Added support for the preferences path and writing there

src/binocle/core/binocle_sdl.c

@@ -288,4 +288,13 @@ bool binocle_sdl_directory_exists(const char *path) {
   else
     binocle_log_warning( "%s is not a directory\n", path );
   return false;
+}
+
+
+char *binocle_sdl_preferences_dir(const char *org, const char *app) {
+  char *binocle_preferences_dir = SDL_GetPrefPath(org, app);
+  if (binocle_preferences_dir == NULL) {
+    return "";
+  }
+  return binocle_preferences_dir;
 }

src/binocle/core/binocle_sdl.h

@@ -102,6 +102,15 @@ char *binocle_sdl_assets_dir();
  */
 bool binocle_sdl_filename_ends_with(const char *str, const char *suffix);
 
+/**
+ * \brief Returns the path where files can be written.
+ * This is specific per platform.
+ * @param org the name of the organization
+ * @param app the name of the application
+ * @return the path where files can be written. An empty string if the path can't be found.
+ */
+char *binocle_sdl_preferences_dir(const char *org, const char *app);
+
 char *binocle_sdl_str_replace(char *orig, char *rep, char *with);
 bool binocle_sdl_file_exists(const char *filename);
 bool binocle_sdl_directory_exists(const char *path);

src/binocle/core/binocle_sdl_wrap.c

@@ -27,10 +27,29 @@ int l_binocle_sdl_load_text_file(lua_State *L) {
   // TODO: keep track of the buffer to free it when done
   return 1;
 }
+
+int l_binocle_sdl_save_text_file(lua_State *L) {
+  const char *filename = luaL_checkstring(L, 1);
+  const char *buffer = luaL_checkstring(L, 2);
+  size_t buffer_size = (size_t)luaL_checknumber(L, 3);
+  bool res = binocle_sdl_write_text_file(filename, buffer, buffer_size);
+  return 1;
+}
+
+int l_binocle_sdl_preferences_dir(lua_State *L) {
+  const char *org = luaL_checkstring(L, 1);
+  const char *app = luaL_checkstring(L, 2);
+  char *preferences_dir = binocle_sdl_preferences_dir(org, app);
+  lua_pushstring(L, preferences_dir);
+  return 1;
+}
+
 static const struct luaL_Reg sdl [] = {
   {"assets_dir", l_binocle_sdl_assets_dir},
+  {"preferences_dir", l_binocle_sdl_preferences_dir},
   {"get_last_modification_time", l_binocle_sdl_get_last_modification_time},
   {"load_text_file", l_binocle_sdl_load_text_file},
+  {"save_text_file", l_binocle_sdl_save_text_file},
   {NULL, NULL}
 };