v8/src/debug-agent.cc

// Copyright 2009 the V8 project authors. All rights reserved.
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#include "v8.h"
#include "debug-agent.h"

namespace v8 { namespace internal {


// Public V8 debugger API message handler function. This function just delegates
// to the debugger agent through it's data parameter.
void DebuggerAgentMessageHandler(const uint16_t* message, int length,
                                 void *data) {
  reinterpret_cast<DebuggerAgent*>(data)->DebuggerMessage(message, length);
}


// Debugger agent main thread.
void DebuggerAgent::Run() {
  const int kOneSecondInMicros = 1000000;

  // First bind the socket to the requested port.
  bool bound = false;
  while (!bound && !terminate_) {
    bound = server_->Bind(port_);

    // If an error occoured wait a bit before retrying. The most common error
    // would be that the port is already in use so this avoids a busy loop and
    // make the agent take over the port when it becomes free.
    if (!bound) {
      terminate_now_->Wait(kOneSecondInMicros);
    }
  }

  // Accept connections on the bound port.
  while (!terminate_) {
    bool ok = server_->Listen(1);
    if (ok) {
      // Accept the new connection.
      Socket* client = server_->Accept();
      ok = client != NULL;
      if (ok) {
        // Create and start a new session.
        CreateSession(client);
      }
    }
  }
}


void DebuggerAgent::Shutdown() {
  // Set the termination flag.
  terminate_ = true;

  // Signal termination and make the server exit either its listen call or its
  // binding loop. This makes sure that no new sessions can be established.
  terminate_now_->Signal();
  server_->Shutdown();
  Join();

  // Close existing session if any.
  CloseSession();
}


void DebuggerAgent::CreateSession(Socket* client) {
  ScopedLock with(session_access_);

  // If another session is already established terminate this one.
  if (session_ != NULL) {
    static const char* message = "Remote debugging session already active\n";

    client->Send(message, strlen(message));
    delete client;
    return;
  }

  // Create a new session and hook up the debug message handler.
  session_ = new DebuggerAgentSession(this, client);
  v8::Debug::SetMessageHandler(DebuggerAgentMessageHandler, this);
  session_->Start();
}


void DebuggerAgent::CloseSession() {
  ScopedLock with(session_access_);

  // Terminate the session.
  if (session_ != NULL) {
    session_->Shutdown();
    session_->Join();
    delete session_;
    session_ = NULL;
  }
}


void DebuggerAgent::DebuggerMessage(const uint16_t* message, int length) {
  ScopedLock with(session_access_);

  // Forward the message handling to the session.
  if (session_ != NULL) {
    session_->DebuggerMessage(Vector<uint16_t>(const_cast<uint16_t*>(message),
                              length));
  }
}


void DebuggerAgent::OnSessionClosed(DebuggerAgentSession* session) {
  // Don't do anything during termination.
  if (terminate_) {
    return;
  }

  // Terminate the session.
  ScopedLock with(session_access_);
  ASSERT(session == session_);
  if (session == session_) {
    CloseSession();
  }
}


void DebuggerAgentSession::Run() {
  while (true) {
    // Read data from the debugger front end.
    SmartPointer<char> message = DebuggerAgentUtil::ReceiveMessage(client_);
    if (*message == NULL) {
      // Session is closed.
      agent_->OnSessionClosed(this);
      return;
    }

    // Convert UTF-8 to UTF-16.
    unibrow::Utf8InputBuffer<> buf(*message, strlen(*message));
    int len = 0;
    while (buf.has_more()) {
      buf.GetNext();
      len++;
    }
    int16_t* temp = NewArray<int16_t>(len + 1);
    buf.Reset(*message, strlen(*message));
    for (int i = 0; i < len; i++) {
      temp[i] = buf.GetNext();
    }

    // Send the request received to the debugger.
    v8::Debug::SendCommand(reinterpret_cast<const uint16_t *>(temp), len);
    DeleteArray(temp);
  }
}


void DebuggerAgentSession::DebuggerMessage(Vector<uint16_t> message) {
  DebuggerAgentUtil::SendMessage(client_, message);
}


void DebuggerAgentSession::Shutdown() {
  // Shutdown the socket to end the blocking receive.
  client_->Shutdown();
}


const char* DebuggerAgentUtil::kContentLength = "Content-Length";
int DebuggerAgentUtil::kContentLengthSize = strlen(kContentLength);


SmartPointer<char> DebuggerAgentUtil::ReceiveMessage(const Socket* conn) {
  int received;

  // Read header.
  const int kHeaderBufferSize = 80;
  char header_buffer[kHeaderBufferSize];
  int header_buffer_position = 0;
  char c = '\0';  // One character receive buffer.
  char last_c = '\0';  // Previous character.
  int content_length = 0;
  while (!(c == '\n' && last_c == '\n')) {
    last_c = c;
    received = conn->Receive(&c, 1);
    if (received <= 0) {
      PrintF("Error %d\n", Socket::LastError());
      return SmartPointer<char>();
    }

    // Check for end of header line.
    if (c == '\n') {
      // Empty header line.
      if (header_buffer_position == 0) {
        continue;
      }

      // Terminate header.
      ASSERT(header_buffer_position < kHeaderBufferSize);
      if (header_buffer_position < kHeaderBufferSize) {
        header_buffer[header_buffer_position] = '\0';
      }

      // Split header.
      char* key = header_buffer;
      char* value = NULL;
      for (int i = 0; i < header_buffer_position; i++) {
        if (header_buffer[i] == ':') {
          header_buffer[i] = '\0';
          value = header_buffer + i + 1;
          while (*value == ' ') {
            value++;
          }
          break;
        }
      }

      // Check that key is Content-Length.
      if (strcmp(key, kContentLength) == 0) {
        // Get the content length value if within a sensible range.
        if (strlen(value) > 7) {
          return SmartPointer<char>();
        }
        for (int i = 0; value[i] != '\0'; i++) {
          // Bail out if illegal data.
          if (value[i] < '0' || value[i] > '9') {
            return SmartPointer<char>();
          }
          content_length = 10 * content_length + (value[i] - '0');
        }
      }

      // Start collecting new header.
      header_buffer_position = 0;
    } else {
      // Add character to header buffer (reserve room for terminating '\0').
      if (header_buffer_position < kHeaderBufferSize - 1) {
        header_buffer[header_buffer_position++] = c;
      }
    }
  }

  // Read body.
  char* buffer = NewArray<char>(content_length + 1);
  received = ReceiveAll(conn, buffer, content_length);
  if (received < content_length) {
    PrintF("Error %d\n", Socket::LastError());
    return SmartPointer<char>();
  }
  buffer[content_length] = '\0';

  return SmartPointer<char>(buffer);
}


bool DebuggerAgentUtil::SendMessage(const Socket* conn,
                                    const Vector<uint16_t> message) {
  static const int kBufferSize = 80;
  char buffer[kBufferSize];  // Sending buffer both for header and body.

  // Calculate the message size in UTF-8 encoding.
  int utf8_len = 0;
  for (int i = 0; i < message.length(); i++) {
    utf8_len += unibrow::Utf8::Length(message[i]);
  }

  // Send the header.
  int len;
  len = OS::SNPrintF(Vector<char>(buffer, kBufferSize),
                     "Content-Length: %d\n", utf8_len);
  conn->Send(buffer, len);

  // Terminate header with empty line.
  len = OS::SNPrintF(Vector<char>(buffer, kBufferSize), "\n");
  conn->Send(buffer, len);

  // Send message body as UTF-8.
  int buffer_position = 0;  // Current buffer position.
  for (int i = 0; i < message.length(); i++) {
    // Write next UTF-8 encoded character to buffer.
    buffer_position +=
        unibrow::Utf8::Encode(buffer + buffer_position, message[i]);
    ASSERT(buffer_position < kBufferSize);

    // Send buffer if full or last character is encoded.
    if (kBufferSize - buffer_position < 3 || i == message.length() - 1) {
      conn->Send(buffer, buffer_position);
      buffer_position = 0;
    }
  }

  return true;
}


bool DebuggerAgentUtil::SendMessage(const Socket* conn,
                                    const v8::Handle<v8::String> request) {
  static const int kBufferSize = 80;
  char buffer[kBufferSize];  // Sending buffer both for header and body.

  // Convert the request to UTF-8 encoding.
  v8::String::Utf8Value utf8_request(request);

  // Send the header.
  int len;
  len = OS::SNPrintF(Vector<char>(buffer, kBufferSize),
                     "Content-Length: %d\n", utf8_request.length());
  conn->Send(buffer, len);

  // Terminate header with empty line.
  len = OS::SNPrintF(Vector<char>(buffer, kBufferSize), "\n");
  conn->Send(buffer, len);

  // Send message body as UTF-8.
  conn->Send(*utf8_request, utf8_request.length());

  return true;
}


// Receive the full buffer before returning unless an error occours.
int DebuggerAgentUtil::ReceiveAll(const Socket* conn, char* data, int len) {
  int total_received = 0;
  while (total_received < len) {
    int received = conn->Receive(data + total_received, len - total_received);
    if (received <= 0) {
      return total_received;
    }
    total_received += received;
  }
  return total_received;
}


} }  // namespace v8::internal