A data section indexes its instances from its own constructor, through
addLazyInstance(), under the section id it WILL be given - and
lazyFileReader::initP21() registers the section only afterwards, and only
if its scan succeeded. A section that fails part way therefore leaves
every instance it had already indexed naming a section that does not
exist.
typeFromFile() then indexes _dataSections with it unconditionally, and
loadInstance() does the same behind an assert() that Release compiles
out. On an empty vector that is an access violation. sourceRecord()
already makes exactly this test; the other two now make it too and answer
0 with a diagnostic, as they already do for an instance found in no
section.
The instances stay in the index - totalInstanceCount() still counts them
and getInstances() still lists them. What changes is that asking for one
of them fails the way every other unloadable instance fails.
Reachable from a thirteen-line file, added as test/lazy_broken_section.stp
and checked by the lazy_index test: a DATA section holding one instance
and then a line that is not one. Without the two changes below it, that
test dies with SIGSEGV inside typeFromFile().
Note that the new break in loadInstance() leaves `inst` null, and
isNilSTEPentity( 0 ) is false, so the null would be cached as a loaded
instance were it not for the guard added in "lazy: do not cache a null
instance as a loaded one" earlier in this branch. With the bounds test
alone the process survives the two calls and then dies on the way out.
Attila Prokai
18f7b43c99