Zip文件格式

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标识头

50 4B 01 02 kCentralFileHeader

50 4B 03 04 kLocalFileHeader

50 4B 05 06 kEndOfCentralDir

kEndOfCentralDir:

文件最后位置, cdStartOffset 定位 kCentralFileHeader

struct CEcd{  UInt16 thisDiskNumber;  UInt16 startCDDiskNumber;  UInt16 numEntriesInCDOnThisDisk;  UInt16 numEntriesInCD;  UInt32 cdSize;  UInt32 cdStartOffset;  UInt16 commentSize;  void Parse(const Byte *p);};void CEcd::Parse(const Byte *p){  thisDiskNumber = Get16(p);  startCDDiskNumber = Get16(p + 2);  numEntriesInCDOnThisDisk = Get16(p + 4);  numEntriesInCD = Get16(p + 6);  cdSize = Get32(p + 8);  cdStartOffset = Get32(p + 12);  commentSize = Get16(p + 16);}

kCentralFileHeader:

集中数据压缩包内项目, LocalHeaderPosition 为实际数据偏移 kLocalFileHeader

<span style="font-family: Arial, Helvetica, sans-serif;">HRESULT CInArchive::ReadCdItem(CItemEx &item)</span>

{  item.FromCentral = true;  const int kBufSize = 42;  Byte p[kBufSize];  SafeReadBytes(p, kBufSize);  item.MadeByVersion.Version = p[0];  item.MadeByVersion.HostOS = p[1];  item.ExtractVersion.Version = p[2];  item.ExtractVersion.HostOS = p[3];  item.Flags = Get16(p + 4);  item.CompressionMethod = Get16(p + 6);  item.Time = Get32(p + 8);  item.FileCRC = Get32(p + 12);  item.PackSize = Get32(p + 16);  item.UnPackSize = Get32(p + 20);  UInt16 headerNameSize = Get16(p + 24);  UInt16 headerExtraSize = Get16(p + 26);  UInt16 headerCommentSize = Get16(p + 28);  UInt32 headerDiskNumberStart = Get16(p + 30);  item.InternalAttributes = Get16(p + 32);  item.ExternalAttributes = Get32(p + 34);  item.LocalHeaderPosition = Get32(p + 38);  ReadFileName(headerNameSize, item.Name);    if (headerExtraSize > 0)  {    ReadExtra(headerExtraSize, item.CentralExtra, item.UnPackSize, item.PackSize,        item.LocalHeaderPosition, headerDiskNumberStart);  }  if (headerDiskNumberStart != 0)    throw CInArchiveException(CInArchiveException::kMultiVolumeArchiveAreNotSupported);    // May be these strings must be deleted  /*  if (item.IsDir())    item.UnPackSize = 0;  */    ReadBuffer(item.Comment, headerCommentSize);  return S_OK;}

kLocalFileHeader

数据后面紧跟项目压缩后的数据

HRESULT CInArchive::ReadLocalItem(CItemEx &item){  const int kBufSize = 26;  Byte p[kBufSize];  SafeReadBytes(p, kBufSize);  item.ExtractVersion.Version = p[0];  item.ExtractVersion.HostOS = p[1];  item.Flags = Get16(p + 2);  item.CompressionMethod = Get16(p + 4);  item.Time = Get32(p + 6);  item.FileCRC = Get32(p + 10);  item.PackSize = Get32(p + 14);  item.UnPackSize = Get32(p + 18);  UInt32 fileNameSize = Get16(p + 22);  item.LocalExtraSize = Get16(p + 24);  ReadFileName(fileNameSize, item.Name);  item.FileHeaderWithNameSize = 4 + NFileHeader::kLocalBlockSize + fileNameSize;  if (item.LocalExtraSize > 0)  {    UInt64 localHeaderOffset = 0;    UInt32 diskStartNumber = 0;    ReadExtra(item.LocalExtraSize, item.LocalExtra, item.UnPackSize, item.PackSize,      localHeaderOffset, diskStartNumber);  }  /*  if (item.IsDir())    item.UnPackSize = 0;       // check It  */  return S_OK;}

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