zip 文件格式说明书

秒速五厘米 2022-08-13 14:42 312阅读 0赞

Files stored in arbitrary order.  Large .ZIP files can span multiple
    volumes or be split into user-defined segment sizes. All values
    are stored in little-endian byte order unless otherwise specified. 
    
    总览 .zip 文件格式：
    [文件标头 1]
    [文件数据 1]
    [数据描述符记录 1]
    .
    .
    .
    [文件标头 n]
    [文件数据 n]
    [数据描述符记录 n]
    [归档解密标头]
    [归档额外数据记录]
    [中央目录结构]
    [中央目录记录的 Zip64 结尾]
    [中央目录定位器的 Zip64 结尾]
    [中央目录记录的结尾]
    
    - A 文件标头 --------------------
    
    文件标头签名       4 字节 [开始 0] (0x04034b50)
    所需版本           2 字节 [开始 4]
    一般用途位标记     2 字节 [开始 6]
    压缩方法           2 字节 [开始 8] (8=DEFLATE; 0=UNCOMPRESSED)
    文件的最后修改时间 2 字节 [开始 10]
    文件的最后修改日期 2 字节 [开始 12]
    crc-32             4 字节 [开始 14]
    压缩后的大小       4 字节 [开始 18]
    解压缩后的大小     4 字节 [开始 22]
    文件名长度         2 字节 [开始 26]
    额外字段长度       2 字节 [开始 28]
    
    文件名             变量
    额外字段           变量
    
    
    
    - B 文件数据 --------------------
    
    紧接着文件标头就是已压缩的或未压缩的文件数据。
    在 zip 归档里面的每一个文件都是一系列重复的
    [文件标头][文件数据][数据描述符记录]。
    
    
    
    - C 数据描述符记录 --------------------
    
      crc-32         4 字节 [开始 0]
      压缩后的大小   4 字节 [开始 4]
      解压缩后的大小 4 字节 [开始 8]
    
          This descriptor exists only if bit 3 of the general
          purpose bit flag is set (see below).  It is byte aligned
          and immediately follows the last byte of compressed data.
          This descriptor is used only when it was not possible to
          seek in the output .ZIP file, e.g., when the output .ZIP file
          was standard output or a non-seekable device.  For ZIP64(tm) format
          archives, the compressed and uncompressed sizes are 8 bytes each.
    
          When compressing files, compressed and uncompressed sizes 
          should be stored in ZIP64 format (as 8 byte values) when a 
          files size exceeds 0xFFFFFFFF.   However ZIP64 format may be 
          used regardless of the size of a file.  When extracting, if 
          the zip64 extended information extra field is present for 
          the file the compressed and uncompressed sizes will be 8
          byte values.  
    
          Although not originally assigned a signature, the value 
          0x08074b50 has commonly been adopted as a signature value 
          for the data descriptor record.  Implementers should be 
          aware that ZIP files may be encountered with or without this 
          signature marking data descriptors and should account for
          either case when reading ZIP files to ensure compatibility.
          When writing ZIP files, it is recommended to include the
          signature value marking the data descriptor record.  When
          the signature is used, the fields currently defined for
          the data descriptor record will immediately follow the
          signature.
    
          An extensible data descriptor will be released in a future
          version of this APPNOTE.  This new record is intended to
          resolve conflicts with the use of this record going forward,
          and to provide better support for streamed file processing.
    
          When the Central Directory Encryption method is used, the data
          descriptor record is not required, but may be used.  If present,
          and bit 3 of the general purpose bit field is set to indicate
          its presence, the values in fields of the data descriptor
          record should be set to binary zeros.
    
    
    - D 归档解密标头 --------------------
    
          The Archive Decryption Header is introduced in version 6.2
          of the ZIP format specification.  This record exists in support
          of the Central Directory Encryption Feature implemented as part of 
          the Strong Encryption Specification as described in this document.
          When the Central Directory Structure is encrypted, this decryption
          header will precede the encrypted data segment.  The encrypted
          data segment will consist of the Archive extra data record (if
          present) and the encrypted Central Directory Structure data.
          The format of this data record is identical to the Decryption
          header record preceding compressed file data.  If the central 
          directory structure is encrypted, the location of the start of
          this data record is determined using the Start of Central Directory
          field in the Zip64 End of Central Directory record.  Refer to the 
          section on the Strong Encryption Specification for information
          on the fields used in the Archive Decryption Header record.
    
    
    - E 归档额外数据记录 --------------------
    
      归档额外数据签名 4 字节 [开始 0] (0x08064b50)
      额外字段长度     4 字节 [开始 4]
      额外字段         4 字节 [开始 8]
    
          The Archive Extra Data Record is introduced in version 6.2
          of the ZIP format specification.  This record exists in support
          of the Central Directory Encryption Feature implemented as part of 
          the Strong Encryption Specification as described in this document.
          When present, this record immediately precedes the central 
          directory data structure.  The size of this data record will be
          included in the Size of the Central Directory field in the
          End of Central Directory record.  If the central directory structure
          is compressed, but not encrypted, the location of the start of
          this data record is determined using the Start of Central Directory
          field in the Zip64 End of Central Directory record.  
    
    - F 中央目录结构 --------------------
    
    [文件标头 1]
    .
    .
    .
    [文件标头 n]
    [数字签名]
    
    文件标头:
      中央文件标头签名   4 字节 [开始 0] (0x02014b50)
      version made by    2 字节 [开始 4]
      所需版本           2 字节 [开始 6]
      一般用途位标记     2 字节 [开始 8]
      压缩方法           2 字节 [开始 10] (8=DEFLATE; 0=UNCOMPRESSED)
      文件的最后修改时间 2 字节 [开始 12]
      文件的最后修改日期 2 字节 [开始 14]
      crc-32             4 字节 [开始 16]
      压缩后的大小       4 字节 [开始 20]
      解压缩后的大小     4 字节 [开始 24]
      文件名长度         2 字节 [开始 28]
      额外字段长度       2 字节 [开始 30]
      文件注释长度       2 字节 [开始 32]
      磁盘开始号         2 字节 [开始 34]
      内部文件属性       2 字节 [开始 36]
      外部文件属性       4 字节 [开始 38]
      相关的标头偏移量   4 字节 [开始 42]
      
      文件名             变量
      额外字段           变量
      文件注释           变量
    
    数字签名:
      标头签名 4 字节 [开始 0] (0x05054b50)
      数据大小 2 字节 [开始 4]
      签名数据 变量
    
          With the introduction of the Central Directory Encryption 
          feature in version 6.2 of this specification, the Central 
          Directory Structure may be stored both compressed and encrypted. 
          Although not required, it is assumed when encrypting the
          Central Directory Structure, that it will be compressed
          for greater storage efficiency.  Information on the
          Central Directory Encryption feature can be found in the section
          describing the Strong Encryption Specification. The Digital 
          Signature record will be neither compressed nor encrypted.
    
    - G 中央目录记录的 Zip64 结尾 --------------------
    
    中央目录的 Zip64 结尾签名       4 字节 [开始 0] (0x06064b50)
    中央目录记录的 Zip64 结尾大小   8 字节 [开始 4]
    version made by                 2 字节 [开始 12]
    所需版本                        2 字节 [开始 14]
    磁盘数目                        4 字节 [开始 16]
    number of the disk with the
     start of the central directory 4 字节 [开始 20]
    total number of entries in the
     central directory on this disk 8 字节 [开始 24]
    中央目录入口总数                8 字节 [开始 32]
    中央目录的大小                  8 字节 [开始 40]
    offset of start of central
     directory with respect to
     the starting disk number       8 字节 [开始 48]
    zip64 extensible data sector    变量   [开始 56]
    
            The value stored into the "size of zip64 end of central
            directory record" should be the size of the remaining
            record and should not include the leading 12 bytes.
      
            Size = SizeOfFixedFields + SizeOfVariableData - 12.
    
            The above record structure defines Version 1 of the 
            zip64 end of central directory record. Version 1 was 
            implemented in versions of this specification preceding 
            6.2 in support of the ZIP64 large file feature. The 
            introduction of the Central Directory Encryption feature 
            implemented in version 6.2 as part of the Strong Encryption 
            Specification defines Version 2 of this record structure. 
            Refer to the section describing the Strong Encryption 
            Specification for details on the version 2 format for 
            this record.
    
            Special purpose data may reside in the zip64 extensible data
            sector field following either a V1 or V2 version of this
            record.  To ensure identification of this special purpose data
            it must include an identifying header block consisting of the
            following:
    
               Header ID  -  2 bytes
               Data Size  -  4 bytes
    
            The Header ID field indicates the type of data that is in the 
            data block that follows.
    
            Data Size identifies the number of bytes that follow for this
            data block type.
    
            Multiple special purpose data blocks may be present, but each
            must be preceded by a Header ID and Data Size field.  Current
            mappings of Header ID values supported in this field are as
            defined in APPENDIX C.
    
    
    
    - H 中央目录定位器的 Zip64 结尾 --------------------
    
    中央目录定位器的 Zip64 结尾签名       4 字节 [开始 0] (0x07064b50)
    number of the disk with the
     start of the zip64 end of 
     central directory                    4 字节 [开始 4]
    相关的中央目录记录的 Zip64 结尾偏移量 8 字节 [开始 8]
    磁盘总数                              4 字节 [开始 16]
    
    
    - I 中央目录记录的结尾 --------------------
    
    中央目录记录签名                4 字节 [开始 0] (0x06054b50) 注：使用“冒泡”从文件尾追查上来，找到这个签名。
    磁盘编号                        2 字节 [开始 4]
    中央目录开始磁盘编号            2 字节 [开始 6]
    本磁盘上在中央目录里的入口总数  2 字节 [开始 8]
    中央目录里的入口总数            2 字节 [开始 10] 注：文件总数，文件夹也算一个文件。
    中央目录的大小                  4 字节 [开始 12]
    中央目录对第一张磁盘的偏移量    4 字节 [开始 16]
    .ZIP 文件注释长度               2 字节 [开始 20]
    .ZIP 文件注释                   变量   [开始 22] 注：此处需要使用ByteArray.readMultiByte()，在第二个参数里指明“gb2312”才能支持中文。
     
     
     转帖：http://riaoo.com/wp-content/uploads/2009/09/ZIP-File-Format-Specification-2007-zh_cn.txt