saveload.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "../stdafx.h"
#include "../debug.h"
#include "../station_base.h"
#include "../thread.h"
#include "../town.h"
#include "../network/network.h"
#include "../window_func.h"
#include "../strings_func.h"
#include "../core/endian_func.hpp"
#include "../core/string_builder.hpp"
#include "../core/string_consumer.hpp"
#include "../vehicle_base.h"
#include "../company_func.h"
#include "../timer/timer_game_economy.h"
#include "../autoreplace_base.h"
#include "../roadstop_base.h"
#include "../linkgraph/linkgraph.h"
#include "../linkgraph/linkgraphjob.h"
#include "../statusbar_gui.h"
#include "../fileio_func.h"
#include "../gamelog.h"
#include "../string_func.h"
#include "../fios.h"
#include "../error.h"
#include "../strings_type.h"
#include "../newgrf_railtype.h"
#include "../newgrf_roadtype.h"
#include "../settings_internal.h"
#include "saveload_internal.h"
#include "saveload_filter.h"
 
#include <atomic>
#ifdef __EMSCRIPTEN__
# include <emscripten.h>
#endif
 
#ifdef WITH_LZO
#include <lzo/lzo1x.h>
#endif
 
#if defined(WITH_ZLIB)
#include <zlib.h>
#endif /* WITH_ZLIB */
 
#if defined(WITH_LIBLZMA)
#include <lzma.h>
#endif /* WITH_LIBLZMA */
 
#include "table/strings.h"
 
#include "../safeguards.h"
 
extern const SaveLoadVersion SAVEGAME_VERSION{to_underlying(SaveLoadVersion::MaxVersion) - 1}; 
 
SavegameType _savegame_type; 
FileToSaveLoad _file_to_saveload; 
 
uint32_t _ttdp_version;         
SaveLoadVersion _sl_version;  
uint8_t   _sl_minor_version;     
std::string _savegame_format; 
bool _do_autosave;            

enum class SaveLoadAction : uint8_t {
  Load, 
  Save, 
  Ptrs, 
  Null, 
  LoadCheck, 
};
 
enum class NeedLength : uint8_t {
  None, 
  WantLength, 
  CalcLength, 
};

static const size_t MEMORY_CHUNK_SIZE = 128 * 1024;

struct ReadBuffer {
  uint8_t buf[MEMORY_CHUNK_SIZE]; 
  uint8_t *bufp = nullptr; 
  uint8_t *bufe = nullptr; 
  std::shared_ptr<LoadFilter> reader{}; 
  size_t read = 0; 

  ReadBuffer(std::shared_ptr<LoadFilter> reader) : reader(std::move(reader))
  {
  }
 
  inline uint8_t ReadByte()
  {
    if (this->bufp == this->bufe) {
      size_t len = this->reader->Read(this->buf, lengthof(this->buf));
      if (len == 0) SlErrorCorrupt("Unexpected end of chunk");
 
      this->read += len;
      this->bufp = this->buf;
      this->bufe = this->buf + len;
    }
 
    return *this->bufp++;
  }

  size_t GetSize() const
  {
    return this->read - (this->bufe - this->bufp);
  }
};
 

struct MemoryDumper {
  std::vector<std::unique_ptr<uint8_t[]>> blocks{}; 
  uint8_t *buf = nullptr; 
  uint8_t *bufe = nullptr; 

  inline void WriteByte(uint8_t b)
  {
    /* Are we at the end of this chunk? */
    if (this->buf == this->bufe) {
      this->buf = this->blocks.emplace_back(std::make_unique<uint8_t[]>(MEMORY_CHUNK_SIZE)).get();
      this->bufe = this->buf + MEMORY_CHUNK_SIZE;
    }
 
    *this->buf++ = b;
  }

  void Flush(std::shared_ptr<SaveFilter> writer)
  {
    uint i = 0;
    size_t t = this->GetSize();
 
    while (t > 0) {
      size_t to_write = std::min(MEMORY_CHUNK_SIZE, t);
 
      writer->Write(this->blocks[i++].get(), to_write);
      t -= to_write;
    }
 
    writer->Finish();
  }

  size_t GetSize() const
  {
    return this->blocks.size() * MEMORY_CHUNK_SIZE - (this->bufe - this->buf);
  }
};

struct SaveLoadParams {
  SaveLoadAction action;               
  NeedLength need_length;              
  ChunkType chunk_type; 
  bool error;                          
 
  size_t obj_len;                      
  int array_index, last_array_index;   
  bool expect_table_header;            
 
  std::unique_ptr<MemoryDumper> dumper; 
  std::shared_ptr<SaveFilter> sf; 
 
  std::unique_ptr<ReadBuffer> reader; 
  std::shared_ptr<LoadFilter> lf; 
 
  StringID error_str;                  
  std::string extra_msg;               
 
  bool saveinprogress;                 
};
 
static SaveLoadParams _sl; 
 
static const std::vector<ChunkHandlerRef> &ChunkHandlers()
{
  /* These define the chunks */
  extern const ChunkHandlerTable _gamelog_chunk_handlers;
  extern const ChunkHandlerTable _map_chunk_handlers;
  extern const ChunkHandlerTable _misc_chunk_handlers;
  extern const ChunkHandlerTable _name_chunk_handlers;
  extern const ChunkHandlerTable _cheat_chunk_handlers;
  extern const ChunkHandlerTable _setting_chunk_handlers;
  extern const ChunkHandlerTable _company_chunk_handlers;
  extern const ChunkHandlerTable _engine_chunk_handlers;
  extern const ChunkHandlerTable _veh_chunk_handlers;
  extern const ChunkHandlerTable _waypoint_chunk_handlers;
  extern const ChunkHandlerTable _depot_chunk_handlers;
  extern const ChunkHandlerTable _order_chunk_handlers;
  extern const ChunkHandlerTable _town_chunk_handlers;
  extern const ChunkHandlerTable _sign_chunk_handlers;
  extern const ChunkHandlerTable _station_chunk_handlers;
  extern const ChunkHandlerTable _industry_chunk_handlers;
  extern const ChunkHandlerTable _economy_chunk_handlers;
  extern const ChunkHandlerTable _subsidy_chunk_handlers;
  extern const ChunkHandlerTable _cargomonitor_chunk_handlers;
  extern const ChunkHandlerTable _goal_chunk_handlers;
  extern const ChunkHandlerTable _story_page_chunk_handlers;
  extern const ChunkHandlerTable _league_chunk_handlers;
  extern const ChunkHandlerTable _ai_chunk_handlers;
  extern const ChunkHandlerTable _game_chunk_handlers;
  extern const ChunkHandlerTable _animated_tile_chunk_handlers;
  extern const ChunkHandlerTable _newgrf_chunk_handlers;
  extern const ChunkHandlerTable _group_chunk_handlers;
  extern const ChunkHandlerTable _cargopacket_chunk_handlers;
  extern const ChunkHandlerTable _autoreplace_chunk_handlers;
  extern const ChunkHandlerTable _labelmaps_chunk_handlers;
  extern const ChunkHandlerTable _linkgraph_chunk_handlers;
  extern const ChunkHandlerTable _airport_chunk_handlers;
  extern const ChunkHandlerTable _object_chunk_handlers;
  extern const ChunkHandlerTable _persistent_storage_chunk_handlers;
  extern const ChunkHandlerTable _water_region_chunk_handlers;
  extern const ChunkHandlerTable _randomizer_chunk_handlers;

  static const ChunkHandlerTable _chunk_handler_tables[] = {
    _gamelog_chunk_handlers,
    _map_chunk_handlers,
    _misc_chunk_handlers,
    _name_chunk_handlers,
    _cheat_chunk_handlers,
    _setting_chunk_handlers,
    _veh_chunk_handlers,
    _waypoint_chunk_handlers,
    _depot_chunk_handlers,
    _order_chunk_handlers,
    _industry_chunk_handlers,
    _economy_chunk_handlers,
    _subsidy_chunk_handlers,
    _cargomonitor_chunk_handlers,
    _goal_chunk_handlers,
    _story_page_chunk_handlers,
    _league_chunk_handlers,
    _engine_chunk_handlers,
    _town_chunk_handlers,
    _sign_chunk_handlers,
    _station_chunk_handlers,
    _company_chunk_handlers,
    _ai_chunk_handlers,
    _game_chunk_handlers,
    _animated_tile_chunk_handlers,
    _newgrf_chunk_handlers,
    _group_chunk_handlers,
    _cargopacket_chunk_handlers,
    _autoreplace_chunk_handlers,
    _labelmaps_chunk_handlers,
    _linkgraph_chunk_handlers,
    _airport_chunk_handlers,
    _object_chunk_handlers,
    _persistent_storage_chunk_handlers,
    _water_region_chunk_handlers,
    _randomizer_chunk_handlers,
  };
 
  static std::vector<ChunkHandlerRef> _chunk_handlers;
 
  if (_chunk_handlers.empty()) {
    for (auto &chunk_handler_table : _chunk_handler_tables) {
      for (auto &chunk_handler : chunk_handler_table) {
        _chunk_handlers.push_back(chunk_handler);
      }
    }
  }
 
  return _chunk_handlers;
}

static void SlNullPointers()
{
  _sl.action = SaveLoadAction::Null;
 
  /* We don't want any savegame conversion code to run
   * during NULLing; especially those that try to get
   * pointers from other pools. */
  _sl_version = SAVEGAME_VERSION;
 
  for (const ChunkHandler &ch : ChunkHandlers()) {
    Debug(Facility::Sl, Severity::Notice, "Nulling pointers for {}", ch.GetName());
    ch.FixPointers();
  }
 
  assert(_sl.action == SaveLoadAction::Null);
}

[[noreturn]] void SlError(StringID string, const std::string &extra_msg)
{
  /* Distinguish between loading into _load_check_data vs. normal save/load. */
  if (_sl.action == SaveLoadAction::LoadCheck) {
    _load_check_data.error = string;
    _load_check_data.error_msg = extra_msg;
  } else {
    _sl.error_str = string;
    _sl.extra_msg = extra_msg;
  }
 
  /* We have to nullptr all pointers here; we might be in a state where
   * the pointers are actually filled with indices, which means that
   * when we access them during cleaning the pool dereferences of
   * those indices will be made with segmentation faults as result. */
  if (_sl.action == SaveLoadAction::Load || _sl.action == SaveLoadAction::Ptrs) SlNullPointers();
 
  /* Logging could be active. */
  _gamelog.StopAnyAction();
 
  throw std::exception();
}

[[noreturn]] void SlErrorCorrupt(const std::string &msg)
{
  SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_SAVEGAME, msg);
}
 
 
typedef void (*AsyncSaveFinishProc)();                      
static std::atomic<AsyncSaveFinishProc> _async_save_finish; 
static std::thread _save_thread;                            

static void SetAsyncSaveFinish(AsyncSaveFinishProc proc)
{
  if (_exit_game) return;
  while (_async_save_finish.load(std::memory_order_acquire) != nullptr) CSleep(10);
 
  _async_save_finish.store(proc, std::memory_order_release);
}

void ProcessAsyncSaveFinish()
{
  AsyncSaveFinishProc proc = _async_save_finish.exchange(nullptr, std::memory_order_acq_rel);
  if (proc == nullptr) return;
 
  proc();
 
  if (_save_thread.joinable()) {
    _save_thread.join();
  }
}

uint8_t SlReadByte()
{
  return _sl.reader->ReadByte();
}

void SlWriteByte(uint8_t b)
{
  _sl.dumper->WriteByte(b);
}
 
static inline int SlReadUint16()
{
  int x = SlReadByte() << 8;
  return x | SlReadByte();
}
 
static inline uint32_t SlReadUint32()
{
  uint32_t x = SlReadUint16() << 16;
  return x | SlReadUint16();
}
 
static inline uint64_t SlReadUint64()
{
  uint32_t x = SlReadUint32();
  uint32_t y = SlReadUint32();
  return static_cast<uint64_t>(x) << 32 | y;
}
 
static inline void SlWriteUint16(uint16_t v)
{
  SlWriteByte(GB(v, 8, 8));
  SlWriteByte(GB(v, 0, 8));
}
 
static inline void SlWriteUint32(uint32_t v)
{
  SlWriteUint16(GB(v, 16, 16));
  SlWriteUint16(GB(v,  0, 16));
}
 
static inline void SlWriteUint64(uint64_t x)
{
  SlWriteUint32(static_cast<uint32_t>(x >> 32));
  SlWriteUint32(static_cast<uint32_t>(x));
}

static inline ChunkId SlReadChunkId()
{
  ChunkId label{};
  for (uint8_t &b : label) b = SlReadByte();
  return label;
}

static uint SlReadSimpleGamma()
{
  uint i = SlReadByte();
  if (HasBit(i, 7)) {
    i &= ~0x80;
    if (HasBit(i, 6)) {
      i &= ~0x40;
      if (HasBit(i, 5)) {
        i &= ~0x20;
        if (HasBit(i, 4)) {
          i &= ~0x10;
          if (HasBit(i, 3)) {
            SlErrorCorrupt("Unsupported gamma");
          }
          i = SlReadByte(); // 32 bits only.
        }
        i = (i << 8) | SlReadByte();
      }
      i = (i << 8) | SlReadByte();
    }
    i = (i << 8) | SlReadByte();
  }
  return i;
}

 
static void SlWriteSimpleGamma(size_t i)
{
  if (i >= (1 << 7)) {
    if (i >= (1 << 14)) {
      if (i >= (1 << 21)) {
        if (i >= (1 << 28)) {
          assert(i <= UINT32_MAX); // We can only support 32 bits for now.
          SlWriteByte(static_cast<uint8_t>(0xF0));
          SlWriteByte(static_cast<uint8_t>(i >> 24));
        } else {
          SlWriteByte(static_cast<uint8_t>(0xE0 | (i >> 24)));
        }
        SlWriteByte(static_cast<uint8_t>(i >> 16));
      } else {
        SlWriteByte(static_cast<uint8_t>(0xC0 | (i >> 16)));
      }
      SlWriteByte(static_cast<uint8_t>(i >> 8));
    } else {
      SlWriteByte(static_cast<uint8_t>(0x80 | (i >> 8)));
    }
  }
  SlWriteByte(static_cast<uint8_t>(i));
}

static inline uint SlGetGammaLength(size_t i)
{
  return 1 + (i >= (1 << 7)) + (i >= (1 << 14)) + (i >= (1 << 21)) + (i >= (1 << 28));
}
 
static inline uint SlReadSparseIndex()
{
  return SlReadSimpleGamma();
}
 
static inline void SlWriteSparseIndex(uint index)
{
  SlWriteSimpleGamma(index);
}
 
static inline uint SlReadArrayLength()
{
  return SlReadSimpleGamma();
}
 
static inline void SlWriteArrayLength(size_t length)
{
  SlWriteSimpleGamma(length);
}
 
static inline uint SlGetArrayLength(size_t length)
{
  return SlGetGammaLength(length);
}

struct SavegameFileType {
  static constexpr uint8_t HAS_FIELD_LENGTH_BIT = 4; 
  uint8_t storage{}; 

  SavegameFileType() {}

  SavegameFileType(VarFileType file_type, bool has_field_length = false) : storage(to_underlying(file_type))
  {
    /* 0 is not allowed as it's the end-of-table marker, larger is not allowed due to the field length bit. */
    assert(IsInsideMM(to_underlying(file_type), 1, 1 << HAS_FIELD_LENGTH_BIT));
    AssignBit(this->storage, HAS_FIELD_LENGTH_BIT, has_field_length);
  }

  constexpr bool IsEnd() const { return storage == 0; }

  constexpr bool HasFieldLength() const
  {
    assert(!this->IsEnd());
    return HasBit(storage, HAS_FIELD_LENGTH_BIT);
  }

  constexpr VarFileType Type() const
  {
    assert(!this->IsEnd());
    return static_cast<VarFileType>(GB(storage, 0, HAS_FIELD_LENGTH_BIT));
  }
};

static SavegameFileType GetSavegameFileType(const SaveLoad &sld)
{
  switch (sld.cmd) {
    case SaveLoadType::Variable:
      return sld.conv.file;
 
    case SaveLoadType::String:
    case SaveLoadType::Array:
    case SaveLoadType::Vector:
      return { sld.conv.file, true };
 
    case SaveLoadType::Reference:
      return IsSavegameVersionBefore(SaveLoadVersion::MoreCargoPackets) ? VarFileType::U16 : VarFileType::U32;
 
    case SaveLoadType::ReferenceList:
    case SaveLoadType::ReferenceVector:
      return { IsSavegameVersionBefore(SaveLoadVersion::MoreCargoPackets) ? VarFileType::U16 : VarFileType::U32, true };
 
    case SaveLoadType::SaveByte:
      return VarFileType::U8;
 
    case SaveLoadType::Struct:
    case SaveLoadType::StructList:
      return { VarFileType::Struct, true };
 
    default: NOT_REACHED();
  }
}

static inline uint SlCalcConvMemLen(VarMemType conv)
{
  switch (conv) {
    case VarMemType::Bool: return sizeof(bool);
    case VarMemType::I8: return sizeof(int8_t);
    case VarMemType::U8: return sizeof(uint8_t);
    case VarMemType::I16: return sizeof(int16_t);
    case VarMemType::U16: return sizeof(uint16_t);
    case VarMemType::I32: return sizeof(int32_t);
    case VarMemType::U32: return sizeof(uint32_t);
    case VarMemType::I64: return sizeof(int64_t);
    case VarMemType::U64: return sizeof(uint64_t);
    case VarMemType::Null: return 0;
    case VarMemType::Label: return sizeof(BaseLabel);
 
    case VarMemType::Str:
      return SlReadArrayLength();
 
    case VarMemType::Name:
    default:
      NOT_REACHED();
  }
}

static inline uint8_t SlCalcConvFileLen(VarType conv)
{
  switch (conv.file) {
    case VarFileType::I8: return sizeof(int8_t);
    case VarFileType::U8: return sizeof(uint8_t);
    case VarFileType::I16: return sizeof(int16_t);
    case VarFileType::U16: return sizeof(uint16_t);
    case VarFileType::I32: return sizeof(int32_t);
    case VarFileType::U32: return sizeof(uint32_t);
    case VarFileType::I64: return sizeof(int64_t);
    case VarFileType::U64: return sizeof(uint64_t);
    case VarFileType::StringID: return sizeof(uint16_t);
 
    case VarFileType::String:
      return SlReadArrayLength();
 
    case VarFileType::Struct:
    default:
      NOT_REACHED();
  }
}

static inline size_t SlCalcRefLen()
{
  return IsSavegameVersionBefore(SaveLoadVersion::MoreCargoPackets) ? 2 : 4;
}
 
void SlSetArrayIndex(uint index)
{
  _sl.need_length = NeedLength::WantLength;
  _sl.array_index = index;
}
 
static size_t _next_offs;

int SlIterateArray()
{
  /* After reading in the whole array inside the loop
   * we must have read in all the data, so we must be at end of current block. */
  if (_next_offs != 0 && _sl.reader->GetSize() != _next_offs) {
    SlErrorCorruptFmt("Invalid chunk size iterating array - expected to be at position {}, actually at {}", _next_offs, _sl.reader->GetSize());
  }
 
  for (;;) {
    uint length = SlReadArrayLength();
    if (length == 0) {
      assert(!_sl.expect_table_header);
      _next_offs = 0;
      return -1;
    }
 
    _sl.obj_len = --length;
    _next_offs = _sl.reader->GetSize() + length;
 
    if (_sl.expect_table_header) {
      _sl.expect_table_header = false;
      return INT32_MAX;
    }
 
    int index;
    switch (_sl.chunk_type) {
      case ChunkType::SparseTable:
      case ChunkType::SparseArray: index = static_cast<int>(SlReadSparseIndex()); break;
      case ChunkType::Table:
      case ChunkType::Array: index = _sl.array_index++; break;
      default:
        Debug(Facility::Sl, Severity::Critical, "SlIterateArray error");
        return -1; // error
    }
 
    if (length != 0) return index;
  }
}

void SlSkipArray()
{
  while (SlIterateArray() != -1) {
    SlSkipBytes(_next_offs - _sl.reader->GetSize());
  }
}

void SlSetLength(size_t length)
{
  assert(_sl.action == SaveLoadAction::Save);
 
  switch (_sl.need_length) {
    case NeedLength::WantLength:
      _sl.need_length = NeedLength::None;
      if ((_sl.chunk_type == ChunkType::Table || _sl.chunk_type == ChunkType::SparseTable) && _sl.expect_table_header) {
        _sl.expect_table_header = false;
        SlWriteArrayLength(length + 1);
        break;
      }
 
      switch (_sl.chunk_type) {
        case ChunkType::Riff:
          /* Ugly encoding of >16M RIFF chunks
           * The lower 24 bits are normal
           * The uppermost 4 bits are bits 24:27 */
          assert(length < (1 << 28));
          SlWriteUint32((uint32_t)((length & 0xFFFFFF) | ((length >> 24) << 28)));
          break;
        case ChunkType::Table:
        case ChunkType::Array:
          assert(_sl.last_array_index <= _sl.array_index);
          while (++_sl.last_array_index <= _sl.array_index) {
            SlWriteArrayLength(1);
          }
          SlWriteArrayLength(length + 1);
          break;
        case ChunkType::SparseTable:
        case ChunkType::SparseArray:
          SlWriteArrayLength(length + 1 + SlGetArrayLength(_sl.array_index)); // Also include length of sparse index.
          SlWriteSparseIndex(_sl.array_index);
          break;
        default: NOT_REACHED();
      }
      break;
 
    case NeedLength::CalcLength:
      _sl.obj_len += static_cast<int>(length);
      break;
 
    default: NOT_REACHED();
  }
}

static void SlCopyBytes(void *ptr, size_t length)
{
  uint8_t *p = static_cast<uint8_t *>(ptr);
 
  switch (_sl.action) {
    case SaveLoadAction::LoadCheck:
    case SaveLoadAction::Load:
      for (; length != 0; length--) *p++ = SlReadByte();
      break;
    case SaveLoadAction::Save:
      for (; length != 0; length--) SlWriteByte(*p++);
      break;
    default: NOT_REACHED();
  }
}

size_t SlGetFieldLength()
{
  return _sl.obj_len;
}

int64_t ReadValue(const void *ptr, VarMemType conv)
{
  switch (conv) {
    case VarMemType::Bool: return (*static_cast<const bool *>(ptr) != 0);
    case VarMemType::I8: return *static_cast<const int8_t *>(ptr);
    case VarMemType::U8: return *static_cast<const uint8_t *>(ptr);
    case VarMemType::I16: return *static_cast<const int16_t *>(ptr);
    case VarMemType::U16: return *static_cast<const uint16_t *>(ptr);
    case VarMemType::I32: return *static_cast<const int32_t *>(ptr);
    case VarMemType::U32: return *static_cast<const uint32_t *>(ptr);
    case VarMemType::I64: return *static_cast<const int64_t *>(ptr);
    case VarMemType::U64: return *static_cast<const uint64_t *>(ptr);
    case VarMemType::Null: return 0;
    default: NOT_REACHED();
  }
}

void WriteValue(void *ptr, VarMemType conv, int64_t val)
{
  switch (conv) {
    case VarMemType::Bool: *static_cast<bool *>(ptr) = (val != 0); break;
    case VarMemType::I8: *static_cast<int8_t *>(ptr) = val; break;
    case VarMemType::U8: *static_cast<uint8_t *>(ptr) = val; break;
    case VarMemType::I16: *static_cast<int16_t *>(ptr) = val; break;
    case VarMemType::U16: *static_cast<uint16_t *>(ptr) = val; break;
    case VarMemType::I32: *static_cast<int32_t *>(ptr) = val; break;
    case VarMemType::U32: *static_cast<uint32_t *>(ptr) = val; break;
    case VarMemType::I64: *static_cast<int64_t *>(ptr) = val; break;
    case VarMemType::U64: *static_cast<uint64_t *>(ptr) = val; break;
    case VarMemType::Name: *reinterpret_cast<std::string *>(ptr) = CopyFromOldName(static_cast<StringID>(val)); break;
    case VarMemType::Null: break;
    default: NOT_REACHED();
  }
}

static void SlSaveLoadConv(void *ptr, VarType conv)
{
  switch (_sl.action) {
    case SaveLoadAction::Save: {
      if (conv == VarTypes::LABEL) {
        /* Labels are written in reverse order as that is the way GrfIDs used to be written.
         * Changing the order means changing external applications that extract this data. */
        BaseLabel *label = static_cast<BaseLabel *>(ptr);
        for (auto it = label->rbegin(); it != label->rend(); it++) SlWriteByte(*it);
        break;
      }
 
      int64_t x = ReadValue(ptr, conv.mem);
 
      /* Write the value to the file and check if its value is in the desired range */
      switch (conv.file) {
        case VarFileType::I8:
          assert(x >= -128 && x <= 127);
          SlWriteByte(x);
          break;
 
        case VarFileType::U8:
          assert(x >= 0 && x <= 255);
          SlWriteByte(x);
          break;
 
        case VarFileType::I16:
          assert(x >= -32768 && x <= 32767);
          SlWriteUint16(x);
          break;
 
        case VarFileType::StringID:
        case VarFileType::U16:
          assert(x >= 0 && x <= 65535);
          SlWriteUint16(x);
          break;
 
        case VarFileType::I32:
        case VarFileType::U32:
          SlWriteUint32(static_cast<uint32_t>(x));
          break;
 
        case VarFileType::I64:
        case VarFileType::U64:
          SlWriteUint64(x);
          break;
 
        default: NOT_REACHED();
      }
      break;
    }
    case SaveLoadAction::LoadCheck:
    case SaveLoadAction::Load: {
      if (conv == VarTypes::LABEL) {
        /* Labels are written in reverse order as that is the way GrfIDs used to be written.
         * Changing the order means changing external applications that extract this data.
         * The road/rail type labels were in forward order. They are fixed when needed in
         * their respective loaders. */
        BaseLabel *label = static_cast<BaseLabel *>(ptr);
        for (auto it = label->rbegin(); it != label->rend(); it++) *it = SlReadByte();
        break;
      }
 
      int64_t x;
      /* Read a value from the file */
      switch (conv.file) {
        case VarFileType::I8: x = static_cast<int8_t>(SlReadByte()); break;
        case VarFileType::U8: x = static_cast<uint8_t>(SlReadByte()); break;
        case VarFileType::I16: x = static_cast<int16_t>(SlReadUint16()); break;
        case VarFileType::U16: x = static_cast<uint16_t>(SlReadUint16()); break;
        case VarFileType::I32: x = static_cast<int32_t>(SlReadUint32()); break;
        case VarFileType::U32: x = static_cast<uint32_t>(SlReadUint32()); break;
        case VarFileType::I64: x = static_cast<int64_t>(SlReadUint64()); break;
        case VarFileType::U64: x = static_cast<uint64_t>(SlReadUint64()); break;
        case VarFileType::StringID: x = RemapOldStringID(static_cast<StringID>(SlReadUint16())).base(); break;
        default: NOT_REACHED();
      }
 
      /* Write The value to the struct. These ARE endian safe. */
      WriteValue(ptr, conv.mem, x);
      break;
    }
    case SaveLoadAction::Ptrs: break;
    case SaveLoadAction::Null: break;
    default: NOT_REACHED();
  }
}

static inline size_t SlCalcStdStringLen(const void *ptr)
{
  const std::string *str = reinterpret_cast<const std::string *>(ptr);
 
  size_t len = str->length();
  return len + SlGetArrayLength(len); // also include the length of the index
}
 

void FixSCCEncoded(std::string &str, bool fix_code)
{
  if (str.empty()) return;
 
  /* We need to convert from old escape-style encoding to record separator encoding.
   * Initial `<SCC_ENCODED><STRINGID>` stays the same.
   *
   * `:<SCC_ENCODED><STRINGID>` becomes `<RS><SCC_ENCODED><STRINGID>`
   * `:<HEX>`                   becomes `<RS><SCC_ENCODED_NUMERIC><HEX>`
   * `:"<STRING>"`              becomes `<RS><SCC_ENCODED_STRING><STRING>`
   */
  std::string result;
  StringBuilder builder(result);
 
  bool is_encoded = false; // Set if we determine by the presence of SCC_ENCODED that the string is an encoded string.
  bool in_string = false; // Set if we in a string, between double-quotes.
  bool need_type = true; // Set if a parameter type needs to be emitted.
 
  StringConsumer consumer(str);
  while (consumer.AnyBytesLeft()) {
    char32_t c;
    if (auto r = consumer.TryReadUtf8(); r.has_value()) {
      c = *r;
    } else {
      break;
    }
    if (c == SCC_ENCODED || (fix_code && (c == 0xE028 || c == 0xE02A))) {
      builder.PutUtf8(SCC_ENCODED);
      need_type = false;
      is_encoded = true;
      continue;
    }
 
    /* If the first character is not SCC_ENCODED then we don't have to do any conversion. */
    if (!is_encoded) return;
 
    if (c == '"') {
      in_string = !in_string;
      if (in_string && need_type) {
        /* Started a new string parameter. */
        builder.PutUtf8(SCC_ENCODED_STRING);
        need_type = false;
      }
      continue;
    }
 
    if (!in_string && c == ':') {
      builder.PutUtf8(SCC_RECORD_SEPARATOR);
      need_type = true;
      continue;
    }
    if (need_type) {
      /* Started a new numeric parameter. */
      builder.PutUtf8(SCC_ENCODED_NUMERIC);
      need_type = false;
    }
 
    builder.PutUtf8(c);
  }
 
  str = std::move(result);
}

void FixSCCEncodedNegative(std::string &str)
{
  if (str.empty()) return;
 
  StringConsumer consumer(str);
 
  /* Check whether this is an encoded string */
  if (!consumer.ReadUtf8If(SCC_ENCODED)) return;
 
  std::string result;
  StringBuilder builder(result);
  builder.PutUtf8(SCC_ENCODED);
  while (consumer.AnyBytesLeft()) {
    /* Copy until next record */
    builder.Put(consumer.ReadUntilUtf8(SCC_RECORD_SEPARATOR, StringConsumer::READ_ONE_SEPARATOR));
 
    /* Check whether this is a numeric parameter */
    if (!consumer.ReadUtf8If(SCC_ENCODED_NUMERIC)) continue;
    builder.PutUtf8(SCC_ENCODED_NUMERIC);
 
    /* First try unsigned */
    if (auto u = consumer.TryReadIntegerBase<uint64_t>(16); u.has_value()) {
      builder.PutIntegerBase<uint64_t>(*u, 16);
    } else {
      /* Read as signed, store as unsigned */
      auto s = consumer.ReadIntegerBase<int64_t>(16);
      builder.PutIntegerBase<uint64_t>(static_cast<uint64_t>(s), 16);
    }
  }
 
  str = std::move(result);
}

void SlReadString(std::string &str, size_t length)
{
  str.resize(length);
  SlCopyBytes(str.data(), length);
}

static void SlStdString(void *ptr, VarType conv)
{
  std::string *str = reinterpret_cast<std::string *>(ptr);
 
  switch (_sl.action) {
    case SaveLoadAction::Save: {
      size_t len = str->length();
      SlWriteArrayLength(len);
      SlCopyBytes(const_cast<void *>(static_cast<const void *>(str->data())), len);
      break;
    }
 
    case SaveLoadAction::LoadCheck:
    case SaveLoadAction::Load: {
      size_t len = SlReadArrayLength();
      if (conv.mem == VarMemType::Null) {
        SlSkipBytes(len);
        return;
      }
 
      SlReadString(*str, len);
 
      StringValidationSettings settings = conv.string_validation_settings;
      settings.Set(StringValidationSetting::ReplaceWithQuestionMark);
      if (settings.Test(StringValidationSetting::AllowControlCode)) {
        if (IsSavegameVersionBefore(SaveLoadVersion::EncodedStringFormat)) FixSCCEncoded(*str, IsSavegameVersionBefore(SaveLoadVersion::MoveSccEncoded));
        if (IsSavegameVersionBefore(SaveLoadVersion::FixSccEncodedNegative)) FixSCCEncodedNegative(*str);
      }
      StrMakeValidInPlace(*str, settings);
    }
 
    case SaveLoadAction::Ptrs: break;
    case SaveLoadAction::Null: break;
    default: NOT_REACHED();
  }
}

static void SlCopyInternal(void *object, size_t length, VarType conv)
{
  if (conv.mem == VarMemType::Null) {
    assert(_sl.action != SaveLoadAction::Save); // Use SaveLoadType::Null if you want to write null-bytes
    SlSkipBytes(length * SlCalcConvFileLen(conv));
    return;
  }
 
  /* NOTICE - handle some buggy stuff, in really old versions everything was saved
   * as a byte-type. So detect this, and adjust object size accordingly */
  if (_sl.action != SaveLoadAction::Save && _sl_version == SaveLoadVersion::MinVersion) {
    /* all objects except difficulty settings */
    if (conv == VarTypes::I16 || conv == VarTypes::U16 || conv == VarTypes::STRINGID ||
        conv == VarTypes::I32 || conv == VarTypes::U32) {
      SlCopyBytes(object, length * SlCalcConvFileLen(conv));
      return;
    }
    /* used for conversion of Money 32bit->64bit */
    if (conv == (VarFileType::I32 | VarMemType::I64)) {
      for (uint i = 0; i < length; i++) {
        static_cast<int64_t *>(object)[i] = std::byteswap(SlReadUint32());
      }
      return;
    }
  }
 
  /* If the size of elements is 1 byte both in file and memory, no special
   * conversion is needed, use specialized copy-copy function to speed up things */
  if (conv == VarTypes::I8 || conv == VarTypes::U8) {
    SlCopyBytes(object, length);
  } else {
    uint8_t *a = static_cast<uint8_t *>(object);
    uint8_t mem_size = SlCalcConvMemLen(conv.mem);
 
    for (; length != 0; length --) {
      SlSaveLoadConv(a, conv);
      a += mem_size; // get size
    }
  }
}

void SlCopy(void *object, size_t length, VarType conv)
{
  assert(object != nullptr); // Use SlSkipBytes instead
  if (_sl.action == SaveLoadAction::Ptrs || _sl.action == SaveLoadAction::Null) return;
 
  /* Automatically calculate the length? */
  if (_sl.need_length != NeedLength::None) {
    SlSetLength(length * SlCalcConvFileLen(conv));
    /* Determine length only? */
    if (_sl.need_length == NeedLength::CalcLength) return;
  }
 
  SlCopyInternal(object, length, conv);
}

static inline size_t SlCalcArrayLen(size_t length, VarType conv)
{
  return SlCalcConvFileLen(conv) * length + SlGetArrayLength(length);
}

static void SlArray(void *array, size_t length, VarType conv)
{
  switch (_sl.action) {
    case SaveLoadAction::Save:
      SlWriteArrayLength(length);
      SlCopyInternal(array, length, conv);
      return;
 
    case SaveLoadAction::LoadCheck:
    case SaveLoadAction::Load: {
      if (!IsSavegameVersionBefore(SaveLoadVersion::SaveloadListLength)) {
        size_t sv_length = SlReadArrayLength();
        if (conv.mem == VarMemType::Null) {
          /* We don't know this field, so we assume the length in the savegame is correct. */
          length = sv_length;
        } else if (sv_length != length) {
          /* If the SLE_ARR changes size, a savegame bump is required
           * and the developer should have written conversion lines.
           * Error out to make this more visible. */
          SlErrorCorrupt("Fixed-length array is of wrong length");
        }
      }
 
      SlCopyInternal(array, length, conv);
      return;
    }
 
    case SaveLoadAction::Ptrs:
    case SaveLoadAction::Null:
      return;
 
    default:
      NOT_REACHED();
  }
}

static uint32_t ReferenceToInt(const void *obj, SLRefType rt)
{
  assert(_sl.action == SaveLoadAction::Save);
 
  if (obj == nullptr) return 0;
 
  switch (rt) {
    case SLRefType::OldVehicle: // Old vehicles we save as new ones
    case SLRefType::Vehicle: return static_cast<const Vehicle *>(obj)->index + 1;
    case SLRefType::Station: return static_cast<const Station *>(obj)->index + 1;
    case SLRefType::Town: return static_cast<const Town *>(obj)->index + 1;
    case SLRefType::RoadStop: return static_cast<const RoadStop *>(obj)->index + 1;
    case SLRefType::EngineRenew: return static_cast<const EngineRenew *>(obj)->index + 1;
    case SLRefType::CargoPacket: return static_cast<const CargoPacket *>(obj)->index + 1;
    case SLRefType::OrderList: return static_cast<const OrderList *>(obj)->index + 1;
    case SLRefType::Storage: return static_cast<const PersistentStorage *>(obj)->index + 1;
    case SLRefType::LinkGraph: return static_cast<const LinkGraph *>(obj)->index + 1;
    case SLRefType::LinkGraphJob: return static_cast<const LinkGraphJob *>(obj)->index + 1;
    default: NOT_REACHED();
  }
}

static void *IntToReference(size_t index, SLRefType rt)
{
  static_assert(sizeof(size_t) <= sizeof(void *));
 
  assert(_sl.action == SaveLoadAction::Ptrs);
 
  /* After version 4.3 SLRefType::OldVehicle is saved as SLRefType::Vehicle,
   * and should be loaded like that */
  if (rt == SLRefType::OldVehicle && !IsSavegameVersionBefore(SaveLoadVersion::TownTolerancePauseMode, 4)) {
    rt = SLRefType::Vehicle;
  }
 
  /* No need to look up nullptr pointers, just return immediately */
  if (index == (rt == SLRefType::OldVehicle ? 0xFFFF : 0)) return nullptr;
 
  /* Correct index. Old vehicles were saved differently:
   * invalid vehicle was 0xFFFF, now we use 0x0000 for everything invalid. */
  if (rt != SLRefType::OldVehicle) index--;
 
  switch (rt) {
    case SLRefType::OrderList:
      if (OrderList::IsValidID(index)) return OrderList::Get(index);
      SlErrorCorrupt("Referencing invalid OrderList");
 
    case SLRefType::OldVehicle:
    case SLRefType::Vehicle:
      if (Vehicle::IsValidID(index)) return Vehicle::Get(index);
      SlErrorCorrupt("Referencing invalid Vehicle");
 
    case SLRefType::Station:
      if (Station::IsValidID(index)) return Station::Get(index);
      SlErrorCorrupt("Referencing invalid Station");
 
    case SLRefType::Town:
      if (Town::IsValidID(index)) return Town::Get(index);
      SlErrorCorrupt("Referencing invalid Town");
 
    case SLRefType::RoadStop:
      if (RoadStop::IsValidID(index)) return RoadStop::Get(index);
      SlErrorCorrupt("Referencing invalid RoadStop");
 
    case SLRefType::EngineRenew:
      if (EngineRenew::IsValidID(index)) return EngineRenew::Get(index);
      SlErrorCorrupt("Referencing invalid EngineRenew");
 
    case SLRefType::CargoPacket:
      if (CargoPacket::IsValidID(index)) return CargoPacket::Get(index);
      SlErrorCorrupt("Referencing invalid CargoPacket");
 
    case SLRefType::Storage:
      if (PersistentStorage::IsValidID(index)) return PersistentStorage::Get(index);
      SlErrorCorrupt("Referencing invalid PersistentStorage");
 
    case SLRefType::LinkGraph:
      if (LinkGraph::IsValidID(index)) return LinkGraph::Get(index);
      SlErrorCorrupt("Referencing invalid LinkGraph");
 
    case SLRefType::LinkGraphJob:
      if (LinkGraphJob::IsValidID(index)) return LinkGraphJob::Get(index);
      SlErrorCorrupt("Referencing invalid LinkGraphJob");
 
    default: NOT_REACHED();
  }
}

void SlSaveLoadRef(void *ptr, VarType conv)
{
  switch (_sl.action) {
    case SaveLoadAction::Save:
      SlWriteUint32(ReferenceToInt(*static_cast<void **>(ptr), conv.ref));
      break;
    case SaveLoadAction::LoadCheck:
    case SaveLoadAction::Load:
      *static_cast<size_t *>(ptr) = IsSavegameVersionBefore(SaveLoadVersion::MoreCargoPackets) ? SlReadUint16() : SlReadUint32();
      break;
    case SaveLoadAction::Ptrs:
      *static_cast<void **>(ptr) = IntToReference(*static_cast<size_t *>(ptr), conv.ref);
      break;
    case SaveLoadAction::Null:
      *static_cast<void **>(ptr) = nullptr;
      break;
    default: NOT_REACHED();
  }
}

template <template <typename, typename> typename Tstorage, typename Tvar, typename Tallocator = std::allocator<Tvar>>
class SlStorageHelper {
  typedef Tstorage<Tvar, Tallocator> SlStorageT;
public:
  static size_t SlCalcLen(const void *storage, VarType conv, SaveLoadType cmd = SaveLoadType::Variable)
  {
    assert(cmd == SaveLoadType::Variable || cmd == SaveLoadType::Reference);
 
    const SlStorageT *list = static_cast<const SlStorageT *>(storage);
 
    int type_size = SlGetArrayLength(list->size());
    int item_size = SlCalcConvFileLen(cmd == SaveLoadType::Variable ? conv : VarType{VarFileType::U32, {}});
    return list->size() * item_size + type_size;
  }
 
  static void SlSaveLoadMember(SaveLoadType cmd, Tvar *item, VarType conv)
  {
    switch (cmd) {
      case SaveLoadType::Variable: SlSaveLoadConv(item, conv); break;
      case SaveLoadType::Reference: SlSaveLoadRef(item, conv); break;
      case SaveLoadType::String: SlStdString(item, conv); break;
      default:
        NOT_REACHED();
    }
  }

  static void SlSaveLoad(void *storage, VarType conv, SaveLoadType cmd = SaveLoadType::Variable)
  {
    assert(cmd == SaveLoadType::Variable || cmd == SaveLoadType::Reference || cmd == SaveLoadType::String);
 
    SlStorageT *list = static_cast<SlStorageT *>(storage);
 
    switch (_sl.action) {
      case SaveLoadAction::Save:
        SlWriteArrayLength(list->size());
 
        for (auto &item : *list) {
          SlSaveLoadMember(cmd, &item, conv);
        }
        break;
 
      case SaveLoadAction::LoadCheck:
      case SaveLoadAction::Load: {
        size_t length;
        switch (cmd) {
          case SaveLoadType::Variable: length = IsSavegameVersionBefore(SaveLoadVersion::SaveloadListLength) ? SlReadUint32() : SlReadArrayLength(); break;
          case SaveLoadType::Reference: length = IsSavegameVersionBefore(SaveLoadVersion::MoreCargoPackets) ? SlReadUint16() : IsSavegameVersionBefore(SaveLoadVersion::SaveloadListLength) ? SlReadUint32() : SlReadArrayLength(); break;
          case SaveLoadType::String: length = SlReadArrayLength(); break;
          default: NOT_REACHED();
        }
 
        list->clear();
        if constexpr (std::is_same_v<SlStorageT, std::vector<Tvar, Tallocator>>) {
          list->reserve(length);
        }
 
        /* Load each value and push to the end of the storage. */
        for (size_t i = 0; i < length; i++) {
          Tvar &data = list->emplace_back();
          SlSaveLoadMember(cmd, &data, conv);
        }
        break;
      }
 
      case SaveLoadAction::Ptrs:
        for (auto &item : *list) {
          SlSaveLoadMember(cmd, &item, conv);
        }
        break;
 
      case SaveLoadAction::Null:
        list->clear();
        break;
 
      default: NOT_REACHED();
    }
  }
};

static inline size_t SlCalcRefListLen(const void *list, VarType conv)
{
  return SlStorageHelper<std::list, void *>::SlCalcLen(list, conv, SaveLoadType::Reference);
}

static void SlRefList(void *list, VarType conv)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NeedLength::None) {
    SlSetLength(SlCalcRefListLen(list, conv));
    /* Determine length only? */
    if (_sl.need_length == NeedLength::CalcLength) return;
  }
 
  SlStorageHelper<std::list, void *>::SlSaveLoad(list, conv, SaveLoadType::Reference);
}

static size_t SlCalcRefVectorLen(const void *vector, VarType conv)
{
  return SlStorageHelper<std::vector, void *>::SlCalcLen(vector, conv, SaveLoadType::Reference);
}

static void SlRefVector(void *vector, VarType conv)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NeedLength::None) {
    SlSetLength(SlCalcRefVectorLen(vector, conv));
    /* Determine length only? */
    if (_sl.need_length == NeedLength::CalcLength) return;
  }
 
  SlStorageHelper<std::vector, void *>::SlSaveLoad(vector, conv, SaveLoadType::Reference);
}

static inline size_t SlCalcVectorLen(const void *vector, VarType conv)
{
  switch (conv.mem) {
    case VarMemType::Bool: NOT_REACHED(); // Not supported
    case VarMemType::I8: return SlStorageHelper<std::vector, int8_t>::SlCalcLen(vector, conv);
    case VarMemType::U8: return SlStorageHelper<std::vector, uint8_t>::SlCalcLen(vector, conv);
    case VarMemType::I16: return SlStorageHelper<std::vector, int16_t>::SlCalcLen(vector, conv);
    case VarMemType::U16: return SlStorageHelper<std::vector, uint16_t>::SlCalcLen(vector, conv);
    case VarMemType::I32: return SlStorageHelper<std::vector, int32_t>::SlCalcLen(vector, conv);
    case VarMemType::U32: return SlStorageHelper<std::vector, uint32_t>::SlCalcLen(vector, conv);
    case VarMemType::I64: return SlStorageHelper<std::vector, int64_t>::SlCalcLen(vector, conv);
    case VarMemType::U64: return SlStorageHelper<std::vector, uint64_t>::SlCalcLen(vector, conv);
 
    case VarMemType::Str:
      /* Strings are a length-prefixed field type in the savegame table format,
       * these may not be directly stored in another length-prefixed container type. */
      NOT_REACHED();
 
    default: NOT_REACHED();
  }
}

static void SlVector(void *vector, VarType conv)
{
  switch (conv.mem) {
    case VarMemType::Bool: NOT_REACHED(); // Not supported
    case VarMemType::I8: SlStorageHelper<std::vector, int8_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::U8: SlStorageHelper<std::vector, uint8_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::I16: SlStorageHelper<std::vector, int16_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::U16: SlStorageHelper<std::vector, uint16_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::I32: SlStorageHelper<std::vector, int32_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::U32: SlStorageHelper<std::vector, uint32_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::I64: SlStorageHelper<std::vector, int64_t>::SlSaveLoad(vector, conv); break;
    case VarMemType::U64: SlStorageHelper<std::vector, uint64_t>::SlSaveLoad(vector, conv); break;
 
    case VarMemType::Str:
      /* Strings are a length-prefixed field type in the savegame table format,
       * these may not be directly stored in another length-prefixed container type.
       * This is permitted for load-related actions, because invalid fields of this type are present
       * from SaveLoadVersion::CompanyAllowList up to SaveLoadVersion::CompanyAllowListV2. */
      assert(_sl.action != SaveLoadAction::Save);
      SlStorageHelper<std::vector, std::string>::SlSaveLoad(vector, conv, SaveLoadType::String);
      break;
 
    default: NOT_REACHED();
  }
}

static inline bool SlIsObjectValidInSavegame(const SaveLoad &sld)
{
  return (_sl_version >= sld.version_from && _sl_version < sld.version_to);
}

static size_t SlCalcTableHeader(const SaveLoadTable &slt)
{
  size_t length = 0;
 
  for (auto &sld : slt) {
    if (!SlIsObjectValidInSavegame(sld)) continue;
 
    length += SlCalcConvFileLen(VarTypes::U8);
    length += SlCalcStdStringLen(&sld.name);
  }
 
  length += SlCalcConvFileLen(VarTypes::U8); // End-of-list entry.
 
  for (auto &sld : slt) {
    if (!SlIsObjectValidInSavegame(sld)) continue;
    if (sld.cmd == SaveLoadType::StructList || sld.cmd == SaveLoadType::Struct) {
      length += SlCalcTableHeader(sld.handler->GetDescription());
    }
  }
 
  return length;
}

size_t SlCalcObjLength(const void *object, const SaveLoadTable &slt)
{
  size_t length = 0;
 
  /* Need to determine the length and write a length tag. */
  for (auto &sld : slt) {
    length += SlCalcObjMemberLength(object, sld);
  }
  return length;
}
 
size_t SlCalcObjMemberLength(const void *object, const SaveLoad &sld)
{
  assert(_sl.action == SaveLoadAction::Save);
 
  if (!SlIsObjectValidInSavegame(sld)) return 0;
 
  switch (sld.cmd) {
    case SaveLoadType::Variable: return SlCalcConvFileLen(sld.conv);
    case SaveLoadType::Reference: return SlCalcRefLen();
    case SaveLoadType::Array: return SlCalcArrayLen(sld.length, sld.conv);
    case SaveLoadType::ReferenceList: return SlCalcRefListLen(GetVariableAddress(object, sld), sld.conv);
    case SaveLoadType::ReferenceVector: return SlCalcRefVectorLen(GetVariableAddress(object, sld), sld.conv);
    case SaveLoadType::Vector: return SlCalcVectorLen(GetVariableAddress(object, sld), sld.conv);
    case SaveLoadType::String: return SlCalcStdStringLen(GetVariableAddress(object, sld));
    case SaveLoadType::SaveByte: return 1; // a byte is logically of size 1
    case SaveLoadType::Null: return SlCalcConvFileLen(sld.conv) * sld.length;
 
    case SaveLoadType::Struct:
    case SaveLoadType::StructList: {
      NeedLength old_need_length = _sl.need_length;
      size_t old_obj_len = _sl.obj_len;
 
      _sl.need_length = NeedLength::CalcLength;
      _sl.obj_len = 0;
 
      /* Pretend that we are saving to collect the object size. Other
       * means are difficult, as we don't know the length of the list we
       * are about to store. */
      sld.handler->Save(const_cast<void *>(object));
      size_t length = _sl.obj_len;
 
      _sl.obj_len = old_obj_len;
      _sl.need_length = old_need_length;
 
      if (sld.cmd == SaveLoadType::Struct) {
        length += SlGetArrayLength(1);
      }
 
      return length;
    }
 
    default: NOT_REACHED();
  }
  return 0;
}
 
static bool SlObjectMember(void *object, const SaveLoad &sld)
{
  if (!SlIsObjectValidInSavegame(sld)) return false;
 
  switch (sld.cmd) {
    case SaveLoadType::Variable:
    case SaveLoadType::Reference:
    case SaveLoadType::Array:
    case SaveLoadType::ReferenceList:
    case SaveLoadType::ReferenceVector:
    case SaveLoadType::Vector:
    case SaveLoadType::String: {
      void *ptr = GetVariableAddress(object, sld);
 
      switch (sld.cmd) {
        case SaveLoadType::Variable: SlSaveLoadConv(ptr, sld.conv); break;
        case SaveLoadType::Reference: SlSaveLoadRef(ptr, sld.conv); break;
        case SaveLoadType::Array: SlArray(ptr, sld.length, sld.conv); break;
        case SaveLoadType::ReferenceList: SlRefList(ptr, sld.conv); break;
        case SaveLoadType::ReferenceVector: SlRefVector(ptr, sld.conv); break;
        case SaveLoadType::Vector: SlVector(ptr, sld.conv); break;
        case SaveLoadType::String: SlStdString(ptr, sld.conv); break;
        default: NOT_REACHED();
      }
      break;
    }
 
    /* SaveLoadType::SaveByte writes a value to the savegame to identify the type of an object.
     * When loading, the value is read explicitly with SlReadByte() to determine which
     * object description to use. */
    case SaveLoadType::SaveByte: {
      void *ptr = GetVariableAddress(object, sld);
 
      switch (_sl.action) {
        case SaveLoadAction::Save: SlWriteByte(*static_cast<uint8_t *>(ptr)); break;
        case SaveLoadAction::LoadCheck:
        case SaveLoadAction::Load:
        case SaveLoadAction::Ptrs:
        case SaveLoadAction::Null: break;
        default: NOT_REACHED();
      }
      break;
    }
 
    case SaveLoadType::Null: {
      assert(sld.conv.mem == VarMemType::Null);
 
      switch (_sl.action) {
        case SaveLoadAction::LoadCheck:
        case SaveLoadAction::Load: SlSkipBytes(SlCalcConvFileLen(sld.conv) * sld.length); break;
        case SaveLoadAction::Save: for (int i = 0; i < SlCalcConvFileLen(sld.conv) * sld.length; i++) SlWriteByte(0); break;
        case SaveLoadAction::Ptrs:
        case SaveLoadAction::Null: break;
        default: NOT_REACHED();
      }
      break;
    }
 
    case SaveLoadType::Struct:
    case SaveLoadType::StructList:
      switch (_sl.action) {
        case SaveLoadAction::Save: {
          if (sld.cmd == SaveLoadType::Struct) {
            /* Store in the savegame if this struct was written or not. */
            SlSetStructListLength(SlCalcObjMemberLength(object, sld) > SlGetArrayLength(1) ? 1 : 0);
          }
          sld.handler->Save(object);
          break;
        }
 
        case SaveLoadAction::LoadCheck: {
          if (sld.cmd == SaveLoadType::Struct && !IsSavegameVersionBefore(SaveLoadVersion::SaveloadListLength)) {
            SlGetStructListLength(1);
          }
          sld.handler->LoadCheck(object);
          break;
        }
 
        case SaveLoadAction::Load: {
          if (sld.cmd == SaveLoadType::Struct && !IsSavegameVersionBefore(SaveLoadVersion::SaveloadListLength)) {
            SlGetStructListLength(1);
          }
          sld.handler->Load(object);
          break;
        }
 
        case SaveLoadAction::Ptrs:
          sld.handler->FixPointers(object);
          break;
 
        case SaveLoadAction::Null: break;
        default: NOT_REACHED();
      }
      break;
 
    default: NOT_REACHED();
  }
  return true;
}

void SlSetStructListLength(size_t length)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NeedLength::None) {
    SlSetLength(SlGetArrayLength(length));
    if (_sl.need_length == NeedLength::CalcLength) return;
  }
 
  SlWriteArrayLength(length);
}

size_t SlGetStructListLength(size_t limit)
{
  size_t length = SlReadArrayLength();
  if (length > limit) SlErrorCorrupt("List exceeds storage size");
 
  return length;
}

void SlObject(void *object, const SaveLoadTable &slt)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NeedLength::None) {
    SlSetLength(SlCalcObjLength(object, slt));
    if (_sl.need_length == NeedLength::CalcLength) return;
  }
 
  for (auto &sld : slt) {
    SlObjectMember(object, sld);
  }
}

class SlSkipHandler : public SaveLoadHandler {
  void Save(void *) const override
  {
    NOT_REACHED();
  }
 
  void Load(void *object) const override
  {
    size_t length = SlGetStructListLength(UINT32_MAX);
    for (; length > 0; length--) {
      SlObject(object, this->GetLoadDescription());
    }
  }
 
  void LoadCheck(void *object) const override
  {
    this->Load(object);
  }
 
  SaveLoadTable GetDescription() const override
  {
    return {};
  }
 
  SaveLoadCompatTable GetCompatDescription() const override
  {
    NOT_REACHED();
  }
};

std::vector<SaveLoad> SlTableHeader(const SaveLoadTable &slt)
{
  /* You can only use SlTableHeader if you are a ChunkType::Table or ChunkType::SparseTable. */
  assert(_sl.chunk_type == ChunkType::Table || _sl.chunk_type == ChunkType::SparseTable);
 
  switch (_sl.action) {
    case SaveLoadAction::LoadCheck:
    case SaveLoadAction::Load: {
      std::vector<SaveLoad> saveloads;
 
      /* Build a key lookup mapping based on the available fields. */
      std::map<std::string, const SaveLoad *> key_lookup;
      for (auto &sld : slt) {
        if (!SlIsObjectValidInSavegame(sld)) continue;
 
        /* Check that there is only one active SaveLoad for a given name. */
        assert(key_lookup.find(sld.name) == key_lookup.end());
        key_lookup[sld.name] = &sld;
      }
 
      while (true) {
        SavegameFileType type{};
        SlSaveLoadConv(&type.storage, VarTypes::U8);
        if (type.IsEnd()) break;
 
        std::string key;
        SlStdString(&key, VarTypes::STR);
 
        auto sld_it = key_lookup.find(key);
        if (sld_it == key_lookup.end()) {
          /* SLA_LOADCHECK triggers this debug statement a lot and is perfectly normal. */
          Debug(Facility::Sl, _sl.action == SaveLoadAction::Load ? Severity::Warning : Severity::Debug2, "Field '{}' of type 0x{:02x} not found, skipping", key, type.storage);
 
          std::shared_ptr<SaveLoadHandler> handler = nullptr;
          SaveLoadType saveload_type;
          switch (type.Type()) {
            case VarFileType::String:
              saveload_type = SaveLoadType::String;
              break;
 
            case VarFileType::Struct:
              saveload_type = SaveLoadType::StructList;
              handler = std::make_shared<SlSkipHandler>();
              break;
 
            default:
              saveload_type = type.HasFieldLength() ? SaveLoadType::Array : SaveLoadType::Variable;
              break;
          }
 
          /* We don't know this field, so read to nothing. */
          saveloads.emplace_back(std::move(key), saveload_type, type.Type() | VarMemType::Null, 1, SaveLoadVersion::MinVersion, SaveLoadVersion::MaxVersion, nullptr, 0, std::move(handler));
          continue;
        }
 
        /* Validate the type of the field. If it is changed, the
         * savegame should have been bumped so we know how to do the
         * conversion. If this error triggers, that clearly didn't
         * happen and this is a friendly poke to the developer to bump
         * the savegame version and add conversion code. */
        SavegameFileType correct_type = GetSavegameFileType(*sld_it->second);
        if (correct_type.storage != type.storage) {
          Debug(Facility::Sl, Severity::Error, "Field type for '{}' was expected to be 0x{:02x} but 0x{:02x} was found", key, correct_type.storage, type.storage);
          SlErrorCorrupt("Field type is different than expected");
        }
        saveloads.emplace_back(*sld_it->second);
      }
 
      for (auto &sld : saveloads) {
        if (sld.cmd == SaveLoadType::StructList || sld.cmd == SaveLoadType::Struct) {
          sld.handler->load_description = SlTableHeader(sld.handler->GetDescription());
        }
      }
 
      return saveloads;
    }
 
    case SaveLoadAction::Save: {
      /* Automatically calculate the length? */
      if (_sl.need_length != NeedLength::None) {
        SlSetLength(SlCalcTableHeader(slt));
        if (_sl.need_length == NeedLength::CalcLength) break;
      }
 
      for (auto &sld : slt) {
        if (!SlIsObjectValidInSavegame(sld)) continue;
        /* Make sure we are not storing empty keys. */
        assert(!sld.name.empty());
 
        SavegameFileType type = GetSavegameFileType(sld);
        assert(!type.IsEnd());
 
        SlSaveLoadConv(&type.storage, VarTypes::U8);
        SlStdString(const_cast<std::string *>(&sld.name), VarTypes::STR);
      }
 
      /* Add an end-of-header marker. */
      SavegameFileType type{};
      SlSaveLoadConv(&type.storage, VarTypes::U8);
 
      /* After the table, write down any sub-tables we might have. */
      for (auto &sld : slt) {
        if (!SlIsObjectValidInSavegame(sld)) continue;
        if (sld.cmd == SaveLoadType::StructList || sld.cmd == SaveLoadType::Struct) {
          /* SlCalcTableHeader already looks in sub-lists, so avoid the length being added twice. */
          NeedLength old_need_length = _sl.need_length;
          _sl.need_length = NeedLength::None;
 
          SlTableHeader(sld.handler->GetDescription());
 
          _sl.need_length = old_need_length;
        }
      }
 
      break;
    }
 
    default: NOT_REACHED();
  }
 
  return std::vector<SaveLoad>();
}

std::vector<SaveLoad> SlCompatTableHeader(const SaveLoadTable &slt, const SaveLoadCompatTable &slct)
{
  assert(_sl.action == SaveLoadAction::Load || _sl.action == SaveLoadAction::LoadCheck);
  /* ChunkType::Table / ChunkType::SparseTable always have a header. */
  if (_sl.chunk_type == ChunkType::Table || _sl.chunk_type == ChunkType::SparseTable) return SlTableHeader(slt);
 
  std::vector<SaveLoad> saveloads;
 
  /* Build a key lookup mapping based on the available fields. */
  std::map<std::string_view, std::vector<const SaveLoad *>> key_lookup;
  for (auto &sld : slt) {
    /* All entries should have a name; otherwise the entry should just be removed. */
    assert(!sld.name.empty());
 
    key_lookup[sld.name].push_back(&sld);
  }
 
  for (auto &slc : slct) {
    if (slc.name.empty()) {
      /* In old savegames there can be data we no longer care for. We
       * skip this by simply reading the amount of bytes indicated and
       * send those to /dev/null. */
      saveloads.emplace_back("", SaveLoadType::Null, VarFileType::U8 | VarMemType::Null, slc.null_length, slc.version_from, slc.version_to, nullptr, 0, nullptr);
    } else {
      auto sld_it = key_lookup.find(slc.name);
      /* If this branch triggers, it means that an entry in the
       * SaveLoadCompat list is not mentioned in the SaveLoad list. Did
       * you rename a field in one and not in the other? */
      if (sld_it == key_lookup.end()) {
        /* This isn't an assert, as that leaves no information what
         * field was to blame. This way at least we have breadcrumbs. */
        Debug(Facility::Sl, Severity::Critical, "internal error: saveload compatibility field '{}' not found", slc.name);
        SlErrorCorrupt("Internal error with savegame compatibility");
      }
      for (auto &sld : sld_it->second) {
        saveloads.push_back(*sld);
      }
    }
  }
 
  for (auto &sld : saveloads) {
    if (!SlIsObjectValidInSavegame(sld)) continue;
    if (sld.cmd == SaveLoadType::StructList || sld.cmd == SaveLoadType::Struct) {
      sld.handler->load_description = SlCompatTableHeader(sld.handler->GetDescription(), sld.handler->GetCompatDescription());
    }
  }
 
  return saveloads;
}

void SlGlobList(const SaveLoadTable &slt)
{
  SlObject(nullptr, slt);
}

void SlAutolength(AutolengthProc *proc, int arg)
{
  assert(_sl.action == SaveLoadAction::Save);
 
  /* Tell it to calculate the length */
  _sl.need_length = NeedLength::CalcLength;
  _sl.obj_len = 0;
  proc(arg);
 
  /* Setup length */
  _sl.need_length = NeedLength::WantLength;
  SlSetLength(_sl.obj_len);
 
  size_t start_pos = _sl.dumper->GetSize();
  size_t expected_offs = start_pos + _sl.obj_len;
 
  /* And write the stuff */
  proc(arg);
 
  if (expected_offs != _sl.dumper->GetSize()) {
    SlErrorCorruptFmt("Invalid chunk size when writing autolength block, expected {}, got {}", _sl.obj_len, _sl.dumper->GetSize() - start_pos);
  }
}
 
void ChunkHandler::LoadCheck(size_t len) const
{
  switch (_sl.chunk_type) {
    case ChunkType::Table:
    case ChunkType::SparseTable:
      SlTableHeader({});
      [[fallthrough]];
    case ChunkType::Array:
    case ChunkType::SparseArray:
      SlSkipArray();
      break;
    case ChunkType::Riff:
      SlSkipBytes(len);
      break;
    default:
      NOT_REACHED();
  }
}

static void SlLoadChunk(const ChunkHandler &ch)
{
  uint8_t m = SlReadByte();
 
  _sl.chunk_type = static_cast<ChunkType>(m & to_underlying(ChunkType::FileTypeMask));
  _sl.obj_len = 0;
  _sl.expect_table_header = (_sl.chunk_type == ChunkType::Table || _sl.chunk_type == ChunkType::SparseTable);
 
  /* The header should always be at the start. Read the length; the
   * Load() should as first action process the header. */
  if (_sl.expect_table_header) {
    if (SlIterateArray() != INT32_MAX) SlErrorCorrupt("Table chunk without header");
  }
 
  switch (_sl.chunk_type) {
    case ChunkType::Table:
    case ChunkType::Array:
      _sl.array_index = 0;
      ch.Load();
      if (_next_offs != 0) SlErrorCorrupt("Invalid array length");
      break;
    case ChunkType::SparseTable:
    case ChunkType::SparseArray:
      ch.Load();
      if (_next_offs != 0) SlErrorCorrupt("Invalid array length");
      break;
    case ChunkType::Riff: {
      /* Read length */
      size_t len = (SlReadByte() << 16) | ((m >> 4) << 24);
      len += SlReadUint16();
      _sl.obj_len = len;
      size_t start_pos = _sl.reader->GetSize();
      size_t endoffs = start_pos + len;
      ch.Load();
 
      if (_sl.reader->GetSize() != endoffs) {
        SlErrorCorruptFmt("Invalid chunk size in RIFF in {} - expected {}, got {}", ch.GetName(), len, _sl.reader->GetSize() - start_pos);
      }
      break;
    }
    default:
      SlErrorCorrupt("Invalid chunk type");
      break;
  }
 
  if (_sl.expect_table_header) SlErrorCorrupt("Table chunk without header");
}

static void SlLoadCheckChunk(const ChunkHandler &ch)
{
  uint8_t m = SlReadByte();
 
  _sl.chunk_type = static_cast<ChunkType>(m & to_underlying(ChunkType::FileTypeMask));
  _sl.obj_len = 0;
  _sl.expect_table_header = (_sl.chunk_type == ChunkType::Table || _sl.chunk_type == ChunkType::SparseTable);
 
  /* The header should always be at the start. Read the length; the
   * LoadCheck() should as first action process the header. */
  if (_sl.expect_table_header) {
    if (SlIterateArray() != INT32_MAX) SlErrorCorrupt("Table chunk without header");
  }
 
  switch (_sl.chunk_type) {
    case ChunkType::Table:
    case ChunkType::Array:
      _sl.array_index = 0;
      ch.LoadCheck();
      break;
    case ChunkType::SparseTable:
    case ChunkType::SparseArray:
      ch.LoadCheck();
      break;
    case ChunkType::Riff: {
      /* Read length */
      size_t len = (SlReadByte() << 16) | ((m >> 4) << 24);
      len += SlReadUint16();
      _sl.obj_len = len;
      size_t start_pos = _sl.reader->GetSize();
      size_t endoffs = start_pos + len;
      ch.LoadCheck(len);
 
      if (_sl.reader->GetSize() != endoffs) {
        SlErrorCorruptFmt("Invalid chunk size in RIFF in {} - expected {}, got {}", ch.GetName(), len, _sl.reader->GetSize() - start_pos);
      }
      break;
    }
    default:
      SlErrorCorrupt("Invalid chunk type");
      break;
  }
 
  if (_sl.expect_table_header) SlErrorCorrupt("Table chunk without header");
}

static void SlSaveChunk(const ChunkHandler &ch)
{
  if (ch.type == ChunkType::ReadOnly) return;
 
  for (uint8_t b : ch.id) SlWriteByte(b);
  Debug(Facility::Sl, Severity::Warning, "Saving chunk {}", ch.GetName());
 
  _sl.chunk_type = ch.type;
  _sl.expect_table_header = (_sl.chunk_type == ChunkType::Table || _sl.chunk_type == ChunkType::SparseTable);
 
  _sl.need_length = (_sl.expect_table_header || _sl.chunk_type == ChunkType::Riff) ? NeedLength::WantLength : NeedLength::None;
 
  switch (_sl.chunk_type) {
    case ChunkType::Riff:
      ch.Save();
      break;
    case ChunkType::Table:
    case ChunkType::Array:
      _sl.last_array_index = 0;
      SlWriteByte(to_underlying(_sl.chunk_type));
      ch.Save();
      SlWriteArrayLength(0); // Terminate arrays
      break;
    case ChunkType::SparseTable:
    case ChunkType::SparseArray:
      SlWriteByte(to_underlying(_sl.chunk_type));
      ch.Save();
      SlWriteArrayLength(0); // Terminate arrays
      break;
    default: NOT_REACHED();
  }
 
  if (_sl.expect_table_header) SlErrorCorrupt("Table chunk without header");
}

static void SlSaveChunks()
{
  for (auto &ch : ChunkHandlers()) {
    SlSaveChunk(ch);
  }
 
  /* Terminator */
  SlWriteUint32(0);
}

static const ChunkHandler *SlFindChunkHandler(ChunkId id)
{
  for (const ChunkHandler &ch : ChunkHandlers()) if (ch.id == id) return &ch;
  return nullptr;
}

static void SlLoadChunks()
{
  for (ChunkId id = SlReadChunkId(); !id.Empty(); id = SlReadChunkId()) {
    Debug(Facility::Sl, Severity::Warning, "Loading chunk {}", id.AsString());
 
    const ChunkHandler *ch = SlFindChunkHandler(id);
    if (ch == nullptr) SlErrorCorrupt("Unknown chunk type");
    SlLoadChunk(*ch);
  }
}

static void SlLoadCheckChunks()
{
  for (ChunkId id = SlReadChunkId(); !id.Empty(); id = SlReadChunkId()) {
    Debug(Facility::Sl, Severity::Warning, "Loading chunk {}", id.AsString());
 
    const ChunkHandler *ch = SlFindChunkHandler(id);
    if (ch == nullptr) SlErrorCorrupt("Unknown chunk type");
    SlLoadCheckChunk(*ch);
  }
}

static void SlFixPointers()
{
  _sl.action = SaveLoadAction::Ptrs;
 
  for (const ChunkHandler &ch : ChunkHandlers()) {
    Debug(Facility::Sl, Severity::Notice, "Fixing pointers for {}", ch.GetName());
    ch.FixPointers();
  }
 
  assert(_sl.action == SaveLoadAction::Ptrs);
}
 

struct FileReader : LoadFilter {
  std::optional<FileHandle> file; 
  long begin; 

  FileReader(FileHandle &&file) : LoadFilter(nullptr), file(std::move(file)), begin(ftell(*this->file))
  {
  }

  ~FileReader() override
  {
    if (this->file.has_value()) {
      _game_session_stats.savegame_size = ftell(*this->file) - this->begin;
    }
  }
 
  size_t Read(uint8_t *buf, size_t size) override
  {
    /* We're in the process of shutting down, i.e. in "failure" mode. */
    if (!this->file.has_value()) return 0;
 
    return fread(buf, 1, size, *this->file);
  }
 
  void Reset() override
  {
    clearerr(*this->file);
    if (fseek(*this->file, this->begin, SEEK_SET)) {
      Debug(Facility::Sl, Severity::Error, "Could not reset the file reading");
    }
  }
};

struct FileWriter : SaveFilter {
  std::optional<FileHandle> file; 

  FileWriter(FileHandle &&file) : SaveFilter(nullptr), file(std::move(file))
  {
  }

  ~FileWriter() override
  {
    this->Finish();
  }
 
  void Write(const uint8_t *buf, size_t size) override
  {
    /* We're in the process of shutting down, i.e. in "failure" mode. */
    if (!this->file.has_value()) return;
 
    if (fwrite(buf, 1, size, *this->file) != size) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE);
  }
 
  void Finish() override
  {
    if (this->file.has_value()) {
      _game_session_stats.savegame_size = ftell(*this->file);
      this->file.reset();
    }
  }
};
 
/*******************************************
 ********** START OF LZO CODE **************
 *******************************************/
 
#ifdef WITH_LZO

static const uint LZO_BUFFER_SIZE = 8192;

struct LZOLoadFilter : LoadFilter {
  LZOLoadFilter(std::shared_ptr<LoadFilter> chain) : LoadFilter(std::move(chain))
  {
    if (lzo_init() != LZO_E_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
  }
 
  size_t Read(uint8_t *buf, size_t ssize) override
  {
    assert(ssize >= LZO_BUFFER_SIZE);
 
    /* Buffer size is from the LZO docs plus the chunk header size. */
    uint8_t out[LZO_BUFFER_SIZE + LZO_BUFFER_SIZE / 16 + 64 + 3 + sizeof(uint32_t) * 2];
    uint32_t tmp[2];
    uint32_t size;
    lzo_uint len = ssize;
 
    /* Read header*/
    if (this->chain->Read((uint8_t*)tmp, sizeof(tmp)) != sizeof(tmp)) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE, "File read failed");
 
    /* Check if size is bad */
    ((uint32_t*)out)[0] = size = tmp[1];
 
    if (_sl_version != SaveLoadVersion::MinVersion) {
      tmp[0] = TO_BE32(tmp[0]);
      size = TO_BE32(size);
    }
 
    if (size >= sizeof(out)) SlErrorCorrupt("Inconsistent size");
 
    /* Read block */
    if (this->chain->Read(out + sizeof(uint32_t), size) != size) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
 
    /* Verify checksum */
    if (tmp[0] != lzo_adler32(0, out, size + sizeof(uint32_t))) SlErrorCorrupt("Bad checksum");
 
    /* Decompress */
    int ret = lzo1x_decompress_safe(out + sizeof(uint32_t) * 1, size, buf, &len, nullptr);
    if (ret != LZO_E_OK) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
    return len;
  }
};

struct LZOSaveFilter : SaveFilter {
  LZOSaveFilter(std::shared_ptr<SaveFilter> chain, uint8_t) : SaveFilter(std::move(chain))
  {
    if (lzo_init() != LZO_E_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
  }
 
  void Write(const uint8_t *buf, size_t size) override
  {
    const lzo_bytep in = buf;
    /* Buffer size is from the LZO docs plus the chunk header size. */
    uint8_t out[LZO_BUFFER_SIZE + LZO_BUFFER_SIZE / 16 + 64 + 3 + sizeof(uint32_t) * 2];
    uint8_t wrkmem[LZO1X_1_MEM_COMPRESS];
    lzo_uint outlen;
 
    do {
      /* Compress up to LZO_BUFFER_SIZE bytes at once. */
      lzo_uint len = size > LZO_BUFFER_SIZE ? LZO_BUFFER_SIZE : static_cast<lzo_uint>(size);
      lzo1x_1_compress(in, len, out + sizeof(uint32_t) * 2, &outlen, wrkmem);
      ((uint32_t*)out)[1] = TO_BE32(static_cast<uint32_t>(outlen));
      ((uint32_t*)out)[0] = TO_BE32(lzo_adler32(0, out + sizeof(uint32_t), outlen + sizeof(uint32_t)));
      this->chain->Write(out, outlen + sizeof(uint32_t) * 2);
 
      /* Move to next data chunk. */
      size -= len;
      in += len;
    } while (size > 0);
  }
};
 
#endif /* WITH_LZO */
 
/*********************************************
 ******** START OF NOCOMP CODE (uncompressed)*
 *********************************************/

struct NoCompLoadFilter : LoadFilter {
  NoCompLoadFilter(std::shared_ptr<LoadFilter> chain) : LoadFilter(std::move(chain))
  {
  }
 
  size_t Read(uint8_t *buf, size_t size) override
  {
    return this->chain->Read(buf, size);
  }
};

struct NoCompSaveFilter : SaveFilter {
  NoCompSaveFilter(std::shared_ptr<SaveFilter> chain, uint8_t) : SaveFilter(std::move(chain))
  {
  }
 
  void Write(const uint8_t *buf, size_t size) override
  {
    this->chain->Write(buf, size);
  }
};
 
/********************************************
 ********** START OF ZLIB CODE **************
 ********************************************/
 
#if defined(WITH_ZLIB)

struct ZlibLoadFilter : LoadFilter {
  z_stream z{}; 
  uint8_t fread_buf[MEMORY_CHUNK_SIZE]; 

  ZlibLoadFilter(std::shared_ptr<LoadFilter> chain) : LoadFilter(std::move(chain))
  {
    if (inflateInit(&this->z) != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
  }

  ~ZlibLoadFilter() override
  {
    inflateEnd(&this->z);
  }
 
  size_t Read(uint8_t *buf, size_t size) override
  {
    this->z.next_out  = buf;
    this->z.avail_out = static_cast<uint>(size);
 
    do {
      /* read more bytes from the file? */
      if (this->z.avail_in == 0) {
        this->z.next_in = this->fread_buf;
        this->z.avail_in = static_cast<uint>(this->chain->Read(this->fread_buf, sizeof(this->fread_buf)));
      }
 
      /* inflate the data */
      int r = inflate(&this->z, 0);
      if (r == Z_STREAM_END) break;
 
      if (r != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "inflate() failed");
    } while (this->z.avail_out != 0);
 
    return size - this->z.avail_out;
  }
};

struct ZlibSaveFilter : SaveFilter {
  z_stream z{}; 
  uint8_t fwrite_buf[MEMORY_CHUNK_SIZE]; 

  ZlibSaveFilter(std::shared_ptr<SaveFilter> chain, uint8_t compression_level) : SaveFilter(std::move(chain))
  {
    if (deflateInit(&this->z, compression_level) != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
  }

  ~ZlibSaveFilter() override
  {
    deflateEnd(&this->z);
  }

  void WriteLoop(const uint8_t *p, size_t len, int mode)
  {
    uint n;
    this->z.next_in = const_cast<uint8_t *>(p); // zlib does not modify the data, but is non-const for legacy reasons
    this->z.avail_in = static_cast<uInt>(len);
    do {
      this->z.next_out = this->fwrite_buf;
      this->z.avail_out = sizeof(this->fwrite_buf);

      int r = deflate(&this->z, mode);
 
      /* bytes were emitted? */
      if ((n = sizeof(this->fwrite_buf) - this->z.avail_out) != 0) {
        this->chain->Write(this->fwrite_buf, n);
      }
      if (r == Z_STREAM_END) break;
 
      if (r != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "zlib returned error code");
    } while (this->z.avail_in || !this->z.avail_out);
  }
 
  void Write(const uint8_t *buf, size_t size) override
  {
    this->WriteLoop(buf, size, 0);
  }
 
  void Finish() override
  {
    this->WriteLoop(nullptr, 0, Z_FINISH);
    this->chain->Finish();
  }
};
 
#endif /* WITH_ZLIB */
 
/********************************************
 ********** START OF LZMA CODE **************
 ********************************************/
 
#if defined(WITH_LIBLZMA)

static const lzma_stream _lzma_init = LZMA_STREAM_INIT;

struct LZMALoadFilter : LoadFilter {
  lzma_stream lzma;                  
  uint8_t fread_buf[MEMORY_CHUNK_SIZE]; 

  LZMALoadFilter(std::shared_ptr<LoadFilter> chain) : LoadFilter(std::move(chain)), lzma(_lzma_init)
  {
    /* Allow saves up to 256 MB uncompressed */
    if (lzma_auto_decoder(&this->lzma, 1 << 28, 0) != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
  }

  ~LZMALoadFilter() override
  {
    lzma_end(&this->lzma);
  }
 
  size_t Read(uint8_t *buf, size_t size) override
  {
    this->lzma.next_out  = buf;
    this->lzma.avail_out = size;
 
    do {
      /* read more bytes from the file? */
      if (this->lzma.avail_in == 0) {
        this->lzma.next_in  = this->fread_buf;
        this->lzma.avail_in = this->chain->Read(this->fread_buf, sizeof(this->fread_buf));
      }
 
      /* inflate the data */
      lzma_ret r = lzma_code(&this->lzma, LZMA_RUN);
      if (r == LZMA_STREAM_END) break;
      if (r != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "liblzma returned error code");
    } while (this->lzma.avail_out != 0);
 
    return size - this->lzma.avail_out;
  }
};

struct LZMASaveFilter : SaveFilter {
  lzma_stream lzma; 
  uint8_t fwrite_buf[MEMORY_CHUNK_SIZE]; 

  LZMASaveFilter(std::shared_ptr<SaveFilter> chain, uint8_t compression_level) : SaveFilter(std::move(chain)), lzma(_lzma_init)
  {
    if (lzma_easy_encoder(&this->lzma, compression_level, LZMA_CHECK_CRC32) != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
  }

  ~LZMASaveFilter() override
  {
    lzma_end(&this->lzma);
  }

  void WriteLoop(const uint8_t *p, size_t len, lzma_action action)
  {
    size_t n;
    this->lzma.next_in = p;
    this->lzma.avail_in = len;
    do {
      this->lzma.next_out = this->fwrite_buf;
      this->lzma.avail_out = sizeof(this->fwrite_buf);
 
      lzma_ret r = lzma_code(&this->lzma, action);
 
      /* bytes were emitted? */
      if ((n = sizeof(this->fwrite_buf) - this->lzma.avail_out) != 0) {
        this->chain->Write(this->fwrite_buf, n);
      }
      if (r == LZMA_STREAM_END) break;
      if (r != LZMA_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "liblzma returned error code");
    } while (this->lzma.avail_in || !this->lzma.avail_out);
  }
 
  void Write(const uint8_t *buf, size_t size) override
  {
    this->WriteLoop(buf, size, LZMA_RUN);
  }
 
  void Finish() override
  {
    this->WriteLoop(nullptr, 0, LZMA_FINISH);
    this->chain->Finish();
  }
};
 
#endif /* WITH_LIBLZMA */
 
/*******************************************
 ************* END OF CODE *****************
 *******************************************/

using SaveLoadFormatTag = Label<struct SaveLoadFormatLabelTag>;

struct SaveLoadFormat {
  std::shared_ptr<LoadFilter> (*init_load)(std::shared_ptr<LoadFilter> chain); 
  std::shared_ptr<SaveFilter> (*init_write)(std::shared_ptr<SaveFilter> chain, uint8_t compression); 
 
  std::string_view name; 
  SaveLoadFormatTag tag; 
 
  uint8_t min_compression;                 
  uint8_t default_compression;             
  uint8_t max_compression;                 
};
 
static const SaveLoadFormatTag SAVEGAME_TAG_LZO{"OTTD"}; 
static const SaveLoadFormatTag SAVEGAME_TAG_NONE{"OTTN"}; 
static const SaveLoadFormatTag SAVEGAME_TAG_ZLIB{"OTTZ"}; 
static const SaveLoadFormatTag SAVEGAME_TAG_LZMA{"OTTX"}; 

static const SaveLoadFormat _saveload_formats[] = {
#if defined(WITH_LZO)
  /* Roughly 75% larger than zlib level 6 at only ~7% of the CPU usage. */
  {CreateLoadFilter<LZOLoadFilter>, CreateSaveFilter<LZOSaveFilter>, "lzo", SAVEGAME_TAG_LZO, 0, 0, 0},
#else
  {nullptr, nullptr, "lzo", SAVEGAME_TAG_LZO, 0, 0, 0},
#endif
  /* Roughly 5 times larger at only 1% of the CPU usage over zlib level 6. */
  {CreateLoadFilter<NoCompLoadFilter>, CreateSaveFilter<NoCompSaveFilter>, "none", SAVEGAME_TAG_NONE, 0, 0, 0},
#if defined(WITH_ZLIB)
  /* After level 6 the speed reduction is significant (1.5x to 2.5x slower per level), but the reduction in filesize is
   * fairly insignificant (~1% for each step). Lower levels become ~5-10% bigger by each level than level 6 while level
   * 1 is "only" 3 times as fast. Level 0 results in uncompressed savegames at about 8 times the cost of "none". */
  {CreateLoadFilter<ZlibLoadFilter>, CreateSaveFilter<ZlibSaveFilter>, "zlib", SAVEGAME_TAG_ZLIB, 0, 6, 9},
#else
  {nullptr, nullptr, "zlib", SAVEGAME_TAG_ZLIB, 0, 0, 0},
#endif
#if defined(WITH_LIBLZMA)
  /* Level 2 compression is speed wise as fast as zlib level 6 compression (old default), but results in ~10% smaller saves.
   * Higher compression levels are possible, and might improve savegame size by up to 25%, but are also up to 10 times slower.
   * The next significant reduction in file size is at level 4, but that is already 4 times slower. Level 3 is primarily 50%
   * slower while not improving the filesize, while level 0 and 1 are faster, but don't reduce savegame size much.
   * It's OTTX and not e.g. OTTL because liblzma is part of xz-utils and .tar.xz is preferred over .tar.lzma. */
  {CreateLoadFilter<LZMALoadFilter>, CreateSaveFilter<LZMASaveFilter>, "lzma", SAVEGAME_TAG_LZMA, 0, 2, 9},
#else
  {nullptr, nullptr, "lzma", SAVEGAME_TAG_LZMA, 0, 0, 0},
#endif
};

static std::pair<const SaveLoadFormat &, uint8_t> GetSavegameFormat(std::string_view full_name)
{
  /* Find default savegame format, the highest one with which files can be written. */
  auto it = std::find_if(std::rbegin(_saveload_formats), std::rend(_saveload_formats), [](const auto &slf) { return slf.init_write != nullptr; });
  if (it == std::rend(_saveload_formats)) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "no writeable savegame formats");
 
  const SaveLoadFormat &def = *it;
 
  if (!full_name.empty()) {
    /* Get the ":..." of the compression level out of the way */
    size_t separator = full_name.find(':');
    bool has_comp_level = separator != std::string::npos;
    std::string_view name = has_comp_level ? full_name.substr(0, separator) : full_name;
 
    for (const auto &slf : _saveload_formats) {
      if (slf.init_write != nullptr && name == slf.name) {
        if (has_comp_level) {
          auto complevel = full_name.substr(separator + 1);
 
          /* Get the level and determine whether all went fine. */
          auto level = ParseInteger<uint8_t>(complevel);
          if (!level.has_value() || *level != Clamp(*level, slf.min_compression, slf.max_compression)) {
            ShowErrorMessage(
              GetEncodedString(STR_CONFIG_ERROR),
              GetEncodedString(STR_CONFIG_ERROR_INVALID_SAVEGAME_COMPRESSION_LEVEL, complevel),
              WarningLevel::Critical);
          } else {
            return {slf, *level};
          }
        }
        return {slf, slf.default_compression};
      }
    }
 
    ShowErrorMessage(
      GetEncodedString(STR_CONFIG_ERROR),
      GetEncodedString(STR_CONFIG_ERROR_INVALID_SAVEGAME_COMPRESSION_ALGORITHM, name, def.name),
      WarningLevel::Critical);
  }
  return {def, def.default_compression};
}
 
/* actual loader/saver function */
void InitializeGame(uint size_x, uint size_y, bool reset_date, bool reset_settings);
extern bool AfterLoadGame();
extern bool LoadOldSaveGame(std::string_view file);

static void ResetSettings()
{
  for (auto &desc : GetSaveLoadSettingTable()) {
    const SettingDesc *sd = GetSettingDesc(desc);
    if (sd->flags.Test(SettingFlag::NotInSave)) continue;
    if (sd->flags.Test(SettingFlag::NoNetworkSync) && _networking && !_network_server) continue;
 
    sd->ResetToDefault(&_settings_game);
  }
}
 
extern void ClearOldOrders();

static void ResetSaveloadData()
{
  ClearOldOrders();
  ResetTempEngineData();
  ClearRailTypeLabelList();
  ClearRoadTypeLabelList();
  ResetOldWaypoints();
  ResetSettings();
}

static inline void ClearSaveLoadState()
{
  _sl.dumper = nullptr;
  _sl.sf = nullptr;
  _sl.reader = nullptr;
  _sl.lf = nullptr;
}

static void SaveFileStart()
{
  SetMouseCursorBusy(true);
 
  InvalidateWindowData(WindowClass::Statusbar, 0, SBI_SAVELOAD_START);
  _sl.saveinprogress = true;
}

static void SaveFileDone()
{
  SetMouseCursorBusy(false);
 
  InvalidateWindowData(WindowClass::Statusbar, 0, SBI_SAVELOAD_FINISH);
  _sl.saveinprogress = false;
 
#ifdef __EMSCRIPTEN__
  EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
#endif
}

void SetSaveLoadError(StringID str)
{
  _sl.error_str = str;
}

EncodedString GetSaveLoadErrorType()
{
  return GetEncodedString(_sl.action == SaveLoadAction::Save ? STR_ERROR_GAME_SAVE_FAILED : STR_ERROR_GAME_LOAD_FAILED);
}

EncodedString GetSaveLoadErrorMessage()
{
  return GetEncodedString(_sl.error_str, _sl.extra_msg);
}

static void SaveFileError()
{
  ShowErrorMessage(GetSaveLoadErrorType(), GetSaveLoadErrorMessage(), WarningLevel::Error);
  SaveFileDone();
}

static SaveLoadResult SaveFileToDisk(bool threaded)
{
  try {
    auto [fmt, compression] = GetSavegameFormat(_savegame_format);
 
    /* We have written our stuff to memory, now write it to file! */
    _sl.sf->Write(fmt.tag.data(), fmt.tag.size());
 
    uint32_t version = TO_BE32(to_underlying(SAVEGAME_VERSION) << 16);
    _sl.sf->Write(reinterpret_cast<uint8_t *>(&version), sizeof(version));
 
    _sl.sf = fmt.init_write(_sl.sf, compression);
    _sl.dumper->Flush(_sl.sf);
 
    ClearSaveLoadState();
 
    if (threaded) SetAsyncSaveFinish(SaveFileDone);
 
    return SaveLoadResult::Ok;
  } catch (...) {
    ClearSaveLoadState();
 
    AsyncSaveFinishProc asfp = SaveFileDone;
 
    /* We don't want to shout when saving is just
     * cancelled due to a client disconnecting. */
    if (_sl.error_str != STR_NETWORK_ERROR_LOSTCONNECTION) {
      Debug(Facility::Sl, Severity::Critical, "{} {}", GetSaveLoadErrorType().GetDecodedString(), GetSaveLoadErrorMessage().GetDecodedString());
      asfp = SaveFileError;
    }
 
    if (threaded) {
      SetAsyncSaveFinish(asfp);
    } else {
      asfp();
    }
    return SaveLoadResult::Error;
  }
}
 
void WaitTillSaved()
{
  if (!_save_thread.joinable()) return;
 
  _save_thread.join();
 
  /* Make sure every other state is handled properly as well. */
  ProcessAsyncSaveFinish();
}

static SaveLoadResult DoSave(std::shared_ptr<SaveFilter> writer, bool threaded)
{
  assert(!_sl.saveinprogress);
 
  _sl.dumper = std::make_unique<MemoryDumper>();
  _sl.sf = std::move(writer);
 
  _sl_version = SAVEGAME_VERSION;
 
  SaveViewportBeforeSaveGame();
  SlSaveChunks();
 
  SaveFileStart();
 
  if (!threaded || !StartNewThread(&_save_thread, "ottd:savegame", &SaveFileToDisk, true)) {
    if (threaded) Debug(Facility::Sl, Severity::Error, "Cannot create savegame thread, reverting to single-threaded mode...");
 
    SaveLoadResult result = SaveFileToDisk(false);
    SaveFileDone();
 
    return result;
  }
 
  return SaveLoadResult::Ok;
}

SaveLoadResult SaveWithFilter(std::shared_ptr<SaveFilter> writer, bool threaded)
{
  try {
    _sl.action = SaveLoadAction::Save;
    return DoSave(std::move(writer), threaded);
  } catch (...) {
    ClearSaveLoadState();
    return SaveLoadResult::Error;
  }
}

static const SaveLoadFormat *DetermineSaveLoadFormat(SaveLoadFormatTag tag, uint32_t raw_version)
{
  auto fmt = std::ranges::find(_saveload_formats, tag, &SaveLoadFormat::tag);
  if (fmt != std::end(_saveload_formats)) {
    /* Check version number */
    _sl_version = (SaveLoadVersion)(TO_BE32(raw_version) >> 16);
    /* Minor is not used anymore from version 18.0, but it is still needed
     * in versions before that (4 cases) which can't be removed easy.
     * Therefore it is loaded, but never saved (or, it saves a 0 in any scenario). */
    _sl_minor_version = (TO_BE32(raw_version) >> 8) & 0xFF;
 
    Debug(Facility::Sl, Severity::Error, "Loading savegame version {}", _sl_version);
 
    /* Is the version higher than the current? */
    if (_sl_version > SAVEGAME_VERSION) SlError(STR_GAME_SAVELOAD_ERROR_TOO_NEW_SAVEGAME);
    if (_sl_version >= SaveLoadVersion::StartPatchpacks && _sl_version <= SaveLoadVersion::EndPatchpacks) SlError(STR_GAME_SAVELOAD_ERROR_PATCHPACK);
    return fmt;
  }
 
  Debug(Facility::Sl, Severity::Critical, "Unknown savegame type, trying to load it as the buggy format");
  _sl.lf->Reset();
  _sl_version = SaveLoadVersion::MinVersion;
  _sl_minor_version = 0;
 
  /* Try to find the LZO savegame format; it uses 'OTTD' as tag. */
  fmt = std::ranges::find(_saveload_formats, SAVEGAME_TAG_LZO, &SaveLoadFormat::tag);
  if (fmt == std::end(_saveload_formats)) {
    /* Who removed the LZO savegame format definition? When built without LZO support,
     * the formats must still list it just without a method to read the file.
     * The caller of this function has to check for the existence of load function. */
    NOT_REACHED();
  }
  return fmt;
}

static SaveLoadResult DoLoad(std::shared_ptr<LoadFilter> reader, bool load_check)
{
  _sl.lf = std::move(reader);
 
  if (load_check) {
    /* Clear previous check data */
    _load_check_data.Clear();
    /* Mark SL_LOAD_CHECK as supported for this savegame. */
    _load_check_data.checkable = true;
  }
 
  SaveLoadFormatTag tag{};
  if (_sl.lf->Read(tag.data(), tag.size()) != tag.size()) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
 
  uint32_t version;
  if (_sl.lf->Read(reinterpret_cast<uint8_t*>(&version), sizeof(version)) != sizeof(version)) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
 
  /* see if we have any loader for this type. */
  const SaveLoadFormat *fmt = DetermineSaveLoadFormat(tag, version);
 
  /* loader for this savegame type is not implemented? */
  if (fmt->init_load == nullptr) {
    SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, fmt::format("Loader for '{}' is not available.", fmt->name));
  }
 
  _sl.lf = fmt->init_load(_sl.lf);
  _sl.reader = std::make_unique<ReadBuffer>(_sl.lf);
  _next_offs = 0;
 
  if (!load_check) {
    ResetSaveloadData();
 
    /* Old maps were hardcoded to 256x256 and thus did not contain
     * any mapsize information. Pre-initialize to 256x256 to not to
     * confuse old games */
    InitializeGame(256, 256, true, true);
 
    _gamelog.Reset();
 
    if (IsSavegameVersionBefore(SaveLoadVersion::TownTolerancePauseMode)) {
      /*
       * NewGRFs were introduced between 0.3,4 and 0.3.5, which both
       * shared savegame version 4. Anything before that 'obviously'
       * does not have any NewGRFs. Between the introduction and
       * savegame version 41 (just before 0.5) the NewGRF settings
       * were not stored in the savegame and they were loaded by
       * using the settings from the main menu.
       * So, to recap:
       * - savegame version  <  4:  do not load any NewGRFs.
       * - savegame version >= 41:  load NewGRFs from savegame, which is
       *                            already done at this stage by
       *                            overwriting the main menu settings.
       * - other savegame versions: use main menu settings.
       *
       * This means that users *can* crash savegame version 4..40
       * savegames if they set incompatible NewGRFs in the main menu,
       * but can't crash anymore for savegame version < 4 savegames.
       *
       * Note: this is done here because AfterLoadGame is also called
       * for TTO/TTD/TTDP savegames which have their own NewGRF logic.
       */
      ClearGRFConfigList(_grfconfig);
    }
  }
 
  if (load_check) {
    /* Load chunks into _load_check_data.
     * No pools are loaded. References are not possible, and thus do not need resolving. */
    SlLoadCheckChunks();
  } else {
    /* Load chunks and resolve references */
    SlLoadChunks();
    SlFixPointers();
  }
 
  ClearSaveLoadState();
 
  _savegame_type = SavegameType::OTTD;
 
  if (load_check) {
    /* The only part from AfterLoadGame() we need */
    _load_check_data.grf_compatibility = IsGoodGRFConfigList(_load_check_data.grfconfig);
  } else {
    _gamelog.StartAction(GamelogActionType::Load);
 
    /* After loading fix up savegame for any internal changes that
     * might have occurred since then. If it fails, load back the old game. */
    if (!AfterLoadGame()) {
      _gamelog.StopAction();
      return SaveLoadResult::ReInit;
    }
 
    _gamelog.StopAction();
  }
 
  return SaveLoadResult::Ok;
}

SaveLoadResult LoadWithFilter(std::shared_ptr<LoadFilter> reader)
{
  try {
    _sl.action = SaveLoadAction::Load;
    return DoLoad(std::move(reader), false);
  } catch (...) {
    ClearSaveLoadState();
    return SaveLoadResult::ReInit;
  }
}

SaveLoadResult SaveOrLoad(std::string_view filename, SaveLoadOperation fop, DetailedFileType dft, Subdirectory sb, bool threaded)
{
  /* An instance of saving is already active, so don't go saving again */
  if (_sl.saveinprogress && fop == SaveLoadOperation::Save && dft == DetailedFileType::GameFile && threaded) {
    /* if not an autosave, but a user action, show error message */
    if (!_do_autosave) ShowErrorMessage(GetEncodedString(STR_ERROR_SAVE_STILL_IN_PROGRESS), {}, WarningLevel::Error);
    return SaveLoadResult::Ok;
  }
  WaitTillSaved();
 
  try {
    /* Load a TTDLX or TTDPatch game */
    if (fop == SaveLoadOperation::Load && dft == DetailedFileType::OldGameFile) {
      ResetSaveloadData();
 
      InitializeGame(256, 256, true, true); // set a mapsize of 256x256 for TTDPatch games or it might get confused
 
      /* TTD/TTO savegames have no NewGRFs, TTDP savegame have them
       * and if so a new NewGRF list will be made in LoadOldSaveGame.
       * Note: this is done here because AfterLoadGame is also called
       * for OTTD savegames which have their own NewGRF logic. */
      ClearGRFConfigList(_grfconfig);
      _gamelog.Reset();
      if (!LoadOldSaveGame(filename)) return SaveLoadResult::ReInit;
      _sl_version = SaveLoadVersion::MinVersion;
      _sl_minor_version = 0;
      _gamelog.StartAction(GamelogActionType::Load);
      if (!AfterLoadGame()) {
        _gamelog.StopAction();
        return SaveLoadResult::ReInit;
      }
      _gamelog.StopAction();
      return SaveLoadResult::Ok;
    }
 
    assert(dft == DetailedFileType::GameFile);
    switch (fop) {
      case SaveLoadOperation::Check:
        _sl.action = SaveLoadAction::LoadCheck;
        break;
 
      case SaveLoadOperation::Load:
        _sl.action = SaveLoadAction::Load;
        break;
 
      case SaveLoadOperation::Save:
        _sl.action = SaveLoadAction::Save;
        break;
 
      default: NOT_REACHED();
    }
 
    auto fh = (fop == SaveLoadOperation::Save) ? FioFOpenFile(filename, "wb", sb) : FioFOpenFile(filename, "rb", sb);
 
    /* Make it a little easier to load savegames from the console */
    if (!fh.has_value() && fop != SaveLoadOperation::Save) fh = FioFOpenFile(filename, "rb", Subdirectory::Save);
    if (!fh.has_value() && fop != SaveLoadOperation::Save) fh = FioFOpenFile(filename, "rb", Subdirectory::Base);
    if (!fh.has_value() && fop != SaveLoadOperation::Save) fh = FioFOpenFile(filename, "rb", Subdirectory::Scenario);
 
    if (!fh.has_value()) {
      SlError(fop == SaveLoadOperation::Save ? STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE : STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
    }
 
    if (fop == SaveLoadOperation::Save) { // SAVE game
      Debug(Facility::Desync, Severity::Error, "save: {:08x}; {:02x}; {}", TimerGameEconomy::date, TimerGameEconomy::date_fract, filename);
      if (!_settings_client.gui.threaded_saves) threaded = false;
 
      return DoSave(std::make_shared<FileWriter>(std::move(*fh)), threaded);
    }
 
    /* LOAD game */
    assert(fop == SaveLoadOperation::Load || fop == SaveLoadOperation::Check);
    Debug(Facility::Desync, Severity::Error, "load: {}", filename);
    return DoLoad(std::make_shared<FileReader>(std::move(*fh)), fop == SaveLoadOperation::Check);
  } catch (...) {
    /* This code may be executed both for old and new save games. */
    ClearSaveLoadState();
 
    if (fop != SaveLoadOperation::Check) Debug(Facility::Sl, Severity::Critical, "{} {}", GetSaveLoadErrorType().GetDecodedString(), GetSaveLoadErrorMessage().GetDecodedString());
 
    /* A saver/loader exception!! reinitialize all variables to prevent crash! */
    return (fop == SaveLoadOperation::Load) ? SaveLoadResult::ReInit : SaveLoadResult::Error;
  }
}

void DoAutoOrNetsave(FiosNumberedSaveName &counter)
{
  std::string filename;
 
  if (_settings_client.gui.keep_all_autosave) {
    filename = GenerateDefaultSaveName() + counter.Extension();
  } else {
    filename = counter.Filename();
  }
 
  Debug(Facility::Sl, Severity::Warning, "Autosaving to '{}'", filename);
  if (SaveOrLoad(filename, SaveLoadOperation::Save, DetailedFileType::GameFile, Subdirectory::Autosave) != SaveLoadResult::Ok) {
    ShowErrorMessage(GetEncodedString(STR_ERROR_AUTOSAVE_FAILED), {}, WarningLevel::Error);
  }
}
 

void DoExitSave()
{
  SaveOrLoad("exit.sav", SaveLoadOperation::Save, DetailedFileType::GameFile, Subdirectory::Autosave);
}

std::string GenerateDefaultSaveName()
{
  /* Check if we have a name for this map, which is the name of the first
   * available company. When there's no company available we'll use
   * 'Spectator' as "company" name. */
  CompanyID cid = _local_company;
  if (!Company::IsValidID(cid)) {
    for (const Company *c : Company::Iterate()) {
      cid = c->index;
      break;
    }
  }
 
  std::array<StringParameter, 4> params{};
  auto it = params.begin();
  *it++ = cid;
 
  /* We show the current game time differently depending on the timekeeping units used by this game. */
  if (TimerGameEconomy::UsingWallclockUnits()) {
    /* Insert time played. */
    const auto play_time = TimerGameTick::counter / Ticks::TICKS_PER_SECOND;
    *it++ = STR_SAVEGAME_DURATION_REALTIME;
    *it++ = play_time / 60 / 60;
    *it++ = (play_time / 60) % 60;
  } else {
    /* Insert current date */
    switch (_settings_client.gui.date_format_in_default_names) {
      case 0: *it++ = STR_JUST_DATE_LONG; break;
      case 1: *it++ = STR_JUST_DATE_TINY; break;
      case 2: *it++ = STR_JUST_DATE_ISO; break;
      default: NOT_REACHED();
    }
    *it++ = TimerGameEconomy::date;
  }
 
  /* Get the correct string (special string for when there's not company) */
  std::string filename = GetStringWithArgs(!Company::IsValidID(cid) ? STR_SAVEGAME_NAME_SPECTATOR : STR_SAVEGAME_NAME_DEFAULT, params);
  SanitizeFilename(filename);
  return filename;
}

void FileToSaveLoad::SetMode(const FiosType &ft, SaveLoadOperation fop)
{
  if (ft.abstract == AbstractFileType::Invalid || ft.abstract == AbstractFileType::None) {
    this->file_op = SaveLoadOperation::Invalid;
    this->ftype = FIOS_TYPE_INVALID;
    return;
  }
 
  this->file_op = fop;
  this->ftype = ft;
}

void FileToSaveLoad::Set(const FiosItem &item)
{
  this->SetMode(item.type);
  this->name = item.name;
  this->title = item.title;
}
 
SaveLoadTable SaveLoadHandler::GetLoadDescription() const
{
  assert(this->load_description.has_value());
  return *this->load_description;
}