Add option to gen_snapshot for creating a Makefile describing a snapshot's dependencies.

runtime/bin/file_win.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 "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/file.h"
 
 #include <fcntl.h>     // NOLINT
@@ skipping 167 matching lines @@
   } else {
     // If we've done _setmode(fd, _O_WTEXT) then _write() expects
     // a buffer of wchar_t with an even unmber of bytes.
     Utf8ToWideScope wide(reinterpret_cast<const char*>(buffer), num_bytes);
     ASSERT((wide.size_in_bytes() % 2) == 0);
     return _write(fd, wide.wide(), wide.size_in_bytes());
   }
 }
 
 
+bool File::VPrint(const char* format, va_list args) {
+  // Measure.
+  va_list measure_args;
+  va_copy(measure_args, args);
+  intptr_t len = _vscprintf(format, measure_args);
+  va_end(measure_args);
+
+  char* buffer = reinterpret_cast<char*>(malloc(len + 1));
+
+  // Print.
+  va_list print_args;
+  va_copy(print_args, args);
+  _vsnprintf(buffer, len + 1, format, print_args);
+  va_end(print_args);
+
+  bool result = WriteFully(buffer, len);
+  free(buffer);
+  return result;
+}
+
+
 int64_t File::Position() {
   ASSERT(handle_->fd() >= 0);
   return _lseeki64(handle_->fd(), 0, SEEK_CUR);
 }
 
 
 bool File::SetPosition(int64_t position) {
   ASSERT(handle_->fd() >= 0);
   return _lseeki64(handle_->fd(), position, SEEK_SET) >= 0;
 }
@@ skipping 606 matching lines @@
     return kIdentical;
   } else {
     return kDifferent;
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)