Don't allow path traversal paths on the base file helpers

base/file_util.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"
 
 #if defined(OS_WIN)
 #include <io.h>
 #endif
 #include <stdio.h>
@@ skipping 134 matching lines @@
       line2.erase(end2 + 1);
 
     if (line1 != line2)
       return false;
   } while (!file1.eof() || !file2.eof());
 
   return true;
 }
 
 bool ReadFileToString(const FilePath& path, std::string* contents) {
+  if (path.ReferencesParent())

[Nico, 2013/01/08 19:20:03]

Should this DCHECK(), so that devs trying to do this in a test don't waste 20
minutes trying to understand what's going on?

+    return false;
   FILE* file = OpenFile(path, "rb");
   if (!file) {
     return false;
   }
 
   char buf[1 << 16];
   size_t len;
   while ((len = fread(buf, 1, sizeof(buf), file)) > 0) {
     if (contents)
       contents->append(buf, len);
@@ skipping 223 matching lines @@
 // FileEnumerator
 //
 // Note: the main logic is in file_util_<platform>.cc
 
 bool FileEnumerator::ShouldSkip(const FilePath& path) {
   FilePath::StringType basename = path.BaseName().value();
   return IsDot(path) || (IsDotDot(path) && !(INCLUDE_DOT_DOT & file_type_));
 }
 
 }  // namespace