For those who can't play a video game without dissecting it
Here’s a small update. There is a structure in the SDK code that looks like it could be defining “primary” header for a block, including pointers to another header and the data:
struct SaveRestoreBlockHeader_t
{
char szName[MAX_BLOCK_NAME_LEN + 1];
int locHeader;
int locBody;
DECLARE_SIMPLE_DATADESC();
};
Two of the blocks from the save file:
Hex View 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00008EC0 45 6E 74 69 74 69 65 73 00 00 00 00 00 00 00 00 Entities........
00008ED0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00008EE0 04 00 B2 2F 74 01 00 00 04 00 76 00 01 00 00 00 .../t.....v.....
00008EF0 3C 00 14 0F 04 00 09 09 03 00 00 00 20 00 E3 06 <........... ...
Hex View 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
00008FD0 50 79 74 68 6F 6E 00 00 Python..
00008FE0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00008FF0 00 00 00 00 00 00 00 00 04 00 B2 2F D5 ED 00 00 .........../....
00009000 04 00 98 09 43 BC 0A 00 04 00 98 09 FF FF FF FF ....C...........
Trying to overlay the struct definition shows that it isn’t entirely consistent with the source code, but the build used for Vampire is a decades older, so we’ll just ignore that for now:
45 6E 74 69 74 69 65 73 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 - szName, "Entities"
04 00 B2 2F - static?
74 01 00 00 - locHeader (offset)
04 00 76 00 - locBody?
01 00 00 00 3C 00 14 0F 04 00 09 09 03 00 00 00 20 00 E3 06 - datadesc?
50 79 74 68 6F 6E 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 - szName, "Python"
04 00 B2 2F - static?
D5 ED 00 00 - locHeader (offset)
04 00 98 09 - locBody?
BC 0A 00 04 00 98 09 FF FF FF FF - datadesc?
So far, I’ve been able to make things easy by referencing the source code, but the Python block handler is a Vampire-specific addition, and there’s no associated code in the SDK. However, since the various SaveRestoreBlockHandlers derive from the same interface, it’s still fairly easy to find the methods of interest.
Incidentally, setting a breakpoint on CPython_SaveRestoreBlockHandler::ReadRestoreHeaders as well as CEntity_SaveRestoreBlockHandler::ReadRestoreHeaders revealed that the Python block either does in fact get processed later than the entities block, or the game touches both blocks multiple times during loading.
We can take a shortcut around trying to comprehend the header format by noticing that CSaveRestoreBlockSet::CallBlockHandlerRestore calls GetBlockHeaderLoc and sets the read location on the IRestore instance that CPython_SaveRestoreBlockHandler::Restore gets as an argument. This gives us an offset into the save data file after it has been mapped into memory.