Class TarEntry

  • All Implemented Interfaces:
    Cloneable

    public class TarEntry
    extends Object
    implements Cloneable
    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.

    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.

    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.

    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.

    
     Original Unix Tar Header:
    
     Field  Field     Field
     Width  Name      Meaning
     -----  --------- ---------------------------
       100  name      name of file
         8  mode      file mode
         8  uid       owner user ID
         8  gid       owner group ID
        12  size      length of file in bytes
        12  mtime     modify time of file
         8  chksum    checksum for header
         1  link      indicator for links
       100  linkname  name of linked file
    
     
    
     POSIX "ustar" Style Tar Header:
    
     Field  Field     Field
     Width  Name      Meaning
     -----  --------- ---------------------------
       100  name      name of file
         8  mode      file mode
         8  uid       owner user ID
         8  gid       owner group ID
        12  size      length of file in bytes
        12  mtime     modify time of file
         8  chksum    checksum for header
         1  typeflag  type of file
       100  linkname  name of linked file
         6  magic     USTAR indicator
         2  version   USTAR version
        32  uname     owner user name
        32  gname     owner group name
         8  devmajor  device major number
         8  devminor  device minor number
       155  prefix    prefix for file name
    
     struct posix_header
       {                     byte offset
       char name[100];            0
       char mode[8];            100
       char uid[8];             108
       char gid[8];             116
       char size[12];           124
       char mtime[12];          136
       char chksum[8];          148
       char typeflag;           156
       char linkname[100];      157
       char magic[6];           257
       char version[2];         263
       char uname[32];          265
       char gname[32];          297
       char devmajor[8];        329
       char devminor[8];        337
       char prefix[155];        345
       };                       500
    
     
    Note that while the class does recognize GNU formatted headers, it does not perform proper processing of GNU archives. I hope to add the GNU support someday. Directory "size" fix contributed by: Bert Becker
    Author:
    Timothy Gerard Endres,
    See Also:
    TarHeader
    • Field Detail

      • file

        protected File file
        If this entry represents a File, this references it.
      • header

        protected TarHeader header
        This is the entry's header information.
      • unixFormat

        protected boolean unixFormat
        Set to true if this is a "old-unix" format entry.
      • ustarFormat

        protected boolean ustarFormat
        Set to true if this is a 'ustar' format entry.
      • gnuFormat

        protected boolean gnuFormat
        Set to true if this is a GNU 'ustar' format entry.
    • Constructor Detail

      • TarEntry

        protected TarEntry()
        The default constructor is protected for use only by subclasses.
      • TarEntry

        public TarEntry​(String name)
        Construct an entry with only a name. This allows the programmer to construct the entry's header "by hand". File is set to null.
      • TarEntry

        public TarEntry​(File file)
                 throws InvalidHeaderException
        Construct an entry for a file. File is set to file, and the header is constructed from information from the file.
        Parameters:
        file - The file that the entry represents.
        Throws:
        InvalidHeaderException
      • TarEntry

        public TarEntry​(byte[] headerBuf)
                 throws InvalidHeaderException
        Construct an entry from an archive's header bytes. File is set to null.
        Parameters:
        headerBuf - The header bytes from a tar archive entry.
        Throws:
        InvalidHeaderException
    • Method Detail

      • isUSTarFormat

        public boolean isUSTarFormat()
        Returns true if this entry's header is in "ustar" format.
        Returns:
        True if the entry's header is in "ustar" format.
      • setUSTarFormat

        public void setUSTarFormat()
        Sets this entry's header format to "ustar".
      • isGNUTarFormat

        public boolean isGNUTarFormat()
        Returns true if this entry's header is in the GNU 'ustar' format.
        Returns:
        True if the entry's header is in the GNU 'ustar' format.
      • setGNUTarFormat

        public void setGNUTarFormat()
        Sets this entry's header format to GNU "ustar".
      • isUnixTarFormat

        public boolean isUnixTarFormat()
        Returns true if this entry's header is in the old "unix-tar" format.
        Returns:
        True if the entry's header is in the old "unix-tar" format.
      • setUnixTarFormat

        public void setUnixTarFormat()
        Sets this entry's header format to "unix-style".
      • equals

        public boolean equals​(TarEntry it)
        Determine if the two entries are equal. Equality is determined by the header names being equal.
        Returns:
        it Entry to be checked for equality.
      • isDescendent

        public boolean isDescendent​(TarEntry desc)
        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.
        Parameters:
        desc - Entry to be checked as a descendent of this.
        Returns:
        True if entry is a descendant of this.
      • getHeader

        public TarHeader getHeader()
        Get this entry's header.
        Returns:
        This entry's TarHeader.
      • getName

        public String getName()
        Get this entry's name.
        Returns:
        This entry's name.
      • setName

        public void setName​(String name)
        Set this entry's name.
        Parameters:
        name - This entry's new name.
      • getUserId

        public int getUserId()
        Get this entry's user id.
        Returns:
        This entry's user id.
      • setUserId

        public void setUserId​(int userId)
        Set this entry's user id.
        Parameters:
        userId - This entry's new user id.
      • getGroupId

        public int getGroupId()
        Get this entry's group id.
        Returns:
        This entry's group id.
      • setGroupId

        public void setGroupId​(int groupId)
        Set this entry's group id.
        Parameters:
        groupId - This entry's new group id.
      • getUserName

        public String getUserName()
        Get this entry's user name.
        Returns:
        This entry's user name.
      • setUserName

        public void setUserName​(String userName)
        Set this entry's user name.
        Parameters:
        userName - This entry's new user name.
      • getGroupName

        public String getGroupName()
        Get this entry's group name.
        Returns:
        This entry's group name.
      • setGroupName

        public void setGroupName​(String groupName)
        Set this entry's group name.
        Parameters:
        groupName - This entry's new group name.
      • setIds

        public void setIds​(int userId,
                           int groupId)
        Convenience method to set this entry's group and user ids.
        Parameters:
        userId - This entry's new user id.
        groupId - This entry's new group id.
      • setNames

        public void setNames​(String userName,
                             String groupName)
        Convenience method to set this entry's group and user names.
        Parameters:
        userName - This entry's new user name.
        groupName - This entry's new group name.
      • setModTime

        public void setModTime​(long time)
        Set this entry's modification time. The parameter passed to this method is in "Java time".
        Parameters:
        time - This entry's new modification time.
      • setModTime

        public void setModTime​(Date time)
        Set this entry's modification time.
        Parameters:
        time - This entry's new modification time.
      • getModTime

        public Date getModTime()
        Set this entry's modification time.
        Parameters:
        time - This entry's new modification time.
      • getFile

        public File getFile()
        Get this entry's file.
        Returns:
        This entry's file.
      • getSize

        public long getSize()
        Get this entry's file size.
        Returns:
        This entry's file size.
      • setSize

        public void setSize​(long size)
        Set this entry's file size.
        Parameters:
        size - This entry's new file size.
      • isDirectory

        public boolean isDirectory()
        Return whether or not this entry represents a directory.
        Returns:
        True if this entry is a directory.
      • getFileTarHeader

        public void getFileTarHeader​(TarHeader hdr,
                                     File file)
                              throws InvalidHeaderException
        Fill in a TarHeader with information from a File.
        Parameters:
        hdr - The TarHeader to fill in.
        file - The file from which to get the header information.
        Throws:
        InvalidHeaderException
      • getDirectoryEntries

        public TarEntry[] getDirectoryEntries()
                                       throws InvalidHeaderException
        If this entry represents a file, and the file is a directory, return an array of TarEntries for this entry's children.
        Returns:
        An array of TarEntry's for this entry's children.
        Throws:
        InvalidHeaderException
      • computeCheckSum

        public long computeCheckSum​(byte[] buf)
        Compute the checksum of a tar entry header.
        Parameters:
        buf - The tar entry's header buffer.
        Returns:
        The computed checksum.
      • writeEntryHeader

        public void writeEntryHeader​(byte[] outbuf)
                              throws InvalidHeaderException
        Write an entry's header information to a header buffer. This method can throw an InvalidHeaderException
        Parameters:
        outbuf - The tar entry header buffer to fill in.
        Throws:
        InvalidHeaderException - If the name will not fit in the header.
      • parseTarHeader

        public void parseTarHeader​(TarHeader hdr,
                                   byte[] headerBuf)
                            throws InvalidHeaderException
        Parse an entry's TarHeader information from a header buffer. Old unix-style code contributed by David Mehringer .
        Parameters:
        hdr - The TarHeader to fill in from the buffer information.
        header - The tar entry header buffer to get information from.
        Throws:
        InvalidHeaderException
      • nameTarHeader

        public void nameTarHeader​(TarHeader hdr,
                                  String name)
        Fill in a TarHeader given only the entry's name.
        Parameters:
        hdr - The TarHeader to fill in.
        name - The tar entry name.