alkis commented on code in PR #42174: URL: https://github.com/apache/arrow/pull/42174#discussion_r1682988962
########## cpp/tools/parquet/parquet_dump_footer.cc: ########## @@ -0,0 +1,248 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +#include <cstdint> +#include <cstring> +#include <exception> +#include <fstream> +#include <iostream> +#include <limits> +#include <optional> +#include <random> + +#include <thrift/protocol/TCompactProtocol.h> +#include <thrift/transport/TBufferTransports.h> + +#include "arrow/filesystem/filesystem.h" +#include "arrow/util/endian.h" +#include "arrow/util/ubsan.h" +#include "generated/parquet_types.h" +#include "parquet/thrift_internal.h" + +using apache::thrift::protocol::TCompactProtocol; +using apache::thrift::transport::TMemoryBuffer; +using apache::thrift::transport::TTransport; + +namespace { +int PrintHelp() { + std::cerr << R"( +Usage: parquet-dump-footer + -h|--help Print help and exit + --no-scrub Do not scrub potentially PII metadata + --json Output JSON instead of binary + --in Input file: required + --out Output file: defaults to stdout + + Dumps the footer of a Parquet file to stdout or a file, optionally with + potentially user specific metadata scrubbed. +)"; + return 1; +} + +uint32_t ReadLE32(const void* p) { + uint32_t x = arrow::util::SafeLoadAs<uint32_t>(static_cast<const uint8_t*>(p)); + return arrow::bit_util::FromLittleEndian(x); +} + +void AppendLE32(uint32_t v, std::string* out) { + v = arrow::bit_util::ToLittleEndian(v); + out->append(reinterpret_cast<const char*>(&v), sizeof(v)); +} + +template <typename T> +bool Deserialize(const char* data, uint32_t len, T* obj) { + parquet::ThriftDeserializer des(/*string_size_limit=*/1 << 30, + /*container_size_limit=*/1 << 30); + try { + des.DeserializeMessage(reinterpret_cast<const uint8_t*>(data), &len, obj); + return true; + } catch (const std::exception& e) { + std::cerr << "Failed to deserialize: " << e.what() << "\n"; + return false; + } +} + +template <typename T> +bool Serialize(const T& obj, std::string* out) { + parquet::ThriftSerializer ser(/*initial_buffer_size=*/10 << 20); + try { + ser.SerializeToString(&obj, out); + return true; + } catch (const std::exception& e) { + std::cerr << "Failed to serialize: " << e.what() << "\n"; + return false; + } +} + +// Replace the contents of s with random data of the same length. +void Scrub(std::string* s) { + static char pool[4096]; + static std::mt19937 rng(std::random_device{}()); + static const bool kPoolInit = [] { + std::uniform_int_distribution<> caps(65, 90); + for (size_t i = 0; i < sizeof(pool); i++) pool[i] = caps(rng); + return true; + }(); + (void)kPoolInit; + + const size_t n = s->size(); + s->clear(); + while (s->size() < n) { + // To avoid repeating patterns we start somewhere up to halfway through the pool and + // append up to half the pool chars. + std::uniform_int_distribution<size_t> half(0, sizeof(pool) / 2 - 1); + size_t m = std::min(n, half(rng) + 1 /* at least one */); + s->append(&pool[half(rng)], m); + } +} + +void Scrub(parquet::format::FileMetaData* md) { + for (auto& s : md->schema) { + Scrub(&s.name); + } + for (auto& r : md->row_groups) { + for (auto& c : r.columns) { + Scrub(&c.file_path); + if (c.__isset.meta_data) { + auto& m = c.meta_data; + for (auto& p : m.path_in_schema) Scrub(&p); + for (auto& kv : m.key_value_metadata) { + Scrub(&kv.key); + Scrub(&kv.value); + } + Scrub(&m.statistics.max_value); + Scrub(&m.statistics.min_value); + Scrub(&m.statistics.min); + Scrub(&m.statistics.max); + } + + if (c.crypto_metadata.__isset.ENCRYPTION_WITH_COLUMN_KEY) { + auto& m = c.crypto_metadata.ENCRYPTION_WITH_COLUMN_KEY; + for (auto& p : m.path_in_schema) Scrub(&p); + Scrub(&m.key_metadata); + } + Scrub(&c.encrypted_column_metadata); + } + } + for (auto& kv : md->key_value_metadata) { + Scrub(&kv.key); + Scrub(&kv.value); + } + Scrub(&md->footer_signing_key_metadata); +} + +// Returns: +// - 0 on success +// - -1 on error +// - the size of the footer if tail is too small Review Comment: Because it makes control flow more complex at the callsite. -- This is an automated message from the Apache Git Service. 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