fix: general bug fixes

1) prevent integer overflow if the PC is less than 0x0000_0004
2) gracefully exit when gdb gracefully exits
3) rename server to socket in Server.zig

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "lib/zig-network"]
-	path = lib/zig-network
-	url = https://github.com/MasterQ32/zig-network

build.zig

@@ -1,50 +1,54 @@
 const std = @import("std");
-const CompileStep = std.Build.CompileStep;
-
-fn path(comptime suffix: []const u8) []const u8 {
-    if (suffix[0] == '/') @compileError("expected a relative path");
-    return comptime (std.fs.path.dirname(@src().file) orelse ".") ++ std.fs.path.sep_str ++ suffix;
-}
-
-pub fn getModule(b: *std.Build) *std.build.Module {
-    // https://github.com/MasterQ32/zig-network
-    const network = b.createModule(.{ .source_file = .{ .path = path("lib/zig-network/network.zig") } });
-
-    return b.createModule(.{
-        .source_file = .{ .path = path("src/lib.zig") },
-        .dependencies = &.{.{ .name = "network", .module = network }},
-    });
-}
 
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
 pub fn build(b: *std.Build) void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
     const target = b.standardTargetOptions(.{});
-    // const optimize = b.standardOptimizeOption(.{});
 
-    // -- Library --
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
+    const optimize = b.standardOptimizeOption(.{});
 
-    const lib_test = b.addTest(.{
+    _ = b.addModule("gdbstub", .{
+        .source_file = .{ .path = "src/lib.zig" },
+        .dependencies = &.{},
+    });
+
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const lib_tests = b.addTest(.{
         .root_source_file = .{ .path = "src/lib.zig" },
         .target = target,
+        .optimize = optimize,
     });
 
-    const test_step = b.step("test", "Run Library Tests");
-    test_step.dependOn(&lib_test.step);
+    const run_lib_tests = b.addRunArtifact(lib_tests);
 
-    // -- Executable --
-
-    // const exe = b.addExecutable(.{
-    //     .name = "gdbserver",
-    //     .root_source_file = .{ .path = "src/main.zig" },
-    //     .target = target,
-    //     .optimize = optimize,
-    // });
-    // link(exe);
-    // exe.install();
-
-    // const run_cmd = exe.run();
-    // run_cmd.step.dependOn(b.getInstallStep());
-    // if (b.args) |args| run_cmd.addArgs(args);
-
-    // const run_step = b.step("run", "Run the app");
-    // run_step.dependOn(&run_cmd.step);
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build test`
+    // This will evaluate the `test` step rather than the default, which is "install".
+    const test_step = b.step("test", "Run library tests");
+    test_step.dependOn(&run_lib_tests.step);
+}
+
+pub fn module(b: *std.Build) *std.Build.Module {
+    return b.createModule(.{
+        .source_file = .{ .path = path("/src/lib.zig") },
+        .dependencies = &.{},
+    });
+}
+
+// https://github.com/MasterQ32/SDL.zig/blob/4d565b54227b862c1540719e0e21a36d649e87d5/build.zig#L114-L120
+fn path(comptime suffix: []const u8) []const u8 {
+    if (suffix[0] != '/') @compileError("relToPath requires an absolute path!");
+    return comptime blk: {
+        const root_dir = std.fs.path.dirname(@src().file) orelse ".";
+        break :blk root_dir ++ suffix;
+    };
 }

build.zig.zon

@@ -0,0 +1,5 @@
+.{
+    .name = "zba-gdbstub",
+    .version = "0.1.0",
+    .dependencies = .{},
+}

src/Packet.zig

@@ -3,6 +3,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 const Emulator = @import("lib.zig").Emulator;
 const State = @import("State.zig");
+const Server = @import("Server.zig");
 
 const target = @import("Server.zig").target;
 const memory_map = @import("Server.zig").memory_map;
@@ -46,7 +47,7 @@ const String = union(enum) {
     }
 };
 
-pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
+pub fn parse(self: *Self, allocator: Allocator, state: *Server.State, emu: *Emulator) !String {
     switch (self.contents[0]) {
         // Required
         '?' => return .{ .static = "T05" }, // FIXME: which errno?
@@ -61,7 +62,7 @@ pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
                 var i: u32 = 0;
                 while (i < r.len + 1) : (i += 1) {
                     var reg: u32 = if (i < r.len) r[i] else cpsr;
-                    if (i == 15) reg -= if (cpsr >> 5 & 1 == 1) 4 else 8; // PC is ahead
+                    if (i == 15) reg -|= if (cpsr >> 5 & 1 == 1) 4 else 8; // PC is ahead
 
                     // writes the formatted integer to the buffer, returns a slice to the buffer but we ignore that
                     // GDB also expects the bytes to be in the opposite order for whatever reason
@@ -191,6 +192,8 @@ pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
         // TODO: Figure out the difference between 'M' and 'X'
         'D' => {
             log.info("Disconnecting...", .{});
+
+            state.should_quit = true;
             return .{ .static = "OK" };
         },
         'H' => return .{ .static = "" },
@@ -293,7 +296,7 @@ pub fn checksum(input: []const u8) u8 {
     var sum: usize = 0;
     for (input) |char| sum += char;
 
-    return @truncate(u8, sum);
+    return @truncate(sum);
 }
 
 fn verify(input: []const u8, chksum: u8) bool {

src/Server.zig

@@ -1,12 +1,12 @@
 const std = @import("std");
-const network = @import("network");
 const Packet = @import("Packet.zig");
-
-const Socket = network.Socket;
-const Allocator = std.mem.Allocator;
-const Atomic = std.atomic.Atomic;
 const Emulator = @import("lib.zig").Emulator;
 
+const Atomic = std.atomic.Atomic;
+const Allocator = std.mem.Allocator;
+const Server = std.net.StreamServer;
+const Connection = Server.Connection;
+
 const Self = @This();
 const log = std.log.scoped(.Server);
 const port: u16 = 2424;
@@ -57,32 +57,23 @@ pub const memory_map: []const u8 =
 // FIXME: Shouldn't this be a Packet Struct?
 pkt_cache: ?[]const u8 = null,
 
-client: Socket,
-_socket: Socket,
+socket: Server,
+state: State = .{},
 
 emu: Emulator,
 
+pub const State = struct { should_quit: bool = false };
+
 pub fn init(emulator: Emulator) !Self {
-    try network.init();
+    var server = std.net.StreamServer.init(.{});
+    try server.listen(std.net.Address.initIp4([_]u8{0} ** 4, port));
 
-    var socket = try Socket.create(.ipv4, .tcp);
-    try socket.bindToPort(port);
-    try socket.listen();
-
-    var client = try socket.accept(); // TODO: This blocks, is this OK?
-
-    const endpoint = try client.getLocalEndPoint();
-    log.info("client connected from {}", .{endpoint});
-
-    return .{ .emu = emulator, ._socket = socket, .client = client };
+    return .{ .emu = emulator, .socket = server };
 }
 
 pub fn deinit(self: *Self, allocator: Allocator) void {
     self.reset(allocator);
-
-    self.client.close();
-    self._socket.close();
-    network.deinit();
+    self.socket.deinit();
 
     self.* = undefined;
 }
@@ -98,13 +89,19 @@ const Action = union(enum) {
 pub fn run(self: *Self, allocator: Allocator, quit: *Atomic(bool)) !void {
     var buf: [Packet.max_len]u8 = undefined;
 
+    var client = try self.socket.accept();
+    log.info("client connected from {}", .{client.address});
+
     while (true) {
-        const len = try self.client.receive(&buf);
+        if (self.state.should_quit) break;
+
+        const len = try client.stream.read(&buf);
         if (len == 0) break;
 
         if (quit.load(.Monotonic)) break;
         const action = try self.parse(allocator, buf[0..len]);
-        try self.send(allocator, action);
+
+        try self.send(allocator, client, action);
     }
 
     // Just in case its the gdbstub that exited first,
@@ -113,7 +110,7 @@ pub fn run(self: *Self, allocator: Allocator, quit: *Atomic(bool)) !void {
 }
 
 fn parse(self: *Self, allocator: Allocator, input: []const u8) !Action {
-    // log.debug("-> {s}", .{input});
+    log.debug("-> {s}", .{input});
 
     return switch (input[0]) {
         '+' => blk: {
@@ -135,7 +132,7 @@ fn handlePacket(self: *Self, allocator: Allocator, input: []const u8) !Action {
     var packet = Packet.from(allocator, input) catch return .nack;
     defer packet.deinit(allocator);
 
-    var string = packet.parse(allocator, &self.emu) catch return .nack;
+    var string = packet.parse(allocator, &self.state, &self.emu) catch return .nack;
     defer string.deinit(allocator);
 
     const reply = string.inner();
@@ -146,11 +143,11 @@ fn handlePacket(self: *Self, allocator: Allocator, input: []const u8) !Action {
     return .{ .send = response };
 }
 
-fn send(self: *Self, allocator: Allocator, action: Action) !void {
+fn send(self: *Self, allocator: Allocator, client: Server.Connection, action: Action) !void {
     switch (action) {
         .send => |pkt| {
-            _ = try self.client.send(pkt);
-            // log.debug("<- {s}", .{pkt});
+            _ = try client.stream.writeAll(pkt);
+            log.debug("<- {s}", .{pkt});
 
             self.reset(allocator);
             self.pkt_cache = pkt;
@@ -159,19 +156,19 @@ fn send(self: *Self, allocator: Allocator, action: Action) !void {
             log.warn("received nack, resending: \"{?s}\"", .{self.pkt_cache});
 
             if (self.pkt_cache) |pkt| {
-                _ = try self.client.send(pkt);
-                // log.debug("<- {s}", .{pkt});
+                _ = try client.stream.writeAll(pkt);
+                log.debug("<- {s}", .{pkt});
             }
         },
         .ack => {
-            _ = try self.client.send("+");
-            // log.debug("<- +", .{});
+            _ = try client.stream.writeAll("+");
+            log.debug("<- +", .{});
 
             self.reset(allocator);
         },
         .nack => {
-            _ = try self.client.send("-");
-            // log.debug("<- -", .{});
+            _ = try client.stream.writeAll("-");
+            log.debug("<- -", .{});
 
             self.reset(allocator);
         },

src/lib.zig

@@ -35,35 +35,33 @@ pub const Emulator = struct {
         if (ptr_info != .Pointer) @compileError("ptr must be a pointer");
         if (ptr_info.Pointer.size != .One) @compileError("ptr must be a single-item pointer");
 
-        const alignment = ptr_info.Pointer.alignment;
-
         const gen = struct {
             pub fn readImpl(pointer: *anyopaque, addr: u32) u8 {
-                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+                const self: Ptr = @ptrCast(@alignCast(pointer));
 
                 return @call(.always_inline, ptr_info.Pointer.child.read, .{ self, addr });
             }
 
             pub fn writeImpl(pointer: *anyopaque, addr: u32, value: u8) void {
-                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+                const self: Ptr = @ptrCast(@alignCast(pointer));
 
                 return @call(.always_inline, ptr_info.Pointer.child.write, .{ self, addr, value });
             }
 
             pub fn registersImpl(pointer: *anyopaque) *[16]u32 {
-                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+                const self: Ptr = @ptrCast(@alignCast(pointer));
 
                 return @call(.always_inline, ptr_info.Pointer.child.registers, .{self});
             }
 
             pub fn cpsrImpl(pointer: *anyopaque) u32 {
-                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+                const self: Ptr = @ptrCast(@alignCast(pointer));
 
                 return @call(.always_inline, ptr_info.Pointer.child.cpsr, .{self});
             }
 
             pub fn stepImpl(pointer: *anyopaque) void {
-                const self = @ptrCast(Ptr, @alignCast(alignment, pointer));
+                const self: Ptr = @ptrCast(@alignCast(pointer));
 
                 return @call(.always_inline, ptr_info.Pointer.child.step, .{self});
             }
@@ -144,3 +142,7 @@ pub const Emulator = struct {
         }
     }
 };
+
+test {
+    _ = @import("test.zig");
+}

src/main.zig

@@ -1,18 +0,0 @@
-const std = @import("std");
-const Server = @import("gdbstub").Server;
-
-pub fn main() !void {
-    const log = std.log.scoped(.Main);
-
-    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
-    defer std.debug.assert(!gpa.deinit());
-
-    const allocator = gpa.allocator();
-
-    var server = try Server.init();
-    defer server.deinit(allocator);
-
-    try server.run(allocator);
-
-    log.info("Client disconnected", .{});
-}

src/test.zig

@@ -0,0 +1,108 @@
+const std = @import("std");
+const builtin = @import("builtin");
+
+const Emulator = @import("lib.zig").Emulator;
+const Server = @import("Server.zig");
+
+const Allocator = std.mem.Allocator;
+
+const BarebonesEmulator = struct {
+    r: [16]u32 = [_]u32{0} ** 16,
+
+    pub fn interface(self: *@This(), allocator: Allocator) Emulator {
+        return Emulator.init(allocator, self);
+    }
+
+    pub fn read(_: *const @This(), _: u32) u8 {
+        return 0;
+    }
+
+    pub fn write(_: *@This(), _: u32, _: u8) void {}
+
+    pub fn registers(self: *@This()) *[16]u32 {
+        return &self.r;
+    }
+
+    pub fn cpsr(_: *const @This()) u32 {
+        return 0;
+    }
+
+    pub fn step(_: *@This()) void {
+        // execute 1 instruction
+    }
+};
+
+test Server {
+    // https://github.com/ziglang/zig/blob/225fe6ddbfae016395762850e0cd5c51f9e7751c/lib/std/net/test.zig#L146C1-L156
+    if (builtin.single_threaded) return error.SkipZigTest;
+    if (builtin.os.tag == .wasi) return error.SkipZigTest;
+
+    if (builtin.os.tag == .windows)
+        _ = try std.os.windows.WSAStartup(2, 2);
+
+    defer if (builtin.os.tag == .windows) std.os.windows.WSACleanup() catch unreachable;
+
+    const allocator = std.testing.allocator;
+
+    var impl = BarebonesEmulator{};
+    var iface = impl.interface(allocator);
+    defer iface.deinit();
+
+    const clientFn = struct {
+        fn inner(address: std.net.Address) !void {
+            const socket = try std.net.tcpConnectToAddress(address);
+            defer socket.close();
+
+            _ = try socket.writer().writeAll("+");
+        }
+    }.inner;
+
+    var server = try Server.init(iface);
+    defer server.deinit(allocator);
+
+    const t = try std.Thread.spawn(.{}, clientFn, .{server.socket.listen_address});
+    defer t.join();
+
+    var should_quit = std.atomic.Atomic(bool).init(false);
+
+    try server.run(std.testing.allocator, &should_quit);
+}
+
+test Emulator {
+    const ExampleImpl = struct {
+        r: [16]u32 = [_]u32{0} ** 16,
+
+        pub fn interface(self: *@This(), allocator: std.mem.Allocator) Emulator {
+            return Emulator.init(allocator, self);
+        }
+
+        pub fn read(_: *const @This(), _: u32) u8 {
+            return 0;
+        }
+
+        pub fn write(_: *@This(), _: u32, _: u8) void {}
+
+        pub fn registers(self: *@This()) *[16]u32 {
+            return &self.r;
+        }
+
+        pub fn cpsr(_: *const @This()) u32 {
+            return 0;
+        }
+
+        pub fn step(_: *@This()) void {
+            // execute 1 instruction
+        }
+    };
+
+    var impl = ExampleImpl{};
+    var emu = Emulator.init(std.testing.allocator, &impl);
+
+    _ = emu.read(0x0000_0000);
+    emu.write(0x0000_0000, 0x00);
+
+    _ = emu.registers();
+    _ = emu.cpsr();
+
+    _ = emu.step();
+}