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jeanlemotan
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#include "StdAfx.h"
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#include "fs/zip/ZipWriter.h"
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#include "fs/CRCStream.h"
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#include "fs/IStreamSource.h"
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#include "fs/ISink.h"
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#include "tl/narrow_cast.h"
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// This writer is implemented pretty close to the https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT standard
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namespace fs
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{
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//////////////////////////////////////////////////////////////////////////
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ZipWriter::ZipWriter(ISink& sink, size_t fileDataAlignment)
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: m_sink(sink)
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, m_fileDataAlignment(fileDataAlignment == 0 ? 1 : fileDataAlignment)
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{}
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//////////////////////////////////////////////////////////////////////////
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tl::result<void> ZipWriter::addFile(tl::string name, const DataWriter& dataWriter)
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{
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return addFile(std::move(name),
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//
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{},
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{},
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GeneralBitFlags(),
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tl::nullopt,
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dataWriter);
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}
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tl::result<void> ZipWriter::addFile(tl::string name, tl::optional<time_t> lastModificationTime, const DataWriter& dataWriter)
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{
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return addFile(std::move(name),
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//
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{},
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{},
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GeneralBitFlags(),
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std::move(lastModificationTime),
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dataWriter);
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}
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//////////////////////////////////////////////////////////////////////////
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tl::result<void> ZipWriter::addFile(tl::string name,
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tl::span<const uint8_t> comment,
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tl::span<const uint8_t> extraField,
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GeneralBitFlags generalBitFlags,
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tl::optional<time_t> lastModificationTime,
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const DataWriter& dataWriter)
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{
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if (name.size() > tl::numeric_limits<uint16_t>::max())
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return tl::make_generic_error("Name too long");
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if (comment.size() > tl::numeric_limits<uint16_t>::max())
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return tl::make_generic_error("Comment too long");
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if (extraField.size() + sizeof(ExtendedInformationExtraField64) > tl::numeric_limits<uint16_t>::max())
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return tl::make_generic_error("Extra field too long");
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//////////////////////////////////////////////////////////////////////////
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// Cannot compute the whole header as we don't know how big the data will be.
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// So we compute as much as possible from the header, enough to figure out the padding.
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// The we skip to the data section and write it - computing its size at the same time.
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// Then we go back to the header section, fill in all the info (since we now know the size, and implictly if it's zip32/64 format) and write the header, name
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// etc) NOTE - because of this we always have to write the ExtendedInformationExtraField64 section, even if the final format will not be zip64
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LocalFileHeader header;
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header.extraFieldLength = tl::narrow<uint16_t>(extraField.size()) + sizeof(ExtendedInformationExtraField64);
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header.generalBitFlag = generalBitFlags.value() | tl::narrow<uint16_t>(GeneralBitFlag::LanguageEncodingFlag);
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header.lastModFileDate = 0;
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header.lastModFileTime = 0;
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if (lastModificationTime != tl::nullopt)
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computeMsDosTime(*lastModificationTime, header.lastModFileDate, header.lastModFileTime);
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header.filenameLength = tl::narrow<uint16_t>(name.size());
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const uint64_t padding = computePadding(m_sink.tell(), header);
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m_sink.seekRel(padding);
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const uint64_t localHeaderOffset = m_sink.tell();
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// now skip to the data
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m_sink.seekRel(sizeof(LocalFileHeader) + header.filenameLength + header.extraFieldLength);
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const uint64_t startOffset = m_sink.tell();
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// write the data - this computes the size as well
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DataWriterResult dataProviderRes = dataWriter(m_sink);
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if (!dataProviderRes)
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return dataProviderRes.error();
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const DataWriterPayload payload = dataProviderRes.value();
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header.compressionMethod = tl::narrow<uint16_t>(payload.compressionMethod);
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header.crc32 = payload.uncompressedCRC32;
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const uint64_t endOffset = m_sink.tell();
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const uint64_t compressedSize = endOffset - startOffset;
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const uint64_t uncompressedSize = payload.uncompressedSize ? payload.uncompressedSize : compressedSize;
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// write the size fields (in zip64, these are -1)
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header.compressedSize = static_cast<uint32_t>(-1);
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header.uncompressedSize = static_cast<uint32_t>(-1);
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// now go back and write the header
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m_sink.seekBeg(localHeaderOffset);
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m_sink.write({ reinterpret_cast<const uint8_t*>(&header), sizeof(LocalFileHeader) });
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// the filename
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if (!name.empty())
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m_sink.write({ reinterpret_cast<const uint8_t*>(name.data()), name.size() });
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// extended field - always present!
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{
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ExtendedInformationExtraField64 extended;
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extended.size = static_cast<uint16_t>(sizeof(ExtendedInformationExtraField64) - 4); // Substract the tag + size fields.
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extended.compressedSize = compressedSize;
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extended.originalSize = uncompressedSize;
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extended.localHeaderOffset = localHeaderOffset;
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m_sink.write({ reinterpret_cast<const uint8_t*>(&extended), sizeof(ExtendedInformationExtraField64) });
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}
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// custom fields
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if (!extraField.empty())
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m_sink.write(extraField);
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m_sink.seekBeg(endOffset);
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// store the central directory record
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CentralDirectoryRecord record;
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record.header = computeCentralDirectoryFileHeader(header, true);
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record.compressedSize = compressedSize;
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record.uncompressedSize = uncompressedSize;
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record.localHeaderOffset = localHeaderOffset;
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record.header.localHeaderOffset = static_cast<uint32_t>(-1); //zip64 mandates -1
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record.zip64 = true;
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record.header.fileCommentLength = tl::narrow<uint16_t>(comment.size());
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record.name = std::move(name);
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record.comment.assign(comment.begin(), comment.end());
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record.extraField.assign(extraField.begin(), extraField.end());
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m_records.push_back(std::move(record));
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return tl::success();
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}
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//////////////////////////////////////////////////////////////////////////
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void ZipWriter::finish()
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{
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const uint64_t centralDirectoryRecordsOffset = m_sink.tell();
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for (const CentralDirectoryRecord& record : m_records)
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{
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TL_ASSERT(record.header.filenameLength == record.name.size());
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TL_ASSERT(record.header.extraFieldLength == record.extraField.size() + (record.zip64 ? sizeof(ExtendedInformationExtraField64) : 0));
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TL_ASSERT(record.header.fileCommentLength == record.comment.size());
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m_sink.write({ reinterpret_cast<const uint8_t*>(&record.header), sizeof(CentralDirectoryFileHeader) });
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if (!record.name.empty())
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m_sink.write({ reinterpret_cast<const uint8_t*>(record.name.data()), record.name.size() });
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if (!record.extraField.empty())
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m_sink.write(record.extraField);
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if (record.zip64)
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{
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ExtendedInformationExtraField64 extended;
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extended.size = tl::narrow<uint16_t>(sizeof(ExtendedInformationExtraField64) - 4); // Subtract the tag + size fields.
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extended.originalSize = record.uncompressedSize;
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extended.compressedSize = record.compressedSize;
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extended.localHeaderOffset = record.localHeaderOffset;
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m_sink.write({ reinterpret_cast<const uint8_t*>(&extended), sizeof(ExtendedInformationExtraField64) });
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}
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if (!record.comment.empty())
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m_sink.write(record.comment);
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}
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const uint64_t sizeOfCentralDirectoryRecords = m_sink.tell() - centralDirectoryRecordsOffset;
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const bool zip64 = centralDirectoryRecordsOffset >= tl::numeric_limits<uint32_t>::max() || //
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sizeOfCentralDirectoryRecords >= tl::numeric_limits<uint32_t>::max() || //
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m_records.size() >= tl::numeric_limits<uint16_t>::max();
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if (zip64)
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{
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const uint64_t endOfCentralDirectoryRecord64Offset = m_sink.tell();
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{
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EndOfCentralDirectoryRecord64 header;
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header.endOfCentralDirectorySize = sizeof(EndOfCentralDirectoryRecord64) - 12;
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header.centralDirectoryRecordCountOnThisDisk = m_records.size();
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header.centralDirectoryRecordCount = m_records.size();
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header.centralDirectorySize = sizeOfCentralDirectoryRecords;
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header.centralDirectoryOffset = centralDirectoryRecordsOffset;
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m_sink.write({ reinterpret_cast<const uint8_t*>(&header), sizeof(EndOfCentralDirectoryRecord64) });
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}
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{
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EndOfCentralDirectoryLocator64 header;
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header.endOfCentralDirectoryRecordOffset = endOfCentralDirectoryRecord64Offset;
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header.diskCount = 1;
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m_sink.write({ reinterpret_cast<const uint8_t*>(&header), sizeof(EndOfCentralDirectoryLocator64) });
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}
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}
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EndOfCentralDirectoryRecord header;
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header.centralDirectoryRecordCountOnThisDisk = zip64 ? static_cast<uint16_t>(-1) : tl::narrow<uint16_t>(m_records.size());
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header.centralDirectoryRecordCount = zip64 ? static_cast<uint16_t>(-1) : tl::narrow<uint16_t>(m_records.size());
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header.centralDirectorySize = zip64 ? static_cast<uint32_t>(-1) : tl::narrow<uint32_t>(sizeOfCentralDirectoryRecords);
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header.centralDirectoryOffset = zip64 ? static_cast<uint32_t>(-1) : tl::narrow<uint32_t>(centralDirectoryRecordsOffset);
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m_sink.write({ reinterpret_cast<const uint8_t*>(&header), sizeof(EndOfCentralDirectoryRecord) });
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}
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//////////////////////////////////////////////////////////////////////////
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inline uint64_t ZipWriter::computePadding(uint64_t offset, const LocalFileHeader& header) const
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{
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const uint64_t dataOffset = offset + sizeof(LocalFileHeader) + header.filenameLength + header.extraFieldLength;
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const uint64_t m = dataOffset % m_fileDataAlignment;
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if (m == 0)
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return 0;
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return m_fileDataAlignment - m;
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}
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//////////////////////////////////////////////////////////////////////////
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}
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