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 <http://www.gnu.org/licenses/>.
 */
 
#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 "../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
 
#include "table/strings.h"
 
#include "../safeguards.h"
 
extern const SaveLoadVersion SAVEGAME_VERSION = (SaveLoadVersion)(SL_MAX_VERSION - 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 SaveLoadAction : uint8_t {
  SLA_LOAD,        
  SLA_SAVE,        
  SLA_PTRS,        
  SLA_NULL,        
  SLA_LOAD_CHECK,  
};
 
enum NeedLength : uint8_t {
  NL_NONE = 0,       
  NL_WANTLENGTH = 1, 
  NL_CALCLENGTH = 2, 
};
 
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;              
  uint8_t block_mode;                     
  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 = SLA_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(sl, 3, "Nulling pointers for {}", ch.GetName());
    ch.FixPointers();
  }
 
  assert(_sl.action == SLA_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 == SLA_LOAD_CHECK) {
    _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 == SLA_LOAD || _sl.action == SLA_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 (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((uint32_t)(x >> 32));
  SlWriteUint32((uint32_t)x);
}
 
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((uint8_t)(0xF0));
          SlWriteByte((uint8_t)(i >> 24));
        } else {
          SlWriteByte((uint8_t)(0xE0 | (i >> 24)));
        }
        SlWriteByte((uint8_t)(i >> 16));
      } else {
        SlWriteByte((uint8_t)(0xC0 | (i >> 16)));
      }
      SlWriteByte((uint8_t)(i >> 8));
    } else {
      SlWriteByte((uint8_t)(0x80 | (i >> 8)));
    }
  }
  SlWriteByte((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);
}
 
static uint8_t GetSavegameFileType(const SaveLoad &sld)
{
  switch (sld.cmd) {
    case SL_VAR:
      return GetVarFileType(sld.conv); break;
 
    case SL_STDSTR:
    case SL_ARR:
    case SL_VECTOR:
    case SL_DEQUE:
      return GetVarFileType(sld.conv) | SLE_FILE_HAS_LENGTH_FIELD; break;
 
    case SL_REF:
      return IsSavegameVersionBefore(SLV_69) ? SLE_FILE_U16 : SLE_FILE_U32;
 
    case SL_REFLIST:
    case SL_REFVECTOR:
      return (IsSavegameVersionBefore(SLV_69) ? SLE_FILE_U16 : SLE_FILE_U32) | SLE_FILE_HAS_LENGTH_FIELD;
 
    case SL_SAVEBYTE:
      return SLE_FILE_U8;
 
    case SL_STRUCT:
    case SL_STRUCTLIST:
      return SLE_FILE_STRUCT | SLE_FILE_HAS_LENGTH_FIELD;
 
    default: NOT_REACHED();
  }
}
 
static inline uint SlCalcConvMemLen(VarType conv)
{
  switch (GetVarMemType(conv)) {
    case SLE_VAR_BL: return sizeof(bool);
    case SLE_VAR_I8: return sizeof(int8_t);
    case SLE_VAR_U8: return sizeof(uint8_t);
    case SLE_VAR_I16: return sizeof(int16_t);
    case SLE_VAR_U16: return sizeof(uint16_t);
    case SLE_VAR_I32: return sizeof(int32_t);
    case SLE_VAR_U32: return sizeof(uint32_t);
    case SLE_VAR_I64: return sizeof(int64_t);
    case SLE_VAR_U64: return sizeof(uint64_t);
    case SLE_VAR_NULL: return 0;
 
    case SLE_VAR_STR:
    case SLE_VAR_STRQ:
      return SlReadArrayLength();
 
    case SLE_VAR_NAME:
    default:
      NOT_REACHED();
  }
}
 
static inline uint8_t SlCalcConvFileLen(VarType conv)
{
  switch (GetVarFileType(conv)) {
    case SLE_FILE_END: return 0;
    case SLE_FILE_I8: return sizeof(int8_t);
    case SLE_FILE_U8: return sizeof(uint8_t);
    case SLE_FILE_I16: return sizeof(int16_t);
    case SLE_FILE_U16: return sizeof(uint16_t);
    case SLE_FILE_I32: return sizeof(int32_t);
    case SLE_FILE_U32: return sizeof(uint32_t);
    case SLE_FILE_I64: return sizeof(int64_t);
    case SLE_FILE_U64: return sizeof(uint64_t);
    case SLE_FILE_STRINGID: return sizeof(uint16_t);
 
    case SLE_FILE_STRING:
      return SlReadArrayLength();
 
    case SLE_FILE_STRUCT:
    default:
      NOT_REACHED();
  }
}
 
static inline size_t SlCalcRefLen()
{
  return IsSavegameVersionBefore(SLV_69) ? 2 : 4;
}
 
void SlSetArrayIndex(uint index)
{
  _sl.need_length = NL_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.block_mode) {
      case CH_SPARSE_TABLE:
      case CH_SPARSE_ARRAY: index = (int)SlReadSparseIndex(); break;
      case CH_TABLE:
      case CH_ARRAY:        index = _sl.array_index++; break;
      default:
        Debug(sl, 0, "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 == SLA_SAVE);
 
  switch (_sl.need_length) {
    case NL_WANTLENGTH:
      _sl.need_length = NL_NONE;
      if ((_sl.block_mode == CH_TABLE || _sl.block_mode == CH_SPARSE_TABLE) && _sl.expect_table_header) {
        _sl.expect_table_header = false;
        SlWriteArrayLength(length + 1);
        break;
      }
 
      switch (_sl.block_mode) {
        case CH_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 CH_TABLE:
        case CH_ARRAY:
          assert(_sl.last_array_index <= _sl.array_index);
          while (++_sl.last_array_index <= _sl.array_index) {
            SlWriteArrayLength(1);
          }
          SlWriteArrayLength(length + 1);
          break;
        case CH_SPARSE_TABLE:
        case CH_SPARSE_ARRAY:
          SlWriteArrayLength(length + 1 + SlGetArrayLength(_sl.array_index)); // Also include length of sparse index.
          SlWriteSparseIndex(_sl.array_index);
          break;
        default: NOT_REACHED();
      }
      break;
 
    case NL_CALCLENGTH:
      _sl.obj_len += (int)length;
      break;
 
    default: NOT_REACHED();
  }
}
 
static void SlCopyBytes(void *ptr, size_t length)
{
  uint8_t *p = (uint8_t *)ptr;
 
  switch (_sl.action) {
    case SLA_LOAD_CHECK:
    case SLA_LOAD:
      for (; length != 0; length--) *p++ = SlReadByte();
      break;
    case SLA_SAVE:
      for (; length != 0; length--) SlWriteByte(*p++);
      break;
    default: NOT_REACHED();
  }
}
 
size_t SlGetFieldLength()
{
  return _sl.obj_len;
}
 
int64_t ReadValue(const void *ptr, VarType conv)
{
  switch (GetVarMemType(conv)) {
    case SLE_VAR_BL:  return (*(const bool *)ptr != 0);
    case SLE_VAR_I8:  return *(const int8_t  *)ptr;
    case SLE_VAR_U8:  return *(const uint8_t  *)ptr;
    case SLE_VAR_I16: return *(const int16_t *)ptr;
    case SLE_VAR_U16: return *(const uint16_t*)ptr;
    case SLE_VAR_I32: return *(const int32_t *)ptr;
    case SLE_VAR_U32: return *(const uint32_t*)ptr;
    case SLE_VAR_I64: return *(const int64_t *)ptr;
    case SLE_VAR_U64: return *(const uint64_t*)ptr;
    case SLE_VAR_NULL:return 0;
    default: NOT_REACHED();
  }
}
 
void WriteValue(void *ptr, VarType conv, int64_t val)
{
  switch (GetVarMemType(conv)) {
    case SLE_VAR_BL:  *(bool  *)ptr = (val != 0);  break;
    case SLE_VAR_I8:  *(int8_t  *)ptr = val; break;
    case SLE_VAR_U8:  *(uint8_t  *)ptr = val; break;
    case SLE_VAR_I16: *(int16_t *)ptr = val; break;
    case SLE_VAR_U16: *(uint16_t*)ptr = val; break;
    case SLE_VAR_I32: *(int32_t *)ptr = val; break;
    case SLE_VAR_U32: *(uint32_t*)ptr = val; break;
    case SLE_VAR_I64: *(int64_t *)ptr = val; break;
    case SLE_VAR_U64: *(uint64_t*)ptr = val; break;
    case SLE_VAR_NAME: *reinterpret_cast<std::string *>(ptr) = CopyFromOldName(val); break;
    case SLE_VAR_NULL: break;
    default: NOT_REACHED();
  }
}
 
static void SlSaveLoadConv(void *ptr, VarType conv)
{
  switch (_sl.action) {
    case SLA_SAVE: {
      int64_t x = ReadValue(ptr, conv);
 
      /* Write the value to the file and check if its value is in the desired range */
      switch (GetVarFileType(conv)) {
        case SLE_FILE_I8: assert(x >= -128 && x <= 127);     SlWriteByte(x);break;
        case SLE_FILE_U8: assert(x >= 0 && x <= 255);        SlWriteByte(x);break;
        case SLE_FILE_I16:assert(x >= -32768 && x <= 32767); SlWriteUint16(x);break;
        case SLE_FILE_STRINGID:
        case SLE_FILE_U16:assert(x >= 0 && x <= 65535);      SlWriteUint16(x);break;
        case SLE_FILE_I32:
        case SLE_FILE_U32:                                   SlWriteUint32((uint32_t)x);break;
        case SLE_FILE_I64:
        case SLE_FILE_U64:                                   SlWriteUint64(x);break;
        default: NOT_REACHED();
      }
      break;
    }
    case SLA_LOAD_CHECK:
    case SLA_LOAD: {
      int64_t x;
      /* Read a value from the file */
      switch (GetVarFileType(conv)) {
        case SLE_FILE_I8:  x = (int8_t  )SlReadByte();   break;
        case SLE_FILE_U8:  x = (uint8_t  )SlReadByte();   break;
        case SLE_FILE_I16: x = (int16_t )SlReadUint16(); break;
        case SLE_FILE_U16: x = (uint16_t)SlReadUint16(); break;
        case SLE_FILE_I32: x = (int32_t )SlReadUint32(); break;
        case SLE_FILE_U32: x = (uint32_t)SlReadUint32(); break;
        case SLE_FILE_I64: x = (int64_t )SlReadUint64(); break;
        case SLE_FILE_U64: x = (uint64_t)SlReadUint64(); break;
        case SLE_FILE_STRINGID: x = RemapOldStringID((uint16_t)SlReadUint16()); break;
        default: NOT_REACHED();
      }
 
      /* Write The value to the struct. These ARE endian safe. */
      WriteValue(ptr, conv, x);
      break;
    }
    case SLA_PTRS: break;
    case SLA_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.
 
  for (auto it = std::begin(str); it != std::end(str); /* nothing */) {
    size_t len = Utf8EncodedCharLen(*it);
    if (len == 0 || it + len > std::end(str)) break;
 
    char32_t c;
    Utf8Decode(&c, &*it);
    it += len;
    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 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 SLA_SAVE: {
      size_t len = str->length();
      SlWriteArrayLength(len);
      SlCopyBytes(const_cast<void *>(static_cast<const void *>(str->c_str())), len);
      break;
    }
 
    case SLA_LOAD_CHECK:
    case SLA_LOAD: {
      size_t len = SlReadArrayLength();
      if (GetVarMemType(conv) == SLE_VAR_NULL) {
        SlSkipBytes(len);
        return;
      }
 
      SlReadString(*str, len);
 
      StringValidationSettings settings = StringValidationSetting::ReplaceWithQuestionMark;
      if ((conv & SLF_ALLOW_CONTROL) != 0) {
        settings.Set(StringValidationSetting::AllowControlCode);
        if (IsSavegameVersionBefore(SLV_ENCODED_STRING_FORMAT)) FixSCCEncoded(*str, IsSavegameVersionBefore(SLV_169));
      }
      if ((conv & SLF_ALLOW_NEWLINE) != 0) {
        settings.Set(StringValidationSetting::AllowNewline);
      }
      StrMakeValidInPlace(*str, settings);
    }
 
    case SLA_PTRS: break;
    case SLA_NULL: break;
    default: NOT_REACHED();
  }
}
 
static void SlCopyInternal(void *object, size_t length, VarType conv)
{
  if (GetVarMemType(conv) == SLE_VAR_NULL) {
    assert(_sl.action != SLA_SAVE); // Use SL_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 != SLA_SAVE && _sl_version == 0) {
    /* all objects except difficulty settings */
    if (conv == SLE_INT16 || conv == SLE_UINT16 || conv == SLE_STRINGID ||
        conv == SLE_INT32 || conv == SLE_UINT32) {
      SlCopyBytes(object, length * SlCalcConvFileLen(conv));
      return;
    }
    /* used for conversion of Money 32bit->64bit */
    if (conv == (SLE_FILE_I32 | SLE_VAR_I64)) {
      for (uint i = 0; i < length; i++) {
        ((int64_t*)object)[i] = (int32_t)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 == SLE_INT8 || conv == SLE_UINT8) {
    SlCopyBytes(object, length);
  } else {
    uint8_t *a = (uint8_t*)object;
    uint8_t mem_size = SlCalcConvMemLen(conv);
 
    for (; length != 0; length --) {
      SlSaveLoadConv(a, conv);
      a += mem_size; // get size
    }
  }
}
 
void SlCopy(void *object, size_t length, VarType conv)
{
  if (_sl.action == SLA_PTRS || _sl.action == SLA_NULL) return;
 
  /* Automatically calculate the length? */
  if (_sl.need_length != NL_NONE) {
    SlSetLength(length * SlCalcConvFileLen(conv));
    /* Determine length only? */
    if (_sl.need_length == NL_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 SLA_SAVE:
      SlWriteArrayLength(length);
      SlCopyInternal(array, length, conv);
      return;
 
    case SLA_LOAD_CHECK:
    case SLA_LOAD: {
      if (!IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH)) {
        size_t sv_length = SlReadArrayLength();
        if (GetVarMemType(conv) == SLE_VAR_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 SLA_PTRS:
    case SLA_NULL:
      return;
 
    default:
      NOT_REACHED();
  }
}
 
static size_t ReferenceToInt(const void *obj, SLRefType rt)
{
  assert(_sl.action == SLA_SAVE);
 
  if (obj == nullptr) return 0;
 
  switch (rt) {
    case REF_VEHICLE_OLD: // Old vehicles we save as new ones
    case REF_VEHICLE:   return ((const  Vehicle*)obj)->index + 1;
    case REF_STATION:   return ((const  Station*)obj)->index + 1;
    case REF_TOWN:      return ((const     Town*)obj)->index + 1;
    case REF_ORDER:     return ((const    Order*)obj)->index + 1;
    case REF_ROADSTOPS: return ((const RoadStop*)obj)->index + 1;
    case REF_ENGINE_RENEWS:  return ((const       EngineRenew*)obj)->index + 1;
    case REF_CARGO_PACKET:   return ((const       CargoPacket*)obj)->index + 1;
    case REF_ORDERLIST:      return ((const         OrderList*)obj)->index + 1;
    case REF_STORAGE:        return ((const PersistentStorage*)obj)->index + 1;
    case REF_LINK_GRAPH:     return ((const         LinkGraph*)obj)->index + 1;
    case REF_LINK_GRAPH_JOB: return ((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 == SLA_PTRS);
 
  /* After version 4.3 REF_VEHICLE_OLD is saved as REF_VEHICLE,
   * and should be loaded like that */
  if (rt == REF_VEHICLE_OLD && !IsSavegameVersionBefore(SLV_4, 4)) {
    rt = REF_VEHICLE;
  }
 
  /* No need to look up nullptr pointers, just return immediately */
  if (index == (rt == REF_VEHICLE_OLD ? 0xFFFF : 0)) return nullptr;
 
  /* Correct index. Old vehicles were saved differently:
   * invalid vehicle was 0xFFFF, now we use 0x0000 for everything invalid. */
  if (rt != REF_VEHICLE_OLD) index--;
 
  switch (rt) {
    case REF_ORDERLIST:
      if (OrderList::IsValidID(index)) return OrderList::Get(index);
      SlErrorCorrupt("Referencing invalid OrderList");
 
    case REF_ORDER:
      if (Order::IsValidID(index)) return Order::Get(index);
      /* in old versions, invalid order was used to mark end of order list */
      if (IsSavegameVersionBefore(SLV_5, 2)) return nullptr;
      SlErrorCorrupt("Referencing invalid Order");
 
    case REF_VEHICLE_OLD:
    case REF_VEHICLE:
      if (Vehicle::IsValidID(index)) return Vehicle::Get(index);
      SlErrorCorrupt("Referencing invalid Vehicle");
 
    case REF_STATION:
      if (Station::IsValidID(index)) return Station::Get(index);
      SlErrorCorrupt("Referencing invalid Station");
 
    case REF_TOWN:
      if (Town::IsValidID(index)) return Town::Get(index);
      SlErrorCorrupt("Referencing invalid Town");
 
    case REF_ROADSTOPS:
      if (RoadStop::IsValidID(index)) return RoadStop::Get(index);
      SlErrorCorrupt("Referencing invalid RoadStop");
 
    case REF_ENGINE_RENEWS:
      if (EngineRenew::IsValidID(index)) return EngineRenew::Get(index);
      SlErrorCorrupt("Referencing invalid EngineRenew");
 
    case REF_CARGO_PACKET:
      if (CargoPacket::IsValidID(index)) return CargoPacket::Get(index);
      SlErrorCorrupt("Referencing invalid CargoPacket");
 
    case REF_STORAGE:
      if (PersistentStorage::IsValidID(index)) return PersistentStorage::Get(index);
      SlErrorCorrupt("Referencing invalid PersistentStorage");
 
    case REF_LINK_GRAPH:
      if (LinkGraph::IsValidID(index)) return LinkGraph::Get(index);
      SlErrorCorrupt("Referencing invalid LinkGraph");
 
    case REF_LINK_GRAPH_JOB:
      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 SLA_SAVE:
      SlWriteUint32((uint32_t)ReferenceToInt(*(void **)ptr, (SLRefType)conv));
      break;
    case SLA_LOAD_CHECK:
    case SLA_LOAD:
      *(size_t *)ptr = IsSavegameVersionBefore(SLV_69) ? SlReadUint16() : SlReadUint32();
      break;
    case SLA_PTRS:
      *(void **)ptr = IntToReference(*(size_t *)ptr, (SLRefType)conv);
      break;
    case SLA_NULL:
      *(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 = SL_VAR)
  {
    assert(cmd == SL_VAR || cmd == SL_REF);
 
    const SlStorageT *list = static_cast<const SlStorageT *>(storage);
 
    int type_size = SlGetArrayLength(list->size());
    int item_size = SlCalcConvFileLen(cmd == SL_VAR ? conv : (VarType)SLE_FILE_U32);
    return list->size() * item_size + type_size;
  }
 
  static void SlSaveLoadMember(SaveLoadType cmd, Tvar *item, VarType conv)
  {
    switch (cmd) {
      case SL_VAR: SlSaveLoadConv(item, conv); break;
      case SL_REF: SlSaveLoadRef(item, conv); break;
      case SL_STDSTR: SlStdString(item, conv); break;
      default:
        NOT_REACHED();
    }
  }
 
  static void SlSaveLoad(void *storage, VarType conv, SaveLoadType cmd = SL_VAR)
  {
    assert(cmd == SL_VAR || cmd == SL_REF || cmd == SL_STDSTR);
 
    SlStorageT *list = static_cast<SlStorageT *>(storage);
 
    switch (_sl.action) {
      case SLA_SAVE:
        SlWriteArrayLength(list->size());
 
        for (auto &item : *list) {
          SlSaveLoadMember(cmd, &item, conv);
        }
        break;
 
      case SLA_LOAD_CHECK:
      case SLA_LOAD: {
        size_t length;
        switch (cmd) {
          case SL_VAR: length = IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH) ? SlReadUint32() : SlReadArrayLength(); break;
          case SL_REF: length = IsSavegameVersionBefore(SLV_69) ? SlReadUint16() : IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH) ? SlReadUint32() : SlReadArrayLength(); break;
          case SL_STDSTR: 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 SLA_PTRS:
        for (auto &item : *list) {
          SlSaveLoadMember(cmd, &item, conv);
        }
        break;
 
      case SLA_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, SL_REF);
}
 
static void SlRefList(void *list, VarType conv)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NL_NONE) {
    SlSetLength(SlCalcRefListLen(list, conv));
    /* Determine length only? */
    if (_sl.need_length == NL_CALCLENGTH) return;
  }
 
  SlStorageHelper<std::list, void *>::SlSaveLoad(list, conv, SL_REF);
}
 
static size_t SlCalcRefVectorLen(const void *vector, VarType conv)
{
  return SlStorageHelper<std::vector, void *>::SlCalcLen(vector, conv, SL_REF);
}
 
static void SlRefVector(void *vector, VarType conv)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NL_NONE) {
    SlSetLength(SlCalcRefVectorLen(vector, conv));
    /* Determine length only? */
    if (_sl.need_length == NL_CALCLENGTH) return;
  }
 
  SlStorageHelper<std::vector, void *>::SlSaveLoad(vector, conv, SL_REF);
}
 
static inline size_t SlCalcDequeLen(const void *deque, VarType conv)
{
  switch (GetVarMemType(conv)) {
    case SLE_VAR_BL: return SlStorageHelper<std::deque, bool>::SlCalcLen(deque, conv);
    case SLE_VAR_I8: return SlStorageHelper<std::deque, int8_t>::SlCalcLen(deque, conv);
    case SLE_VAR_U8: return SlStorageHelper<std::deque, uint8_t>::SlCalcLen(deque, conv);
    case SLE_VAR_I16: return SlStorageHelper<std::deque, int16_t>::SlCalcLen(deque, conv);
    case SLE_VAR_U16: return SlStorageHelper<std::deque, uint16_t>::SlCalcLen(deque, conv);
    case SLE_VAR_I32: return SlStorageHelper<std::deque, int32_t>::SlCalcLen(deque, conv);
    case SLE_VAR_U32: return SlStorageHelper<std::deque, uint32_t>::SlCalcLen(deque, conv);
    case SLE_VAR_I64: return SlStorageHelper<std::deque, int64_t>::SlCalcLen(deque, conv);
    case SLE_VAR_U64: return SlStorageHelper<std::deque, uint64_t>::SlCalcLen(deque, conv);
 
    case SLE_VAR_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 SlDeque(void *deque, VarType conv)
{
  switch (GetVarMemType(conv)) {
    case SLE_VAR_BL: SlStorageHelper<std::deque, bool>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_I8: SlStorageHelper<std::deque, int8_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_U8: SlStorageHelper<std::deque, uint8_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_I16: SlStorageHelper<std::deque, int16_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_U16: SlStorageHelper<std::deque, uint16_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_I32: SlStorageHelper<std::deque, int32_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_U32: SlStorageHelper<std::deque, uint32_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_I64: SlStorageHelper<std::deque, int64_t>::SlSaveLoad(deque, conv); break;
    case SLE_VAR_U64: SlStorageHelper<std::deque, uint64_t>::SlSaveLoad(deque, conv); break;
 
    case SLE_VAR_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 SLV_COMPANY_ALLOW_LIST up to SLV_COMPANY_ALLOW_LIST_V2. */
      assert(_sl.action != SLA_SAVE);
      SlStorageHelper<std::deque, std::string>::SlSaveLoad(deque, conv, SL_STDSTR);
      break;
 
    default: NOT_REACHED();
  }
}
 
static inline size_t SlCalcVectorLen(const void *vector, VarType conv)
{
  switch (GetVarMemType(conv)) {
    case SLE_VAR_BL: NOT_REACHED(); // Not supported
    case SLE_VAR_I8: return SlStorageHelper<std::vector, int8_t>::SlCalcLen(vector, conv);
    case SLE_VAR_U8: return SlStorageHelper<std::vector, uint8_t>::SlCalcLen(vector, conv);
    case SLE_VAR_I16: return SlStorageHelper<std::vector, int16_t>::SlCalcLen(vector, conv);
    case SLE_VAR_U16: return SlStorageHelper<std::vector, uint16_t>::SlCalcLen(vector, conv);
    case SLE_VAR_I32: return SlStorageHelper<std::vector, int32_t>::SlCalcLen(vector, conv);
    case SLE_VAR_U32: return SlStorageHelper<std::vector, uint32_t>::SlCalcLen(vector, conv);
    case SLE_VAR_I64: return SlStorageHelper<std::vector, int64_t>::SlCalcLen(vector, conv);
    case SLE_VAR_U64: return SlStorageHelper<std::vector, uint64_t>::SlCalcLen(vector, conv);
 
    case SLE_VAR_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 (GetVarMemType(conv)) {
    case SLE_VAR_BL: NOT_REACHED(); // Not supported
    case SLE_VAR_I8: SlStorageHelper<std::vector, int8_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_U8: SlStorageHelper<std::vector, uint8_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_I16: SlStorageHelper<std::vector, int16_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_U16: SlStorageHelper<std::vector, uint16_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_I32: SlStorageHelper<std::vector, int32_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_U32: SlStorageHelper<std::vector, uint32_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_I64: SlStorageHelper<std::vector, int64_t>::SlSaveLoad(vector, conv); break;
    case SLE_VAR_U64: SlStorageHelper<std::vector, uint64_t>::SlSaveLoad(vector, conv); break;
 
    case SLE_VAR_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 SLV_COMPANY_ALLOW_LIST up to SLV_COMPANY_ALLOW_LIST_V2. */
      assert(_sl.action != SLA_SAVE);
      SlStorageHelper<std::vector, std::string>::SlSaveLoad(vector, conv, SL_STDSTR);
      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(SLE_UINT8);
    length += SlCalcStdStringLen(&sld.name);
  }
 
  length += SlCalcConvFileLen(SLE_UINT8); // End-of-list entry.
 
  for (auto &sld : slt) {
    if (!SlIsObjectValidInSavegame(sld)) continue;
    if (sld.cmd == SL_STRUCTLIST || sld.cmd == SL_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 == SLA_SAVE);
 
  if (!SlIsObjectValidInSavegame(sld)) return 0;
 
  switch (sld.cmd) {
    case SL_VAR: return SlCalcConvFileLen(sld.conv);
    case SL_REF: return SlCalcRefLen();
    case SL_ARR: return SlCalcArrayLen(sld.length, sld.conv);
    case SL_REFLIST: return SlCalcRefListLen(GetVariableAddress(object, sld), sld.conv);
    case SL_REFVECTOR: return SlCalcRefVectorLen(GetVariableAddress(object, sld), sld.conv);
    case SL_DEQUE: return SlCalcDequeLen(GetVariableAddress(object, sld), sld.conv);
    case SL_VECTOR: return SlCalcVectorLen(GetVariableAddress(object, sld), sld.conv);
    case SL_STDSTR: return SlCalcStdStringLen(GetVariableAddress(object, sld));
    case SL_SAVEBYTE: return 1; // a byte is logically of size 1
    case SL_NULL: return SlCalcConvFileLen(sld.conv) * sld.length;
 
    case SL_STRUCT:
    case SL_STRUCTLIST: {
      NeedLength old_need_length = _sl.need_length;
      size_t old_obj_len = _sl.obj_len;
 
      _sl.need_length = NL_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 == SL_STRUCT) {
        length += SlGetArrayLength(1);
      }
 
      return length;
    }
 
    default: NOT_REACHED();
  }
  return 0;
}
 
static bool SlObjectMember(void *object, const SaveLoad &sld)
{
  if (!SlIsObjectValidInSavegame(sld)) return false;
 
  VarType conv = GB(sld.conv, 0, 8);
  switch (sld.cmd) {
    case SL_VAR:
    case SL_REF:
    case SL_ARR:
    case SL_REFLIST:
    case SL_REFVECTOR:
    case SL_DEQUE:
    case SL_VECTOR:
    case SL_STDSTR: {
      void *ptr = GetVariableAddress(object, sld);
 
      switch (sld.cmd) {
        case SL_VAR: SlSaveLoadConv(ptr, conv); break;
        case SL_REF: SlSaveLoadRef(ptr, conv); break;
        case SL_ARR: SlArray(ptr, sld.length, conv); break;
        case SL_REFLIST: SlRefList(ptr, conv); break;
        case SL_REFVECTOR: SlRefVector(ptr, conv); break;
        case SL_DEQUE: SlDeque(ptr, conv); break;
        case SL_VECTOR: SlVector(ptr, conv); break;
        case SL_STDSTR: SlStdString(ptr, sld.conv); break;
        default: NOT_REACHED();
      }
      break;
    }
 
    /* SL_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 SL_SAVEBYTE: {
      void *ptr = GetVariableAddress(object, sld);
 
      switch (_sl.action) {
        case SLA_SAVE: SlWriteByte(*(uint8_t *)ptr); break;
        case SLA_LOAD_CHECK:
        case SLA_LOAD:
        case SLA_PTRS:
        case SLA_NULL: break;
        default: NOT_REACHED();
      }
      break;
    }
 
    case SL_NULL: {
      assert(GetVarMemType(sld.conv) == SLE_VAR_NULL);
 
      switch (_sl.action) {
        case SLA_LOAD_CHECK:
        case SLA_LOAD: SlSkipBytes(SlCalcConvFileLen(sld.conv) * sld.length); break;
        case SLA_SAVE: for (int i = 0; i < SlCalcConvFileLen(sld.conv) * sld.length; i++) SlWriteByte(0); break;
        case SLA_PTRS:
        case SLA_NULL: break;
        default: NOT_REACHED();
      }
      break;
    }
 
    case SL_STRUCT:
    case SL_STRUCTLIST:
      switch (_sl.action) {
        case SLA_SAVE: {
          if (sld.cmd == SL_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 SLA_LOAD_CHECK: {
          if (sld.cmd == SL_STRUCT && !IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH)) {
            SlGetStructListLength(1);
          }
          sld.handler->LoadCheck(object);
          break;
        }
 
        case SLA_LOAD: {
          if (sld.cmd == SL_STRUCT && !IsSavegameVersionBefore(SLV_SAVELOAD_LIST_LENGTH)) {
            SlGetStructListLength(1);
          }
          sld.handler->Load(object);
          break;
        }
 
        case SLA_PTRS:
          sld.handler->FixPointers(object);
          break;
 
        case SLA_NULL: break;
        default: NOT_REACHED();
      }
      break;
 
    default: NOT_REACHED();
  }
  return true;
}
 
void SlSetStructListLength(size_t length)
{
  /* Automatically calculate the length? */
  if (_sl.need_length != NL_NONE) {
    SlSetLength(SlGetArrayLength(length));
    if (_sl.need_length == NL_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 != NL_NONE) {
    SlSetLength(SlCalcObjLength(object, slt));
    if (_sl.need_length == NL_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);
  }
 
  virtual SaveLoadTable GetDescription() const override
  {
    return {};
  }
 
  virtual SaveLoadCompatTable GetCompatDescription() const override
  {
    NOT_REACHED();
  }
};
 
std::vector<SaveLoad> SlTableHeader(const SaveLoadTable &slt)
{
  /* You can only use SlTableHeader if you are a CH_TABLE. */
  assert(_sl.block_mode == CH_TABLE || _sl.block_mode == CH_SPARSE_TABLE);
 
  switch (_sl.action) {
    case SLA_LOAD_CHECK:
    case SLA_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) {
        uint8_t type = 0;
        SlSaveLoadConv(&type, SLE_UINT8);
        if (type == SLE_FILE_END) break;
 
        std::string key;
        SlStdString(&key, SLE_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(sl, _sl.action == SLA_LOAD ? 2 : 6, "Field '{}' of type 0x{:02x} not found, skipping", key, type);
 
          std::shared_ptr<SaveLoadHandler> handler = nullptr;
          SaveLoadType saveload_type;
          switch (type & SLE_FILE_TYPE_MASK) {
            case SLE_FILE_STRING:
              /* Strings are always marked with SLE_FILE_HAS_LENGTH_FIELD, as they are a list of chars. */
              saveload_type = SL_STDSTR;
              break;
 
            case SLE_FILE_STRUCT:
              /* Structs are always marked with SLE_FILE_HAS_LENGTH_FIELD as SL_STRUCT is seen as a list of 0/1 in length. */
              saveload_type = SL_STRUCTLIST;
              handler = std::make_shared<SlSkipHandler>();
              break;
 
            default:
              saveload_type = (type & SLE_FILE_HAS_LENGTH_FIELD) ? SL_ARR : SL_VAR;
              break;
          }
 
          /* We don't know this field, so read to nothing. */
          saveloads.emplace_back(std::move(key), saveload_type, ((VarType)type & SLE_FILE_TYPE_MASK) | SLE_VAR_NULL, 1, SL_MIN_VERSION, SL_MAX_VERSION, 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. */
        uint8_t correct_type = GetSavegameFileType(*sld_it->second);
        if (correct_type != type) {
          Debug(sl, 1, "Field type for '{}' was expected to be 0x{:02x} but 0x{:02x} was found", key, correct_type, type);
          SlErrorCorrupt("Field type is different than expected");
        }
        saveloads.emplace_back(*sld_it->second);
      }
 
      for (auto &sld : saveloads) {
        if (sld.cmd == SL_STRUCTLIST || sld.cmd == SL_STRUCT) {
          sld.handler->load_description = SlTableHeader(sld.handler->GetDescription());
        }
      }
 
      return saveloads;
    }
 
    case SLA_SAVE: {
      /* Automatically calculate the length? */
      if (_sl.need_length != NL_NONE) {
        SlSetLength(SlCalcTableHeader(slt));
        if (_sl.need_length == NL_CALCLENGTH) break;
      }
 
      for (auto &sld : slt) {
        if (!SlIsObjectValidInSavegame(sld)) continue;
        /* Make sure we are not storing empty keys. */
        assert(!sld.name.empty());
 
        uint8_t type = GetSavegameFileType(sld);
        assert(type != SLE_FILE_END);
 
        SlSaveLoadConv(&type, SLE_UINT8);
        SlStdString(const_cast<std::string *>(&sld.name), SLE_STR);
      }
 
      /* Add an end-of-header marker. */
      uint8_t type = SLE_FILE_END;
      SlSaveLoadConv(&type, SLE_UINT8);
 
      /* After the table, write down any sub-tables we might have. */
      for (auto &sld : slt) {
        if (!SlIsObjectValidInSavegame(sld)) continue;
        if (sld.cmd == SL_STRUCTLIST || sld.cmd == SL_STRUCT) {
          /* SlCalcTableHeader already looks in sub-lists, so avoid the length being added twice. */
          NeedLength old_need_length = _sl.need_length;
          _sl.need_length = NL_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 == SLA_LOAD || _sl.action == SLA_LOAD_CHECK);
  /* CH_TABLE / CH_SPARSE_TABLE always have a header. */
  if (_sl.block_mode == CH_TABLE || _sl.block_mode == CH_SPARSE_TABLE) return SlTableHeader(slt);
 
  std::vector<SaveLoad> saveloads;
 
  /* Build a key lookup mapping based on the available fields. */
  std::map<std::string, 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("", SL_NULL, GetVarFileType(slc.null_type) | SLE_VAR_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(sl, 0, "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 == SL_STRUCTLIST || sld.cmd == SL_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 == SLA_SAVE);
 
  /* Tell it to calculate the length */
  _sl.need_length = NL_CALCLENGTH;
  _sl.obj_len = 0;
  proc(arg);
 
  /* Setup length */
  _sl.need_length = NL_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.block_mode) {
    case CH_TABLE:
    case CH_SPARSE_TABLE:
      SlTableHeader({});
      [[fallthrough]];
    case CH_ARRAY:
    case CH_SPARSE_ARRAY:
      SlSkipArray();
      break;
    case CH_RIFF:
      SlSkipBytes(len);
      break;
    default:
      NOT_REACHED();
  }
}
 
static void SlLoadChunk(const ChunkHandler &ch)
{
  uint8_t m = SlReadByte();
 
  _sl.block_mode = m & CH_TYPE_MASK;
  _sl.obj_len = 0;
  _sl.expect_table_header = (_sl.block_mode == CH_TABLE || _sl.block_mode == CH_SPARSE_TABLE);
 
  /* 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.block_mode) {
    case CH_TABLE:
    case CH_ARRAY:
      _sl.array_index = 0;
      ch.Load();
      if (_next_offs != 0) SlErrorCorrupt("Invalid array length");
      break;
    case CH_SPARSE_TABLE:
    case CH_SPARSE_ARRAY:
      ch.Load();
      if (_next_offs != 0) SlErrorCorrupt("Invalid array length");
      break;
    case CH_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.block_mode = m & CH_TYPE_MASK;
  _sl.obj_len = 0;
  _sl.expect_table_header = (_sl.block_mode == CH_TABLE || _sl.block_mode == CH_SPARSE_TABLE);
 
  /* 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.block_mode) {
    case CH_TABLE:
    case CH_ARRAY:
      _sl.array_index = 0;
      ch.LoadCheck();
      break;
    case CH_SPARSE_TABLE:
    case CH_SPARSE_ARRAY:
      ch.LoadCheck();
      break;
    case CH_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 == CH_READONLY) return;
 
  SlWriteUint32(ch.id);
  Debug(sl, 2, "Saving chunk {}", ch.GetName());
 
  _sl.block_mode = ch.type;
  _sl.expect_table_header = (_sl.block_mode == CH_TABLE || _sl.block_mode == CH_SPARSE_TABLE);
 
  _sl.need_length = (_sl.expect_table_header || _sl.block_mode == CH_RIFF) ? NL_WANTLENGTH : NL_NONE;
 
  switch (_sl.block_mode) {
    case CH_RIFF:
      ch.Save();
      break;
    case CH_TABLE:
    case CH_ARRAY:
      _sl.last_array_index = 0;
      SlWriteByte(_sl.block_mode);
      ch.Save();
      SlWriteArrayLength(0); // Terminate arrays
      break;
    case CH_SPARSE_TABLE:
    case CH_SPARSE_ARRAY:
      SlWriteByte(_sl.block_mode);
      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(uint32_t id)
{
  for (const ChunkHandler &ch : ChunkHandlers()) if (ch.id == id) return &ch;
  return nullptr;
}
 
static void SlLoadChunks()
{
  uint32_t id;
  const ChunkHandler *ch;
 
  for (id = SlReadUint32(); id != 0; id = SlReadUint32()) {
    Debug(sl, 2, "Loading chunk {:c}{:c}{:c}{:c}", id >> 24, id >> 16, id >> 8, id);
 
    ch = SlFindChunkHandler(id);
    if (ch == nullptr) SlErrorCorrupt("Unknown chunk type");
    SlLoadChunk(*ch);
  }
}
 
static void SlLoadCheckChunks()
{
  uint32_t id;
  const ChunkHandler *ch;
 
  for (id = SlReadUint32(); id != 0; id = SlReadUint32()) {
    Debug(sl, 2, "Loading chunk {:c}{:c}{:c}{:c}", id >> 24, id >> 16, id >> 8, id);
 
    ch = SlFindChunkHandler(id);
    if (ch == nullptr) SlErrorCorrupt("Unknown chunk type");
    SlLoadCheckChunk(*ch);
  }
}
 
static void SlFixPointers()
{
  _sl.action = SLA_PTRS;
 
  for (const ChunkHandler &ch : ChunkHandlers()) {
    Debug(sl, 3, "Fixing pointers for {}", ch.GetName());
    ch.FixPointers();
  }
 
  assert(_sl.action == SLA_PTRS);
}
 
 
struct FileReader : LoadFilter {
  std::optional<FileHandle> file; 
  long begin; 
 
  FileReader(FileHandle &&file) : LoadFilter(nullptr), file(std::move(file)), begin(ftell(*this->file))
  {
  }
 
  ~FileReader()
  {
    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(sl, 1, "Could not reset the file reading");
    }
  }
};
 
struct FileWriter : SaveFilter {
  std::optional<FileHandle> file; 
 
  FileWriter(FileHandle &&file) : SaveFilter(nullptr), file(std::move(file))
  {
  }
 
  ~FileWriter()
  {
    this->Finish();
  }
 
  void Write(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
#include <lzo/lzo1x.h>
 
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 != SL_MIN_VERSION) {
      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(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 : (lzo_uint)size;
      lzo1x_1_compress(in, len, out + sizeof(uint32_t) * 2, &outlen, wrkmem);
      ((uint32_t*)out)[1] = TO_BE32((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(uint8_t *buf, size_t size) override
  {
    this->chain->Write(buf, size);
  }
};
 
/********************************************
 ********** START OF ZLIB CODE **************
 ********************************************/
 
#if defined(WITH_ZLIB)
#include <zlib.h>
 
struct ZlibLoadFilter : LoadFilter {
  z_stream z;                        
  uint8_t fread_buf[MEMORY_CHUNK_SIZE]; 
 
  ZlibLoadFilter(std::shared_ptr<LoadFilter> chain) : LoadFilter(std::move(chain))
  {
    memset(&this->z, 0, sizeof(this->z));
    if (inflateInit(&this->z) != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize decompressor");
  }
 
  ~ZlibLoadFilter()
  {
    inflateEnd(&this->z);
  }
 
  size_t Read(uint8_t *buf, size_t size) override
  {
    this->z.next_out  = buf;
    this->z.avail_out = (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 = (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))
  {
    memset(&this->z, 0, sizeof(this->z));
    if (deflateInit(&this->z, compression_level) != Z_OK) SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_INTERNAL_ERROR, "cannot initialize compressor");
  }
 
  ~ZlibSaveFilter()
  {
    deflateEnd(&this->z);
  }
 
  void WriteLoop(uint8_t *p, size_t len, int mode)
  {
    uint n;
    this->z.next_in = p;
    this->z.avail_in = (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(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)
#include <lzma.h>
 
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()
  {
    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()
  {
    lzma_end(&this->lzma);
  }
 
  void WriteLoop(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(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 *****************
 *******************************************/
 
struct SaveLoadFormat {
  const char *name;                     
  uint32_t tag;                           
 
  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); 
 
  uint8_t min_compression;                 
  uint8_t default_compression;             
  uint8_t max_compression;                 
};
 
static const uint32_t SAVEGAME_TAG_LZO = TO_BE32('OTTD');
static const uint32_t SAVEGAME_TAG_NONE = TO_BE32('OTTN');
static const uint32_t SAVEGAME_TAG_ZLIB = TO_BE32('OTTZ');
static const uint32_t SAVEGAME_TAG_LZMA = TO_BE32('OTTX');
 
static const SaveLoadFormat _saveload_formats[] = {
#if defined(WITH_LZO)
  /* Roughly 75% larger than zlib level 6 at only ~7% of the CPU usage. */
  {"lzo",  SAVEGAME_TAG_LZO,  CreateLoadFilter<LZOLoadFilter>,    CreateSaveFilter<LZOSaveFilter>,    0, 0, 0},
#else
  {"lzo",  SAVEGAME_TAG_LZO,  nullptr,                            nullptr,                            0, 0, 0},
#endif
  /* Roughly 5 times larger at only 1% of the CPU usage over zlib level 6. */
  {"none", SAVEGAME_TAG_NONE, CreateLoadFilter<NoCompLoadFilter>, CreateSaveFilter<NoCompSaveFilter>, 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". */
  {"zlib", SAVEGAME_TAG_ZLIB, CreateLoadFilter<ZlibLoadFilter>,   CreateSaveFilter<ZlibSaveFilter>,   0, 6, 9},
#else
  {"zlib", SAVEGAME_TAG_ZLIB, nullptr,                            nullptr,                            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. */
  {"lzma", SAVEGAME_TAG_LZMA, CreateLoadFilter<LZMALoadFilter>,   CreateSaveFilter<LZMASaveFilter>,   0, 2, 9},
#else
  {"lzma", SAVEGAME_TAG_LZMA, nullptr,                            nullptr,                            0, 0, 0},
#endif
};
 
static std::pair<const SaveLoadFormat &, uint8_t> GetSavegameFormat(const std::string &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;
    const std::string name(full_name, 0, has_comp_level ? separator : full_name.size());
 
    for (const auto &slf : _saveload_formats) {
      if (slf.init_write != nullptr && name.compare(slf.name) == 0) {
        if (has_comp_level) {
          const std::string complevel(full_name, separator + 1);
 
          /* Get the level and determine whether all went fine. */
          size_t processed;
          long level = std::stol(complevel, &processed, 10);
          if (processed == 0 || level != Clamp(level, slf.min_compression, slf.max_compression)) {
            ShowErrorMessage(
              GetEncodedString(STR_CONFIG_ERROR),
              GetEncodedString(STR_CONFIG_ERROR_INVALID_SAVEGAME_COMPRESSION_LEVEL, complevel),
              WL_CRITICAL);
          } else {
            return {slf, ClampTo<uint8_t>(level)};
          }
        }
        return {slf, slf.default_compression};
      }
    }
 
    ShowErrorMessage(
      GetEncodedString(STR_CONFIG_ERROR),
      GetEncodedString(STR_CONFIG_ERROR_INVALID_SAVEGAME_COMPRESSION_ALGORITHM, name, def.name),
      WL_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(const std::string &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);
  }
}
 
static void ResetSaveloadData()
{
  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(WC_STATUS_BAR, 0, SBI_SAVELOAD_START);
  _sl.saveinprogress = true;
}
 
static void SaveFileDone()
{
  SetMouseCursorBusy(false);
 
  InvalidateWindowData(WC_STATUS_BAR, 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 == SLA_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(), WL_ERROR);
  SaveFileDone();
}
 
static SaveOrLoadResult SaveFileToDisk(bool threaded)
{
  try {
    auto [fmt, compression] = GetSavegameFormat(_savegame_format);
 
    /* We have written our stuff to memory, now write it to file! */
    uint32_t hdr[2] = { fmt.tag, TO_BE32(SAVEGAME_VERSION << 16) };
    _sl.sf->Write((uint8_t*)hdr, sizeof(hdr));
 
    _sl.sf = fmt.init_write(_sl.sf, compression);
    _sl.dumper->Flush(_sl.sf);
 
    ClearSaveLoadState();
 
    if (threaded) SetAsyncSaveFinish(SaveFileDone);
 
    return SL_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) {
      /* Skip the "colour" character */
      Debug(sl, 0, "{}", GetSaveLoadErrorType().GetDecodedString().substr(3) + GetSaveLoadErrorMessage().GetDecodedString());
      asfp = SaveFileError;
    }
 
    if (threaded) {
      SetAsyncSaveFinish(asfp);
    } else {
      asfp();
    }
    return SL_ERROR;
  }
}
 
void WaitTillSaved()
{
  if (!_save_thread.joinable()) return;
 
  _save_thread.join();
 
  /* Make sure every other state is handled properly as well. */
  ProcessAsyncSaveFinish();
}
 
static SaveOrLoadResult 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(sl, 1, "Cannot create savegame thread, reverting to single-threaded mode...");
 
    SaveOrLoadResult result = SaveFileToDisk(false);
    SaveFileDone();
 
    return result;
  }
 
  return SL_OK;
}
 
SaveOrLoadResult SaveWithFilter(std::shared_ptr<SaveFilter> writer, bool threaded)
{
  try {
    _sl.action = SLA_SAVE;
    return DoSave(std::move(writer), threaded);
  } catch (...) {
    ClearSaveLoadState();
    return SL_ERROR;
  }
}
 
static const SaveLoadFormat *DetermineSaveLoadFormat(uint32_t 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(sl, 1, "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 >= SLV_START_PATCHPACKS && _sl_version <= SLV_END_PATCHPACKS) SlError(STR_GAME_SAVELOAD_ERROR_PATCHPACK);
    return fmt;
  }
 
  Debug(sl, 0, "Unknown savegame type, trying to load it as the buggy format");
  _sl.lf->Reset();
  _sl_version = SL_MIN_VERSION;
  _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 SaveOrLoadResult 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;
  }
 
  uint32_t hdr[2];
  if (_sl.lf->Read((uint8_t*)hdr, sizeof(hdr)) != sizeof(hdr)) SlError(STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
 
  /* see if we have any loader for this type. */
  const SaveLoadFormat *fmt = DetermineSaveLoadFormat(hdr[0], hdr[1]);
 
  /* 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(SLV_4)) {
      /*
       * 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 = SGT_OTTD;
 
  if (load_check) {
    /* The only part from AfterLoadGame() we need */
    _load_check_data.grf_compatibility = IsGoodGRFConfigList(_load_check_data.grfconfig);
  } else {
    _gamelog.StartAction(GLAT_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 SL_REINIT;
    }
 
    _gamelog.StopAction();
  }
 
  return SL_OK;
}
 
SaveOrLoadResult LoadWithFilter(std::shared_ptr<LoadFilter> reader)
{
  try {
    _sl.action = SLA_LOAD;
    return DoLoad(std::move(reader), false);
  } catch (...) {
    ClearSaveLoadState();
    return SL_REINIT;
  }
}
 
SaveOrLoadResult SaveOrLoad(const std::string &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 == SLO_SAVE && dft == DFT_GAME_FILE && threaded) {
    /* if not an autosave, but a user action, show error message */
    if (!_do_autosave) ShowErrorMessage(GetEncodedString(STR_ERROR_SAVE_STILL_IN_PROGRESS), {}, WL_ERROR);
    return SL_OK;
  }
  WaitTillSaved();
 
  try {
    /* Load a TTDLX or TTDPatch game */
    if (fop == SLO_LOAD && dft == DFT_OLD_GAME_FILE) {
      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 SL_REINIT;
      _sl_version = SL_MIN_VERSION;
      _sl_minor_version = 0;
      _gamelog.StartAction(GLAT_LOAD);
      if (!AfterLoadGame()) {
        _gamelog.StopAction();
        return SL_REINIT;
      }
      _gamelog.StopAction();
      return SL_OK;
    }
 
    assert(dft == DFT_GAME_FILE);
    switch (fop) {
      case SLO_CHECK:
        _sl.action = SLA_LOAD_CHECK;
        break;
 
      case SLO_LOAD:
        _sl.action = SLA_LOAD;
        break;
 
      case SLO_SAVE:
        _sl.action = SLA_SAVE;
        break;
 
      default: NOT_REACHED();
    }
 
    auto fh = (fop == SLO_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 != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SAVE_DIR);
    if (!fh.has_value() && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", BASE_DIR);
    if (!fh.has_value() && fop != SLO_SAVE) fh = FioFOpenFile(filename, "rb", SCENARIO_DIR);
 
    if (!fh.has_value()) {
      SlError(fop == SLO_SAVE ? STR_GAME_SAVELOAD_ERROR_FILE_NOT_WRITEABLE : STR_GAME_SAVELOAD_ERROR_FILE_NOT_READABLE);
    }
 
    if (fop == SLO_SAVE) { // SAVE game
      Debug(desync, 1, "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 == SLO_LOAD || fop == SLO_CHECK);
    Debug(desync, 1, "load: {}", filename);
    return DoLoad(std::make_shared<FileReader>(std::move(*fh)), fop == SLO_CHECK);
  } catch (...) {
    /* This code may be executed both for old and new save games. */
    ClearSaveLoadState();
 
    /* Skip the "colour" character */
    if (fop != SLO_CHECK) Debug(sl, 0, "{}", GetSaveLoadErrorType().GetDecodedString().substr(3) + GetSaveLoadErrorMessage().GetDecodedString());
 
    /* A saver/loader exception!! reinitialize all variables to prevent crash! */
    return (fop == SLO_LOAD) ? SL_REINIT : SL_ERROR;
  }
}
 
void DoAutoOrNetsave(FiosNumberedSaveName &counter)
{
  std::string filename;
 
  if (_settings_client.gui.keep_all_autosave) {
    filename = GenerateDefaultSaveName() + counter.Extension();
  } else {
    filename = counter.Filename();
  }
 
  Debug(sl, 2, "Autosaving to '{}'", filename);
  if (SaveOrLoad(filename, SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR) != SL_OK) {
    ShowErrorMessage(GetEncodedString(STR_ERROR_AUTOSAVE_FAILED), {}, WL_ERROR);
  }
}
 
 
void DoExitSave()
{
  SaveOrLoad("exit.sav", SLO_SAVE, DFT_GAME_FILE, AUTOSAVE_DIR);
}
 
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(FiosType ft)
{
  this->SetMode(SLO_LOAD, GetAbstractFileType(ft), GetDetailedFileType(ft));
}
 
void FileToSaveLoad::SetMode(SaveLoadOperation fop, AbstractFileType aft, DetailedFileType dft)
{
  if (aft == FT_INVALID || aft == FT_NONE) {
    this->file_op = SLO_INVALID;
    this->detail_ftype = DFT_INVALID;
    this->abstract_ftype = FT_INVALID;
    return;
  }
 
  this->file_op = fop;
  this->detail_ftype = dft;
  this->abstract_ftype = aft;
}
 
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;
}