Don't expand path to use long names in CreateTemporaryFileInDir.

base/file_util_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/file_util.h"
 
 #include <windows.h>
 #include <psapi.h>
 #include <shellapi.h>
 #include <shlobj.h>
@@ skipping 375 matching lines @@
                               FilePath* temp_file) {
   base::ThreadRestrictions::AssertIOAllowed();
 
   wchar_t temp_name[MAX_PATH + 1];
 
   if (!GetTempFileName(dir.value().c_str(), L"", 0, temp_name)) {
     DPLOG(WARNING) << "Failed to get temporary file name in " << dir.value();
     return false;
   }
 
-  DWORD path_len = GetLongPathName(temp_name, temp_name, MAX_PATH);
-  if (path_len > MAX_PATH + 1 || path_len == 0) {
-    DPLOG(WARNING) << "Failed to get long path name for " << temp_name;
-    return false;
+  wchar_t long_temp_name[MAX_PATH + 1];

[asanka, 2012/11/09 22:02:54]

Added |long_temp_name| because I couldn't find any guarantees that
GetLongPathName() would leave the destination buffer untouched on failure.

+  DWORD long_name_len = GetLongPathName(temp_name, long_temp_name, MAX_PATH);
+  if (long_name_len > MAX_PATH || long_name_len == 0) {
+    // GetLongPathName() failed, but we still have a temporary file.
+    *temp_file = FilePath(temp_name);
+    return true;
   }
 
-  std::wstring temp_file_str;
-  temp_file_str.assign(temp_name, path_len);
-  *temp_file = FilePath(temp_file_str);
+  FilePath::StringType long_temp_name_str;
+  long_temp_name_str.assign(long_temp_name, long_name_len);
+  *temp_file = FilePath(long_temp_name_str);
   return true;
 }
 
 bool CreateTemporaryDirInDir(const FilePath& base_dir,
                              const FilePath::StringType& prefix,
                              FilePath* new_dir) {
   base::ThreadRestrictions::AssertIOAllowed();
 
   FilePath path_to_create;
   srand(static_cast<uint32>(time(NULL)));
@@ skipping 547 matching lines @@
   HANDLE cp = GetCurrentProcess();
   if (::GetMappedFileNameW(cp, file_view, mapped_file_path, kMaxPathLength)) {
     *nt_path = FilePath(mapped_file_path);
     success = true;
   }
   ::UnmapViewOfFile(file_view);
   return success;
 }
 
 }  // namespace file_util