chore: replace link() with getModule()

fix stack overflow bug in State.deinit
allow for code in another thread to signal shutdown to gdbstub

build.zig

@@ -1,54 +1,44 @@
 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;
 }
 
-const pkgs = struct {
-    const Pkg = std.build.Pkg;
-
-    pub const gdbstub: Pkg = .{
-        .name = "gdbstub",
-        .source = .{ .path = path("src/lib.zig") },
-        .dependencies = &[_]Pkg{network},
-    };
-
+pub fn getModule(b: *std.Build) *std.build.Module {
     // https://github.com/MasterQ32/zig-network
-    pub const network: Pkg = .{
-        .name = "network",
-        .source = .{ .path = path("lib/zig-network/network.zig") },
-    };
-};
+    const network = b.createModule(.{ .source_file = .{ .path = path("lib/zig-network/network.zig") } });
 
-pub fn link(exe: *std.build.LibExeObjStep) void {
-    exe.addPackage(pkgs.gdbstub);
+    return b.createModule(.{
+        .source_file = .{ .path = path("src/lib.zig") },
+        .dependencies = &.{.{ .name = "network", .module = network }},
+    });
 }
 
-pub fn build(b: *std.build.Builder) void {
+pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
-    _ = target;
-    const mode = b.standardReleaseOptions();
+    // const optimize = b.standardOptimizeOption(.{});
 
-    // -- library --
-    const lib = b.addStaticLibrary("gdbstub", "src/lib.zig");
-    lib.addPackage(pkgs.network);
+    // -- Library --
 
-    lib.setBuildMode(mode);
-    lib.install();
+    const lib_test = b.addTest(.{
+        .root_source_file = .{ .path = "src/lib.zig" },
+        .target = target,
+    });
 
-    const lib_tests = b.addTest("src/lib.zig");
-    lib_tests.setBuildMode(mode);
+    const test_step = b.step("test", "Run Library Tests");
+    test_step.dependOn(&lib_test.step);
 
-    const test_step = b.step("lib-test", "Run Library Tests");
-    test_step.dependOn(&lib_tests.step);
+    // -- Executable --
 
-    // // -- Executable --
-    // const exe = b.addExecutable("gdbserver", "src/main.zig");
+    // const exe = b.addExecutable(.{
+    //     .name = "gdbserver",
+    //     .root_source_file = .{ .path = "src/main.zig" },
+    //     .target = target,
+    //     .optimize = optimize,
+    // });
     // link(exe);
-
-    // exe.setTarget(target);
-    // exe.setBuildMode(mode);
     // exe.install();
 
     // const run_cmd = exe.run();

src/Packet.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 
 const Allocator = std.mem.Allocator;
 const Emulator = @import("lib.zig").Emulator;
+const State = @import("State.zig");
 
 const target = @import("Server.zig").target;
 const memory_map = @import("Server.zig").memory_map;
@@ -45,13 +46,10 @@ const String = union(enum) {
     }
 };
 
-pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
+pub fn parse(self: *Self, allocator: Allocator, emu: *Emulator) !String {
     switch (self.contents[0]) {
         // Required
-        '?' => {
-            const ret = try std.fmt.allocPrint(allocator, "S{x:0>2}", .{@enumToInt(Signal.Int)});
-            return .{ .alloc = ret };
-        },
+        '?' => return .{ .static = "T05" }, // FIXME: which errno?
         'g' => {
             const r = emu.registers();
             const cpsr = emu.cpsr();
@@ -76,8 +74,8 @@ pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
         'G' => @panic("TODO: Register Write"),
         'm' => {
             var tokens = std.mem.tokenize(u8, self.contents[1..], ",");
-            const addr_str = tokens.next() orelse return .{ .static = "E9999" }; // EUNKNOWN
-            const length_str = tokens.next() orelse return .{ .static = "E9999" }; // EUNKNOWN
+            const addr_str = tokens.next() orelse return error.InvalidPacket;
+            const length_str = tokens.next() orelse return error.InvalidPacket;
 
             const addr = try std.fmt.parseInt(u32, addr_str, 16);
             const len = try std.fmt.parseInt(u32, length_str, 16);
@@ -87,9 +85,6 @@ pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
             {
                 var i: u32 = 0;
                 while (i < len) : (i += 1) {
-                    const value = emu.read(addr + i);
-                    log.debug("read 0x{X:0>2} from 0x{X:0>8}", .{ value, addr + i });
-
                     // writes the formatted integer to the buffer, returns a slice to the buffer but we ignore that
                     _ = std.fmt.bufPrintIntToSlice(ret[i * 2 ..][0..2], emu.read(addr + i), 16, .lower, .{ .fill = '0', .width = 2 });
                 }
@@ -97,40 +92,124 @@ pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
 
             return .{ .alloc = ret };
         },
-        'M' => @panic("TODO: Memory Write"),
-        'c' => @panic("TODO: Continue"),
+        'M' => {
+            var tokens = std.mem.tokenize(u8, self.contents[1..], ",:");
+
+            const addr_str = tokens.next() orelse return error.InvalidPacket;
+            const length_str = tokens.next() orelse return error.InvalidPacket;
+            const bytes = tokens.next() orelse return error.InvalidPacket;
+
+            const addr = try std.fmt.parseInt(u32, addr_str, 16);
+            const len = try std.fmt.parseInt(u32, length_str, 16);
+
+            {
+                var i: u32 = 0;
+                while (i < len) : (i += 1) {
+                    const str = bytes[2 * i ..][0..2];
+                    const value = try std.fmt.parseInt(u8, str, 16);
+
+                    emu.write(addr + i, value);
+                }
+            }
+
+            return .{ .static = "OK" };
+        },
+        'c' => {
+            switch (emu.contd()) {
+                .SingleStep => unreachable,
+                .Trap => |r| switch (r) {
+                    .HwBkpt => return .{ .static = "T05 hwbreak:;" },
+                    .SwBkpt => return .{ .static = "T05 swbreak:;" },
+                },
+            }
+        },
         's' => {
             // var tokens = std.mem.tokenize(u8, self.contents[1..], " ");
             // const addr = if (tokens.next()) |s| try std.fmt.parseInt(u32, s, 16) else null;
 
-            emu.step();
-
-            const ret = try std.fmt.allocPrint(allocator, "S{x:0>2}", .{@enumToInt(Signal.Trap)});
-            return .{ .alloc = ret };
+            switch (emu.step()) {
+                .SingleStep => return .{ .static = "T05" },
+                .Trap => |r| switch (r) {
+                    .HwBkpt => return .{ .static = "T05 hwbreak:;" },
+                    .SwBkpt => return .{ .static = "T05 swbreak:;" },
+                },
+            }
         },
 
-        // Optional
+        // Breakpoints
+        'z' => {
+            var tokens = std.mem.tokenize(u8, self.contents[2..], ",");
+
+            const addr_str = tokens.next() orelse return error.InvalidPacket;
+            const addr = try std.fmt.parseInt(u32, addr_str, 16);
+
+            switch (self.contents[1]) {
+                '0' => {
+                    emu.removeBkpt(.Software, addr);
+                    return .{ .static = "OK" };
+                },
+                '1' => {
+                    emu.removeBkpt(.Hardware, addr);
+                    return .{ .static = "OK" };
+                },
+                '2' => return .{ .static = "" }, // TODO: Remove Write Watchpoint
+                '3' => return .{ .static = "" }, // TODO: Remove Read Watchpoint
+                '4' => return .{ .static = "" }, // TODO: Remove Access Watchpoint
+                else => return .{ .static = "" },
+            }
+        },
+        'Z' => {
+            var tokens = std.mem.tokenize(u8, self.contents[2..], ",");
+            const addr_str = tokens.next() orelse return error.InvalidPacket;
+            const kind_str = tokens.next() orelse return error.InvalidPacket;
+
+            const addr = try std.fmt.parseInt(u32, addr_str, 16);
+            const kind = try std.fmt.parseInt(u32, kind_str, 16);
+
+            switch (self.contents[1]) {
+                '0' => {
+                    try emu.addBkpt(.Software, addr, kind);
+                    return .{ .static = "OK" };
+                },
+                '1' => {
+                    emu.addBkpt(.Hardware, addr, kind) catch |e| {
+                        switch (e) {
+                            error.OutOfSpace => return .{ .static = "E22" }, // FIXME: which errno?
+                            else => return e,
+                        }
+                    };
+
+                    return .{ .static = "OK" };
+                },
+                '2' => return .{ .static = "" }, // TODO: Insert Write Watchpoint
+                '3' => return .{ .static = "" }, // TODO: Insert Read Watchpoint
+                '4' => return .{ .static = "" }, // TODO: Insert Access Watchpoint
+                else => return .{ .static = "" },
+            }
+        },
+
+        // TODO: Figure out the difference between 'M' and 'X'
         'D' => {
             log.info("Disconnecting...", .{});
             return .{ .static = "OK" };
         },
         'H' => return .{ .static = "" },
         'v' => {
-            if (substr(self.contents[1..], "MustReplyEmpty")) {
-                return .{ .static = "" };
+            if (!substr(self.contents[1..], "MustReplyEmpty")) {
+                log.warn("Unimplemented: {s}", .{self.contents});
             }
 
-            log.warn("Unimplemented: {s}", .{self.contents});
             return .{ .static = "" };
         },
         'q' => {
             if (self.contents[1] == 'C' and self.contents.len == 2) return .{ .static = "QC1" };
+
             if (substr(self.contents[1..], "fThreadInfo")) return .{ .static = "m1" };
             if (substr(self.contents[1..], "sThreadInfo")) return .{ .static = "l" };
             if (substr(self.contents[1..], "Attached")) return .{ .static = "1" }; // Tell GDB we're attached to a process
 
             if (substr(self.contents[1..], "Supported")) {
-                const format = "PacketSize={x:};qXfer:features:read+;qXfer:memory-map:read+";
+                const format = "PacketSize={x:};swbreak+;hwbreak+;qXfer:features:read+;qXfer:memory-map:read+";
                 // TODO: Anything else?
 
                 const ret = try std.fmt.allocPrint(allocator, format, .{Self.max_len});
@@ -142,9 +221,10 @@ pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
                 _ = tokens.next(); // Xfer
                 _ = tokens.next(); // features
                 _ = tokens.next(); // read
-                const annex = tokens.next() orelse return .{ .static = "E9999" };
-                const offset_str = tokens.next() orelse return .{ .static = "E99999" };
-                const length_str = tokens.next() orelse return .{ .static = "E9999" };
+
+                const annex = tokens.next() orelse return error.InvalidPacket;
+                const offset_str = tokens.next() orelse return error.InvalidPacket;
+                const length_str = tokens.next() orelse return error.InvalidPacket;
 
                 if (std.mem.eql(u8, annex, "target.xml")) {
                     const offset = try std.fmt.parseInt(usize, offset_str, 16);
@@ -173,8 +253,8 @@ pub fn parse(self: *Self, allocator: Allocator, emu: Emulator) !String {
                 _ = tokens.next(); // Xfer
                 _ = tokens.next(); // memory-map
                 _ = tokens.next(); // read
-                const offset_str = tokens.next() orelse return .{ .static = "E9999" };
-                const length_str = tokens.next() orelse return .{ .static = "E9999" };
+                const offset_str = tokens.next() orelse return error.InvalidPacket;
+                const length_str = tokens.next() orelse return error.InvalidPacket;
 
                 const offset = try std.fmt.parseInt(usize, offset_str, 16);
                 const length = try std.fmt.parseInt(usize, length_str, 16);

src/Server.zig

@@ -4,6 +4,7 @@ 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 Self = @This();
@@ -94,16 +95,21 @@ const Action = union(enum) {
     nack,
 };
 
-pub fn run(self: *Self, allocator: Allocator) !void {
+pub fn run(self: *Self, allocator: Allocator, quit: *Atomic(bool)) !void {
     var buf: [Packet.max_len]u8 = undefined;
 
     while (true) {
         const len = try self.client.receive(&buf);
         if (len == 0) break;
 
+        if (quit.load(.Monotonic)) break;
         const action = try self.parse(allocator, buf[0..len]);
         try self.send(allocator, action);
     }
+
+    // Just in case its the gdbstub that exited first,
+    // attempt to signal to the GUI that it should also exit
+    quit.store(true, .Monotonic);
 }
 
 fn parse(self: *Self, allocator: Allocator, input: []const u8) !Action {
@@ -129,7 +135,7 @@ 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.emu) catch return .nack;
     defer string.deinit(allocator);
 
     const reply = string.inner();

src/State.zig

@@ -0,0 +1,122 @@
+const std = @import("std");
+
+const Allocator = std.mem.Allocator;
+const ArrayList = std.ArrayList;
+
+hw_bkpt: HwBkpt = .{},
+sw_bkpt: SwBkpt,
+
+pub fn init(allocator: Allocator) @This() {
+    return .{ .sw_bkpt = SwBkpt.init(allocator) };
+}
+
+pub fn deinit(self: *@This()) void {
+    self.sw_bkpt.deinit();
+    self.* = undefined;
+}
+
+const SwBkpt = struct {
+    const log = std.log.scoped(.SwBkpt);
+
+    list: std.ArrayList(Bkpt),
+
+    pub fn init(allocator: Allocator) @This() {
+        return .{ .list = ArrayList(Bkpt).init(allocator) };
+    }
+
+    pub fn deinit(self: *@This()) void {
+        self.list.deinit();
+        self.* = undefined;
+    }
+
+    pub fn isHit(self: *const @This(), addr: u32) bool {
+        for (self.list.items) |bkpt| {
+            if (bkpt.addr == addr) return true;
+        }
+
+        return false;
+    }
+
+    pub fn add(self: *@This(), addr: u32, kind: u32) !void {
+        for (self.list.items) |bkpt| {
+            if (bkpt.addr == addr) return; // indempotent
+        }
+
+        try self.list.append(.{ .addr = addr, .kind = try Bkpt.Kind.from(u32, kind) });
+        log.warn("Added Breakpoint at 0x{X:0>8}", .{addr});
+    }
+
+    pub fn remove(self: *@This(), addr: u32) void {
+        for (self.list.items, 0..) |bkpt, i| {
+            if (bkpt.addr == addr) {
+                _ = self.list.orderedRemove(i);
+                log.debug("Removed Breakpoint at 0x{X:0>8}", .{addr});
+
+                return;
+            }
+        }
+    }
+};
+
+const HwBkpt = struct {
+    const log = std.log.scoped(.HwBkpt);
+
+    list: [2]?Bkpt = .{ null, null },
+
+    pub fn isHit(self: *const @This(), addr: u32) bool {
+        for (self.list) |bkpt_opt| {
+            const bkpt = bkpt_opt orelse continue;
+            if (bkpt.addr == addr) return true;
+        }
+
+        return false;
+    }
+
+    pub fn add(self: *@This(), addr: u32, kind: u32) !void {
+        for (&self.list) |*bkpt_opt| {
+            if (bkpt_opt.*) |bkpt| {
+                if (bkpt.addr == addr) return; // idempotent
+            } else {
+                bkpt_opt.* = .{ .addr = addr, .kind = try Bkpt.Kind.from(u32, kind) };
+                log.debug("Added Breakpoint at 0x{X:0>8}", .{addr});
+
+                return;
+            }
+        }
+
+        return error.OutOfSpace;
+    }
+
+    pub fn remove(self: *@This(), addr: u32) void {
+        for (&self.list) |*bkpt_opt| {
+            const bkpt = bkpt_opt.* orelse continue;
+
+            if (bkpt.addr == addr) {
+                bkpt_opt.* = null;
+                log.debug("Removed Breakpoint at 0x{X:0>8}", .{addr});
+
+                break;
+            }
+        }
+    }
+};
+
+const Bkpt = struct {
+    addr: u32,
+    kind: Kind,
+
+    const Kind = enum(u3) {
+        Arm = 2,
+        Thumb = 4,
+
+        pub fn from(comptime T: type, num: T) !@This() {
+            comptime std.debug.assert(@typeInfo(T) == .Int);
+
+            return switch (num) {
+                2 => .Arm,
+                4 => .Thumb,
+                else => error.UnknownBkptKind,
+            };
+        }
+    };
+};

src/lib.zig

@@ -1,10 +1,23 @@
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
 /// Re-export of the server interface
 pub const Server = @import("Server.zig");
+const State = @import("State.zig");
 
 /// Interface for interacting between GDB and a GBA emu
 pub const Emulator = struct {
     const Self = @This();
 
+    const Signal = union(enum) {
+        const Kind = enum { HwBkpt, SwBkpt };
+
+        Trap: Kind,
+        SingleStep: void,
+    };
+
+    state: State,
+
     ptr: *anyopaque,
 
     readFn: *const fn (*anyopaque, u32) u8,
@@ -15,7 +28,7 @@ pub const Emulator = struct {
 
     stepFn: *const fn (*anyopaque) void,
 
-    pub fn init(ptr: anytype) Self {
+    pub fn init(allocator: Allocator, ptr: anytype) Self {
         const Ptr = @TypeOf(ptr);
         const ptr_info = @typeInfo(Ptr);
 
@@ -56,7 +69,21 @@ pub const Emulator = struct {
             }
         };
 
-        return .{ .ptr = ptr, .readFn = gen.readImpl, .writeFn = gen.writeImpl, .registersFn = gen.registersImpl, .cpsrFn = gen.cpsrImpl, .stepFn = gen.stepImpl };
+        return .{
+            .ptr = ptr,
+            .readFn = gen.readImpl,
+            .writeFn = gen.writeImpl,
+            .registersFn = gen.registersImpl,
+            .cpsrFn = gen.cpsrImpl,
+            .stepFn = gen.stepImpl,
+
+            .state = State.init(allocator),
+        };
+    }
+
+    pub fn deinit(self: *Self) void {
+        self.state.deinit();
+        self.* = undefined;
     }
 
     pub inline fn read(self: Self, addr: u32) u8 {
@@ -75,7 +102,45 @@ pub const Emulator = struct {
         return self.cpsrFn(self.ptr);
     }
 
-    pub inline fn step(self: Self) void {
+    pub inline fn contd(self: *Self) Signal {
+        while (true) {
+            const signal = self.step();
+
+            switch (signal) {
+                .SingleStep => {},
+                .Trap => return signal,
+            }
+        }
+    }
+
+    pub inline fn step(self: *Self) Signal {
         self.stepFn(self.ptr);
+
+        const r = self.registersFn(self.ptr);
+        const is_thumb = self.cpsrFn(self.ptr) >> 5 & 1 == 1;
+
+        const r15 = r[15] -| if (is_thumb) @as(u32, 4) else 8;
+
+        if (self.state.sw_bkpt.isHit(r15)) return .{ .Trap = .SwBkpt };
+        if (self.state.hw_bkpt.isHit(r15)) return .{ .Trap = .HwBkpt };
+
+        return .SingleStep;
+    }
+
+    const BkptType = enum { Hardware, Software };
+
+    // TODO: Consider properly implementing Software interrupts?
+    pub fn addBkpt(self: *Self, comptime @"type": BkptType, addr: u32, kind: u32) !void {
+        switch (@"type") {
+            .Hardware => try self.state.hw_bkpt.add(addr, kind),
+            .Software => try self.state.sw_bkpt.add(addr, kind),
+        }
+    }
+
+    pub fn removeBkpt(self: *Self, comptime @"type": BkptType, addr: u32) void {
+        switch (@"type") {
+            .Hardware => self.state.hw_bkpt.remove(addr),
+            .Software => self.state.sw_bkpt.remove(addr),
+        }
     }
 };