Add qRegisterInfo parsing to GDBHostCommand.init

Author: MaxDesiatov

Sources/GDBRemoteProtocol/GDBHostCommand.swift

@@ -1,7 +1,12 @@
 /// See GDB and LLDB remote protocol documentation for more details:
 /// * https://sourceware.org/gdb/current/onlinedocs/gdb.html/General-Query-Packets.html
 /// * https://lldb.llvm.org/resources/lldbgdbremote.html
-package struct GDBHostCommand: Equatable {
+package struct GDBHostCommand {
+    enum Error: Swift.Error {
+        case unexpectedArgumentsValue
+        case unknownCommand(kind: String, arguments: String)
+    }
+
     package enum Kind: String, Equatable {
         // Currently listed in the order that LLDB sends them in.
         case startNoAckMode
@@ -17,6 +22,7 @@ package struct GDBHostCommand: Equatable {
         case firstThreadInfo
         case subsequentThreadInfo
         case targetStatus
+        case registerInfo
 
         case generalRegisters
 
@@ -61,8 +67,22 @@ package struct GDBHostCommand: Equatable {
 
     package let arguments: String
 
-    package init(kind: Kind, arguments: String) {
-        self.kind = kind
-        self.arguments = arguments
+    package init(kind: String, arguments: String) throws {
+        let registerInfoPrefix = "qRegisterInfo"
+        if kind.starts(with: registerInfoPrefix) {
+            self.kind = .registerInfo
+
+            guard arguments.isEmpty else {
+                throw Error.unexpectedArgumentsValue
+            }
+            self.arguments = String(kind.dropFirst(registerInfoPrefix.count))
+            return
+        } else if let kind = Kind(rawValue: kind) {
+            self.kind = kind
+        } else {
+            throw Error.unknownCommand(kind: kind, arguments: arguments)
+        }
+
+       self.arguments = arguments
     }
 }

Sources/GDBRemoteProtocol/GDBHostCommandDecoder.swift

@@ -17,7 +17,7 @@ package struct GDBHostCommandDecoder: ByteToMessageDecoder {
         case expectedCommandStart
         case unknownCommandKind(String)
         case expectedChecksum
-        case checksumIncorrect
+        case checksumIncorrect(expectedChecksum: Int, receivedChecksum: UInt8)
     }
 
     package typealias InboundOut = GDBPacket<GDBHostCommand>
@@ -106,37 +106,34 @@ package struct GDBHostCommandDecoder: ByteToMessageDecoder {
             self.accummulatedSum = 0
         }
 
-        let kindString = String(decoding: self.accummulatedKind, as: UTF8.self)
+        buffer.moveReaderIndex(forwardBy: 1)
 
-        if let commandKind = GDBHostCommand.Kind(rawValue: kindString) {
-            buffer.moveReaderIndex(forwardBy: 1)
+        guard let checksumString = buffer.readString(length: 2),
+            let first = checksumString.first?.hexDigitValue,
+            let last = checksumString.last?.hexDigitValue
+        else {
+            throw Error.expectedChecksum
+        }
 
-            guard let checksumString = buffer.readString(length: 2),
-                let first = checksumString.first?.hexDigitValue,
-                let last = checksumString.last?.hexDigitValue
-            else {
-                throw Error.expectedChecksum
-            }
+        let expectedChecksum = (first * 16) + last
 
-            guard (first * 16) + last == self.accummulatedChecksum else {
-                // FIXME: better diagnostics
-                throw Error.checksumIncorrect
-            }
+        guard expectedChecksum == self.accummulatedChecksum else {
+            throw Error.checksumIncorrect(
+                expectedChecksum: expectedChecksum,
+                receivedChecksum: self.accummulatedChecksum
+            )
+        }
 
-            if commandKind == .startNoAckMode {
-                self.isNoAckModeRequested = true
-            }
+        let payload = try GDBHostCommand(
+            kind: String(decoding: self.accummulatedKind, as: UTF8.self),
+            arguments: String(decoding: self.accummulatedArguments, as: UTF8.self)
+        )
 
-            return .init(
-                payload: .init(
-                    kind: commandKind,
-                    arguments: String(decoding: self.accummulatedArguments, as: UTF8.self)
-                ),
-                checksum: accummulatedChecksum,
-            )
-        } else {
-            throw Error.unknownCommandKind(kindString)
+        if payload.kind == .startNoAckMode {
+            self.isNoAckModeRequested = true
         }
+
+        return .init(payload: payload, checksum: accummulatedChecksum)
     }
 
     mutating package func decode(

Sources/WasmKitGDBHandler/WasmKitDebugger.swift

@@ -37,16 +37,21 @@ package actor WasmKitDebugger {
                 ])
 
             case .supportedFeatures:
-                // FIXME: should return a different set of supported features instead of echoing.
-                .raw(command.arguments)
+                .raw("qXfer:libraries:read+;PacketSize=1000;")
 
             case .vContSupportedActions:
                 .vContSupportedActions([.continue, .step])
 
             case .isVAttachOrWaitSupported, .enableErrorStrings:
                 .empty
             case .processInfo:
-                .raw("pid:1;parent-pid:1;arch:wasm32;endian:little;ptrsize:4;")
+                .keyValuePairs([
+                    "pid": "1",
+                    "parent-pid": "1",
+                    "arch": "wasm32",
+                    "endian": "little",
+                    "ptrsize": "4",
+                ])
 
             case .currentThreadID:
                 .raw("QC1")
@@ -63,6 +68,9 @@ package actor WasmKitDebugger {
                     "reason": "trace",
                 ])
 
+            case .registerInfo:
+                .raw("name:pc;alt-name:pc;bitsize:64;offset:0;encoding:uint;format:hex;set:General Purpose Registers;gcc:16;dwarf:16;generic:pc;")
+
             case .generalRegisters:
                 fatalError()
             }