During a I/O failure of whatever kind the upper-level driver, namely a FSD, can raise a hard error and a deadlock can occur. We wouldn't want that to happen for particular files like hives or logs so in such cases we must disable hard errors before toying with hives until we're done.
In addition to that, annotate the CmpFileSetSize function's parameters with SAL.
- When we are in LiveCD mode (more generally, when hives are shared), load
the system hives as volatile.
- Ignore hive write operations when everything operates in read-only mode
and just return success instead.
- Just return success on hive file I/O if no file is associated with a
given hive. This happens when e.g. a CM hive has a primary but no log.
