unzip

Unzip and zip

The unzip and zip package contains several routines to unzip or zip files on every Lazarus supported platforms. There are 4 units:

• zip a unit which implements an zip mechanism with native Pascal links.
• unzip a unit which implements an unzip mechanism with native Pascal links.
• ziputils contains some tools for the unzip unit.
• zipbase a unit which defines the interface for the info-zip unzip library.

The zip library unit is included in Lazarus 2.

Example

Zip compression is in widespread use. It is also used to compress EPUB files.

uses
  unzip,ziputils;
const  cover  =  'cover.jpeg';
var UnZipper          : unzFile;
    epubfile, UnPackPathFile : String;
    zfinfos  :  unz_file_info_ptr;
    i        :  Integer;
    li_SizeRead,li_SizeWrite,li_TotalW  : Longint;
    lb_FoundFile : Boolean;
    FBuffer  :  TExtFileBuffer;
    li_HandleDest : Integer;    
begin
   epubfile :='/Your/Path/to/epub';
   UnPackPathFile :='/Your/Path/to/uncompressed/file';
   try
     UnZipper:=unzOpen(@epubfile[1]);
     if unzLocateFile(UnZipper,@cover[1],2)= UNZ_OK then
       try
         unzOpenCurrentFile(UnZipper);
         Getmem(zfinfos,SizeOf(zfinfos));
         unzGetCurrentFileInfo(UnZipper,zfinfos,@cover[1],SizeOf(cover),nil,0,nil,0);
         lb_FoundFile := False;
         if not FileExistsUTF8(UnPackPathFile)
           Then  FileCreateUTF8(UnPackPathFile);
         li_HandleDest := FileOpenUTF8(UnPackPathFile, fmopenwrite );
         while not lb_FoundFile do
           begin
             li_SizeRead := unzReadCurrentFile(UnZipper,@FBuffer[0],high ( Fbuffer ) + 1);
             if li_SizeRead < high ( Fbuffer ) + 1 then lb_FoundFile := True;
             li_SizeWrite := Filewrite(li_HandleDest,Fbuffer,li_SizeRead);
             inc( li_TotalW, li_SizeWrite );
           end;
         Break;
       finally
         Freemem(zfinfos,SizeOf(zfinfos));
     end;
   finally
     try
       FileClose(li_HandleDest);
     finally
       unzCloseCurrentFile(UnZipper);
       unzClose(UnZipper);
     end;
   end;   
end.

See also

• zip library link
• paszlib: Object oriented zip file handling which does not require external libraries

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