It has only three consumers, it throws an integer on error, which may be causing SERVER-5633, and the cstdlib function strtoul can be used to implement a saner version of the desired operation. I think we just want to use strotoul to write a function with the following signature:

/**

• Parse a base-10 unsigned from "str", put the result into "result".
  *
• Returns true if all the characters of "str" are consumed to produce a valid "result".
  */
  bool parseBase10(const StringData& str, unsigned *result);