Make Platform.executable return a fully qualified path the the executable

runtime/bin/platform.h

 // 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.
 
 #ifndef BIN_PLATFORM_H_
 #define BIN_PLATFORM_H_
 
 #include "bin/builtin.h"
 
 
@@ skipping 21 matching lines @@
   // Extracts the local hostname.
   static bool LocalHostname(char* buffer, intptr_t buffer_length);
 
   // Extracts the environment variables for the current process.  The
   // array of strings returned must be deallocated using
   // FreeEnvironment. The number of elements in the array is returned
   // in the count argument.
   static char** Environment(intptr_t* count);
   static void FreeEnvironment(char** env, intptr_t count);
 
-  // Stores and gets the executable name.
+  static char* ResolveExecutablePath();
+
+  // Stores the executable name.
   static void SetExecutableName(const char* executable_name) {
     executable_name_ = executable_name;
   }
   static const char* GetExecutableName() {
+    if (!executable_name_resolved_) {
+      // Try to resolve the executable path using platform specific APIs.
+      char* path = Platform::ResolveExecutablePath();
+      if (path != NULL) {
+        executable_name_ = path;
+      }
+      executable_name_resolved_ = true;
+    }
     return executable_name_;
   }
 
   // Stores and gets the package root.
   static void SetPackageRoot(const char* package_root) {
     package_root_ = package_root;
   }
   static const char* GetPackageRoot() {
     return package_root_;
   }
 
   // Stores and gets the flags passed to the executable.
   static void SetExecutableArguments(int script_index, char** argv) {
     script_index_ = script_index;
     argv_ = argv;
   }
   static int GetScriptIndex() {
     return script_index_;
   }
   static char** GetArgv() {
     return argv_;
   }
 
  private:
+  // The path to the executable.
   static const char* executable_name_;
+  // State to indicate whether the executable name has been resolved.
+  static bool executable_name_resolved_;
+
   static const char* package_root_;
   static int script_index_;
   static char** argv_;  // VM flags are argv_[1 ... script_index_ - 1]
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Platform);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_PLATFORM_H_