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Diffstat (limited to 'src/script/common/c_packer.cpp')
-rw-r--r-- | src/script/common/c_packer.cpp | 596 |
1 files changed, 596 insertions, 0 deletions
diff --git a/src/script/common/c_packer.cpp b/src/script/common/c_packer.cpp new file mode 100644 index 000000000..597f5e447 --- /dev/null +++ b/src/script/common/c_packer.cpp @@ -0,0 +1,596 @@ +/* +Minetest +Copyright (C) 2022 sfan5 <sfan5@live.de> + +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU Lesser General Public License as published by +the Free Software Foundation; either version 2.1 of the License, or +(at your option) any later version. + +This program 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 Lesser General Public License for more details. + +You should have received a copy of the GNU Lesser General Public License along +with this program; if not, write to the Free Software Foundation, Inc., +51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. +*/ + +#include <cstdio> +#include <cstring> +#include <cmath> +#include <cassert> +#include <unordered_set> +#include <unordered_map> +#include "c_packer.h" +#include "c_internal.h" +#include "log.h" +#include "debug.h" +#include "threading/mutex_auto_lock.h" + +extern "C" { +#include <lauxlib.h> +} + +// +// Helpers +// + +// convert negative index to absolute position on Lua stack +static inline int absidx(lua_State *L, int idx) +{ + assert(idx < 0); + return lua_gettop(L) + idx + 1; +} + +// does the type put anything into PackedInstr::sdata? +static inline bool uses_sdata(int type) +{ + switch (type) { + case LUA_TSTRING: + case LUA_TFUNCTION: + case LUA_TUSERDATA: + return true; + default: + return false; + } +} + +// does the type put anything into PackedInstr::<union>? +static inline bool uses_union(int type) +{ + switch (type) { + case LUA_TNIL: + case LUA_TSTRING: + case LUA_TFUNCTION: + return false; + default: + return true; + } +} + +static inline bool can_set_into(int ktype, int vtype) +{ + switch (ktype) { + case LUA_TNUMBER: + return !uses_union(vtype); + case LUA_TSTRING: + return !uses_sdata(vtype); + default: + return false; + } +} + +// is the key suitable for use with set_into? +static inline bool suitable_key(lua_State *L, int idx) +{ + if (lua_type(L, idx) == LUA_TSTRING) { + // strings may not have a NULL byte (-> lua_setfield) + size_t len; + const char *str = lua_tolstring(L, idx, &len); + return strlen(str) == len; + } else { + assert(lua_type(L, idx) == LUA_TNUMBER); + // numbers must fit into an s32 and be integers (-> lua_rawseti) + lua_Number n = lua_tonumber(L, idx); + return std::floor(n) == n && n >= S32_MIN && n <= S32_MAX; + } +} + +namespace { + // checks if you left any values on the stack, for debugging + class StackChecker { + lua_State *L; + int top; + public: + StackChecker(lua_State *L) : L(L), top(lua_gettop(L)) {} + ~StackChecker() { + assert(lua_gettop(L) >= top); + if (lua_gettop(L) > top) { + rawstream << "Lua stack not cleaned up: " + << lua_gettop(L) << " != " << top + << " (false-positive if exception thrown)" << std::endl; + } + } + }; + + // Since an std::vector may reallocate, this is the only safe way to keep + // a reference to a particular element. + template <typename T> + class VectorRef { + std::vector<T> *vec; + size_t idx; + VectorRef(std::vector<T> *vec, size_t idx) : vec(vec), idx(idx) {} + public: + constexpr VectorRef() : vec(nullptr), idx(0) {} + static VectorRef<T> front(std::vector<T> &vec) { + return VectorRef(&vec, 0); + } + static VectorRef<T> back(std::vector<T> &vec) { + return VectorRef(&vec, vec.size() - 1); + } + T &operator*() { return (*vec)[idx]; } + T *operator->() { return &(*vec)[idx]; } + operator bool() const { return vec != nullptr; } + }; + + struct Packer { + PackInFunc fin; + PackOutFunc fout; + }; + + typedef std::pair<std::string, Packer> PackerTuple; +} + +static inline auto emplace(PackedValue &pv, s16 type) +{ + pv.i.emplace_back(); + auto ref = VectorRef<PackedInstr>::back(pv.i); + ref->type = type; + // Initialize fields that may be left untouched + if (type == LUA_TTABLE) { + ref->uidata1 = 0; + ref->uidata2 = 0; + } else if (type == LUA_TUSERDATA) { + ref->ptrdata = nullptr; + } else if (type == INSTR_POP) { + ref->sidata2 = 0; + } + return ref; +} + +// +// Management of registered packers +// + +static std::unordered_map<std::string, Packer> g_packers; +static std::mutex g_packers_lock; + +void script_register_packer(lua_State *L, const char *regname, + PackInFunc fin, PackOutFunc fout) +{ + // Store away callbacks + { + MutexAutoLock autolock(g_packers_lock); + auto it = g_packers.find(regname); + if (it == g_packers.end()) { + auto &ref = g_packers[regname]; + ref.fin = fin; + ref.fout = fout; + } else { + FATAL_ERROR_IF(it->second.fin != fin || it->second.fout != fout, + "Packer registered twice with mismatching callbacks"); + } + } + + // Save metatable so we can identify instances later + lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_METATABLE_MAP); + if (lua_isnil(L, -1)) { + lua_newtable(L); + lua_pushvalue(L, -1); + lua_rawseti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_METATABLE_MAP); + } + + luaL_getmetatable(L, regname); + FATAL_ERROR_IF(lua_isnil(L, -1), "No metatable registered with that name"); + + // CUSTOM_RIDX_METATABLE_MAP contains { [metatable] = "regname", ... } + // check first + lua_pushstring(L, regname); + lua_rawget(L, -3); + if (!lua_isnil(L, -1)) { + FATAL_ERROR_IF(lua_topointer(L, -1) != lua_topointer(L, -2), + "Packer registered twice with inconsistent metatable"); + } + lua_pop(L, 1); + // then set + lua_pushstring(L, regname); + lua_rawset(L, -3); + + lua_pop(L, 1); +} + +static bool find_packer(const char *regname, PackerTuple &out) +{ + MutexAutoLock autolock(g_packers_lock); + auto it = g_packers.find(regname); + if (it == g_packers.end()) + return false; + // copy data for thread safety + out.first = it->first; + out.second = it->second; + return true; +} + +static bool find_packer(lua_State *L, int idx, PackerTuple &out) +{ +#ifndef NDEBUG + StackChecker checker(L); +#endif + + // retrieve metatable of the object + if (lua_getmetatable(L, idx) != 1) + return false; + + // use our global table to map it to the registry name + lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_METATABLE_MAP); + assert(lua_istable(L, -1)); + lua_pushvalue(L, -2); + lua_rawget(L, -2); + if (lua_isnil(L, -1)) { + lua_pop(L, 3); + return false; + } + + // load the associated data + bool found = find_packer(lua_tostring(L, -1), out); + FATAL_ERROR_IF(!found, "Inconsistent internal state"); + lua_pop(L, 3); + return true; +} + +// +// Packing implementation +// + +static VectorRef<PackedInstr> record_object(lua_State *L, int idx, PackedValue &pv, + std::unordered_map<const void *, s32> &seen) +{ + const void *ptr = lua_topointer(L, idx); + assert(ptr); + auto found = seen.find(ptr); + if (found == seen.end()) { + seen[ptr] = pv.i.size(); + return VectorRef<PackedInstr>(); + } + s32 ref = found->second; + assert(ref < (s32)pv.i.size()); + // reuse the value from first time + auto r = emplace(pv, INSTR_PUSHREF); + r->ref = ref; + pv.i[ref].keep_ref = true; + return r; +} + +static VectorRef<PackedInstr> pack_inner(lua_State *L, int idx, int vidx, PackedValue &pv, + std::unordered_map<const void *, s32> &seen) +{ +#ifndef NDEBUG + StackChecker checker(L); + assert(idx > 0); + assert(vidx > 0); +#endif + + switch (lua_type(L, idx)) { + case LUA_TNONE: + case LUA_TNIL: + return emplace(pv, LUA_TNIL); + case LUA_TBOOLEAN: { + auto r = emplace(pv, LUA_TBOOLEAN); + r->bdata = lua_toboolean(L, idx); + return r; + } + case LUA_TNUMBER: { + auto r = emplace(pv, LUA_TNUMBER); + r->ndata = lua_tonumber(L, idx); + return r; + } + case LUA_TSTRING: { + auto r = emplace(pv, LUA_TSTRING); + size_t len; + const char *str = lua_tolstring(L, idx, &len); + assert(str); + r->sdata.assign(str, len); + return r; + } + case LUA_TTABLE: { + auto r = record_object(L, idx, pv, seen); + if (r) + return r; + break; // execution continues + } + case LUA_TFUNCTION: { + auto r = record_object(L, idx, pv, seen); + if (r) + return r; + r = emplace(pv, LUA_TFUNCTION); + call_string_dump(L, idx); + size_t len; + const char *str = lua_tolstring(L, -1, &len); + assert(str); + r->sdata.assign(str, len); + lua_pop(L, 1); + return r; + } + case LUA_TUSERDATA: { + auto r = record_object(L, idx, pv, seen); + if (r) + return r; + PackerTuple ser; + if (!find_packer(L, idx, ser)) + throw LuaError("Cannot serialize unsupported userdata"); + pv.contains_userdata = true; + r = emplace(pv, LUA_TUSERDATA); + r->sdata = ser.first; + r->ptrdata = ser.second.fin(L, idx); + return r; + } + default: { + std::string err = "Cannot serialize type "; + err += lua_typename(L, lua_type(L, idx)); + throw LuaError(err); + } + } + + // LUA_TTABLE + lua_checkstack(L, 5); + + auto rtable = emplace(pv, LUA_TTABLE); + const int vi_table = vidx++; + + lua_pushnil(L); + while (lua_next(L, idx) != 0) { + // key at -2, value at -1 + const int ktype = lua_type(L, -2), vtype = lua_type(L, -1); + if (ktype == LUA_TNUMBER) + rtable->uidata1++; // narr + else + rtable->uidata2++; // nrec + + // check if we can use a shortcut + if (can_set_into(ktype, vtype) && suitable_key(L, -2)) { + // push only the value + auto rval = pack_inner(L, absidx(L, -1), vidx, pv, seen); + rval->pop = rval->type != LUA_TTABLE; + // and where to put it: + rval->set_into = vi_table; + if (ktype == LUA_TSTRING) + rval->sdata = lua_tostring(L, -2); + else + rval->sidata1 = lua_tointeger(L, -2); + // pop tables after the fact + if (!rval->pop) { + auto ri1 = emplace(pv, INSTR_POP); + ri1->sidata1 = vidx; + } + } else { + // push the key and value + pack_inner(L, absidx(L, -2), vidx, pv, seen); + vidx++; + pack_inner(L, absidx(L, -1), vidx, pv, seen); + vidx++; + // push an instruction to set them + auto ri1 = emplace(pv, INSTR_SETTABLE); + ri1->set_into = vi_table; + ri1->sidata1 = vidx - 2; + ri1->sidata2 = vidx - 1; + ri1->pop = true; + vidx -= 2; + } + + lua_pop(L, 1); + } + + assert(vidx == vi_table + 1); + return rtable; +} + +PackedValue *script_pack(lua_State *L, int idx) +{ + if (idx < 0) + idx = absidx(L, idx); + + PackedValue pv; + std::unordered_map<const void *, s32> seen; + pack_inner(L, idx, 1, pv, seen); + + return new PackedValue(std::move(pv)); +} + +// +// Unpacking implementation +// + +void script_unpack(lua_State *L, PackedValue *pv) +{ + lua_newtable(L); // table at index top to track ref indices -> objects + const int top = lua_gettop(L); + int ctr = 0; + + for (size_t packed_idx = 0; packed_idx < pv->i.size(); packed_idx++) { + auto &i = pv->i[packed_idx]; + + // If leaving values on stack make sure there's space (every 5th iteration) + if (!i.pop && (ctr++) >= 5) { + lua_checkstack(L, 5); + ctr = 0; + } + + switch (i.type) { + /* Instructions */ + case INSTR_SETTABLE: + lua_pushvalue(L, top + i.sidata1); // key + lua_pushvalue(L, top + i.sidata2); // value + lua_rawset(L, top + i.set_into); + if (i.pop) { + if (i.sidata1 != i.sidata2) { + // removing moves indices so pop higher index first + lua_remove(L, top + std::max(i.sidata1, i.sidata2)); + lua_remove(L, top + std::min(i.sidata1, i.sidata2)); + } else { + lua_remove(L, top + i.sidata1); + } + } + continue; + case INSTR_POP: + lua_remove(L, top + i.sidata1); + if (i.sidata2 > 0) + lua_remove(L, top + i.sidata2); + continue; + case INSTR_PUSHREF: + lua_pushinteger(L, i.ref); + lua_rawget(L, top); + break; + + /* Lua types */ + case LUA_TNIL: + lua_pushnil(L); + break; + case LUA_TBOOLEAN: + lua_pushboolean(L, i.bdata); + break; + case LUA_TNUMBER: + lua_pushnumber(L, i.ndata); + break; + case LUA_TSTRING: + lua_pushlstring(L, i.sdata.data(), i.sdata.size()); + break; + case LUA_TTABLE: + lua_createtable(L, i.uidata1, i.uidata2); + break; + case LUA_TFUNCTION: + luaL_loadbuffer(L, i.sdata.data(), i.sdata.size(), nullptr); + break; + case LUA_TUSERDATA: { + PackerTuple ser; + sanity_check(find_packer(i.sdata.c_str(), ser)); + ser.second.fout(L, i.ptrdata); + i.ptrdata = nullptr; // ownership taken by callback + break; + } + + default: + assert(0); + break; + } + + if (i.keep_ref) { + lua_pushinteger(L, packed_idx); + lua_pushvalue(L, -2); + lua_rawset(L, top); + } + + if (i.set_into) { + if (!i.pop) + lua_pushvalue(L, -1); + if (uses_sdata(i.type)) + lua_rawseti(L, top + i.set_into, i.sidata1); + else + lua_setfield(L, top + i.set_into, i.sdata.c_str()); + } else { + if (i.pop) + lua_pop(L, 1); + } + } + + // as part of the unpacking process we take ownership of all userdata + pv->contains_userdata = false; + // leave exactly one value on the stack + lua_settop(L, top+1); + lua_remove(L, top); +} + +// +// PackedValue +// + +PackedValue::~PackedValue() +{ + if (!contains_userdata) + return; + for (auto &i : this->i) { + if (i.type == LUA_TUSERDATA && i.ptrdata) { + PackerTuple ser; + if (find_packer(i.sdata.c_str(), ser)) { + // tell it to deallocate object + ser.second.fout(nullptr, i.ptrdata); + } else { + assert(false); + } + } + } +} + +// +// script_dump_packed +// + +#ifndef NDEBUG +void script_dump_packed(const PackedValue *val) +{ + printf("instruction stream: [\n"); + for (const auto &i : val->i) { + printf("\t("); + switch (i.type) { + case INSTR_SETTABLE: + printf("SETTABLE(%d, %d)", i.sidata1, i.sidata2); + break; + case INSTR_POP: + printf(i.sidata2 ? "POP(%d, %d)" : "POP(%d)", i.sidata1, i.sidata2); + break; + case INSTR_PUSHREF: + printf("PUSHREF(%d)", i.ref); + break; + case LUA_TNIL: + printf("nil"); + break; + case LUA_TBOOLEAN: + printf(i.bdata ? "true" : "false"); + break; + case LUA_TNUMBER: + printf("%f", i.ndata); + break; + case LUA_TSTRING: + printf("\"%s\"", i.sdata.c_str()); + break; + case LUA_TTABLE: + printf("table(%d, %d)", i.uidata1, i.uidata2); + break; + case LUA_TFUNCTION: + printf("function(%lu byte)", i.sdata.size()); + break; + case LUA_TUSERDATA: + printf("userdata %s %p", i.sdata.c_str(), i.ptrdata); + break; + default: + printf("!!UNKNOWN!!"); + break; + } + if (i.set_into) { + if (i.type >= 0 && uses_sdata(i.type)) + printf(", k=%d, into=%d", i.sidata1, i.set_into); + else if (i.type >= 0) + printf(", k=\"%s\", into=%d", i.sdata.c_str(), i.set_into); + else + printf(", into=%d", i.set_into); + } + if (i.keep_ref) + printf(", keep_ref"); + if (i.pop) + printf(", pop"); + printf(")\n"); + } + printf("]\n"); +} +#endif |