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Datei: TarEntry.java Sprache: JAVA

Original von: Isabelle^©

/*
** Authored by Timothy Gerard Endres
** <mailto:[email protected]>  <http://www.trustice.com>
**
** This work has been placed into the public domain.
** You may use this work in any way and for any purpose you wish.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE.
**
*/

package installer;

import java.io.*;
import java.util.Date;

/**
*
* This class represents an entry in a Tar archive. It consists
* of the entry's header, as well as the entry's File. Entries
* can be instantiated in one of three ways, depending on how
* they are to be used.
* <p>
* TarEntries that are created from the header bytes read from
* an archive are instantiated with the TarEntry( byte[] )
* constructor. These entries will be used when extracting from
* or listing the contents of an archive. These entries have their
* header filled in using the header bytes. They also set the File
* to null, since they reference an archive entry not a file.
* <p>
* TarEntries that are created from Files that are to be written
* into an archive are instantiated with the TarEntry( File )
* constructor. These entries have their header filled in using
* the File's information. They also keep a reference to the File
* for convenience when writing entries.
* <p>
* Finally, TarEntries can be constructed from nothing but a name.
* This allows the programmer to construct the entry by hand, for
* instance when only an InputStream is available for writing to
* the archive, and the header information is constructed from
* other information. In this case the header fields are set to
* defaults and the File is set to null.
*
* <p>
* The C structure for a Tar Entry's header is:
* <pre>
* struct header {
* char name[NAMSIZ];
* char mode[8];
* char uid[8];
* char gid[8];
* char size[12];
* char mtime[12];
* char chksum[8];
* char linkflag;
* char linkname[NAMSIZ];
* char magic[8];
* char uname[TUNMLEN];
* char gname[TGNMLEN];
* char devmajor[8];
* char devminor[8];
* } header;
* </pre>
*
* @see TarHeader
*
*/

public
class  TarEntry
extends  Object
{
/**
* If this entry represents a File, this references it.
*/
protected File    file;

/**
* This is the entry's header information.
*/
protected TarHeader   header;

/**
* Construct an entry with only a name. This allows the programmer
* to construct the entry's header "by hand". File is set to null.
*/
public
TarEntry( String name )
  {
  this.initialize();
  this.nameTarHeader( this.header, name );
  }

/**
* Construct an entry for a file. File is set to file, and the
* header is constructed from information from the file.
*
* @param file The file that the entry represents.
*/
public
TarEntry( File file )
  throws InvalidHeaderException
  {
  this.initialize();
  this.getFileTarHeader( this.header, file );
  }

/**
* Construct an entry from an archive's header bytes. File is set
* to null.
*
* @param headerBuf The header bytes from a tar archive entry.
*/
public
TarEntry( byte[] headerBuf )
  throws InvalidHeaderException
  {
  this.initialize();
  this.parseTarHeader( this.header, headerBuf );
  }

/**
* Initialization code common to all constructors.
*/
private void
initialize()
  {
  this.file = null;
  this.header = new TarHeader();
  }

/**
* Determine if the two entries are equal. Equality is determined
* by the header names being equal.
*
* @return it Entry to be checked for equality.
* @return True if the entries are equal.
*/
public boolean
equals( TarEntry it )
  {
  return
   this.header.name.toString().equals
    ( it.header.name.toString() );
  }

/**
* Determine if the given entry is a descendant of this entry.
* Descendancy is determined by the name of the descendant
* starting with this entry's name.
*
* @param desc Entry to be checked as a descendent of this.
* @return True if entry is a descendant of this.
*/
public boolean
isDescendent( TarEntry desc )
  {
  return
   desc.header.name.toString().startsWith
    ( this.header.name.toString() );
  }

/**
* Get this entry's header.
*
* @return This entry's TarHeader.
*/
public TarHeader
getHeader()
  {
  return this.header;
  }

/**
* Get this entry's name.
*
* @return This entry's name.
*/
public String
getName()
  {
  return this.header.name.toString();
  }

/**
* Set this entry's name.
*
* @param name This entry's new name.
*/
public void
setName( String name )
  {
  this.header.name =
   new StringBuffer( name );
  }

/**
* Get this entry's user id.
*
* @return This entry's user id.
*/
public int
getUserId()
  {
  return this.header.userId;
  }

/**
* Set this entry's user id.
*
* @param userId This entry's new user id.
*/
public void
setUserId( int userId )
  {
  this.header.userId = userId;
  }

/**
* Get this entry's group id.
*
* @return This entry's group id.
*/
public int
getGroupId()
  {
  return this.header.groupId;
  }

/**
* Set this entry's group id.
*
* @param groupId This entry's new group id.
*/
public void
setGroupId( int groupId )
  {
  this.header.groupId = groupId;
  }

/**
* Get this entry's user name.
*
* @return This entry's user name.
*/
public String
getUserName()
  {
  return this.header.userName.toString();
  }

/**
* Set this entry's user name.
*
* @param userName This entry's new user name.
*/
public void
setUserName( String userName )
  {
  this.header.userName =
   new StringBuffer( userName );
  }

/**
* Get this entry's group name.
*
* @return This entry's group name.
*/
public String
getGroupName()
  {
  return this.header.groupName.toString();
  }

/**
* Set this entry's group name.
*
* @param groupName This entry's new group name.
*/
public void
setGroupName( String groupName )
  {
  this.header.groupName =
   new StringBuffer( groupName );
  }

/**
* Convenience method to set this entry's group and user ids.
*
* @param userId This entry's new user id.
* @param groupId This entry's new group id.
*/
public void
setIds( int userId, int groupId )
  {
  this.setUserId( userId );
  this.setGroupId( groupId );
  }

/**
* Convenience method to set this entry's group and user names.
*
* @param userName This entry's new user name.
* @param groupName This entry's new group name.
*/
public void
setNames( String userName, String groupName )
  {
  this.setUserName( userName );
  this.setGroupName( groupName );
  }

/**
* Set this entry's modification time. The parameter passed
* to this method is in "Java time".
*
* @param time This entry's new modification time.
*/
public void
setModTime( long time )
  {
  this.header.modTime = time / 1000;
  }

/**
* Set this entry's modification time.
*
* @param time This entry's new modification time.
*/
public void
setModTime( Date time )
  {
  this.header.modTime = time.getTime() / 1000;
  }

/**
* Set this entry's modification time.
*
* @param time This entry's new modification time.
*/
public Date
getModTime()
  {
  return new Date( this.header.modTime * 1000 );
  }

/**
* Get this entry's file.
*
* @return This entry's file.
*/
public File
getFile()
  {
  return this.file;
  }

/**
* Get this entry's file size.
*
* @return This entry's file size.
*/
public long
getSize()
  {
  return this.header.size;
  }

/**
* Set this entry's file size.
*
* @param size This entry's new file size.
*/
public void
setSize( long size )
  {
  this.header.size = size;
  }

/**
* Convenience method that will modify an entry's name directly
* in place in an entry header buffer byte array.
*
* @param outbuf The buffer containing the entry header to modify.
* @param newName The new name to place into the header buffer.
*/
public void
adjustEntryName( byte[] outbuf, String newName )
  {
  int offset = 0;
  offset = TarHeader.getNameBytes
   ( new StringBuffer( newName ),
    outbuf, offset, TarHeader.NAMELEN );
  }

/**
* Return whether or not this entry represents a directory.
*
* @return True if this entry is a directory.
*/
public boolean
isDirectory()
  {
  if ( this.file != null )
   return this.file.isDirectory();

  if ( this.header != null )
   {
   if ( this.header.linkFlag == TarHeader.LF_DIR )
    return true;

   if ( this.header.name.toString().endsWith( "/" ) )
    return true;
   }

  return false;
  }

/**
* Fill in a TarHeader with information from a File.
*
* @param hdr The TarHeader to fill in.
* @param file The file from which to get the header information.
*/
public void
getFileTarHeader( TarHeader hdr, File file )
  throws InvalidHeaderException
  {
  this.file = file;

  String name = file.getPath();
  String osname = System.getProperty( "os.name" );
  if ( osname != null )
   {
   // Strip off drive letters!
   // REVIEW Would a better check be "(File.separator == '\')"?

   // String Win32Prefix = "Windows";
   // String prefix = osname.substring( 0, Win32Prefix.length() );
   // if ( prefix.equalsIgnoreCase( Win32Prefix ) )

   // if ( File.separatorChar == '\\' )

   // Per Patrick Beard:
   String Win32Prefix = "windows";
   if ( osname.toLowerCase().startsWith( Win32Prefix ) )
    {
    if ( name.length() > 2 )
     {
     char ch1 = name.charAt(0);
     char ch2 = name.charAt(1);
     if ( ch2 == ':'
      && ( (ch1 >= 'a' && ch1 <= 'z')
       || (ch1 >= 'A' && ch1 <= 'Z') ) )
      {
      name = name.substring( 2 );
      }
     }
    }
   }

  name = name.replace( File.separatorChar, '/' );

  // No absolute pathnames
  // Windows (and Posix?) paths can start with "\\NetworkDrive\",
  // so we loop on starting /'s.

  for ( ; name.startsWith( "/" ) ; )
   name = name.substring( 1 );

   hdr.linkName = new StringBuffer( "" );

  hdr.name = new StringBuffer( name );

  if ( file.isDirectory() )
   {
   hdr.mode = 040755;
   hdr.linkFlag = TarHeader.LF_DIR;
   if ( hdr.name.charAt( hdr.name.length() - 1 ) != '/' )
    hdr.name.append( "/" );
   }
  else
   {
   hdr.mode = 0100644;
   hdr.linkFlag = TarHeader.LF_NORMAL;
   }

  // UNDONE When File lets us get the userName, use it!

  hdr.size = file.length();
  hdr.modTime = file.lastModified() / 1000;
  hdr.checkSum = 0;
  hdr.devMajor = 0;
  hdr.devMinor = 0;
  }

/**
* If this entry represents a file, and the file is a directory, return
* an array of TarEntries for this entry's children.
*
* @return An array of TarEntry's for this entry's children.
*/
public TarEntry[]
getDirectoryEntries()
  throws InvalidHeaderException
  {
  if ( this.file == null
    || ! this.file.isDirectory() )
   {
   return new TarEntry[0];
   }

  String[] list = this.file.list();

  TarEntry[] result = new TarEntry[ list.length ];

  for ( int i = 0 ; i < list.length ; ++i )
   {
   result[i] =
    new TarEntry
     ( new File( this.file, list[i] ) );
   }

  return result;
  }

/**
* Compute the checksum of a tar entry header.
*
* @param buf The tar entry's header buffer.
* @return The computed checksum.
*/
public long
computeCheckSum( byte[] buf )
  {
  long sum = 0;

  for ( int i = 0 ; i < buf.length ; ++i )
   {
   sum += 255 & buf[ i ];
   }

  return sum;
  }

/**
* Write an entry's header information to a header buffer.
*
* @param outbuf The tar entry header buffer to fill in.
*/
public void
writeEntryHeader( byte[] outbuf )
  {
  int offset = 0;

  offset = TarHeader.getNameBytes
   ( this.header.name, outbuf, offset, TarHeader.NAMELEN );

  offset = TarHeader.getOctalBytes
   ( this.header.mode, outbuf, offset, TarHeader.MODELEN );

  offset = TarHeader.getOctalBytes
   ( this.header.userId, outbuf, offset, TarHeader.UIDLEN );

  offset = TarHeader.getOctalBytes
   ( this.header.groupId, outbuf, offset, TarHeader.GIDLEN );

  long size = this.header.size;

  offset = TarHeader.getLongOctalBytes
   ( size, outbuf, offset, TarHeader.SIZELEN );

  offset = TarHeader.getLongOctalBytes
   ( this.header.modTime, outbuf, offset, TarHeader.MODTIMELEN );

  int csOffset = offset;
  for ( int c = 0 ; c < TarHeader.CHKSUMLEN ; ++c )
   outbuf[ offset++ ] = (byte) ' ';

  outbuf[ offset++ ] = this.header.linkFlag;

  offset = TarHeader.getNameBytes
   ( this.header.linkName, outbuf, offset, TarHeader.NAMELEN );

  offset = TarHeader.getNameBytes
   ( this.header.magic, outbuf, offset, TarHeader.MAGICLEN );

  offset = TarHeader.getNameBytes
   ( this.header.userName, outbuf, offset, TarHeader.UNAMELEN );

  offset = TarHeader.getNameBytes
   ( this.header.groupName, outbuf, offset, TarHeader.GNAMELEN );

  offset = TarHeader.getOctalBytes
   ( this.header.devMajor, outbuf, offset, TarHeader.DEVLEN );

  offset = TarHeader.getOctalBytes
   ( this.header.devMinor, outbuf, offset, TarHeader.DEVLEN );

  for ( ; offset < outbuf.length ; )
   outbuf[ offset++ ] = 0;

  long checkSum = this.computeCheckSum( outbuf );

  TarHeader.getCheckSumOctalBytes
   ( checkSum, outbuf, csOffset, TarHeader.CHKSUMLEN );
  }

/**
* Parse an entry's TarHeader information from a header buffer.
*
* @param hdr The TarHeader to fill in from the buffer information.
* @param header The tar entry header buffer to get information from.
*/
public void
parseTarHeader( TarHeader hdr, byte[] header )
  throws InvalidHeaderException
  {
  int offset = 0;

  hdr.name =
   TarHeader.parseName( header, offset, TarHeader.NAMELEN );

  offset += TarHeader.NAMELEN;

  hdr.mode = (int)
   TarHeader.parseOctal( header, offset, TarHeader.MODELEN );

  offset += TarHeader.MODELEN;

  hdr.userId = (int)
   TarHeader.parseOctal( header, offset, TarHeader.UIDLEN );

  offset += TarHeader.UIDLEN;

  hdr.groupId = (int)
   TarHeader.parseOctal( header, offset, TarHeader.GIDLEN );

  offset += TarHeader.GIDLEN;

  hdr.size =
   TarHeader.parseOctal( header, offset, TarHeader.SIZELEN );

  offset += TarHeader.SIZELEN;

  hdr.modTime =
   TarHeader.parseOctal( header, offset, TarHeader.MODTIMELEN );

  offset += TarHeader.MODTIMELEN;

  hdr.checkSum = (int)
   TarHeader.parseOctal( header, offset, TarHeader.CHKSUMLEN );

  offset += TarHeader.CHKSUMLEN;

  hdr.linkFlag = header[ offset++ ];

  hdr.linkName =
   TarHeader.parseName( header, offset, TarHeader.NAMELEN );

  offset += TarHeader.NAMELEN;

  hdr.magic =
   TarHeader.parseName( header, offset, TarHeader.MAGICLEN );

  offset += TarHeader.MAGICLEN;

  hdr.userName =
   TarHeader.parseName( header, offset, TarHeader.UNAMELEN );

  offset += TarHeader.UNAMELEN;

  hdr.groupName =
   TarHeader.parseName( header, offset, TarHeader.GNAMELEN );

  offset += TarHeader.GNAMELEN;

  hdr.devMajor = (int)
   TarHeader.parseOctal( header, offset, TarHeader.DEVLEN );

  offset += TarHeader.DEVLEN;

  hdr.devMinor = (int)
   TarHeader.parseOctal( header, offset, TarHeader.DEVLEN );
  }

/**
* Fill in a TarHeader given only the entry's name.
*
* @param hdr The TarHeader to fill in.
* @param name The tar entry name.
*/
public void
nameTarHeader( TarHeader hdr, String name )
  {
  boolean isDir = name.endsWith( "/" );

  hdr.checkSum = 0;
  hdr.devMajor = 0;
  hdr.devMinor = 0;

  hdr.name = new StringBuffer( name );
  hdr.mode = isDir ? 040755 : 0100644;
  hdr.userId = 0;
  hdr.groupId = 0;
  hdr.size = 0;
  hdr.checkSum = 0;

  hdr.modTime =
   (new java.util.Date()).getTime() / 1000;

  hdr.linkFlag =
   isDir ? TarHeader.LF_DIR : TarHeader.LF_NORMAL;

  hdr.linkName = new StringBuffer( "" );
  hdr.userName = new StringBuffer( "" );
  hdr.groupName = new StringBuffer( "" );

  hdr.devMajor = 0;
  hdr.devMinor = 0;
  }

}

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