Add support for working with large files, in dart:io.

runtime/bin/file.h

 // Copyright (c) 2013, 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_FILE_H_
 #define BIN_FILE_H_
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ skipping 72 matching lines @@
   // the whole buffer has been transferred or an error occurs. If an error
   // occurred the result will be set to false.
   bool ReadFully(void* buffer, int64_t num_bytes);
   bool WriteFully(const void* buffer, int64_t num_bytes);
   bool WriteByte(uint8_t byte) {
     return WriteFully(&byte, 1);
   }
 
   // Get the length of the file. Returns a negative value if the length cannot
   // be determined (e.g. not seekable device).
-  off_t Length();
+  off64_t Length();
 
   // Get the current position in the file.
   // Returns a negative value if position cannot be determined.
-  off_t Position();
+  off64_t Position();
 
   // Set the byte position in the file.
-  bool SetPosition(int64_t position);
+  bool SetPosition(off64_t position);
 
   // Truncate (or extend) the file to the given length in bytes.
-  bool Truncate(int64_t length);
+  bool Truncate(off64_t length);
 
   // Flush contents of file.
   bool Flush();
 
   // Returns whether the file has been closed.
   bool IsClosed();
 
   // Open the file with the given path. The file is always opened for
   // reading. If mode contains kWrite the file is opened for both
   // reading and writing. If mode contains kWrite and the file does
   // not exist the file is created. The file is truncated to length 0 if
   // mode contains kTruncate.
   static File* Open(const char* path, FileOpenMode mode);
 
   // Create a file object for the specified stdio file descriptor
   // (stdin, stout or stderr).
   static File* OpenStdio(int fd);
 
   static bool Exists(const char* path);
   static bool Create(const char* path);
   static bool CreateLink(const char* path, const char* target);
   static bool Delete(const char* path);
   static bool DeleteLink(const char* path);
   static bool Rename(const char* old_path, const char* new_path);
   static bool RenameLink(const char* old_path, const char* new_path);
-  static off_t LengthFromPath(const char* path);
+  static off64_t LengthFromPath(const char* path);
   static void Stat(const char* path, int64_t* data);
   static time_t LastModified(const char* path);
   static char* LinkTarget(const char* pathname);
   static bool IsAbsolutePath(const char* path);
   static char* GetCanonicalPath(const char* path);
   static const char* PathSeparator();
   static const char* StringEscapedPathSeparator();
   static Type GetType(const char* path, bool follow_links);
   static Identical AreIdentical(const char* file_1, const char* file_2);
   static StdioHandleType GetStdioHandleType(int fd);
@@ skipping 36 matching lines @@
   // FileHandle is an OS specific class which stores data about the file.
   FileHandle* handle_;  // OS specific handle for the file.
 
   DISALLOW_COPY_AND_ASSIGN(File);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_FILE_H_