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Datei: TarHeader.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;

/**
* This class encapsulates the Tar Entry Header used in Tar Archives.
* The class also holds a number of tar constants, used mostly in headers.
*/

public class
TarHeader extends Object
{
/**
* The length of the name field in a header buffer.
*/
public static final int  NAMELEN = 100;
/**
* The length of the mode field in a header buffer.
*/
public static final int  MODELEN = 8;
/**
* The length of the user id field in a header buffer.
*/
public static final int  UIDLEN = 8;
/**
* The length of the group id field in a header buffer.
*/
public static final int  GIDLEN = 8;
/**
* The length of the checksum field in a header buffer.
*/
public static final int  CHKSUMLEN = 8;
/**
* The length of the size field in a header buffer.
*/
public static final int  SIZELEN = 12;
/**
* The length of the magic field in a header buffer.
*/
public static final int  MAGICLEN = 8;
/**
* The length of the modification time field in a header buffer.
*/
public static final int  MODTIMELEN = 12;
/**
* The length of the user name field in a header buffer.
*/
public static final int  UNAMELEN = 32;
/**
* The length of the group name field in a header buffer.
*/
public static final int  GNAMELEN = 32;
/**
* The length of the devices field in a header buffer.
*/
public static final int  DEVLEN = 8;

/**
* LF_ constants represent the "link flag" of an entry, or more commonly,
* the "entry type". This is the "old way" of indicating a normal file.
*/
public static final byte LF_OLDNORM = 0;
/**
* Normal file type.
*/
public static final byte LF_NORMAL = (byte) '0';
/**
* Link file type.
*/
public static final byte LF_LINK  = (byte) '1';
/**
* Symbolic link file type.
*/
public static final byte LF_SYMLINK = (byte) '2';
/**
* Character device file type.
*/
public static final byte LF_CHR  = (byte) '3';
/**
* Block device file type.
*/
public static final byte LF_BLK  = (byte) '4';
/**
* Directory file type.
*/
public static final byte LF_DIR  = (byte) '5';
/**
* FIFO (pipe) file type.
*/
public static final byte LF_FIFO  = (byte) '6';
/**
* Contiguous file type.
*/
public static final byte LF_CONTIG = (byte) '7';

/**
* The magic tag representing a POSIX tar archive.
*/
public static final String TMAGIC  = "ustar";

/**
* The magic tag representing a GNU tar archive.
*/
public static final String GNU_TMAGIC = "ustar ";

/**
* The entry's name.
*/
public StringBuffer  name;
/**
* The entry's permission mode.
*/
public int    mode;
/**
* The entry's user id.
*/
public int    userId;
/**
* The entry's group id.
*/
public int    groupId;
/**
* The entry's size.
*/
public long    size;
/**
* The entry's modification time.
*/
public long    modTime;
/**
* The entry's checksum.
*/
public int    checkSum;
/**
* The entry's link flag.
*/
public byte    linkFlag;
/**
* The entry's link name.
*/
public StringBuffer  linkName;
/**
* The entry's magic tag.
*/
public StringBuffer  magic;
/**
* The entry's user name.
*/
public StringBuffer  userName;
/**
* The entry's group name.
*/
public StringBuffer  groupName;
/**
* The entry's major device number.
*/
public int    devMajor;
/**
* The entry's minor device number.
*/
public int    devMinor;

public
TarHeader()
  {
  this.magic = new StringBuffer( TarHeader.TMAGIC );

  this.name = new StringBuffer();
  this.linkName = new StringBuffer();

  String user =
   System.getProperty( "user.name", "" );

  if ( user.length() > 31 )
   user = user.substring( 0, 31 );

  this.userId = 0;
  this.groupId = 0;
  this.userName = new StringBuffer( user );
  this.groupName = new StringBuffer( "" );
  }

/**
* TarHeaders can be cloned.
*/
public Object
clone()
  {
  TarHeader hdr = null;

  try {
   hdr = (TarHeader) super.clone();

   hdr.name =
    (this.name == null ) ? null
     : new StringBuffer( this.name.toString() );
   hdr.mode = this.mode;
   hdr.userId = this.userId;
   hdr.groupId = this.groupId;
   hdr.size = this.size;
   hdr.modTime = this.modTime;
   hdr.checkSum = this.checkSum;
   hdr.linkFlag = this.linkFlag;
   hdr.linkName =
    (this.linkName == null ) ? null
     : new StringBuffer( this.linkName.toString() );
   hdr.magic =
    (this.magic == null ) ? null
     : new StringBuffer( this.magic.toString() );
   hdr.userName =
    (this.userName == null ) ? null
     : new StringBuffer( this.userName.toString() );
   hdr.groupName =
    (this.groupName == null ) ? null
     : new StringBuffer( this.groupName.toString() );
   hdr.devMajor = this.devMajor;
   hdr.devMinor = this.devMinor;
   }
  catch ( CloneNotSupportedException ex )
   {
   ex.printStackTrace();
   }

  return hdr;
  }

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

/**
* Parse an octal string from a header buffer. This is used for the
* file permission mode value.
*
* @param header The header buffer from which to parse.
* @param offset The offset into the buffer from which to parse.
* @param length The number of header bytes to parse.
* @return The long value of the octal string.
*/
public static long
parseOctal( byte[] header, int offset, int length )
  throws InvalidHeaderException
  {
  long result = 0;
  boolean stillPadding = true;

  int end = offset + length;
  for ( int i = offset ; i < end ; ++i )
   {
   if ( header[i] == 0 )
    break;

   if ( header[i] == (byte) ' ' || header[i] == '0' )
    {
    if ( stillPadding )
     continue;

    if ( header[i] == (byte) ' ' )
     break;
    }

   stillPadding = false;

   result =
    (result << 3)
     + (header[i] - '0');
   }

  return result;
  }

/**
* Parse an entry name from a header buffer.
*
* @param header The header buffer from which to parse.
* @param offset The offset into the buffer from which to parse.
* @param length The number of header bytes to parse.
* @return The header's entry name.
*/
public static StringBuffer
parseName( byte[] header, int offset, int length )
  throws InvalidHeaderException
  {
  StringBuffer result = new StringBuffer( length );

  int end = offset + length;
  for ( int i = offset ; i < end ; ++i )
   {
   if ( header[i] == 0 )
    break;
   result.append( (char)header[i] );
   }

  return result;
  }

/**
* Determine the number of bytes in an entry name.
*
* @param header The header buffer from which to parse.
* @param offset The offset into the buffer from which to parse.
* @param length The number of header bytes to parse.
* @return The number of bytes in a header's entry name.
*/
public static int
getNameBytes( StringBuffer name, byte[] buf, int offset, int length )
  {
  int i;

  for ( i = 0 ; i < length && i < name.length() ; ++i )
   {
   buf[ offset + i ] = (byte) name.charAt( i );
   }

  for ( ; i < length ; ++i )
   {
   buf[ offset + i ] = 0;
   }

  return offset + length;
  }

/**
* Parse an octal integer from a header buffer.
*
* @param header The header buffer from which to parse.
* @param offset The offset into the buffer from which to parse.
* @param length The number of header bytes to parse.
* @return The integer value of the octal bytes.
*/
public static int
getOctalBytes( long value, byte[] buf, int offset, int length )
  {
  byte[] result = new byte[ length ];

  int idx = length - 1;

  buf[ offset + idx ] = 0;
  --idx;
  buf[ offset + idx ] = (byte) ' ';
  --idx;

  if ( value == 0 )
   {
   buf[ offset + idx ] = (byte) '0';
   --idx;
   }
  else
   {
   for ( long val = value ; idx >= 0 && val > 0 ; --idx )
    {
    buf[ offset + idx ] = (byte)
     ( (byte) '0' + (byte) (val & 7) );
    val = val >> 3;
    }
   }

  for ( ; idx >= 0 ; --idx )
   {
   buf[ offset + idx ] = (byte) ' ';
   }

  return offset + length;
  }

/**
* Parse an octal long integer from a header buffer.
*
* @param header The header buffer from which to parse.
* @param offset The offset into the buffer from which to parse.
* @param length The number of header bytes to parse.
* @return The long value of the octal bytes.
*/
public static int
getLongOctalBytes( long value, byte[] buf, int offset, int length )
  {
  byte[] temp = new byte[ length + 1 ];
  TarHeader.getOctalBytes( value, temp, 0, length + 1 );
  System.arraycopy( temp, 0, buf, offset, length );
  return offset + length;
  }

/**
* Parse the checksum octal integer from a header buffer.
*
* @param header The header buffer from which to parse.
* @param offset The offset into the buffer from which to parse.
* @param length The number of header bytes to parse.
* @return The integer value of the entry's checksum.
*/
public static int
getCheckSumOctalBytes( long value, byte[] buf, int offset, int length )
  {
  TarHeader.getOctalBytes( value, buf, offset, length );
  buf[ offset + length - 1 ] = (byte) ' ';
  buf[ offset + length - 2 ] = 0;
  return offset + length;
  }

}

¤ Dauer der Verarbeitung: 0.27 Sekunden (vorverarbeitet) ¤

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