C++ OpenedFile::SetPosition方法代码示例

void rewind_recording(
	void)
{
	if(replay.game_is_being_recorded)
	{
		/* This is unnecessary, because it is called from reset_player_queues, */
		/* which is always called from revert_game */
		/*
		FilmFile.SetLength(sizeof(recording_header));
		FilmFile.SetPosition(sizeof(recording_header));
		*/
		// Alternative that does not use "SetLength", but instead creates and re-creates the file.
		FilmFile.SetPosition(0);
		byte Header[SIZEOF_recording_header];
		FilmFile.Read(SIZEOF_recording_header,Header);
		FilmFile.Close();
		FilmFileSpec.Delete();
		FilmFileSpec.Create(_typecode_film);
		FilmFileSpec.Open(FilmFile,true);
		FilmFile.Write(SIZEOF_recording_header,Header);
		
		// Use the packed length here!!!
		replay.header.length= SIZEOF_recording_header;
	}
}

void stop_recording(
	void)
{
	if (replay.game_is_being_recorded)
	{
		replay.game_is_being_recorded = false;
		
		short player_index;
		int32 total_length;

		assert(replay.valid);
		for (player_index= 0; player_index<dynamic_world->player_count; player_index++)
		{
			save_recording_queue_chunk(player_index);
		}

		/* Rewrite the header, since it has the new length */
		FilmFile.SetPosition(0);
		byte Header[SIZEOF_recording_header];
		pack_recording_header(Header,&replay.header,1);

		// ZZZ: removing code that does stuff from assert() argument.  BUT...
		// should we really be asserting on this anyway?  I mean, the write could fail
		// in 'normal operation' too, not just when we screwed something up in writing the program?
		bool successfulWrite = FilmFile.Write(SIZEOF_recording_header,Header);
		assert(successfulWrite);
		
		FilmFile.GetLength(total_length);
		assert(total_length==replay.header.length);
		
		FilmFile.Close();
	}

	replay.valid= false;
}

bool SkipChunk(OpenedFile& OFile, ChunkHeaderData& ChunkHeader)
{
	logTrace2("Skipping chunk 0x%04hx size %u",ChunkHeader.ID,ChunkHeader.Size);
	int32 DataSize = ChunkHeader.Size - SIZEOF_ChunkHeaderData;
	
	int32 Location = 0;
	OFile.GetPosition(Location);
	if (!OFile.SetPosition(Location + DataSize)) return false;
	return true;
}

// Determine file type
Typecode FileSpecifier::GetType()
{

	// if there's an extension, assume it's correct
	const char *extension = strrchr(GetPath(), '.');
	if (extension) {
		extension_mapping *mapping = extensions;
		while (mapping->extension)
		{ 
			if (( mapping->case_sensitive && (strcmp(extension + 1, mapping->extension) == 0)) ||
			    (!mapping->case_sensitive && (strcasecmp(extension + 1, mapping->extension) == 0)))
			{
				return mapping->typecode;
			}
			++mapping;
		}
	}

	// Open file
	OpenedFile f;
	if (!Open(f))
		return _typecode_unknown;
	SDL_RWops *p = f.GetRWops();
	int32 file_length = 0;
	f.GetLength(file_length);

	// Check for Sounds file
	{
		f.SetPosition(0);
		uint32 version = SDL_ReadBE32(p);
		uint32 tag = SDL_ReadBE32(p);
		if ((version == 0 || version == 1) && tag == FOUR_CHARS_TO_INT('s', 'n', 'd', '2'))
			return _typecode_sounds;
	}

	// Check for Map/Physics file
	{
		f.SetPosition(0);
		int version = SDL_ReadBE16(p);
		int data_version = SDL_ReadBE16(p);
		if ((version == 0 || version == 1 || version == 2 || version == 4) && (data_version == 0 || data_version == 1 || data_version == 2)) {
			SDL_RWseek(p, 68, SEEK_CUR);
			int32 directory_offset = SDL_ReadBE32(p);
			if (directory_offset >= file_length)
				goto not_map;
			f.SetPosition(128);
			uint32 tag = SDL_ReadBE32(p);
			// ghs: I do not believe this list is comprehensive
			//      I think it's just what we've seen so far?
			switch (tag) {
			case LINE_TAG:
			case POINT_TAG:
			case SIDE_TAG:
				return _typecode_scenario;
				break;
			case MONSTER_PHYSICS_TAG:
				return _typecode_physics;
				break;
			}
				
		}
not_map: ;
	}

	// Check for Shapes file
	{
		f.SetPosition(0);
		for (int i=0; i<32; i++) {
			uint32 status_flags = SDL_ReadBE32(p);
			int32 offset = SDL_ReadBE32(p);
			int32 length = SDL_ReadBE32(p);
			int32 offset16 = SDL_ReadBE32(p);
			int32 length16 = SDL_ReadBE32(p);
			if (status_flags != 0
			 || (offset != NONE && (offset >= file_length || offset + length > file_length))
			 || (offset16 != NONE && (offset16 >= file_length || offset16 + length16 > file_length)))
				goto not_shapes;
			SDL_RWseek(p, 12, SEEK_CUR);
		}
		return _typecode_shapes;
not_shapes: ;
	}

	// Not identified
	return _typecode_unknown;
}