Welcome to SpiceShop Theme

Sea summo mazim ex, ea errem eleifend definitionem vim. Ut nec hinc dolor possim mei ludus efficiendi ei sea summo mazim ex.

7Zip的格式

7Zip的格式

我一直使用7Zip,今天下载了7Zip的代码,才知道7Zip的格式。所以将之Copy到这里。

7z Format description (2.30 Beta 25)
———————————–

This file contains description of 7z archive format.
7z archive can contain files compressed with any method.
See “Methods.txt” for description for defined compressing methods.

Format structure Overview
————————-

Some fields can be optional.

Archive structure
~~~~~~~~~~~~~~~~~ 
SignatureHeader
[PackedStreams]
[PackedStreamsForHeaders]
[
  Header
  or
  {
    Packed Header
    HeaderInfo
  }
]

Header structure
~~~~~~~~~~~~~~~~ 
{
  ArchiveProperties
  AdditionalStreams
  {
    PackInfo
    {
      PackPos
      NumPackStreams
      Sizes[NumPackStreams]
      CRCs[NumPackStreams]
    }
    CodersInfo
    {
      NumFolders
      Folders[NumFolders]
      {
        NumCoders
        CodersInfo[NumCoders]
        {
          ID
          NumInStreams;
          NumOutStreams;
          PropertiesSize
          Properties[PropertiesSize]
        }
        NumBindPairs
        BindPairsInfo[NumBindPairs]
        {
          InIndex;
          OutIndex;
        }
        PackedIndices
      }
      UnPackSize[Folders][Folders.NumOutstreams]
      CRCs[NumFolders]
    }
    SubStreamsInfo
    {
      NumUnPackStreamsInFolders[NumFolders];
      UnPackSizes[]
      CRCs[]
    }
  }

  MainStreamsInfo
  {
    (Same as in AdditionalStreams)
  }
  FilesInfo
  {
    NumFiles
    Properties[]
    {
      ID
      Size
      Data
    }
  }
}

 

HeaderInfo structure
~~~~~~~~~~~~~~~~~~~~
{
  (Same as in AdditionalStreams)
}

Notes about Notation and encoding
———————————

7z uses little endian encoding.

7z archive format has optional headers that are marked as
[]
Header
[]

REAL_UINT64 means real UINT64.

UINT64 means real UINT64 encoded with the following scheme:

  Size of encoding sequence depends from first byte:
  First_Byte  Extra_Bytes        Value
  (binary)  
  0xxxxxxx               : ( xxxxxxx           )
  10xxxxxx    BYTE y[1]  : (  xxxxxx << (8 * 1)) + y
  110xxxxx    BYTE y[2]  : (   xxxxx << (8 * 2)) + y
  …
  1111110x    BYTE y[6]  : (       x << (8 * 6)) + y
  11111110    BYTE y[7]  :                         y
  11111111    BYTE y[8]  :                         y

Property IDs
————

0x00 = kEnd,

0x01 = kHeader,

0x02 = kArchiveProperties,
0x03 = kAdditionalStreamsInfo,
0x04 = kMainStreamsInfo,
0x05 = kFilesInfo,
0x06 = kPackInfo,
0x07 = kUnPackInfo,
0x08 = kSubStreamsInfo,

0x09 = kSize,
0x0A = kCRC,

0x0B = kFolder,

0x0C = kCodersUnPackSize,
0x0D = kNumUnPackStream,

0x0E = kEmptyStream,
0x0F = kEmptyFile,
0x10 = kAnti,

0x11 = kName,
0x12 = kCreationTime,
0x13 = kLastAccessTime,
0x14 = kLastWriteTime,
0x15 = kWinAttributes,
0x16 = kComment,

0x17 = kEncodedHeader,

7z format headers
—————–

SignatureHeader
~~~~~~~~~~~~~~~
  BYTE kSignature[6] = {‘7’, ‘z’, 0xBC, 0xAF, 0x27, 0x1C};

  ArchiveVersion
  {
    BYTE Major;   // now = 0
    BYTE Minor;   // now = 2
  };

  UINT32 StartHeaderCRC;

  StartHeader
  {
    REAL_UINT64 NextHeaderOffset
    REAL_UINT64 NextHeaderSize
    UINT32 NextHeaderCRC
  }

………………………

ArchiveProperties
~~~~~~~~~~~~~~~~~
BYTE NID::kArchiveProperties (0x02)
for (;;)
{
  BYTE PropertyType;
  if (aType == 0)
    break;
  UINT64 PropertySize;
  BYTE PropertyData[PropertySize];
}

Digests (NumStreams)
~~~~~~~~~~~~~~~~~~~~~
  BYTE AllAreDefined
  if (AllAreDefined == 0)
  {
    for(NumStreams)
      BIT Defined
  }
  UINT32 CRCs[NumDefined]

PackInfo
~~~~~~~~~~~~
  BYTE NID::kPackInfo  (0x06)
  UINT64 PackPos
  UINT64 NumPackStreams

  []
  BYTE NID::kSize    (0x09)
  UINT64 PackSizes[NumPackStreams]
  []

  []
  BYTE NID::kCRC      (0x0A)
  PackStreamDigests[NumPackStreams]
  []

  BYTE NID::kEnd

Folder
~~~~~~
  UINT64 NumCoders;
  for (NumCoders)
  {
    BYTE
    {
      0:3 DecompressionMethod.IDSize
      4:
        0 – IsSimple
        1 – Is not simple
      5:
        0 – No Attributes
        1 – There Are Attributes
      7:
        0 – Last Method in Alternative_Method_List
        1 – There are more alternative methods
    }
    BYTE DecompressionMethod.ID[DecompressionMethod.IDSize]
    if (!IsSimple)
    {
      UINT64 NumInStreams;
      UINT64 NumOutStreams;
    }
    if (DecompressionMethod[0] != 0)
    {
      UINT64 PropertiesSize
      BYTE Properties[PropertiesSize]
    }
  }
  NumBindPairs = NumOutStreamsTotal – 1;

  for (NumBindPairs)
  {
    UINT64 InIndex;
    UINT64 OutIndex;
  }

  NumPackedStreams = NumInStreamsTotal – NumBindPairs;
  if (NumPackedStreams > 1)
    for(NumPackedStreams)
    {
      UINT64 Index;
    };

Coders Info
~~~~~~~~~~~

  BYTE NID::kUnPackInfo  (0x07)

  BYTE NID::kFolder  (0x0B)
  UINT64 NumFolders
  BYTE External
  switch(External)
  {
    case 0:
      Folders[NumFolders]
    case 1:
      UINT64 DataStreamIndex
  }

  BYTE ID::kCodersUnPackSize  (0x0C)
  for(Folders)
    for(Folder.NumOutStreams)
     UINT64 UnPackSize;

  []
  BYTE NID::kCRC   (0x0A)
  UnPackDigests[NumFolders]
  []

  BYTE NID::kEnd

SubStreams Info
~~~~~~~~~~~~~~
  BYTE NID::kSubStreamsInfo; (0x08)

  []
  BYTE NID::kNumUnPackStream; (0x0D)
  UINT64 NumUnPackStreamsInFolders[NumFolders];
  []

  []
  BYTE NID::kSize  (0x09)
  UINT64 UnPackSizes[]
  []

  []
  BYTE NID::kCRC  (0x0A)
  Digests[Number of streams with unknown CRC]
  []

  BYTE NID::kEnd

Streams Info
~~~~~~~~~~~~

  []
  PackInfo
  []

  []
  CodersInfo
  []

  []
  SubStreamsInfo
  []

  BYTE NID::kEnd

FilesInfo
~~~~~~~~~
  BYTE NID::kFilesInfo;  (0x05)
  UINT64 NumFiles

  for (;;)
  {
    BYTE PropertyType;
    if (aType == 0)
      break;

    UINT64 Size;

    switch(PropertyType)
    {
      kEmptyStream:   (0x0E)
        for(NumFiles)
          BIT IsEmptyStream

      kEmptyFile:     (0x0F)
        for(EmptyStreams)
          BIT IsEmptyFile

      kAnti:          (0x10)
        for(EmptyStreams)
          BIT IsAntiFile
      case kCreationTime:   (0x12)
      case kLastAccessTime: (0x13)
      case kLastWriteTime:  (0x14)
        BYTE AllAreDefined
        if (AllAreDefined == 0)
        {
          for(NumFiles)
            BIT TimeDefined
        }
        BYTE External;
        if(External != 0)
          UINT64 DataIndex
        []
        for(Definded Items)
          UINT32 Time
        []
      kNames:     (0x11)
        BYTE External;
        if(External != 0)
          UINT64 DataIndex
        []
        for(Files)
        {
          wchar_t Names[NameSize];
          wchar_t 0;
        }
        []

      kAttributes:  (0x15)
        BYTE AllAreDefined
        if (AllAreDefined == 0)
        {
          for(NumFiles)
            BIT AttributesAreDefined
        }
        BYTE External;
        if(External != 0)
          UINT64 DataIndex
        []
        for(Definded Attributes)
          UINT32 Attributes
        []
    }
  }

Header
~~~~~~
  BYTE NID::kHeader (0x01)

  []
  ArchiveProperties
  []

  []
  BYTE NID::kAdditionalStreamsInfo; (0x03)
  StreamsInfo
  []

  []
  BYTE NID::kMainStreamsInfo;    (0x04)
  StreamsInfo
  []

  []
  FilesInfo
  []

  BYTE NID::kEnd

HeaderInfo
~~~~~~~~~~
  []
  BYTE NID::kEncodedHeader; (0x17)
  StreamsInfo for Encoded Header
  []


End of document

张太国

Comments are closed.