Add plugin dependencies

README.md

@@ -6,7 +6,7 @@ You might want to include the game.h file from plugins/game/game.h. Have a look
 
 Controls: WASD to move, Q to quit.
 
-To build the loader and the plugins in the plugins/ folder, simply type `make` or `make all`. There are separate targets for the loader (`dungeon`) and the plugins. All Makefiles that are placed in plugin directories, so you might want to include a makefile in your plugin. The plugins target simply depends on ${PLUGINS}, so just add things to this in your plugin Makefile to add them to the plugins target (usually your plugin.so) 
+To build the loader and the plugins in the plugins/ folder, simply type `make` or `make all`. There are separate targets for the loader (`dungeon`) and the plugins. All Makefiles that are placed in plugin directories, so you might want to include a makefile in your plugin. The plugins target simply depends on ${PLUGINS}, so just add things to this in your plugin Makefile to add them to the plugins target (usually your plugin.so)
 To run the loader, type `./dungeon`. It will load all plugins including the game itself dynamically and run the game.
 
-Plugins are loaded in alphabethical order, with the exception of the game plugin that is loaded first. If you want to make a plugin that depends on another plugin, make sure the other plugin is loaded first by setting the name of your plugin accordingly. A cleaner solution to this is coming soon.
+If you want to make a plugin that depends on another plugin (including the game itself), make sure to depend on that plugin. To add dependencies to a plugin, create a file named dependencies.txt in the plugin folder. Put the names of all plugins your plugin depends on into that file. You can use spaces or newlines as seperators.

dungeon.c

@@ -5,20 +5,63 @@
 #include <dirent.h>
 #include <string.h>
 
+struct plugin_list
+{
+	char *name;
+	void *handle;
+	struct plugin_list *next;
+};
+
+struct plugin_list *plugins = NULL;
+struct plugin_list **next = &plugins;
+
 static void *load_plugin(const char *name)
 {
+	for (struct plugin_list *ptr = plugins; ptr != NULL; ptr = ptr->next) {
+		if (strcmp(ptr->name, name) == 0)
+			return ptr->handle;
+	}
+
 	size_t len = strlen(name);
-	char filename[1 + 1 + 7 + 1 + len + 1 + len + 1 + 2 + 1];
-	sprintf(filename, "./plugins/%s/%s.so", name, name);
 
-	void *plugin_handle = dlmopen(LM_ID_BASE, filename, RTLD_NOW | RTLD_GLOBAL);
+	char dependency_file_name[1 + 1 + 7 + 1 + len + 1 + 12 + 1 + 3 + 1];
+	sprintf(dependency_file_name, "./plugins/%s/dependencies.txt", name);
 
-	if (! plugin_handle) {
+	FILE *dependency_file = fopen(dependency_file_name, "r");
+
+	if (dependency_file) {
+		char dependency[BUFSIZ];
+
+		while (fscanf(dependency_file, "%s", dependency) != EOF)
+			load_plugin(dependency);
+
+		fclose(dependency_file);
+	}
+
+	char library_name[1 + 1 + 7 + 1 + len + 1 + len + 1 + 2 + 1];
+	sprintf(library_name, "./plugins/%s/%s.so", name, name);
+
+	void *handle = dlmopen(LM_ID_BASE, library_name, RTLD_NOW | RTLD_GLOBAL);
+
+	if (! handle) {
 		printf("%s\n", dlerror());
 		exit(EXIT_FAILURE);
 	}
 
-	return plugin_handle;
+	char *namebuf = malloc(len + 1);
+	strcpy(namebuf, name);
+
+	*next = malloc(sizeof(struct plugin_list));
+	**next = (struct plugin_list) {
+		.name = namebuf,
+		.handle = handle,
+		.next = NULL,
+	};
+	next = &(*next)->next;
+
+	printf("Loaded %s\n", name);
+
+	return handle;
 }
 
 int main()
@@ -30,11 +73,9 @@ int main()
 
 	struct dirent *dp;
 
-	while (dp = readdir(dir)) {
-		if (dp->d_name[0] != '.' && strcmp(dp->d_name, "game") != 0) {
+	while (dp = readdir(dir))
+		if (dp->d_name[0] != '.')
 			load_plugin(dp->d_name);
-		}
-	}
 
 	closedir(dir);
 

plugins/apple/dependencies.txt

@@ -0,0 +1 @@
+game

plugins/fireball/dependencies.txt

@@ -0,0 +1 @@
+game

plugins/monster/dependencies.txt

@@ -0,0 +1 @@
+game

plugins/movement/dependencies.txt

@@ -0,0 +1 @@
+game