Function _openFileStream

OgreMain/src/OgreFileSystem.cpp:344–406

        return _openFileStream(concatenate_path(mName, filename), mode, filename);
    }
    DataStreamPtr _openFileStream(const String& full_path, std::ios::openmode mode, const String& name)
    {
        // Use filesystem to determine size 
        // (quicker than streaming to the end and back)
#ifdef _OGRE_FILESYSTEM_ARCHIVE_UNICODE
		struct _stat64i32 tagStat;
		int ret = _wstat(to_wpath(full_path).c_str(), &tagStat);
#else
        struct stat tagStat;
        int ret = stat(full_path.c_str(), &tagStat);
#endif
        size_t st_size = ret == 0 ? tagStat.st_size : 0;

        std::istream* baseStream = 0;
        std::ifstream* roStream = 0;
        std::fstream* rwStream = 0;

        if (mode & std::ios::out)
        {
            rwStream = OGRE_NEW_T(std::fstream, MEMCATEGORY_GENERAL)();
#ifdef _OGRE_FILESYSTEM_ARCHIVE_UNICODE
			rwStream->open(to_wpath(full_path).c_str(), mode);
#else
            rwStream->open(full_path.c_str(), mode);
#endif
            baseStream = rwStream;
        }
        else
        {
            roStream = OGRE_NEW_T(std::ifstream, MEMCATEGORY_GENERAL)();
#ifdef _OGRE_FILESYSTEM_ARCHIVE_UNICODE
			roStream->open(to_wpath(full_path).c_str(), mode);
#else
            roStream->open(full_path.c_str(), mode);
#endif
            baseStream = roStream;
        }


        // Should check ensure open succeeded, in case fail for some reason.
        if (baseStream->fail())
        {
            OGRE_DELETE_T(roStream, basic_ifstream, MEMCATEGORY_GENERAL);
            OGRE_DELETE_T(rwStream, basic_fstream, MEMCATEGORY_GENERAL);
            OGRE_EXCEPT(Exception::ERR_FILE_NOT_FOUND, "Cannot open file: " + full_path);
        }

        /// Construct return stream, tell it to delete on destroy
        FileStreamDataStream* stream = 0;
        const String& streamname = name.empty() ? full_path : name;
        if (rwStream)
        {
            // use the writeable stream
            stream = OGRE_NEW FileStreamDataStream(streamname, rwStream, st_size);
        }
        else
        {
            OgreAssertDbg(ret == 0, "Problem getting file size");