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

base/platform_file.h

Index: base/platform_file.h
===================================================================
--- base/platform_file.h	(revision 175095)
+++ base/platform_file.h	(working copy)
@@ -120,11 +120,20 @@
 // true if a new file was created [or an old one truncated to zero length to
 // simulate a new file, which can happen with PLATFORM_FILE_CREATE_ALWAYS], and
 // false otherwise.  |error_code| can be NULL.
+//
+// This function fails with 'access denied' if the |name| contains path
+// traversal components.
 BASE_EXPORT PlatformFile CreatePlatformFile(const FilePath& name,
                                             int flags,
                                             bool* created,
                                             PlatformFileError* error_code);
 
+// Same as CreatePlatformFile but allows paths with traversal (like \..\)
+// components. Use only with extreme care.
+BASE_EXPORT PlatformFile CreatePlatformFileAllowTraversal(
+    const FilePath& name, int flags, bool* created,

[brettw, 2013/01/07 20:50:26]

Can you horizontally align the params on different lines like the other one
does?

+    PlatformFileError* error_code);
+
 // Closes a file handle. Returns |true| on success and |false| otherwise.
 BASE_EXPORT bool ClosePlatformFile(PlatformFile file);