ClickHouse/src/Formats/FormatFactory.cpp

#include <Formats/FormatFactory.h>

#include <algorithm>
#include <Core/Settings.h>
#include <Formats/FormatSettings.h>
#include <Interpreters/Context.h>
#include <Interpreters/ProcessList.h>
#include <Processors/Formats/IRowInputFormat.h>
#include <Processors/Formats/IRowOutputFormat.h>
#include <Processors/Formats/Impl/MySQLOutputFormat.h>
#include <Processors/Formats/Impl/ParallelFormattingOutputFormat.h>
#include <Processors/Formats/Impl/ParallelParsingInputFormat.h>
#include <Processors/Formats/Impl/ValuesBlockInputFormat.h>
#include <Poco/URI.h>
#include <Common/Exception.h>
#include <fcntl.h>
#include <unistd.h>

#include <boost/algorithm/string/case_conv.hpp>

namespace DB
{

namespace ErrorCodes
{
    extern const int UNKNOWN_FORMAT;
    extern const int LOGICAL_ERROR;
    extern const int FORMAT_IS_NOT_SUITABLE_FOR_INPUT;
    extern const int FORMAT_IS_NOT_SUITABLE_FOR_OUTPUT;
    extern const int BAD_ARGUMENTS;
}

const FormatFactory::Creators & FormatFactory::getCreators(const String & name) const
{
    auto it = dict.find(name);
    if (dict.end() != it)
        return it->second;
    throw Exception("Unknown format " + name, ErrorCodes::UNKNOWN_FORMAT);
}

FormatSettings getFormatSettings(ContextPtr context)
{
    const auto & settings = context->getSettingsRef();

    return getFormatSettings(context, settings);
}

template <typename Settings>
FormatSettings getFormatSettings(ContextPtr context, const Settings & settings)
{
    FormatSettings format_settings;

    format_settings.avro.allow_missing_fields = settings.input_format_avro_allow_missing_fields;
    format_settings.avro.output_codec = settings.output_format_avro_codec;
    format_settings.avro.output_sync_interval = settings.output_format_avro_sync_interval;
    format_settings.avro.schema_registry_url = settings.format_avro_schema_registry_url.toString();
    format_settings.avro.string_column_pattern = settings.output_format_avro_string_column_pattern.toString();
    format_settings.avro.output_rows_in_file = settings.output_format_avro_rows_in_file;
    format_settings.csv.allow_double_quotes = settings.format_csv_allow_double_quotes;
    format_settings.csv.allow_single_quotes = settings.format_csv_allow_single_quotes;
    format_settings.csv.crlf_end_of_line = settings.output_format_csv_crlf_end_of_line;
    format_settings.csv.delimiter = settings.format_csv_delimiter;
    format_settings.csv.tuple_delimiter = settings.format_csv_delimiter;
    format_settings.csv.empty_as_default = settings.input_format_csv_empty_as_default;
    format_settings.csv.input_format_enum_as_number = settings.input_format_csv_enum_as_number;
    format_settings.csv.null_representation = settings.format_csv_null_representation;
    format_settings.csv.input_format_arrays_as_nested_csv = settings.input_format_csv_arrays_as_nested_csv;
    format_settings.csv.input_format_use_best_effort_in_schema_inference = settings.input_format_csv_use_best_effort_in_schema_inference;
    format_settings.hive_text.fields_delimiter = settings.input_format_hive_text_fields_delimiter;
    format_settings.hive_text.collection_items_delimiter = settings.input_format_hive_text_collection_items_delimiter;
    format_settings.hive_text.map_keys_delimiter = settings.input_format_hive_text_map_keys_delimiter;
    format_settings.custom.escaping_rule = settings.format_custom_escaping_rule;
    format_settings.custom.field_delimiter = settings.format_custom_field_delimiter;
    format_settings.custom.result_after_delimiter = settings.format_custom_result_after_delimiter;
    format_settings.custom.result_before_delimiter = settings.format_custom_result_before_delimiter;
    format_settings.custom.row_after_delimiter = settings.format_custom_row_after_delimiter;
    format_settings.custom.row_before_delimiter = settings.format_custom_row_before_delimiter;
    format_settings.custom.row_between_delimiter = settings.format_custom_row_between_delimiter;
    format_settings.date_time_input_format = settings.date_time_input_format;
    format_settings.date_time_output_format = settings.date_time_output_format;
    format_settings.input_format_ipv4_default_on_conversion_error = settings.input_format_ipv4_default_on_conversion_error;
    format_settings.input_format_ipv6_default_on_conversion_error = settings.input_format_ipv6_default_on_conversion_error;
    format_settings.bool_true_representation = settings.bool_true_representation;
    format_settings.bool_false_representation = settings.bool_false_representation;
    format_settings.enable_streaming = settings.output_format_enable_streaming;
    format_settings.import_nested_json = settings.input_format_import_nested_json;
    format_settings.input_allow_errors_num = settings.input_format_allow_errors_num;
    format_settings.input_allow_errors_ratio = settings.input_format_allow_errors_ratio;
    format_settings.json.array_of_rows = settings.output_format_json_array_of_rows;
    format_settings.json.escape_forward_slashes = settings.output_format_json_escape_forward_slashes;
    format_settings.json.named_tuples_as_objects = settings.output_format_json_named_tuples_as_objects;
    format_settings.json.quote_64bit_integers = settings.output_format_json_quote_64bit_integers;
    format_settings.json.quote_denormals = settings.output_format_json_quote_denormals;
    format_settings.json.read_bools_as_numbers = settings.input_format_json_read_bools_as_numbers;
    format_settings.null_as_default = settings.input_format_null_as_default;
    format_settings.decimal_trailing_zeros = settings.output_format_decimal_trailing_zeros;
    format_settings.parquet.row_group_size = settings.output_format_parquet_row_group_size;
    format_settings.parquet.import_nested = settings.input_format_parquet_import_nested;
    format_settings.parquet.case_insensitive_column_matching = settings.input_format_parquet_case_insensitive_column_matching;
    format_settings.parquet.allow_missing_columns = settings.input_format_parquet_allow_missing_columns;
    format_settings.parquet.skip_columns_with_unsupported_types_in_schema_inference = settings.input_format_parquet_skip_columns_with_unsupported_types_in_schema_inference;
    format_settings.parquet.output_string_as_string = settings.output_format_parquet_string_as_string;
    format_settings.pretty.charset = settings.output_format_pretty_grid_charset.toString() == "ASCII" ? FormatSettings::Pretty::Charset::ASCII : FormatSettings::Pretty::Charset::UTF8;
    format_settings.pretty.color = settings.output_format_pretty_color;
    format_settings.pretty.max_column_pad_width = settings.output_format_pretty_max_column_pad_width;
    format_settings.pretty.max_rows = settings.output_format_pretty_max_rows;
    format_settings.pretty.max_value_width = settings.output_format_pretty_max_value_width;
    format_settings.pretty.output_format_pretty_row_numbers = settings.output_format_pretty_row_numbers;
    format_settings.protobuf.input_flatten_google_wrappers = settings.input_format_protobuf_flatten_google_wrappers;
    format_settings.protobuf.output_nullables_with_google_wrappers = settings.output_format_protobuf_nullables_with_google_wrappers;
    format_settings.regexp.escaping_rule = settings.format_regexp_escaping_rule;
    format_settings.regexp.regexp = settings.format_regexp;
    format_settings.regexp.skip_unmatched = settings.format_regexp_skip_unmatched;
    format_settings.schema.format_schema = settings.format_schema;
    format_settings.schema.format_schema_path = context->getFormatSchemaPath();
    format_settings.schema.is_server = context->hasGlobalContext() && (context->getGlobalContext()->getApplicationType() == Context::ApplicationType::SERVER);
    format_settings.skip_unknown_fields = settings.input_format_skip_unknown_fields;
    format_settings.template_settings.resultset_format = settings.format_template_resultset;
    format_settings.template_settings.row_between_delimiter = settings.format_template_rows_between_delimiter;
    format_settings.template_settings.row_format = settings.format_template_row;
    format_settings.tsv.crlf_end_of_line = settings.output_format_tsv_crlf_end_of_line;
    format_settings.tsv.empty_as_default = settings.input_format_tsv_empty_as_default;
    format_settings.tsv.input_format_enum_as_number = settings.input_format_tsv_enum_as_number;
    format_settings.tsv.null_representation = settings.format_tsv_null_representation;
    format_settings.tsv.input_format_use_best_effort_in_schema_inference = settings.input_format_tsv_use_best_effort_in_schema_inference;
    format_settings.values.accurate_types_of_literals = settings.input_format_values_accurate_types_of_literals;
    format_settings.values.deduce_templates_of_expressions = settings.input_format_values_deduce_templates_of_expressions;
    format_settings.values.interpret_expressions = settings.input_format_values_interpret_expressions;
    format_settings.with_names_use_header = settings.input_format_with_names_use_header;
    format_settings.with_types_use_header = settings.input_format_with_types_use_header;
    format_settings.write_statistics = settings.output_format_write_statistics;
    format_settings.arrow.low_cardinality_as_dictionary = settings.output_format_arrow_low_cardinality_as_dictionary;
    format_settings.arrow.import_nested = settings.input_format_arrow_import_nested;
    format_settings.arrow.allow_missing_columns = settings.input_format_arrow_allow_missing_columns;
    format_settings.arrow.skip_columns_with_unsupported_types_in_schema_inference = settings.input_format_arrow_skip_columns_with_unsupported_types_in_schema_inference;
    format_settings.arrow.skip_columns_with_unsupported_types_in_schema_inference = settings.input_format_arrow_skip_columns_with_unsupported_types_in_schema_inference;
    format_settings.arrow.case_insensitive_column_matching = settings.input_format_arrow_case_insensitive_column_matching;
    format_settings.arrow.output_string_as_string = settings.output_format_arrow_string_as_string;
    format_settings.orc.import_nested = settings.input_format_orc_import_nested;
    format_settings.orc.allow_missing_columns = settings.input_format_orc_allow_missing_columns;
    format_settings.orc.row_batch_size = settings.input_format_orc_row_batch_size;
    format_settings.orc.skip_columns_with_unsupported_types_in_schema_inference = settings.input_format_orc_skip_columns_with_unsupported_types_in_schema_inference;
    format_settings.orc.import_nested = settings.input_format_orc_import_nested;
    format_settings.orc.allow_missing_columns = settings.input_format_orc_allow_missing_columns;
    format_settings.orc.row_batch_size = settings.input_format_orc_row_batch_size;
    format_settings.orc.skip_columns_with_unsupported_types_in_schema_inference = settings.input_format_orc_skip_columns_with_unsupported_types_in_schema_inference;
    format_settings.orc.case_insensitive_column_matching = settings.input_format_orc_case_insensitive_column_matching;
    format_settings.orc.output_string_as_string = settings.output_format_orc_string_as_string;
    format_settings.defaults_for_omitted_fields = settings.input_format_defaults_for_omitted_fields;
    format_settings.capn_proto.enum_comparing_mode = settings.format_capn_proto_enum_comparising_mode;
    format_settings.seekable_read = settings.input_format_allow_seeks;
    format_settings.msgpack.number_of_columns = settings.input_format_msgpack_number_of_columns;
    format_settings.msgpack.output_uuid_representation = settings.output_format_msgpack_uuid_representation;
    format_settings.max_rows_to_read_for_schema_inference = settings.input_format_max_rows_to_read_for_schema_inference;
    format_settings.column_names_for_schema_inference = settings.column_names_for_schema_inference;
    format_settings.mysql_dump.table_name = settings.input_format_mysql_dump_table_name;
    format_settings.mysql_dump.map_column_names = settings.input_format_mysql_dump_map_column_names;

    /// Validate avro_schema_registry_url with RemoteHostFilter when non-empty and in Server context
    if (format_settings.schema.is_server)
    {
        const Poco::URI & avro_schema_registry_url = settings.format_avro_schema_registry_url;
        if (!avro_schema_registry_url.empty())
            context->getRemoteHostFilter().checkURL(avro_schema_registry_url);
    }

    return format_settings;
}

template FormatSettings getFormatSettings<FormatFactorySettings>(ContextPtr context, const FormatFactorySettings & settings);

template FormatSettings getFormatSettings<Settings>(ContextPtr context, const Settings & settings);


InputFormatPtr FormatFactory::getInput(
    const String & name,
    ReadBuffer & buf,
    const Block & sample,
    ContextPtr context,
    UInt64 max_block_size,
    const std::optional<FormatSettings> & _format_settings) const
{
    auto format_settings = _format_settings
        ? *_format_settings : getFormatSettings(context);

    if (!getCreators(name).input_creator)
    {
        throw Exception("Format " + name + " is not suitable for input (with processors)", ErrorCodes::FORMAT_IS_NOT_SUITABLE_FOR_INPUT);
    }

    const Settings & settings = context->getSettingsRef();
    const auto & file_segmentation_engine = getCreators(name).file_segmentation_engine;

    // Doesn't make sense to use parallel parsing with less than four threads
    // (segmentator + two parsers + reader).
    bool parallel_parsing = settings.input_format_parallel_parsing && file_segmentation_engine && settings.max_threads >= 4;

    if (settings.max_memory_usage && settings.min_chunk_bytes_for_parallel_parsing * settings.max_threads * 2 > settings.max_memory_usage)
        parallel_parsing = false;

    if (settings.max_memory_usage_for_user && settings.min_chunk_bytes_for_parallel_parsing * settings.max_threads * 2 > settings.max_memory_usage_for_user)
        parallel_parsing = false;

    if (parallel_parsing)
    {
        const auto & non_trivial_prefix_and_suffix_checker = getCreators(name).non_trivial_prefix_and_suffix_checker;
        /// Disable parallel parsing for input formats with non-trivial readPrefix() and readSuffix().
        if (non_trivial_prefix_and_suffix_checker && non_trivial_prefix_and_suffix_checker(buf))
            parallel_parsing = false;
    }

    if (parallel_parsing)
    {
        const auto & input_getter = getCreators(name).input_creator;

        RowInputFormatParams row_input_format_params;
        row_input_format_params.max_block_size = max_block_size;
        row_input_format_params.allow_errors_num = format_settings.input_allow_errors_num;
        row_input_format_params.allow_errors_ratio = format_settings.input_allow_errors_ratio;
        row_input_format_params.max_execution_time = settings.max_execution_time;
        row_input_format_params.timeout_overflow_mode = settings.timeout_overflow_mode;

        /// Const reference is copied to lambda.
        auto parser_creator = [input_getter, sample, row_input_format_params, format_settings]
            (ReadBuffer & input) -> InputFormatPtr
            { return input_getter(input, sample, row_input_format_params, format_settings); };

        ParallelParsingInputFormat::Params params{
            buf, sample, parser_creator, file_segmentation_engine, name, settings.max_threads, settings.min_chunk_bytes_for_parallel_parsing,
               context->getApplicationType() == Context::ApplicationType::SERVER};
        return std::make_shared<ParallelParsingInputFormat>(params);
    }


    auto format = getInputFormat(name, buf, sample, context, max_block_size, format_settings);
    return format;
}

InputFormatPtr FormatFactory::getInputFormat(
    const String & name,
    ReadBuffer & buf,
    const Block & sample,
    ContextPtr context,
    UInt64 max_block_size,
    const std::optional<FormatSettings> & _format_settings) const
{
    const auto & input_getter = getCreators(name).input_creator;
    if (!input_getter)
        throw Exception("Format " + name + " is not suitable for input", ErrorCodes::FORMAT_IS_NOT_SUITABLE_FOR_INPUT);

    const Settings & settings = context->getSettingsRef();

    if (context->hasQueryContext() && settings.log_queries)
        context->getQueryContext()->addQueryFactoriesInfo(Context::QueryLogFactories::Format, name);

    auto format_settings = _format_settings ? *_format_settings : getFormatSettings(context);

    RowInputFormatParams params;
    params.max_block_size = max_block_size;
    params.allow_errors_num = format_settings.input_allow_errors_num;
    params.allow_errors_ratio = format_settings.input_allow_errors_ratio;
    params.max_execution_time = settings.max_execution_time;
    params.timeout_overflow_mode = settings.timeout_overflow_mode;
    auto format = input_getter(buf, sample, params, format_settings);

    /// It's a kludge. Because I cannot remove context from values format.
    if (auto * values = typeid_cast<ValuesBlockInputFormat *>(format.get()))
        values->setContext(context);

    return format;
}

static void addExistingProgressToOutputFormat(OutputFormatPtr format, ContextPtr context)
{
    auto * element_id = context->getProcessListElement();
    if (element_id)
    {
        /// While preparing the query there might have been progress (for example in subscalar subqueries) so add it here
        auto current_progress = element_id->getProgressIn();
        Progress read_progress{current_progress.read_rows, current_progress.read_bytes, current_progress.total_rows_to_read};
        format->onProgress(read_progress);
    }
}

OutputFormatPtr FormatFactory::getOutputFormatParallelIfPossible(
    const String & name,
    WriteBuffer & buf,
    const Block & sample,
    ContextPtr context,
    WriteCallback callback,
    const std::optional<FormatSettings> & _format_settings) const
{
    const auto & output_getter = getCreators(name).output_creator;
    if (!output_getter)
        throw Exception(ErrorCodes::FORMAT_IS_NOT_SUITABLE_FOR_OUTPUT, "Format {} is not suitable for output (with processors)", name);

    auto format_settings = _format_settings ? *_format_settings : getFormatSettings(context);

    const Settings & settings = context->getSettingsRef();

    if (settings.output_format_parallel_formatting && getCreators(name).supports_parallel_formatting
        && !settings.output_format_json_array_of_rows)
    {
        auto formatter_creator = [output_getter, sample, callback, format_settings] (WriteBuffer & output) -> OutputFormatPtr
        {
            return output_getter(output, sample, {callback}, format_settings);
        };

        ParallelFormattingOutputFormat::Params builder{buf, sample, formatter_creator, settings.max_threads};

        if (context->hasQueryContext() && settings.log_queries)
            context->getQueryContext()->addQueryFactoriesInfo(Context::QueryLogFactories::Format, name);

        auto format = std::make_shared<ParallelFormattingOutputFormat>(builder);
        addExistingProgressToOutputFormat(format, context);
        return format;
    }

    return getOutputFormat(name, buf, sample, context, callback, _format_settings);
}


OutputFormatPtr FormatFactory::getOutputFormat(
    const String & name,
    WriteBuffer & buf,
    const Block & sample,
    ContextPtr context,
    WriteCallback callback,
    const std::optional<FormatSettings> & _format_settings) const
{
    const auto & output_getter = getCreators(name).output_creator;
    if (!output_getter)
        throw Exception(ErrorCodes::FORMAT_IS_NOT_SUITABLE_FOR_OUTPUT, "Format {} is not suitable for output (with processors)", name);

    if (context->hasQueryContext() && context->getSettingsRef().log_queries)
        context->getQueryContext()->addQueryFactoriesInfo(Context::QueryLogFactories::Format, name);

    RowOutputFormatParams params;
    params.callback = std::move(callback);

    auto format_settings = _format_settings ? *_format_settings : getFormatSettings(context);

    /** TODO: Materialization is needed, because formats can use the functions `IDataType`,
      *  which only work with full columns.
      */
    auto format = output_getter(buf, sample, params, format_settings);

    /// Enable auto-flush for streaming mode. Currently it is needed by INSERT WATCH query.
    if (format_settings.enable_streaming)
        format->setAutoFlush();

    /// It's a kludge. Because I cannot remove context from MySQL format.
    if (auto * mysql = typeid_cast<MySQLOutputFormat *>(format.get()))
        mysql->setContext(context);

    addExistingProgressToOutputFormat(format, context);

    return format;
}

String FormatFactory::getContentType(
    const String & name,
    ContextPtr context,
    const std::optional<FormatSettings> & _format_settings) const
{
    const auto & output_getter = getCreators(name).output_creator;
    if (!output_getter)
        throw Exception(ErrorCodes::FORMAT_IS_NOT_SUITABLE_FOR_OUTPUT, "Format {} is not suitable for output (with processors)", name);

    auto format_settings = _format_settings ? *_format_settings : getFormatSettings(context);

    Block empty_block;
    RowOutputFormatParams empty_params;
    WriteBufferFromOwnString empty_buffer;
    auto format = output_getter(empty_buffer, empty_block, empty_params, format_settings);

    return format->getContentType();
}

SchemaReaderPtr FormatFactory::getSchemaReader(
    const String & name,
    ReadBuffer & buf,
    ContextPtr & context,
    const std::optional<FormatSettings> & _format_settings) const
{
    const auto & schema_reader_creator = dict.at(name).schema_reader_creator;
    if (!schema_reader_creator)
        throw Exception("FormatFactory: Format " + name + " doesn't support schema inference.", ErrorCodes::LOGICAL_ERROR);

    auto format_settings = _format_settings ? *_format_settings : getFormatSettings(context);
    return schema_reader_creator(buf, format_settings);
}

ExternalSchemaReaderPtr FormatFactory::getExternalSchemaReader(
    const String & name,
    ContextPtr & context,
    const std::optional<FormatSettings> & _format_settings) const
{
    const auto & external_schema_reader_creator = dict.at(name).external_schema_reader_creator;
    if (!external_schema_reader_creator)
        throw Exception("FormatFactory: Format " + name + " doesn't support schema inference.", ErrorCodes::LOGICAL_ERROR);

    auto format_settings = _format_settings ? *_format_settings : getFormatSettings(context);
    return external_schema_reader_creator(format_settings);
}

void FormatFactory::registerInputFormat(const String & name, InputCreator input_creator)
{
    auto & target = dict[name].input_creator;
    if (target)
        throw Exception("FormatFactory: Input format " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(input_creator);
    registerFileExtension(name, name);
}

void FormatFactory::registerNonTrivialPrefixAndSuffixChecker(const String & name, NonTrivialPrefixAndSuffixChecker non_trivial_prefix_and_suffix_checker)
{
    auto & target = dict[name].non_trivial_prefix_and_suffix_checker;
    if (target)
        throw Exception("FormatFactory: Non trivial prefix and suffix checker " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(non_trivial_prefix_and_suffix_checker);
}

void FormatFactory::registerAppendSupportChecker(const String & name, AppendSupportChecker append_support_checker)
{
    auto & target = dict[name].append_support_checker;
    if (target)
        throw Exception("FormatFactory: Suffix checker " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(append_support_checker);
}

void FormatFactory::markFormatHasNoAppendSupport(const String & name)
{
    registerAppendSupportChecker(name, [](const FormatSettings &){ return false; });
}

bool FormatFactory::checkIfFormatSupportAppend(const String & name, ContextPtr context, const std::optional<FormatSettings> & format_settings_)
{
    auto format_settings = format_settings_ ? *format_settings_ : getFormatSettings(context);
    auto & append_support_checker = dict[name].append_support_checker;
    /// By default we consider that format supports append
    return !append_support_checker || append_support_checker(format_settings);
}

void FormatFactory::registerOutputFormat(const String & name, OutputCreator output_creator)
{
    auto & target = dict[name].output_creator;
    if (target)
        throw Exception("FormatFactory: Output format " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(output_creator);
    registerFileExtension(name, name);
}

void FormatFactory::registerFileExtension(const String & extension, const String & format_name)
{
    file_extension_formats[boost::to_lower_copy(extension)] = format_name;
}

String FormatFactory::getFormatFromFileName(String file_name, bool throw_if_not_found)
{
    if (file_name == "stdin")
        return getFormatFromFileDescriptor(STDIN_FILENO);

    CompressionMethod compression_method = chooseCompressionMethod(file_name, "");
    if (CompressionMethod::None != compression_method)
    {
        auto pos = file_name.find_last_of('.');
        if (pos != String::npos)
            file_name = file_name.substr(0, pos);
    }

    auto pos = file_name.find_last_of('.');
    if (pos == String::npos)
    {
        if (throw_if_not_found)
            throw Exception(ErrorCodes::BAD_ARGUMENTS, "Cannot determine the file format by it's extension");
        return "";
    }

    String file_extension = file_name.substr(pos + 1, String::npos);
    boost::algorithm::to_lower(file_extension);
    auto it = file_extension_formats.find(file_extension);
    if (it == file_extension_formats.end())
    {
        if (throw_if_not_found)
            throw Exception(ErrorCodes::BAD_ARGUMENTS, "Cannot determine the file format by it's extension");
        return "";
    }
    return it->second;
}

String FormatFactory::getFormatFromFileDescriptor(int fd)
{
#ifdef OS_LINUX
    char buf[32] = {'\0'};
    snprintf(buf, sizeof(buf), "/proc/self/fd/%d", fd);
    char file_path[PATH_MAX] = {'\0'};
    if (readlink(buf, file_path, sizeof(file_path) - 1) != -1)
        return getFormatFromFileName(file_path, false);
    return "";
#elif defined(__APPLE__)
    char file_path[PATH_MAX] = {'\0'};
    if (fcntl(fd, F_GETPATH, file_path) != -1)
        return getFormatFromFileName(file_path, false);
    return "";
#else
    return "";
#endif
}

void FormatFactory::registerFileSegmentationEngine(const String & name, FileSegmentationEngine file_segmentation_engine)
{
    auto & target = dict[name].file_segmentation_engine;
    if (target)
        throw Exception("FormatFactory: File segmentation engine " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(file_segmentation_engine);
}

void FormatFactory::registerSchemaReader(const String & name, SchemaReaderCreator schema_reader_creator)
{
    auto & target = dict[name].schema_reader_creator;
    if (target)
        throw Exception("FormatFactory: Schema reader " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(schema_reader_creator);
}

void FormatFactory::registerExternalSchemaReader(const String & name, ExternalSchemaReaderCreator external_schema_reader_creator)
{
    auto & target = dict[name].external_schema_reader_creator;
    if (target)
        throw Exception("FormatFactory: Schema reader " + name + " is already registered", ErrorCodes::LOGICAL_ERROR);
    target = std::move(external_schema_reader_creator);
}

void FormatFactory::markOutputFormatSupportsParallelFormatting(const String & name)
{
    auto & target = dict[name].supports_parallel_formatting;
    if (target)
        throw Exception("FormatFactory: Output format " + name + " is already marked as supporting parallel formatting", ErrorCodes::LOGICAL_ERROR);
    target = true;
}


void FormatFactory::markFormatSupportsSubsetOfColumns(const String & name)
{
    auto & target = dict[name].supports_subset_of_columns;
    if (target)
        throw Exception("FormatFactory: Format " + name + " is already marked as supporting subset of columns", ErrorCodes::LOGICAL_ERROR);
    target = true;
}


bool FormatFactory::checkIfFormatSupportsSubsetOfColumns(const String & name) const
{
    const auto & target = getCreators(name);
    return target.supports_subset_of_columns;
}

bool FormatFactory::isInputFormat(const String & name) const
{
    auto it = dict.find(name);
    return it != dict.end() && it->second.input_creator;
}

bool FormatFactory::isOutputFormat(const String & name) const
{
    auto it = dict.find(name);
    return it != dict.end() && it->second.output_creator;
}

bool FormatFactory::checkIfFormatHasSchemaReader(const String & name) const
{
    const auto & target = getCreators(name);
    return bool(target.schema_reader_creator);
}

bool FormatFactory::checkIfFormatHasExternalSchemaReader(const String & name) const
{
    const auto & target = getCreators(name);
    return bool(target.external_schema_reader_creator);
}

bool FormatFactory::checkIfFormatHasAnySchemaReader(const String & name) const
{
    return checkIfFormatHasSchemaReader(name) || checkIfFormatHasExternalSchemaReader(name);
}

void FormatFactory::checkFormatName(const String & name) const
{
    auto it = dict.find(name);
    if (it == dict.end())
        throw Exception("Unknown format " + name, ErrorCodes::UNKNOWN_FORMAT);
}

FormatFactory & FormatFactory::instance()
{
    static FormatFactory ret;
    return ret;
}

}