Rework file system API to support different backends

src/sys.zig

@@ -70,8 +70,6 @@ pub const EventLoop = opaque {
         ///
         ///
         const InitError = error {
-            DataFileNotFound,
-            DataFileInvalid,
             OutOfSemaphores,
             OutOfMutexes,
             OutOfMemory,
@@ -118,7 +116,6 @@ pub const EventLoop = opaque {
                 }
             }
 
-            ext.SDL_free(implementation.user_prefix.ptr);
             ext.SDL_DestroyMutex(implementation.file_system_mutex);
             ext.SDL_DestroySemaphore(implementation.file_system_semaphore);
         }
@@ -148,19 +145,11 @@ pub const EventLoop = opaque {
         ///
         ///
         fn init() InitError!Implementation {
-            const data_file_access = @ptrCast(*FileAccess,
-                ext.SDL_RWFromFile("./data.tar", "r+") orelse return error.DataFileNotFound);
-
             return Implementation{
-                .data_archive = tar.Archive.init(data_file_access) catch |err| switch (err) {
-                    error.Invalid, error.Inaccessible => return error.DataFileInvalid,
-                },
-
                 .file_system_semaphore = ext.SDL_CreateSemaphore(0)
                     orelse return error.OutOfSemaphores,
 
                 .file_system_mutex = ext.SDL_CreateMutex() orelse return error.OutOfMutexes,
-                .data_file = data_file_access,
                 .file_system_thread = null,
             };
         }
@@ -177,14 +166,16 @@ pub const EventLoop = opaque {
 
             while (true) {
                 while (implementation.file_system_messages) |messages| {
+                    const root = @import("./sys.zig");
+
                     switch (messages.request) {
                         .exit => return 0,
-                        .log => |*log_request| .log(log_request.kind, log_request.message),
+                        .log => |*log_request| root.log(log_request.kind, log_request.message),
 
                         .open => |*open_request| open_request.result =
-                            .open(open_request.mode, open_request.file_system_path),
+                            root.open(open_request.mode, open_request.file_system_path.*),
 
-                        .close => |*close_request| .close(close_request.file_access),
+                        .close => |*close_request| root.close(close_request.file_access),
 
                         .read_file => |read_request| {
                             // TODO: Implement.
@@ -444,13 +435,17 @@ pub const FileSystem = struct {
     ///
     ///
     ///
-    pub const Root = struct {
+    pub const Root = union(enum) {
+        native: struct {
             prefix: []const u8,
+        },
+
+        tar: struct {},
 
         ///
         ///
         ///
-        pub fn joinedPath(root: Root, sequences: []const []const u8) PathError!Path {
+        pub fn joinedPath(root: *const Root, sequences: []const []const u8) PathError!Path {
             var path = Path{
                 .root = root,
                 .buffer = std.mem.zeroes([Path.max]u8),
@@ -609,8 +604,8 @@ pub const SeekOrigin = enum {
 ///
 ///
 pub fn close(file_access: *FileAccess) void {
-    if (!ext.SDL_RWclose(@ptrCast(*ext.SDL_RWops,
+    if (ext.SDL_RWclose(@ptrCast(*ext.SDL_RWops,
-        @alignCast(@alignOf(ext.SDL_RWops), file_access)))) {
+        @alignCast(@alignOf(ext.SDL_RWops), file_access))) != 0) {
 
         ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION,
             "Failed to close file - may have been already closed");
@@ -629,21 +624,21 @@ pub fn log(kind: LogKind, message: []const u8) void {
 ///
 ///
 pub fn open(mode: OpenMode, file_system_path: FileSystem.Path) OpenError!*FileAccess {
-    switch (file_system_path.file_system) {
+    switch (file_system_path.root.*) {
-        .data => {
+        .tar => {
-            // TODO: Implement
+            // TODO: Implement.
             return error.NotFound;
         },
 
-        .user => {
+        .native => |native| {
             var path_buffer = std.mem.zeroes([4096]u8);
             var path = stack.Fixed(u8){.buffer = path_buffer[0 .. ]};
 
-            path.pushAll("/home/kayomn/.local/share") catch return error.NotFound;
+            path.pushAll(native.prefix) catch return error.NotFound;
 
             if (file_system_path.write(path.writer())) return error.NotFound;
 
-            return @ptrCast(*FileAccess, ext.SDL_RWFromFile(&path_buffer, switch (mode) {
+            return @ptrCast(?*FileAccess, ext.SDL_RWFromFile(&path_buffer, switch (mode) {
                 .readonly => "rb",
                 .overwrite => "wb",
                 .append => "ab",
@@ -689,25 +684,20 @@ pub fn runGraphics(comptime Errors: anytype, comptime run: GraphicsRunner(Errors
 
     defer ext.SDL_DestroyRenderer(renderer);
 
-    var file_system = FileSystem{
+    const user_prefix = ext.SDL_GetPrefPath("ona", "ona") orelse {
-        .user = .{.prefix = create_pref_path: {
-            const path = ext.SDL_GetPrefPath("ona", "ona") orelse {
         ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION,
             "Failed to load user path");
 
         return error.InitFailure;
     };
 
-            break: create_pref_path path[0 .. std.mem.len(path)];
+    defer ext.SDL_free(user_prefix);
-        }},
 
-        .data = .{.prefix = "./"},
+    var file_system = FileSystem{
+        .user = .{.native = .{.prefix = user_prefix[0 .. std.mem.len(user_prefix)]}},
+        .data = .{.tar = .{}},
     };
 
-    defer {
-        ext.SDL_free(file_system.user.prefix);
-    }
-
     var event_loop = EventLoop.Implementation.init() catch |err| {
         switch (err) {
             error.OutOfMemory => ext.SDL_LogCritical(ext.SDL_LOG_CATEGORY_APPLICATION,
@@ -743,5 +733,6 @@ pub fn runGraphics(comptime Errors: anytype, comptime run: GraphicsRunner(Errors
         },
     };
 
-    return run(@ptrCast(*EventLoop, &event_loop), @ptrCast(*GraphicsContext, &graphics_context));
+    return run(@ptrCast(*EventLoop, &event_loop), &file_system,
+        @ptrCast(*GraphicsContext, &graphics_context));
 }