# oldloader.cpp

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    00001 /* $Id: oldloader.cpp 15903 2009-03-30 23:15:05Z rubidium $ */
    00002
    00005 #include "../stdafx.h"
    00006 #include "../openttd.h"
    00007 #include "../tile_type.h"
    00008 #include "../debug.h"
    00009 #include "../strings_type.h"
    00010 #include "../string_func.h"
    00011 #include "../settings_type.h"
    00012 #include "../fileio_func.h"
    00013
    00014 #include "table/strings.h"
    00015
    00016 #include "saveload_internal.h"
    00017 #include "oldloader.h"
    00018
    00019 enum {
    00020   TTO_HEADER_SIZE = 41,
    00021   TTD_HEADER_SIZE = 49,
    00022 };
    00023
    00024 uint32 _bump_assert_value;
    00025
    00026 static inline OldChunkType GetOldChunkType(OldChunkType type)     {return (OldChunkType)GB(type, 0, 4);}
    00027 static inline OldChunkType GetOldChunkVarType(OldChunkType type)  {return (OldChunkType)(GB(type, 8, 8) << 8);}
    00028 static inline OldChunkType GetOldChunkFileType(OldChunkType type) {return (OldChunkType)(GB(type, 16, 8) << 16);}
    00029
    00030 static inline byte CalcOldVarLen(OldChunkType type)
    00031 {
    00032   static const byte type_mem_size[] = {0, 1, 1, 2, 2, 4, 4, 8};
    00033   byte length = GB(type, 8, 8);
    00034   assert(length != 0 && length < lengthof(type_mem_size));
    00035   return type_mem_size[length];
    00036 }
    00037
    00043 static byte ReadByteFromFile(LoadgameState *ls)
    00044 {
    00045   /* To avoid slow reads, we read BUFFER_SIZE of bytes per time
    00046   and just return a byte per time */
    00047   if (ls->buffer_cur >= ls->buffer_count) {
    00048     /* Read some new bytes from the file */
    00049     int count = (int)fread(ls->buffer, 1, BUFFER_SIZE, ls->file);
    00050
    00051     /* We tried to read, but there is nothing in the file anymore.. */
    00052     if (count == 0) {
    00053       DEBUG(oldloader, 0, "Read past end of file, loading failed");
    00054       ls->failed = true;
    00055     }
    00056
    00057     ls->buffer_count = count;
    00058     ls->buffer_cur   = 0;
    00059   }
    00060
    00061   return ls->buffer[ls->buffer_cur++];
    00062 }
    00063
    00069 byte ReadByte(LoadgameState *ls)
    00070 {
    00071   /* Old savegames have a nice compression algorithm (RLE)
    00072   which means that we have a chunk, which starts with a length
    00073   byte. If that byte is negative, we have to repeat the next byte
    00074   that many times ( + 1). Else, we need to read that amount of bytes.
    00075   Works pretty good if you have many zero's behind eachother */
    00076
    00077   if (ls->chunk_size == 0) {
    00078     /* Read new chunk */
    00079     int8 new_byte = ReadByteFromFile(ls);
    00080
    00081     if (new_byte < 0) {
    00082       /* Repeat next char for new_byte times */
    00083       ls->decoding    = true;
    00084       ls->decode_char = ReadByteFromFile(ls);
    00085       ls->chunk_size  = -new_byte + 1;
    00086     } else {
    00087       ls->decoding    = false;
    00088       ls->chunk_size  = new_byte + 1;
    00089     }
    00090   }
    00091
    00092   ls->total_read++;
    00093   ls->chunk_size--;
    00094
    00095   return ls->decoding ? ls->decode_char : ReadByteFromFile(ls);
    00096 }
    00097
    00103 bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
    00104 {
    00105   byte *base_ptr = (byte*)base;
    00106
    00107   for (const OldChunks *chunk = chunks; chunk->type != OC_END; chunk++) {
    00108     if (((chunk->type & OC_TTD) && (_savegame_type == SGT_TTO)) ||
    00109         ((chunk->type & OC_TTO) && (_savegame_type != SGT_TTO))) {
    00110       /* TTD(P)-only chunk, but TTO savegame || TTO-only chunk, but TTD/TTDP savegame */
    00111       continue;
    00112     }
    00113
    00114     byte *ptr = (byte*)chunk->ptr;
    00115     if (chunk->type & OC_DEREFERENCE_POINTER) ptr = *(byte**)ptr;
    00116
    00117     for (uint i = 0; i < chunk->amount; i++) {
    00118       if (ls->failed) return false;
    00119
    00120       /* Handle simple types */
    00121       if (GetOldChunkType(chunk->type) != 0) {
    00122         switch (GetOldChunkType(chunk->type)) {
    00123           /* Just read the byte and forget about it */
    00124           case OC_NULL: ReadByte(ls); break;
    00125
    00126           case OC_CHUNK:
    00127             /* Call function, with 'i' as parameter to tell which item we
    00128              * are going to read */
    00129             if (!chunk->proc(ls, i)) return false;
    00130             break;
    00131
    00132           case OC_ASSERT:
    00133             DEBUG(oldloader, 4, "Assert point: 0x%X / 0x%X", ls->total_read, chunk->offset + _bump_assert_value);
    00134             if (ls->total_read != chunk->offset + _bump_assert_value) ls->failed = true;
    00135           default: break;
    00136         }
    00137       } else {
    00138         uint64 res = 0;
    00139
    00140         /* Reading from the file: bits 16 to 23 have the FILE type */
    00141         switch (GetOldChunkFileType(chunk->type)) {
    00142           case OC_FILE_I8:  res = (int8)ReadByte(ls); break;
    00143           case OC_FILE_U8:  res = ReadByte(ls); break;
    00144           case OC_FILE_I16: res = (int16)ReadUint16(ls); break;
    00145           case OC_FILE_U16: res = ReadUint16(ls); break;
    00146           case OC_FILE_I32: res = (int32)ReadUint32(ls); break;
    00147           case OC_FILE_U32: res = ReadUint32(ls); break;
    00148           default: NOT_REACHED();
    00149         }
    00150
    00151         /* Sanity check */
    00152         assert(base_ptr != NULL || chunk->ptr != NULL);
    00153
    00154         /* Writing to the var: bits 8 to 15 have the VAR type */
    00155         if (chunk->ptr == NULL) ptr = base_ptr + chunk->offset;
    00156
    00157         /* Write the data */
    00158         switch (GetOldChunkVarType(chunk->type)) {
    00159           case OC_VAR_I8: *(int8  *)ptr = GB(res, 0, 8); break;
    00160           case OC_VAR_U8: *(uint8 *)ptr = GB(res, 0, 8); break;
    00161           case OC_VAR_I16:*(int16 *)ptr = GB(res, 0, 16); break;
    00162           case OC_VAR_U16:*(uint16*)ptr = GB(res, 0, 16); break;
    00163           case OC_VAR_I32:*(int32 *)ptr = res; break;
    00164           case OC_VAR_U32:*(uint32*)ptr = res; break;
    00165           case OC_VAR_I64:*(int64 *)ptr = res; break;
    00166           case OC_VAR_U64:*(uint64*)ptr = res; break;
    00167           default: NOT_REACHED();
    00168         }
    00169
    00170         /* Increase pointer base for arrays when looping */
    00171         if (chunk->amount > 1 && chunk->ptr != NULL) ptr += CalcOldVarLen(chunk->type);
    00172       }
    00173     }
    00174   }
    00175
    00176   return true;
    00177 }
    00178
    00184 static void InitLoading(LoadgameState *ls)
    00185 {
    00186   ls->chunk_size   = 0;
    00187   ls->total_read   = 0;
    00188   ls->failed       = false;
    00189
    00190   ls->decoding     = false;
    00191   ls->decode_char  = 0;
    00192
    00193   ls->buffer_cur   = 0;
    00194   ls->buffer_count = 0;
    00195   memset(ls->buffer, 0, BUFFER_SIZE);
    00196
    00197   _bump_assert_value = 0;
    00198
    00199   _settings_game.construction.freeform_edges = false; // disable so we can convert map array (SetTileType is still used)
    00200 }
    00201
    00208 static bool VerifyOldNameChecksum(char *title, uint len)
    00209 {
    00210   uint16 sum = 0;
    00211   for (uint i = 0; i < len - 2; i++) {
    00212     sum += title[i];
    00213     sum = ROL(sum, 1);
    00214   }
    00215
    00216   sum ^= 0xAAAA; // computed checksum
    00217
    00218   uint16 sum2 = title[len - 2]; // checksum in file
    00219   SB(sum2, 8, 8, title[len - 1]);
    00220
    00221   return sum == sum2;
    00222 }
    00223
    00224 static inline bool CheckOldSavegameType(FILE *f, char *temp, const char *last, uint len)
    00225 {
    00226   assert(last - temp + 1 >= (int)len);
    00227
    00228   if (fread(temp, 1, len, f) != len) {
    00229     temp[0] = '\0'; // if reading failed, make the name empty
    00230     return false;
    00231   }
    00232
    00233   bool ret = VerifyOldNameChecksum(temp, len);
    00234   temp[len - 2] = '\0'; // name is nul-terminated in savegame, but it's better to be sure
    00235   str_validate(temp, last);
    00236
    00237   return ret;
    00238 }
    00239
    00240 assert_compile(TTD_HEADER_SIZE >= TTO_HEADER_SIZE);
    00241 static SavegameType DetermineOldSavegameType(FILE *f, char *title, const char *last)
    00242 {
    00243   char temp[TTD_HEADER_SIZE];
    00244
    00245   SavegameType type = SGT_TTO;
    00246
    00247   /* Can't fseek to 0 as in tar files that is not correct */
    00248   long pos = ftell(f);
    00249   if (!CheckOldSavegameType(f, temp, lastof(temp), TTO_HEADER_SIZE)) {
    00250     type = SGT_TTD;
    00251     fseek(f, pos, SEEK_SET);
    00252     if (!CheckOldSavegameType(f, temp, lastof(temp), TTD_HEADER_SIZE)) {
    00253       type = SGT_INVALID;
    00254     }
    00255   }
    00256
    00257   if (title != NULL) {
    00258     switch (type) {
    00259       case SGT_TTO: title = strecpy(title, "(TTO) ", last);    break;
    00260       case SGT_TTD: title = strecpy(title, "(TTD) ", last);    break;
    00261       default:      title = strecpy(title, "(broken) ", last); break;
    00262     }
    00263     title = strecpy(title, temp, last);
    00264   }
    00265
    00266   return type;
    00267 }
    00268
    00269 typedef bool LoadOldMainProc(LoadgameState *ls);
    00270
    00271 bool LoadOldSaveGame(const char *file)
    00272 {
    00273   LoadgameState ls;
    00274
    00275   DEBUG(oldloader, 3, "Trying to load a TTD(Patch) savegame");
    00276
    00277   InitLoading(&ls);
    00278
    00279   /* Open file */
    00280   ls.file = FioFOpenFile(file, "rb");
    00281
    00282   if (ls.file == NULL) {
    00283     DEBUG(oldloader, 0, "Cannot open file '%s'", file);
    00284     return false;
    00285   }
    00286
    00287   SavegameType type = DetermineOldSavegameType(ls.file, NULL, NULL);
    00288
    00289   LoadOldMainProc *proc = NULL;
    00290
    00291   switch (type) {
    00292     case SGT_TTO: proc = &LoadTTOMain; break;
    00293     case SGT_TTD: proc = &LoadTTDMain; break;
    00294     default: break;
    00295   }
    00296
    00297   _savegame_type = type;
    00298
    00299   if (proc == NULL || !proc(&ls)) {
    00300     SetSaveLoadError(STR_GAME_SAVELOAD_ERROR_DATA_INTEGRITY_CHECK_FAILED);
    00301     fclose(ls.file);
    00302     return false;
    00303   }
    00304
    00305   _pause_game = 2;
    00306
    00307   return true;
    00308 }
    00309
    00310 void GetOldSaveGameName(const char *file, char *title, const char *last)
    00311 {
    00312   FILE *f = FioFOpenFile(file, "rb");
    00313
    00314   if (f == NULL) {
    00315     *title = '\0';
    00316     return;
    00317   }
    00318
    00319   DetermineOldSavegameType(f, title, last);
    00320
    00321   fclose(f);
    00322 }