[Segfaultd]

car_export_m2o now writes exactly what Mafia II Online streams: the car's archive untouched, plus a material library when the car adds materials. Server owners drop the folder in and ship nothing else.

Pairs with mafia2online/Mod#16, which adds streamed cars to M2O (that PR depends on MafiaHub/Framework#314).

What the export writes

<resource>/
  package.json                      name, version, description: no file list needed
  stream/sds/cars/<name>.sds        the car, byte for byte as built
  stream/sds/cars/<name>_z.sds      winter twin, when there is one
  stream/materials/<name>.mtl       only when the car adds materials

• Gone: vehicles.json, the sds/** file list, the table rows and the hashes. M2O registers each archive by its file name (a stock car's name replaces that car), so none of it is read any more.
• Old layout: an export folder in the old layout (sds/cars + vehicles.json) is refused with a clear message instead of being mixed into.

Materials travel as a streamed library

The meshes name materials by hash, and the game resolves them against the libraries in edit\materials, which no server can change on a player's machine.

• Native path: the game already loads a library in addition to default.mtl: a mission pack's, through C_MaterialManager::LoadMTL, released again when the mission closes. M2O streams libraries the same way, for any content (cars now, city parts and crash objects later).
• What's written: each material the car uses that the game didn't ship with (one the toolkit created for it) goes into an MTL v57 library of just those materials, written atomically. A re-export that adds nothing removes a stale library.
• What "shipped with" means: each library in edit\materials as it was before the toolkit first wrote it. That's its oldest backup in backups\, or the file itself if the toolkit never wrote it.
• Refused:
  • a car whose meshes use a material no library has (empty hash-0 slots are ignored);
  • a car named with anything but a-z, 0-9 and _, which a server would not stream;
  • a car that adds materials under a default* name, whose library would collide with the game's own.

The M2O server refuses a car that adds textures no streamed material uses, so a car exported without its library won't ship.

A clone carries its own vehicles.tbl row

Without a row, a new car takes the game's empty first row in M2O. The export now writes a clone's row into both archives as a native table patch, /tables/patch_m2o<name>_vehicles.tbl, which the game appends while the car is loaded (how Joe's Adventures adds its cars).

• Id and title: the row keeps the id and title text of the car it was made from. The game indexes per-car data by id, and a non-stock id crashes; the clone's text exists only on its maker's machine.
• No paint row: the car uses its source car's paint row. The clone copies that row anyway, and a second row under a shared id would also repaint the stock car.
• Stock names: a car under a stock name keeps the stock row.
• New helpers: GameTable.PatchRow and GameTable.Name, plus SdsManifest.AddTableEntry.
• The archives are no longer byte-for-byte copies for clones: they are the built archive plus that one Table entry.

Testing

• --probe-car-m2o against a real install (Steam, Mafia II Classic): 28/28 pass. It covers:
  • each archive being the built one plus its row (the clone's name, Shubert_38's id 14 and title);
  • the new layout and package.json;
  • a stock-material clone shipped with no library;
  • one of the car's materials treated as new: stream/materials/<car>.mtl holds exactly it, the archives stay byte for byte, and a re-export without it removes the library;
  • the refusals: bad resource name, foreign folder, old layout, unreadable package.json, misnamed archive, a car name a server does not stream, unknown material.
• End to end with M2O, using the tester's FBI Shubert (shubert_38_custom.sds, whose FBI_Empire_Bay and FBI_beacon aren't in the stock libraries). ExportFrom wrote the untouched archive plus a 251-byte shubert_38_custom.mtl. Used unchanged as an M2O server resource:
  • the server accepted it, and refused it once the library was removed;
  • the client loaded the library (2 materials, both new), and the car showed the FBI door emblem;
  • the export with the row gave the car Shubert_38_Custom's row (id 14, 14 paint combos) instead of the empty row 0;
  • the two-client streamed suite passed 9/9 (seats, driving, stream out and in, virtual world, destroy);
  • leaving the server released the materials, and reconnecting in the same game process loaded them again.
• The solution builds with 0 warnings and 0 errors.

Not covered

• A new car shows its source car's title and paint, for the reasons above.
• --probe-car-writes was already failing before this PR: it lists 14 files outside its allow-list. CarM2oExport was one of them before this change, and nothing here adds to that list.