Update from chromium https://crrev.com/304586

base/files/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/files/file_util.h"
 
 #include <windows.h>
 #include <io.h>
 #include <psapi.h>
 #include <shellapi.h>
@@ skipping 192 matching lines @@
       }
     }
 
     if (from_is_dir) {
       if (!DirectoryExists(target_path) &&
           !::CreateDirectory(target_path.value().c_str(), NULL)) {
         DLOG(ERROR) << "CopyDirectory() couldn't create directory: "
                     << target_path.value().c_str();
         success = false;
       }
-    } else if (!internal::CopyFileUnsafe(current, target_path)) {
+    } else if (!CopyFile(current, target_path)) {
       DLOG(ERROR) << "CopyDirectory() couldn't create file: "
                   << target_path.value().c_str();
       success = false;
     }
 
     current = traversal.Next();
     if (!current.empty())
       from_is_dir = traversal.GetInfo().IsDirectory();
   }
 
@@ skipping 491 matching lines @@
   }
 
   // Length of |path| with path separator appended.
   size_t prefix = path.StripTrailingSeparators().value().size() + 1;
   // The whole path string must be shorter than MAX_PATH. That is, it must be
   // prefix + component_length < MAX_PATH (or equivalently, <= MAX_PATH - 1).
   int whole_path_limit = std::max(0, MAX_PATH - 1 - static_cast<int>(prefix));
   return std::min(whole_path_limit, static_cast<int>(max_length));
 }
 
+bool CopyFile(const FilePath& from_path, const FilePath& to_path) {
+  ThreadRestrictions::AssertIOAllowed();
+  if (from_path.ReferencesParent() || to_path.ReferencesParent())
+    return false;
+
+  // NOTE: I suspect we could support longer paths, but that would involve
+  // analyzing all our usage of files.
+  if (from_path.value().length() >= MAX_PATH ||
+      to_path.value().length() >= MAX_PATH) {
+    return false;
+  }
+
+  // Unlike the posix implementation that copies the file manually and discards
+  // the ACL bits, CopyFile() copies the complete SECURITY_DESCRIPTOR and access
+  // bits, which is usually not what we want. We can't do much about the
+  // SECURITY_DESCRIPTOR but at least remove the read only bit.
+  const wchar_t* dest = to_path.value().c_str();
+  if (!::CopyFile(from_path.value().c_str(), dest, false)) {
+    // Copy failed.
+    return false;
+  }
+  DWORD attrs = GetFileAttributes(dest);
+  if (attrs == INVALID_FILE_ATTRIBUTES) {
+    return false;
+  }
+  if (attrs & FILE_ATTRIBUTE_READONLY) {
+    SetFileAttributes(dest, attrs & ~FILE_ATTRIBUTE_READONLY);
+  }
+  return true;
+}
+
 // -----------------------------------------------------------------------------
 
 namespace internal {
 
 bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
   ThreadRestrictions::AssertIOAllowed();
 
   // NOTE: I suspect we could support longer paths, but that would involve
   // analyzing all our usage of files.
   if (from_path.value().length() >= MAX_PATH ||
@@ skipping 18 matching lines @@
 
   if (!ret) {
     // Leave a clue about what went wrong so that it can be (at least) picked
     // up by a PLOG entry.
     ::SetLastError(last_error);
   }
 
   return ret;
 }
 
-bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
-  ThreadRestrictions::AssertIOAllowed();
-
-  // NOTE: I suspect we could support longer paths, but that would involve
-  // analyzing all our usage of files.
-  if (from_path.value().length() >= MAX_PATH ||
-      to_path.value().length() >= MAX_PATH) {
-    return false;
-  }
-
-  // Unlike the posix implementation that copies the file manually and discards
-  // the ACL bits, CopyFile() copies the complete SECURITY_DESCRIPTOR and access
-  // bits, which is usually not what we want. We can't do much about the
-  // SECURITY_DESCRIPTOR but at least remove the read only bit.
-  const wchar_t* dest = to_path.value().c_str();
-  if (!::CopyFile(from_path.value().c_str(), dest, false)) {
-    // Copy failed.
-    return false;
-  }
-  DWORD attrs = GetFileAttributes(dest);
-  if (attrs == INVALID_FILE_ATTRIBUTES) {
-    return false;
-  }
-  if (attrs & FILE_ATTRIBUTE_READONLY) {
-    SetFileAttributes(dest, attrs & ~FILE_ATTRIBUTE_READONLY);
-  }
-  return true;
-}
-
 bool CopyAndDeleteDirectory(const FilePath& from_path,
                             const FilePath& to_path) {
   ThreadRestrictions::AssertIOAllowed();
   if (CopyDirectory(from_path, to_path, true)) {
     if (DeleteFile(from_path, true))
       return true;
 
     // Like Move, this function is not transactional, so we just
     // leave the copied bits behind if deleting from_path fails.
     // If to_path exists previously then we have already overwritten
     // it by now, we don't get better off by deleting the new bits.
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace base