Fix script security path normalization in presence of links (#15481)

src/filesys.h

@@ -131,6 +131,12 @@ std::string RemoveRelativePathComponents(std::string path);
 // components and symlinks removed.  Returns "" on error.
 std::string AbsolutePath(const std::string &path);
 
+// This is a combination of RemoveRelativePathComponents() and AbsolutePath()
+// It will resolve symlinks for the leading path components that exist and
+// still remove "." and ".." in the rest of the path.
+// Returns "" on error.
+std::string AbsolutePathPartial(const std::string &path);
+
 // Returns the filename from a path or the entire path if no directory
 // delimiter is found.
 const char *GetFilenameFromPath(const char *path);