mirror of https://github.com/OpenTTD/OpenTTD.git
318 lines
9.2 KiB
C++
318 lines
9.2 KiB
C++
/*
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* This file is part of OpenTTD.
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* 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.
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* 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.
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* 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/>.
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*/
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/** @file oldloader.cpp Functions for handling of TTO/TTD/TTDP savegames. */
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#include "../stdafx.h"
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#include "../debug.h"
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#include "../strings_type.h"
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#include "../string_func.h"
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#include "../settings_type.h"
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#include "../fileio_func.h"
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#include "table/strings.h"
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#include "saveload_internal.h"
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#include "oldloader.h"
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#include "../safeguards.h"
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static const int TTO_HEADER_SIZE = 41;
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static const int TTD_HEADER_SIZE = 49;
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/** The size of the checksum in the name/header of the TTD/TTO savegames. */
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static const int HEADER_CHECKSUM_SIZE = 2;
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uint32_t _bump_assert_value;
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static inline OldChunkType GetOldChunkType(OldChunkType type) {return (OldChunkType)GB(type, 0, 4);}
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static inline OldChunkType GetOldChunkVarType(OldChunkType type) {return (OldChunkType)(GB(type, 8, 8) << 8);}
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static inline OldChunkType GetOldChunkFileType(OldChunkType type) {return (OldChunkType)(GB(type, 16, 8) << 16);}
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/**
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* Return expected size in bytes of a OldChunkType
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* @param type OldChunkType to get size of.
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* @return size of type in bytes.
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*/
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static inline uint8_t CalcOldVarLen(OldChunkType type)
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{
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switch (GetOldChunkVarType(type)) {
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case OC_VAR_I8: return sizeof(int8_t);
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case OC_VAR_U8: return sizeof(uint8_t);
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case OC_VAR_I16: return sizeof(int16_t);
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case OC_VAR_U16: return sizeof(uint16_t);
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case OC_VAR_I32: return sizeof(int32_t);
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case OC_VAR_U32: return sizeof(uint32_t);
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case OC_VAR_I64: return sizeof(int64_t);
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case OC_VAR_U64: return sizeof(uint64_t);
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default: NOT_REACHED();
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}
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}
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/**
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*
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* Reads a byte from a file (do not call yourself, use ReadByte())
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*
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*/
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static uint8_t ReadByteFromFile(LoadgameState *ls)
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{
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/* To avoid slow reads, we read BUFFER_SIZE of bytes per time
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and just return a byte per time */
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if (ls->buffer_cur >= ls->buffer_count) {
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/* Read some new bytes from the file */
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int count = (int)fread(ls->buffer, 1, BUFFER_SIZE, ls->file);
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/* We tried to read, but there is nothing in the file anymore.. */
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if (count == 0) {
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Debug(oldloader, 0, "Read past end of file, loading failed");
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throw std::exception();
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}
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ls->buffer_count = count;
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ls->buffer_cur = 0;
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}
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return ls->buffer[ls->buffer_cur++];
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}
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/**
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*
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* Reads a byte from the buffer and decompress if needed
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*
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*/
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uint8_t ReadByte(LoadgameState *ls)
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{
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/* Old savegames have a nice compression algorithm (RLE)
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which means that we have a chunk, which starts with a length
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byte. If that byte is negative, we have to repeat the next byte
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that many times ( + 1). Else, we need to read that amount of bytes.
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Works pretty well if you have many zeros behind each other */
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if (ls->chunk_size == 0) {
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/* Read new chunk */
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int8_t new_byte = ReadByteFromFile(ls);
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if (new_byte < 0) {
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/* Repeat next char for new_byte times */
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ls->decoding = true;
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ls->decode_char = ReadByteFromFile(ls);
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ls->chunk_size = -new_byte + 1;
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} else {
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ls->decoding = false;
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ls->chunk_size = new_byte + 1;
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}
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}
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ls->total_read++;
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ls->chunk_size--;
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return ls->decoding ? ls->decode_char : ReadByteFromFile(ls);
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}
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/**
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*
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* Loads a chunk from the old savegame
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*
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*/
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bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
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{
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for (const OldChunks *chunk = chunks; chunk->type != OC_END; chunk++) {
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if (((chunk->type & OC_TTD) && _savegame_type == SGT_TTO) ||
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((chunk->type & OC_TTO) && _savegame_type != SGT_TTO)) {
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/* TTD(P)-only chunk, but TTO savegame || TTO-only chunk, but TTD/TTDP savegame */
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continue;
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}
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uint8_t *ptr = (uint8_t*)chunk->ptr;
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if (chunk->type & OC_DEREFERENCE_POINTER) ptr = *(uint8_t**)ptr;
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for (uint i = 0; i < chunk->amount; i++) {
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/* Handle simple types */
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if (GetOldChunkType(chunk->type) != 0) {
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switch (GetOldChunkType(chunk->type)) {
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/* Just read the byte and forget about it */
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case OC_NULL: ReadByte(ls); break;
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case OC_CHUNK:
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/* Call function, with 'i' as parameter to tell which item we
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* are going to read */
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if (!chunk->proc(ls, i)) return false;
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break;
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case OC_ASSERT:
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Debug(oldloader, 4, "Assert point: 0x{:X} / 0x{:X}", ls->total_read, (uint)(size_t)chunk->ptr + _bump_assert_value);
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if (ls->total_read != (size_t)chunk->ptr + _bump_assert_value) throw std::exception();
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default: break;
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}
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} else {
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uint64_t res = 0;
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/* Reading from the file: bits 16 to 23 have the FILE type */
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switch (GetOldChunkFileType(chunk->type)) {
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case OC_FILE_I8: res = (int8_t)ReadByte(ls); break;
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case OC_FILE_U8: res = ReadByte(ls); break;
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case OC_FILE_I16: res = (int16_t)ReadUint16(ls); break;
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case OC_FILE_U16: res = ReadUint16(ls); break;
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case OC_FILE_I32: res = (int32_t)ReadUint32(ls); break;
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case OC_FILE_U32: res = ReadUint32(ls); break;
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default: NOT_REACHED();
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}
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/* When both pointers are nullptr, we are just skipping data */
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if (base == nullptr && chunk->ptr == nullptr) continue;
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/* Chunk refers to a struct member, get address in base. */
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if (chunk->ptr == nullptr) ptr = (uint8_t *)chunk->offset(base);
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/* Write the data */
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switch (GetOldChunkVarType(chunk->type)) {
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case OC_VAR_I8: *(int8_t *)ptr = GB(res, 0, 8); break;
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case OC_VAR_U8: *(uint8_t *)ptr = GB(res, 0, 8); break;
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case OC_VAR_I16:*(int16_t *)ptr = GB(res, 0, 16); break;
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case OC_VAR_U16:*(uint16_t*)ptr = GB(res, 0, 16); break;
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case OC_VAR_I32:*(int32_t *)ptr = res; break;
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case OC_VAR_U32:*(uint32_t*)ptr = res; break;
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case OC_VAR_I64:*(int64_t *)ptr = res; break;
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case OC_VAR_U64:*(uint64_t*)ptr = res; break;
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default: NOT_REACHED();
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}
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/* Increase pointer base for arrays when looping */
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if (chunk->amount > 1 && chunk->ptr != nullptr) ptr += CalcOldVarLen(chunk->type);
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}
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}
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}
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return true;
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}
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/**
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*
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* Initialize some data before reading
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*
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*/
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static void InitLoading(LoadgameState *ls)
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{
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ls->chunk_size = 0;
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ls->total_read = 0;
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ls->decoding = false;
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ls->decode_char = 0;
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ls->buffer_cur = 0;
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ls->buffer_count = 0;
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memset(ls->buffer, 0, BUFFER_SIZE);
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_bump_assert_value = 0;
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_settings_game.construction.freeform_edges = false; // disable so we can convert map array (SetTileType is still used)
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}
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/**
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* Verifies the title has a valid checksum
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* @param title title and checksum
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* @param len the length of the title to read/checksum
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* @return true iff the title is valid
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*/
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static bool VerifyOldNameChecksum(char *title, uint len)
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{
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uint16_t sum = 0;
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for (uint i = 0; i < len - HEADER_CHECKSUM_SIZE; i++) {
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sum += title[i];
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sum = std::rotl(sum, 1);
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}
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sum ^= 0xAAAA; // computed checksum
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uint16_t sum2 = title[len - HEADER_CHECKSUM_SIZE]; // checksum in file
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SB(sum2, 8, 8, title[len - HEADER_CHECKSUM_SIZE + 1]);
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return sum == sum2;
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}
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static std::tuple<SavegameType, std::string> DetermineOldSavegameTypeAndName(FILE *f)
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{
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long pos = ftell(f);
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char buffer[std::max(TTO_HEADER_SIZE, TTD_HEADER_SIZE)];
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if (pos < 0 || fread(buffer, 1, lengthof(buffer), f) != lengthof(buffer)) {
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return { SGT_INVALID, "(broken) Unable to read file" };
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}
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if (VerifyOldNameChecksum(buffer, TTO_HEADER_SIZE) && fseek(f, pos + TTO_HEADER_SIZE, SEEK_SET) == 0) {
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return { SGT_TTO, "(TTO)" + StrMakeValid({buffer, TTO_HEADER_SIZE - HEADER_CHECKSUM_SIZE}) };
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}
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if (VerifyOldNameChecksum(buffer, TTD_HEADER_SIZE) && fseek(f, pos + TTD_HEADER_SIZE, SEEK_SET) == 0) {
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return { SGT_TTD, "(TTD)" + StrMakeValid({buffer, TTD_HEADER_SIZE - HEADER_CHECKSUM_SIZE}) };
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}
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return { SGT_INVALID, "(broken) Unknown" };
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}
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typedef bool LoadOldMainProc(LoadgameState *ls);
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bool LoadOldSaveGame(const std::string &file)
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{
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LoadgameState ls;
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Debug(oldloader, 3, "Trying to load a TTD(Patch) savegame");
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InitLoading(&ls);
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/* Open file */
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ls.file = FioFOpenFile(file, "rb", NO_DIRECTORY);
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if (ls.file == nullptr) {
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Debug(oldloader, 0, "Cannot open file '{}'", file);
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return false;
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}
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SavegameType type;
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std::tie(type, std::ignore) = DetermineOldSavegameTypeAndName(ls.file);
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LoadOldMainProc *proc = nullptr;
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switch (type) {
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case SGT_TTO: proc = &LoadTTOMain; break;
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case SGT_TTD: proc = &LoadTTDMain; break;
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default:
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Debug(oldloader, 0, "Unknown savegame type; cannot be loaded");
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break;
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}
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_savegame_type = type;
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bool game_loaded;
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try {
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game_loaded = proc != nullptr && proc(&ls);
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} catch (...) {
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game_loaded = false;
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}
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if (!game_loaded) {
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SetSaveLoadError(STR_GAME_SAVELOAD_ERROR_DATA_INTEGRITY_CHECK_FAILED);
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fclose(ls.file);
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return false;
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}
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_pause_mode = PM_PAUSED_SAVELOAD;
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return true;
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}
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std::string GetOldSaveGameName(const std::string &file)
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{
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FILE *f = FioFOpenFile(file, "rb", NO_DIRECTORY);
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if (f == nullptr) return {};
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std::string name;
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std::tie(std::ignore, name) = DetermineOldSavegameTypeAndName(f);
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fclose(f);
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return name;
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}
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