Let debug target pick the debugger port

runtime/bin/main.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_debugger_api.h"
@@ skipping 29 matching lines @@
 // free'd.
 static const char* breakpoint_at = NULL;
 
 
 // Global state that indicates whether we should open a connection
 // and listen for a debugger to connect.
 static bool start_debugger = false;
 static const int DEFAULT_DEBUG_PORT = 5858;
 static const char* DEFAULT_DEBUG_IP = "127.0.0.1";
 static const char* debug_ip = DEFAULT_DEBUG_IP;
-static int debug_port = 0;
+static int debug_port = -1;
 
 // Global state that defines the VmStats web server port and root directory.
 static int vmstats_port = -1;
 static const char* vmstats_root = "";
 
 // Value of the --package-root flag.
 // (This pointer points into an argv buffer and does not need to be
 // free'd.)
 static const char* package_root = NULL;
 
@@ skipping 80 matching lines @@
   }
   has_check_function_fingerprints = true;
   return true;
 }
 
 
 static bool ProcessDebugOption(const char* port) {
   // TODO(hausner): Add support for specifying an IP address on which
   // the debugger should listen.
   ASSERT(port != NULL);
-  debug_port = 0;
+  debug_port = -1;
   if (*port == '\0') {
     debug_port = DEFAULT_DEBUG_PORT;
   } else {
     if ((*port == '=') || (*port == ':')) {
       debug_port = atoi(port + 1);
     }
   }
-  if (debug_port == 0) {
+  if (debug_port < 0) {
     Log::PrintErr("unrecognized --debug option syntax. "
                     "Use --debug[:<port number>]\n");
     return false;
   }
   breakpoint_at = "main";
   start_debugger = true;
   return true;
 }
 
 
@@ skipping 548 matching lines @@
                        DartUtils::CloseFile)) {
     fprintf(stderr, "%s", "VM initialization failed\n");
     fflush(stderr);
     return kErrorExitCode;
   }
 
   DartUtils::SetOriginalWorkingDirectory();
 
   // Start the debugger wire protocol handler if necessary.
   if (start_debugger) {
-    ASSERT(debug_port != 0);
-    DebuggerConnectionHandler::StartHandler(debug_ip, debug_port);
-    if (verbose_debug_seen) {
-      Log::Print("Debugger initialized\n");
+    ASSERT(debug_port >= 0);
+    bool print_msg = verbose_debug_seen || (debug_port == 0);
+    debug_port = DebuggerConnectionHandler::StartHandler(debug_ip, debug_port);
+    if (print_msg) {
+      Log::Print("Debugger listening on port %d\n", debug_port);
     }
   }
   VmStats::Start(vmstats_port, vmstats_root, verbose_debug_seen);
 
   // Call CreateIsolateAndSetup which creates an isolate and loads up
   // the specified application script.
   char* error = NULL;
   char* isolate_name = BuildIsolateName(script_name, "main");
   Dart_Isolate isolate = CreateIsolateAndSetupHelper(script_name,
                                                      "main",
@@ skipping 105 matching lines @@
 
   return Process::GlobalExitCode();
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }