Refactor directory file-system abstraction in app library

source/app.cpp

@@ -12,6 +12,10 @@ import coral.math;
 import oar;
 
 namespace app {
+	struct directory : public coral::fs {
+		virtual coral::slice<char const> native_path() const = 0;
+	};
+
 	struct file_reader : public coral::file_reader {
 		enum class [[nodiscard]] close_result {
 			ok,
@@ -25,8 +29,8 @@ namespace app {
 			not_found,
 		};
 
-		file_reader(coral::fs * fs) : rw_ops{nullptr} {
-			this->fs = fs;
+		file_reader(directory * file_directory) : rw_ops{nullptr} {
+			this->file_directory = file_directory;
 		}
 
 		close_result close() {
@@ -48,7 +52,22 @@ namespace app {
 				default: coral::unreachable();
 			}
 
-			this->rw_ops = ::SDL_RWFromFile(reinterpret_cast<char const *>(this->path_buffer), "r");
+			// Windows system path max is something like 512 bytes (depending on the version) and
+			// on Linux it's 4096.
+			coral::fixed_buffer<4096> path_buffer{0};
+
+			if (!path_buffer.write(this->file_directory->native_path().as_bytes()).is_ok())
+				// What kind of directory path is being used that would be longer than 4096 bytes?
+				return open_result::not_found;
+
+			if (!path_buffer.write(file_path.as_slice().as_bytes()).is_ok())
+				// This happening is still implausible but slightly more reasonable?
+				return open_result::not_found;
+
+			// No room for zero terminator.
+			if (path_buffer.is_full()) return open_result::not_found;
+
+			this->rw_ops = ::SDL_RWFromFile(reinterpret_cast<char const *>(path_buffer.begin()), "r");
 
 			if (this->rw_ops == nullptr) return open_result::not_found;
 
@@ -88,17 +107,13 @@ namespace app {
 		}
 
 		private:
-		static constexpr coral::usize path_max{4096};
-
-		coral::u8 path_buffer[path_max];
-
-		coral::fs * fs;
+		directory * file_directory;
 
 		::SDL_RWops * rw_ops;
 	};
 }
 
-struct base_directory : public coral::fs {
+struct base_directory : public app::directory {
 	base_directory() : directory_path{} {
 		char * const path{::SDL_GetBasePath()};
 
@@ -121,6 +136,10 @@ struct base_directory : public coral::fs {
 		::SDL_free(this->directory_path.begin());
 	}
 
+	coral::slice<const char> native_path() const override {
+		return this->directory_path;
+	}
+
 	void read_file(coral::path const & file_path, coral::callable<void(coral::file_reader &)> const & then) override {
 		if (this->directory_path.length == 0) return;
 
@@ -141,7 +160,7 @@ struct base_directory : public coral::fs {
 	coral::slice<char> directory_path;
 };
 
-struct user_directory : public coral::fs {
+struct user_directory : public app::directory {
 	user_directory(coral::path const & title) : directory_path{} {
 		char * const path{::SDL_GetPrefPath("ona", title.begin())};
 
@@ -164,6 +183,10 @@ struct user_directory : public coral::fs {
 		::SDL_free(this->directory_path.begin());
 	}
 
+	coral::slice<const char> native_path() const override {
+		return this->directory_path;
+	}
+
 	void read_file(coral::path const & file_path, coral::callable<void(coral::file_reader &)> const & then) override {
 		if (this->directory_path.length == 0) return;
 
@@ -192,10 +215,11 @@ export namespace app {
 	};
 
 	struct system {
-		system(coral::path const & title) : res{&base, "base_directory.oar"}, user{title} {}
+		system(coral::path const & title) : user_directory{title},
+			res_archive{&base_directory, res_archive_path} {}
 
-		coral::fs & base_fs() {
-			return this->base;
+		app::directory & base_dir() {
+			return this->base_directory;
 		}
 
 		bool poll() {
@@ -209,7 +233,7 @@ export namespace app {
 		}
 
 		coral::fs & res_fs() {
-			return this->res;
+			return this->res_archive;
 		}
 
 		void log(app::log_level level, coral::slice<char const> const & message) {
@@ -224,11 +248,13 @@ export namespace app {
 			return this->allocator;
 		}
 
-		coral::fs & user_fs() {
-			return this->user;
+		app::directory & user_dir() {
+			return this->user_directory;
 		}
 
 		private:
+		static constexpr coral::path res_archive_path{"base.oar"};
+
 		::SDL_Event sdl_event;
 
 		struct : public coral::allocator {
@@ -241,11 +267,11 @@ export namespace app {
 			}
 		} allocator;
 
-		base_directory base;
+		struct base_directory base_directory;
 
-		user_directory user;
+		struct user_directory user_directory;
 
-		oar::archive res;
+		oar::archive res_archive;
 	};
 
 	struct graphics {