Make sure to finish all entities in the internal subset. Nevertheless,
readd a sanity check in xmlParseStartTag2 that was lost in my previous
commit. Also add a sanity check in xmlPopInput. Popping an input
unexpectedly was the source of many recent memory bugs. The check
doesn't mitigate such issues but helps with diagnosis.
Always base entity boundary checks on the input ID, not the input
pointer. The pointer could have been reallocated to the old address.
Always throw a well-formedness error if a boundary check fails. In a
few places, a validity error was thrown.
Fix a few error codes and improve indentation.
For https://bugzilla.gnome.org/show_bug.cgi?id=754946
When hitting the end of the current input buffer while parsing
a name we could end up loosing the beginning of the name, which
led to various issues.
