alkis commented on code in PR #42174: URL: https://github.com/apache/arrow/pull/42174#discussion_r1687177204
########## cpp/tools/parquet/parquet_dump_footer.cc: ########## @@ -0,0 +1,135 @@ +// 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 <fstream> +#include <iostream> +#include <optional> + +#include "arrow/filesystem/filesystem.h" +#include "arrow/util/endian.h" +#include "arrow/util/ubsan.h" +#include "parquet/metadata.h" + +namespace parquet { +namespace { +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)); +} + +int DoIt(std::string in, bool scrub, bool json, std::string out) { + std::string path; + auto fs = ::arrow::fs::FileSystemFromUriOrPath(in, &path).ValueOrDie(); + auto file = fs->OpenInputFile(path).ValueOrDie(); + int64_t file_len = file->GetSize().ValueOrDie(); + if (file_len < 8) { + std::cerr << "File too short: " << in << "\n"; + return 3; + } + // First do an opportunistic read of up to 1 MiB to try and get the entire footer. + int64_t tail_len = std::min(file_len, int64_t{1} << 20); + std::string tail; + tail.resize(tail_len); + char* data = tail.data(); + file->ReadAt(file_len - tail_len, tail_len, data).ValueOrDie(); + if (auto magic = ReadLE32(data + tail_len - 4); magic != ReadLE32("PAR1")) { + std::cerr << "Not a Parquet file: " << in << "\n"; + return 4; + } + uint32_t metadata_len = ReadLE32(data + tail_len - 8); + if (tail_len >= metadata_len + 8) { + // The footer is entirely in the initial read. Trim to size. + tail = tail.substr(tail_len - (metadata_len + 8)); + } else { + // The footer is larger than the initial read, read again the exact size. + if (metadata_len > file_len) { + std::cerr << "File too short: " << in << "\n"; + return 5; + } + tail_len = metadata_len + 8; + tail.resize(tail_len); + data = tail.data(); + file->ReadAt(file_len - tail_len, tail_len, data).ValueOrDie(); + } + auto md = FileMetaData::Make(tail.data(), &metadata_len); + std::string ser = md->SerializeUnencrypted(scrub, json); + if (!json) { + AppendLE32(static_cast<uint32_t>(ser.size()), &ser); + ser.append("PAR1", 4); + } + std::optional<std::fstream> fout; + if (!out.empty()) fout.emplace(out, std::ios::out); + std::ostream& os = fout ? *fout : std::cout; + if (!os.write(ser.data(), ser.size())) { + std::cerr << "Failed to write to output file: " << out << "\n"; + return 6; + } + + return 0; +} +} // namespace +} // namespace parquet + +static int PrintHelp() { + std::cerr << R"(Usage: parquet-dump-footer + -h|--help Print help and exit + --no-scrub Do not scrub potentially confidential metadata + --debug Output text represenation of footer for inspection + --in <uri> Input file (required): must be an URI or an absolute local path + --out <path> Output file (optional, default stdout) + + Dump the footer of a Parquet file to stdout or to a file, optionally with + potentially confidential metadata scrubbed. +)"; + return 1; +} + +int main(int argc, char** argv) { + bool scrub = true; + bool json = false; + std::string in; + std::string out; + for (int i = 1; i < argc; i++) { + char* arg = argv[i]; + if (!std::strcmp(arg, "-h") || !std::strcmp(arg, "--help")) { + return PrintHelp(); + } else if (!std::strcmp(arg, "--no-scrub")) { + scrub = false; + } else if (!std::strcmp(arg, "--json")) { + json = true; Review Comment: https://github.com/apache/arrow/pull/43375 ########## cpp/tools/parquet/parquet_dump_footer.cc: ########## @@ -0,0 +1,135 @@ +// 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 <fstream> +#include <iostream> +#include <optional> + +#include "arrow/filesystem/filesystem.h" +#include "arrow/util/endian.h" +#include "arrow/util/ubsan.h" +#include "parquet/metadata.h" + +namespace parquet { +namespace { +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)); +} + +int DoIt(std::string in, bool scrub, bool json, std::string out) { Review Comment: https://github.com/apache/arrow/pull/43375 -- This is an automated message from the Apache Git Service. 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