Method executeImpl

src/Functions/FunctionFile.cpp:76–162

    bool useDefaultImplementationForConstants() const override { return true; }

    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
    {
        const ColumnPtr column = arguments[0].column;
        const ColumnString * column_src = checkAndGetColumn<ColumnString>(column.get());
        if (!column_src)
            throw Exception(ErrorCodes::ILLEGAL_COLUMN,
                "Illegal column {} of argument of function {}", arguments[0].column->getName(), getName());

        String default_result;

        ColumnUInt8::MutablePtr col_null_map_to;
        ColumnUInt8::Container * vec_null_map_to [[maybe_unused]] = nullptr;

        if (arguments.size() == 2)
        {
            if (result_type->isNullable())
            {
                col_null_map_to = ColumnUInt8::create(input_rows_count, false);
                vec_null_map_to = &col_null_map_to->getData();
            }
            else
            {
                const auto & default_column = arguments[1].column;
                const ColumnConst * default_col = checkAndGetColumn<ColumnConst>(default_column.get());

                if (!default_col)
                    throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Illegal column {} of argument of function {}",
                        arguments[1].column->getName(), getName());

                default_result = default_col->getValue<String>();
            }
        }

        auto result = ColumnString::create();
        auto & res_chars = result->getChars();
        auto & res_offsets = result->getOffsets();

        res_offsets.resize(input_rows_count);

        fs::path user_files_absolute_path = fs::canonical(fs::path(getContext()->getUserFilesPath()));
        std::string user_files_absolute_path_string = user_files_absolute_path.string();

        // If run in Local mode, no need for path checking.
        bool need_check = getContext()->getApplicationType() != Context::ApplicationType::LOCAL;

        for (size_t row = 0; row < input_rows_count; ++row)
        {
            std::string_view filename = column_src->getDataAt(row).toView();
            fs::path file_path(filename.data(), filename.data() + filename.size());

            if (file_path.is_relative())
                file_path = user_files_absolute_path / file_path;

            /// Do not use fs::canonical or fs::weakly_canonical.
            /// Otherwise it will not allow to work with symlinks in `user_files_path` directory.
            file_path = fs::absolute(file_path).lexically_normal();

            try