ClassicAPI/src/addons/LocalTable.cpp

// This file is part of ClassicAPI.
//
// ClassicAPI is free software: you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software Foundation, either
// version 3 of the License, or (at your option) any later version.
//
// ClassicAPI is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
// PURPOSE. See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with
// ClassicAPI. If not, see <https://www.gnu.org/licenses/>.

// `C_AddOns.GetAddOnLocalTable(name)` — the public, gated view of an addon's
// private namespace table (the `local _, addonTable = ...` second vararg each
// addon file is called with; see luasyntax/AddonNamespace.h).
//
// Retail added this in 11.0 alongside the `## AllowAddOnTableAccess` TOC
// directive: one addon can read another's local table ONLY when the target
// opts in. We mirror that gate:
//   1. the named addon is currently LOADED, and
//   2. its `.toc` declares `## AllowAddOnTableAccess: 1`.
// Either check failing returns nil. An addon receiving its OWN table is a
// different, ungated path (its files are called with it at load) — an addon
// never needs permission for its own namespace.
//
// Directive spelling verified against the 1.15.8 Classic Era binary (both the
// `AllowAddOnTableAccess:` TOC key and the `GetAddOnLocalTable` name are
// present there). The vanilla 1.12 TOC parser drops unknown `##` directives,
// so we scan the `.toc` ourselves via `FUN_FILE_READ`.

#include "Game.h"
#include "Offsets.h"
#include "addons/EngineIO.h"
#include "addons/Toc.h"
#include "luasyntax/AddonNamespace.h"

#include <cstddef>
#include <cstdint>
#include <cstdio>

namespace AddOns::LocalTable {

namespace {

// IS_LOADED is a by-name hash lookup returning the loaded byte (`entry+0x18`);
// passing the name string works because the lookup hashes it. See Offsets.h.
using IsLoadedFn_t = uint8_t(__fastcall *)(const char *name);

// FUN_FILE_READ / the Storm free (see addons/EngineIO.h). Calling the raw
// FUN_FILE_READ address routes through Embedded's file-read hook, which forwards
// every non-`!!!ClassicAPI` path to the original untouched — what we want here.
using AddOns::EngineIO::FileReadFn;
using AddOns::EngineIO::SMemFreeFn;

// True iff the addon's `.toc` has a line `## AllowAddOnTableAccess: <nonzero>`.
// The value is read as a TOC boolean flag: parse the leading integer, true iff
// non-zero (so `1` opts in, `0`/absent do not) — matching WoW's numeric TOC
// flag semantics. Not cached: GetAddOnLocalTable is not a hot path.
bool TocAllowsTableAccess(const char *name) {
    // A registered, loaded addon name never carries a path separator; reject
    // any that does so the read stays bounded to the addon's own folder.
    for (const char *p = name; *p; ++p)
        if (*p == '\\' || *p == '/')
            return false;

    char path[300];
    std::snprintf(path, sizeof path, "Interface\\AddOns\\%s\\%s.toc", name, name);

    void *buf = nullptr;
    size_t size = 0;
    auto fileRead = reinterpret_cast<FileReadFn>(Offsets::FUN_FILE_READ);
    if (fileRead(0, path, &buf, &size, 1, 1, 0) == 0 || buf == nullptr)
        return false;

    const char *v = nullptr;
    size_t n = 0;
    bool allowed = false;
    if (AddOns::Toc::FindValue(static_cast<const char *>(buf), size,
                               "AllowAddOnTableAccess", &v, &n)) {
        int value = 0;
        bool anyDigit = false;
        for (size_t k = 0; k < n && v[k] >= '0' && v[k] <= '9'; ++k) {
            value = value * 10 + (v[k] - '0');
            anyDigit = true;
        }
        allowed = anyDigit && value != 0;
    }

    auto smemFree = reinterpret_cast<SMemFreeFn>(Offsets::FUN_STORM_SMEM_FREE);
    smemFree(buf, __FILE__, __LINE__, 0);
    return allowed;
}

// `C_AddOns.GetAddOnLocalTable(name)` -> table, or nil.
//
// Name (string) input only — the local table is a by-name concept (one addon
// asking for another by name), and the namespace map is name-keyed. Numeric
// index is not accepted (returns nil); no addon references another's table by
// load order.
int __fastcall Script_GetAddOnLocalTable(void *L) {
    const char *name = Game::Lua::ToString(L, 1);
    if (name == nullptr || *name == '\0') {
        Game::Lua::PushNil(L);
        return 1;
    }

    auto isLoaded = reinterpret_cast<IsLoadedFn_t>(Offsets::FUN_ADDON_IS_LOADED);
    if (isLoaded(name) == 0) { // not loaded (covers "does not exist")
        Game::Lua::PushNil(L);
        return 1;
    }

    if (!TocAllowsTableAccess(name)) { // opted out / no directive
        Game::Lua::PushNil(L);
        return 1;
    }

    LuaSyntax::PushAddonNamespace(L, name);
    return 1;
}

void RegisterLuaFunctions() {
    Game::Lua::RegisterTableFunction("C_AddOns", "GetAddOnLocalTable",
                                     &Script_GetAddOnLocalTable);
}

const Game::ModuleAutoRegister _autoreg{&RegisterLuaFunctions};

} // namespace

} // namespace AddOns::LocalTable