Add file_util::ReplaceFile and use it in ImportantFileWriter.

It has more strict semantics than file_util::Move.

http://crbug.com/11585

Review URL: http://codereview.chromium.org/113207

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@16291 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 12 insertions, 0 deletions

diff --git a/base/file_util_win.cc b/base/file_util_win.cc
index 8964fbf..77247a4 100644
--- a/base/file_util_win.cc
+++ b/base/file_util_win.cc
@@ -116,6 +116,18 @@ bool Move(const FilePath& from_path, const FilePath& to_path) {
   return false;
 }
 
+bool ReplaceFile(const FilePath& from_path, const FilePath& to_path) {
+  // Make sure that the target file exists.
+  HANDLE target_file = ::CreateFile(to_path.value().c_str(), 0,
+                                    FILE_SHARE_READ | FILE_SHARE_WRITE,
+                                    NULL, CREATE_NEW,
+                                    FILE_ATTRIBUTE_NORMAL, NULL);
+  if (target_file != INVALID_HANDLE_VALUE)
+    ::CloseHandle(target_file);
+  return ::ReplaceFile(to_path.value().c_str(), from_path.value().c_str(),
+                       NULL, 0, NULL, NULL) ? true : false;
+}
+
 bool CopyFile(const FilePath& from_path, const FilePath& to_path) {
   // NOTE: I suspect we could support longer paths, but that would involve
   // analyzing all our usage of files.