oldloader.cpp

Go to the documentation of this file.
00001 /* $Id: oldloader.cpp 17693 2009-10-04 17:16:41Z rubidium $ */
00002 
00003 /*
00004  * This file is part of OpenTTD.
00005  * 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.
00006  * 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.
00007  * 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/>.
00008  */
00009 
00012 #include "../stdafx.h"
00013 #include "../openttd.h"
00014 #include "../debug.h"
00015 #include "../strings_type.h"
00016 #include "../string_func.h"
00017 #include "../settings_type.h"
00018 #include "../fileio_func.h"
00019 
00020 #include "table/strings.h"
00021 
00022 #include "saveload_internal.h"
00023 #include "oldloader.h"
00024 
00025 enum {
00026   TTO_HEADER_SIZE = 41,
00027   TTD_HEADER_SIZE = 49,
00028 };
00029 
00030 uint32 _bump_assert_value;
00031 
00032 static inline OldChunkType GetOldChunkType(OldChunkType type)     {return (OldChunkType)GB(type, 0, 4);}
00033 static inline OldChunkType GetOldChunkVarType(OldChunkType type)  {return (OldChunkType)(GB(type, 8, 8) << 8);}
00034 static inline OldChunkType GetOldChunkFileType(OldChunkType type) {return (OldChunkType)(GB(type, 16, 8) << 16);}
00035 
00036 static inline byte CalcOldVarLen(OldChunkType type)
00037 {
00038   static const byte type_mem_size[] = {0, 1, 1, 2, 2, 4, 4, 8};
00039   byte length = GB(type, 8, 8);
00040   assert(length != 0 && length < lengthof(type_mem_size));
00041   return type_mem_size[length];
00042 }
00043 
00049 static byte ReadByteFromFile(LoadgameState *ls)
00050 {
00051   /* To avoid slow reads, we read BUFFER_SIZE of bytes per time
00052   and just return a byte per time */
00053   if (ls->buffer_cur >= ls->buffer_count) {
00054     /* Read some new bytes from the file */
00055     int count = (int)fread(ls->buffer, 1, BUFFER_SIZE, ls->file);
00056 
00057     /* We tried to read, but there is nothing in the file anymore.. */
00058     if (count == 0) {
00059       DEBUG(oldloader, 0, "Read past end of file, loading failed");
00060       ls->failed = true;
00061     }
00062 
00063     ls->buffer_count = count;
00064     ls->buffer_cur   = 0;
00065   }
00066 
00067   return ls->buffer[ls->buffer_cur++];
00068 }
00069 
00075 byte ReadByte(LoadgameState *ls)
00076 {
00077   /* Old savegames have a nice compression algorithm (RLE)
00078   which means that we have a chunk, which starts with a length
00079   byte. If that byte is negative, we have to repeat the next byte
00080   that many times ( + 1). Else, we need to read that amount of bytes.
00081   Works pretty good if you have many zero's behind eachother */
00082 
00083   if (ls->chunk_size == 0) {
00084     /* Read new chunk */
00085     int8 new_byte = ReadByteFromFile(ls);
00086 
00087     if (new_byte < 0) {
00088       /* Repeat next char for new_byte times */
00089       ls->decoding    = true;
00090       ls->decode_char = ReadByteFromFile(ls);
00091       ls->chunk_size  = -new_byte + 1;
00092     } else {
00093       ls->decoding    = false;
00094       ls->chunk_size  = new_byte + 1;
00095     }
00096   }
00097 
00098   ls->total_read++;
00099   ls->chunk_size--;
00100 
00101   return ls->decoding ? ls->decode_char : ReadByteFromFile(ls);
00102 }
00103 
00109 bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
00110 {
00111   byte *base_ptr = (byte*)base;
00112 
00113   for (const OldChunks *chunk = chunks; chunk->type != OC_END; chunk++) {
00114     if (((chunk->type & OC_TTD) && _savegame_type == SGT_TTO) ||
00115         ((chunk->type & OC_TTO) && _savegame_type != SGT_TTO)) {
00116       /* TTD(P)-only chunk, but TTO savegame || TTO-only chunk, but TTD/TTDP savegame */
00117       continue;
00118     }
00119 
00120     byte *ptr = (byte*)chunk->ptr;
00121     if (chunk->type & OC_DEREFERENCE_POINTER) ptr = *(byte**)ptr;
00122 
00123     for (uint i = 0; i < chunk->amount; i++) {
00124       if (ls->failed) return false;
00125 
00126       /* Handle simple types */
00127       if (GetOldChunkType(chunk->type) != 0) {
00128         switch (GetOldChunkType(chunk->type)) {
00129           /* Just read the byte and forget about it */
00130           case OC_NULL: ReadByte(ls); break;
00131 
00132           case OC_CHUNK:
00133             /* Call function, with 'i' as parameter to tell which item we
00134              * are going to read */
00135             if (!chunk->proc(ls, i)) return false;
00136             break;
00137 
00138           case OC_ASSERT:
00139             DEBUG(oldloader, 4, "Assert point: 0x%X / 0x%X", ls->total_read, chunk->offset + _bump_assert_value);
00140             if (ls->total_read != chunk->offset + _bump_assert_value) ls->failed = true;
00141           default: break;
00142         }
00143       } else {
00144         uint64 res = 0;
00145 
00146         /* Reading from the file: bits 16 to 23 have the FILE type */
00147         switch (GetOldChunkFileType(chunk->type)) {
00148           case OC_FILE_I8:  res = (int8)ReadByte(ls); break;
00149           case OC_FILE_U8:  res = ReadByte(ls); break;
00150           case OC_FILE_I16: res = (int16)ReadUint16(ls); break;
00151           case OC_FILE_U16: res = ReadUint16(ls); break;
00152           case OC_FILE_I32: res = (int32)ReadUint32(ls); break;
00153           case OC_FILE_U32: res = ReadUint32(ls); break;
00154           default: NOT_REACHED();
00155         }
00156 
00157         /* When both pointers are NULL, we are just skipping data */
00158         if (base_ptr == NULL && chunk->ptr == NULL) continue;
00159 
00160         /* Writing to the var: bits 8 to 15 have the VAR type */
00161         if (chunk->ptr == NULL) ptr = base_ptr + chunk->offset;
00162 
00163         /* Write the data */
00164         switch (GetOldChunkVarType(chunk->type)) {
00165           case OC_VAR_I8: *(int8  *)ptr = GB(res, 0, 8); break;
00166           case OC_VAR_U8: *(uint8 *)ptr = GB(res, 0, 8); break;
00167           case OC_VAR_I16:*(int16 *)ptr = GB(res, 0, 16); break;
00168           case OC_VAR_U16:*(uint16*)ptr = GB(res, 0, 16); break;
00169           case OC_VAR_I32:*(int32 *)ptr = res; break;
00170           case OC_VAR_U32:*(uint32*)ptr = res; break;
00171           case OC_VAR_I64:*(int64 *)ptr = res; break;
00172           case OC_VAR_U64:*(uint64*)ptr = res; break;
00173           default: NOT_REACHED();
00174         }
00175 
00176         /* Increase pointer base for arrays when looping */
00177         if (chunk->amount > 1 && chunk->ptr != NULL) ptr += CalcOldVarLen(chunk->type);
00178       }
00179     }
00180   }
00181 
00182   return true;
00183 }
00184 
00190 static void InitLoading(LoadgameState *ls)
00191 {
00192   ls->chunk_size   = 0;
00193   ls->total_read   = 0;
00194   ls->failed       = false;
00195 
00196   ls->decoding     = false;
00197   ls->decode_char  = 0;
00198 
00199   ls->buffer_cur   = 0;
00200   ls->buffer_count = 0;
00201   memset(ls->buffer, 0, BUFFER_SIZE);
00202 
00203   _bump_assert_value = 0;
00204 
00205   _settings_game.construction.freeform_edges = false; // disable so we can convert map array (SetTileType is still used)
00206 }
00207 
00215 static bool VerifyOldNameChecksum(char *title, uint len)
00216 {
00217   uint16 sum = 0;
00218   for (uint i = 0; i < len - 2; i++) {
00219     sum += title[i];
00220     sum = ROL(sum, 1);
00221   }
00222 
00223   sum ^= 0xAAAA; // computed checksum
00224 
00225   uint16 sum2 = title[len - 2]; // checksum in file
00226   SB(sum2, 8, 8, title[len - 1]);
00227 
00228   return sum == sum2;
00229 }
00230 
00231 static inline bool CheckOldSavegameType(FILE *f, char *temp, const char *last, uint len)
00232 {
00233   assert(last - temp + 1 >= (int)len);
00234 
00235   if (fread(temp, 1, len, f) != len) {
00236     temp[0] = '\0'; // if reading failed, make the name empty
00237     return false;
00238   }
00239 
00240   bool ret = VerifyOldNameChecksum(temp, len);
00241   temp[len - 2] = '\0'; // name is nul-terminated in savegame, but it's better to be sure
00242   str_validate(temp, last);
00243 
00244   return ret;
00245 }
00246 
00247 static SavegameType DetermineOldSavegameType(FILE *f, char *title, const char *last)
00248 {
00249   assert_compile(TTD_HEADER_SIZE >= TTO_HEADER_SIZE);
00250   char temp[TTD_HEADER_SIZE];
00251 
00252   SavegameType type = SGT_TTO;
00253 
00254   /* Can't fseek to 0 as in tar files that is not correct */
00255   long pos = ftell(f);
00256   if (!CheckOldSavegameType(f, temp, lastof(temp), TTO_HEADER_SIZE)) {
00257     type = SGT_TTD;
00258     fseek(f, pos, SEEK_SET);
00259     if (!CheckOldSavegameType(f, temp, lastof(temp), TTD_HEADER_SIZE)) {
00260       type = SGT_INVALID;
00261     }
00262   }
00263 
00264   if (title != NULL) {
00265     switch (type) {
00266       case SGT_TTO: title = strecpy(title, "(TTO) ", last);    break;
00267       case SGT_TTD: title = strecpy(title, "(TTD) ", last);    break;
00268       default:      title = strecpy(title, "(broken) ", last); break;
00269     }
00270     title = strecpy(title, temp, last);
00271   }
00272 
00273   return type;
00274 }
00275 
00276 typedef bool LoadOldMainProc(LoadgameState *ls);
00277 
00278 bool LoadOldSaveGame(const char *file)
00279 {
00280   LoadgameState ls;
00281 
00282   DEBUG(oldloader, 3, "Trying to load a TTD(Patch) savegame");
00283 
00284   InitLoading(&ls);
00285 
00286   /* Open file */
00287   ls.file = FioFOpenFile(file, "rb");
00288 
00289   if (ls.file == NULL) {
00290     DEBUG(oldloader, 0, "Cannot open file '%s'", file);
00291     return false;
00292   }
00293 
00294   SavegameType type = DetermineOldSavegameType(ls.file, NULL, NULL);
00295 
00296   LoadOldMainProc *proc = NULL;
00297 
00298   switch (type) {
00299     case SGT_TTO: proc = &LoadTTOMain; break;
00300     case SGT_TTD: proc = &LoadTTDMain; break;
00301     default: break;
00302   }
00303 
00304   _savegame_type = type;
00305 
00306   if (proc == NULL || !proc(&ls)) {
00307     SetSaveLoadError(STR_GAME_SAVELOAD_ERROR_DATA_INTEGRITY_CHECK_FAILED);
00308     fclose(ls.file);
00309     return false;
00310   }
00311 
00312   _pause_mode = 2;
00313 
00314   return true;
00315 }
00316 
00317 void GetOldSaveGameName(const char *file, char *title, const char *last)
00318 {
00319   FILE *f = FioFOpenFile(file, "rb");
00320 
00321   if (f == NULL) {
00322     *title = '\0';
00323     return;
00324   }
00325 
00326   DetermineOldSavegameType(f, title, last);
00327 
00328   fclose(f);
00329 }

Generated on Wed Jan 20 23:38:39 2010 for OpenTTD by  doxygen 1.5.6