[lldb-dap] Refactoring IOStream into Transport handler. (llvm#130026)

Instead of having two discrete InputStream and OutputStream helpers,
this merges the two into a unifed 'Transport' handler.

This handler is responsible for reading the DAP message headers, parsing
the resulting JSON and converting the messages into
`lldb_dap::protocol::Message`s for both input and output.

---------

Co-authored-by: Jonas Devlieghere <[email protected]>

Author: ashgti

lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py

@@ -337,7 +337,7 @@ def send_recv(self, command):
                     self.send_packet(
                         {
                             "type": "response",
-                            "seq": -1,
+                            "seq": 0,
                             "request_seq": response_or_request["seq"],
                             "success": True,
                             "command": "runInTerminal",
@@ -349,7 +349,7 @@ def send_recv(self, command):
                     self.send_packet(
                         {
                             "type": "response",
-                            "seq": -1,
+                            "seq": 0,
                             "request_seq": response_or_request["seq"],
                             "success": True,
                             "command": "startDebugging",

lldb/test/API/tools/lldb-dap/io/TestDAP_io.py

@@ -2,6 +2,8 @@
 Test lldb-dap IO handling.
 """
 
+import sys
+
 from lldbsuite.test.decorators import *
 import lldbdap_testcase
 import dap_server
@@ -19,18 +21,18 @@ def cleanup():
             if process.poll() is None:
                 process.terminate()
                 process.wait()
-            stdout_data = process.stdout.read()
-            stderr_data = process.stderr.read()
-            print("========= STDOUT =========")
-            print(stdout_data)
-            print("========= END =========")
-            print("========= STDERR =========")
-            print(stderr_data)
-            print("========= END =========")
-            print("========= DEBUG ADAPTER PROTOCOL LOGS =========")
+            stdout_data = process.stdout.read().decode()
+            stderr_data = process.stderr.read().decode()
+            print("========= STDOUT =========", file=sys.stderr)
+            print(stdout_data, file=sys.stderr)
+            print("========= END =========", file=sys.stderr)
+            print("========= STDERR =========", file=sys.stderr)
+            print(stderr_data, file=sys.stderr)
+            print("========= END =========", file=sys.stderr)
+            print("========= DEBUG ADAPTER PROTOCOL LOGS =========", file=sys.stderr)
             with open(log_file_path, "r") as file:
-                print(file.read())
-            print("========= END =========")
+                print(file.read(), file=sys.stderr)
+            print("========= END =========", file=sys.stderr)
 
         # Execute the cleanup function during test case tear down.
         self.addTearDownHook(cleanup)
@@ -45,14 +47,23 @@ def test_eof_immediately(self):
         process.stdin.close()
         self.assertEqual(process.wait(timeout=5.0), 0)
 
+    def test_invalid_header(self):
+        """
+        lldb-dap handles invalid message headers.
+        """
+        process = self.launch()
+        process.stdin.write(b"not the corret message header")
+        process.stdin.close()
+        self.assertEqual(process.wait(timeout=5.0), 1)
+
     def test_partial_header(self):
         """
         lldb-dap handles parital message headers.
         """
         process = self.launch()
         process.stdin.write(b"Content-Length: ")
         process.stdin.close()
-        self.assertEqual(process.wait(timeout=5.0), 0)
+        self.assertEqual(process.wait(timeout=5.0), 1)
 
     def test_incorrect_content_length(self):
         """
@@ -61,13 +72,13 @@ def test_incorrect_content_length(self):
         process = self.launch()
         process.stdin.write(b"Content-Length: abc")
         process.stdin.close()
-        self.assertEqual(process.wait(timeout=5.0), 0)
+        self.assertEqual(process.wait(timeout=5.0), 1)
 
     def test_partial_content_length(self):
         """
         lldb-dap handles partial messages.
         """
         process = self.launch()
-        process.stdin.write(b"Content-Length: 10{")
+        process.stdin.write(b"Content-Length: 10\r\n\r\n{")
         process.stdin.close()
-        self.assertEqual(process.wait(timeout=5.0), 0)
+        self.assertEqual(process.wait(timeout=5.0), 1)

lldb/tools/lldb-dap/CMakeLists.txt

@@ -28,14 +28,14 @@ add_lldb_tool(lldb-dap
   FifoFiles.cpp
   FunctionBreakpoint.cpp
   InstructionBreakpoint.cpp
-  IOStream.cpp
   JSONUtils.cpp
   LLDBUtils.cpp
   OutputRedirector.cpp
   ProgressEvent.cpp
+  Protocol.cpp
   RunInTerminal.cpp
   SourceBreakpoint.cpp
-  Protocol.cpp
+  Transport.cpp
   Watchpoint.cpp
 
   Handler/ResponseHandler.cpp

lldb/tools/lldb-dap/DAP.cpp

@@ -12,6 +12,7 @@
 #include "JSONUtils.h"
 #include "LLDBUtils.h"
 #include "OutputRedirector.h"
+#include "Transport.h"
 #include "lldb/API/SBBreakpoint.h"
 #include "lldb/API/SBCommandInterpreter.h"
 #include "lldb/API/SBCommandReturnObject.h"
@@ -63,11 +64,10 @@ const char DEV_NULL[] = "/dev/null";
 
 namespace lldb_dap {
 
-DAP::DAP(llvm::StringRef client_name, llvm::StringRef path, std::ofstream *log,
-         lldb::IOObjectSP input, lldb::IOObjectSP output, ReplMode repl_mode,
-         std::vector<std::string> pre_init_commands)
-    : client_name(client_name), debug_adapter_path(path), log(log),
-      input(std::move(input)), output(std::move(output)),
+DAP::DAP(llvm::StringRef path, std::ofstream *log,
+         const ReplMode default_repl_mode,
+         std::vector<std::string> pre_init_commands, Transport &transport)
+    : debug_adapter_path(path), log(log), transport(transport),
       broadcaster("lldb-dap"), exception_breakpoints(),
       pre_init_commands(std::move(pre_init_commands)),
       focus_tid(LLDB_INVALID_THREAD_ID), stop_at_entry(false), is_attach(false),
@@ -78,7 +78,7 @@ DAP::DAP(llvm::StringRef client_name, llvm::StringRef path, std::ofstream *log,
       configuration_done_sent(false), waiting_for_run_in_terminal(false),
       progress_event_reporter(
           [&](const ProgressEvent &event) { SendJSON(event.ToJSON()); }),
-      reverse_request_seq(0), repl_mode(repl_mode) {}
+      reverse_request_seq(0), repl_mode(default_repl_mode) {}
 
 DAP::~DAP() = default;
 
@@ -221,52 +221,21 @@ void DAP::StopEventHandlers() {
   }
 }
 
-// Send the JSON in "json_str" to the "out" stream. Correctly send the
-// "Content-Length:" field followed by the length, followed by the raw
-// JSON bytes.
-void DAP::SendJSON(const std::string &json_str) {
-  output.write_full("Content-Length: ");
-  output.write_full(llvm::utostr(json_str.size()));
-  output.write_full("\r\n\r\n");
-  output.write_full(json_str);
-}
-
 // Serialize the JSON value into a string and send the JSON packet to
 // the "out" stream.
 void DAP::SendJSON(const llvm::json::Value &json) {
-  std::string json_str;
-  llvm::raw_string_ostream strm(json_str);
-  strm << json;
-  static std::mutex mutex;
-  std::lock_guard<std::mutex> locker(mutex);
-  SendJSON(json_str);
-
-  DAP_LOG(log, "({0}) <-- {1}", client_name, json_str);
-}
-
-// Read a JSON packet from the "in" stream.
-std::string DAP::ReadJSON() {
-  std::string length_str;
-  std::string json_str;
-  int length;
-
-  if (!input.read_expected(log, "Content-Length: "))
-    return json_str;
-
-  if (!input.read_line(log, length_str))
-    return json_str;
-
-  if (!llvm::to_integer(length_str, length))
-    return json_str;
-
-  if (!input.read_expected(log, "\r\n"))
-    return json_str;
-
-  if (!input.read_full(log, length, json_str))
-    return json_str;
-
-  DAP_LOG(log, "({0}) --> {1}", client_name, json_str);
-  return json_str;
+  // FIXME: Instead of parsing the output message from JSON, pass the `Message`
+  // as parameter to `SendJSON`.
+  protocol::Message message;
+  llvm::json::Path::Root root;
+  if (!fromJSON(json, message, root)) {
+    DAP_LOG_ERROR(log, root.getError(), "({1}) encoding failed: {0}",
+                  transport.GetClientName());
+    return;
+  }
+  if (llvm::Error err = transport.Write(message))
+    DAP_LOG_ERROR(log, std::move(err), "({1}) write failed: {0}",
+                  transport.GetClientName());
 }
 
 // "OutputEvent": {
@@ -693,29 +662,10 @@ void DAP::SetTarget(const lldb::SBTarget target) {
   }
 }
 
-PacketStatus DAP::GetNextObject(llvm::json::Object &object) {
-  std::string json = ReadJSON();
-  if (json.empty())
-    return PacketStatus::EndOfFile;
-
-  llvm::StringRef json_sref(json);
-  llvm::Expected<llvm::json::Value> json_value = llvm::json::parse(json_sref);
-  if (!json_value) {
-    DAP_LOG_ERROR(log, json_value.takeError(),
-                  "({1}) failed to parse JSON: {0}", client_name);
-    return PacketStatus::JSONMalformed;
-  }
-
-  llvm::json::Object *object_ptr = json_value->getAsObject();
-  if (!object_ptr) {
-    DAP_LOG(log, "({0}) error: json packet isn't a object", client_name);
-    return PacketStatus::JSONNotObject;
-  }
-  object = *object_ptr;
-  return PacketStatus::Success;
-}
-
-bool DAP::HandleObject(const llvm::json::Object &object) {
+bool DAP::HandleObject(const protocol::Message &M) {
+  // FIXME: Directly handle `Message` instead of serializing to JSON.
+  llvm::json::Value v = toJSON(M);
+  llvm::json::Object object = *v.getAsObject();
   const auto packet_type = GetString(object, "type");
   if (packet_type == "request") {
     const auto command = GetString(object, "command");
@@ -726,7 +676,8 @@ bool DAP::HandleObject(const llvm::json::Object &object) {
       return true; // Success
     }
 
-    DAP_LOG(log, "({0}) error: unhandled command '{1}'", client_name, command);
+    DAP_LOG(log, "({0}) error: unhandled command '{1}'",
+            transport.GetClientName(), command);
     return false; // Fail
   }
 
@@ -749,9 +700,8 @@ bool DAP::HandleObject(const llvm::json::Object &object) {
     // Result should be given, use null if not.
     if (GetBoolean(object, "success").value_or(false)) {
       llvm::json::Value Result = nullptr;
-      if (auto *B = object.get("body")) {
+      if (auto *B = object.get("body"))
         Result = std::move(*B);
-      }
       (*response_handler)(Result);
     } else {
       llvm::StringRef message = GetString(object, "message");
@@ -818,19 +768,15 @@ llvm::Error DAP::Loop() {
     StopEventHandlers();
   });
   while (!disconnecting) {
-    llvm::json::Object object;
-    lldb_dap::PacketStatus status = GetNextObject(object);
+    llvm::Expected<std::optional<protocol::Message>> next = transport.Read();
+    if (!next)
+      return next.takeError();
 
-    if (status == lldb_dap::PacketStatus::EndOfFile) {
+    // nullopt on EOF
+    if (!*next)
       break;
-    }
-
-    if (status != lldb_dap::PacketStatus::Success) {
-      return llvm::createStringError(llvm::inconvertibleErrorCode(),
-                                     "failed to send packet");
-    }
 
-    if (!HandleObject(object)) {
+    if (!HandleObject(**next)) {
       return llvm::createStringError(llvm::inconvertibleErrorCode(),
                                      "unhandled packet");
     }

lldb/tools/lldb-dap/DAP.h

@@ -14,11 +14,12 @@
 #include "FunctionBreakpoint.h"
 #include "Handler/RequestHandler.h"
 #include "Handler/ResponseHandler.h"
-#include "IOStream.h"
 #include "InstructionBreakpoint.h"
 #include "OutputRedirector.h"
 #include "ProgressEvent.h"
+#include "Protocol.h"
 #include "SourceBreakpoint.h"
+#include "Transport.h"
 #include "lldb/API/SBBroadcaster.h"
 #include "lldb/API/SBCommandInterpreter.h"
 #include "lldb/API/SBDebugger.h"
@@ -39,7 +40,6 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/Threading.h"
-#include <map>
 #include <memory>
 #include <mutex>
 #include <optional>
@@ -145,11 +145,9 @@ struct SendEventRequestHandler : public lldb::SBCommandPluginInterface {
 };
 
 struct DAP {
-  llvm::StringRef client_name;
   llvm::StringRef debug_adapter_path;
   std::ofstream *log;
-  InputStream input;
-  OutputStream output;
+  Transport &transport;
   lldb::SBFile in;
   OutputRedirector out;
   OutputRedirector err;
@@ -210,12 +208,30 @@ struct DAP {
   // will contain that expression.
   std::string last_nonempty_var_expression;
 
-  DAP(llvm::StringRef client_name, llvm::StringRef path, std::ofstream *log,
-      lldb::IOObjectSP input, lldb::IOObjectSP output, ReplMode repl_mode,
-      std::vector<std::string> pre_init_commands);
+  /// Creates a new DAP sessions.
+  ///
+  /// \param[in] path
+  ///     Path to the lldb-dap binary.
+  /// \param[in] log
+  ///     Log file stream, if configured.
+  /// \param[in] default_repl_mode
+  ///     Default repl mode behavior, as configured by the binary.
+  /// \param[in] pre_init_commands
+  ///     LLDB commands to execute as soon as the debugger instance is allocaed.
+  /// \param[in] transport
+  ///     Transport for this debug session.
+  DAP(llvm::StringRef path, std::ofstream *log,
+      const ReplMode default_repl_mode,
+      std::vector<std::string> pre_init_commands, Transport &transport);
+
   ~DAP();
+
+  /// DAP is not copyable.
+  /// @{
   DAP(const DAP &rhs) = delete;
   void operator=(const DAP &rhs) = delete;
+  /// @}
+
   ExceptionBreakpoint *GetExceptionBreakpoint(const std::string &filter);
   ExceptionBreakpoint *GetExceptionBreakpoint(const lldb::break_id_t bp_id);
 
@@ -233,8 +249,6 @@ struct DAP {
   // the "out" stream.
   void SendJSON(const llvm::json::Value &json);
 
-  std::string ReadJSON();
-
   void SendOutput(OutputType o, const llvm::StringRef output);
 
   void SendProgressEvent(uint64_t progress_id, const char *message,
@@ -307,8 +321,7 @@ struct DAP {
   /// listeing for its breakpoint events.
   void SetTarget(const lldb::SBTarget target);
 
-  PacketStatus GetNextObject(llvm::json::Object &object);
-  bool HandleObject(const llvm::json::Object &object);
+  bool HandleObject(const protocol::Message &M);
 
   /// Disconnect the DAP session.
   lldb::SBError Disconnect();
@@ -382,12 +395,6 @@ struct DAP {
   InstructionBreakpoint *GetInstructionBreakpoint(const lldb::break_id_t bp_id);
 
   InstructionBreakpoint *GetInstructionBPFromStopReason(lldb::SBThread &thread);
-
-private:
-  // Send the JSON in "json_str" to the "out" stream. Correctly send the
-  // "Content-Length:" field followed by the length, followed by the raw
-  // JSON bytes.
-  void SendJSON(const std::string &json_str);
 };
 
 } // namespace lldb_dap