+    } SDL_UnlockMutex(lock);
+
+    return result;
+}
+
+
+void game_object_tick(void) {
+    game_tick_callback();
+}
+
+void *game_object_get_game_tick_address(void) {
+#pragma GCC diagnostic push 
+#pragma GCC diagnostic ignored "-Wpedantic"
+    return (void *)&game_tick_callback;
+#pragma GCC diagnostic pop
+}