Zip File Header 정보

< zip 파일 구조 >
*출처: http://en.wikipedia.org/wiki/ZIP_(file_format)

< Zip 파일의 내부 구조 분석 >

1. Local File Header(30byte: 가변값 제외)
     local file header signature  - 4 bytes - (0x04034b50) : 고유 값
     version needed to extract    - 2 bytes 
     general purpose bit flag     - 2 bytes 
     compression method           - 2 bytes 
     last mod file time           - 2 bytes 
     last mod file date           - 2 bytes 
     crc-32                       - 4 bytes
     compressed size              - 4 bytes
     uncompressed size            - 4 bytes
     file name length             - 2 bytes
     extra field length           - 2 bytes 
     file name (variable size)
     extra field (variable size)

2. Central File Header(46byte: 가변값 제외)
     central file header signature - 4 bytes - (0x02014b50) : 고유 값
     version made by               - 2 bytes
     version needed to extract     - 2 bytes
     general purpose bit flag      - 2 bytes
     compression method            - 2 bytes
     last mod file time            - 2 bytes
     last mod file date            - 2 bytes
     crc-32                        - 4 bytes
     compressed size               - 4 bytes
     uncompressed size             - 4 bytes
     file name length              - 2 bytes
     extra field length            - 2 bytes
     file comment length           - 2 bytes
     disk number start             - 2 bytes
     internal file attributes      - 2 bytes
     external file attributes      - 4 bytes
     relative offset of local header 4 bytes
     file name (variable size)
     extra field (variable size)
     file comment (variable size)

3. End Header(22byte: comment 제외)
     end of central dir signature  - 4 bytes - (0x06054b50) : 고유값
     number of this disk           - 2 bytes
     number of the disk with the start of the central directory    - 2 bytes
     total number of entries in the central directory on this disk - 2 bytes
     total number of entries in the central directory              - 2 bytes
     size of the central directory - 4 bytes
     offset of start of central directory with respect to the starting disk number - 4 bytes
     .ZIP file comment length      - 2 bytes
     .ZIP file comment (variable size)
 
*참고 사이트: 
 zip 알고리즘(Deflate) - http://ko.wikipedia.org/wiki/DEFLATE, http://en.wikipedia.org/wiki/DEFLATE
 LZ 77 알고리즘 - http://home.postech.ac.kr/~ehoto/lz77.htm

 ZIP File Format Specification - http://www.pkware.com/documents/casestudies/APPNOTE.TXT

 zlib Home page - http://www.zlib.net/
 Winimage.com minizip - http://www.winimage.com/zLibDll/minizip.html

 Zlib Library Manual - http://kaistizen.net/project/Zip/Index.htm
 Zlib 활용(글쓴이: 윤상배) - http://www.joinc.co.kr/modules/moniwiki/wiki.php/article/zlib_prog