sots-re/guides
alex f965c8c769 lane S: std::string is 0x1c binary-wide; ObservedTech element fully mapped
Settles the 0x18-vs-0x1c contradiction lane X raised. 0x1c is right, everywhere,
and there is exactly one std::string instantiation in this binary:
_Bx@0, _Mysize@0x10, _Myres@0x14, _Alval@0x18.

ObservedTech+0x24 is that string's trailing empty-allocator word, not the
unaccounted data field it was read as. Three complete enumerations of the element
each skip it: ObservedTech::Write 0x00817cf0, the ctor 0x008562a0, and the copy
ctor inlined at 0x0079a184. Generalised with a new scanner, tools/strfootprint.py,
which recovers every (base, disp, tag) handed to the Mars::Stream string helpers:
65 std::string members off a non-stack base across every serializer in the exe,
ZERO with a sibling member inside the 0x1c span, and 51 of the 52 measurable
inter-member gaps exactly 0x1c. Corroborated by the vector<string> walk stride
(add esi,0x1c @0x00699c29), PostEvent's by-value strings at [ebp+8]/[ebp+0x24]
with RET 0x4c, and MoraleEvent 0x50 = name@0x34 + 0x1c.

Blast radius: zero recovered struct tables were wrong. Every string-bearing layout
already used 0x1c spans and 0x1c gaps -- ServerPlayer::pswd @0x2dc..0x2f7, the row
flagged for re-checking, included. Only prose carried the 0x18 number: the
loader-prototypes conventions line, the GlobalConst_ParseString prototype, and the
ObservedTech element table. struct-recovery S0 additionally had _Mysize/_Myres
transposed (size@0x14, res@0x18) while every table in the same file used the
correct offsets; fixed.

ObservedTech's four on-disk fields are now mapped rather than guessed, by reading
the serializer as lane X suggested: +0x04 uint16 otnF, +0x06 uint16 otnL, +0x08
bool odet (ONE BYTE, WriteBool), +0x0c std::string otch (0x1c), +0x28 int owith
= 0x2c exactly. That matches save_reader.py's on-disk order already. Game::
ObservedWeapon (0x00817bc0/0x00817b10) is the same element with tag owep.

Oracles unaffected and re-run: save_reader 36/36 and --strict exit 0 on all three
real saves; state_checksum 38 tests OK, coverage PROVED byte-for-byte on turn1 and
turn3. sots-engine wip/strings 32d3e36 syncs the header and corrects two stale
"unpinned" comments: clean_room_check OK, host ctest 33/33.

Standing rule this produced: never size a struct member from the offsets the code
touches. This build's STL puts the empty allocator LAST in both string (0x1c) and
vector (0x10), and an empty allocator is never loaded or stored, so a touch-scan
undercounts by exactly 4 every time. Size from an enumeration instead.
2026-09-08 05:09:33 -04:00
..
re-windows-2000s-howto.md lane S: std::string is 0x1c binary-wide; ObservedTech element fully mapped 2026-09-08 05:09:33 -04:00