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 <becker@informatik.hu-berlin.de>
clone
public Object clone()
Clone the entry.
computeCheckSum
public long computeCheckSum(byte[] buf)
Compute the checksum of a tar entry header.
buf
- The tar entry's header buffer.
equals
public boolean equals(TarEntry it)
Determine if the two entries are equal. Equality is determined
by the header names being equal.
- it Entry to be checked for equality.
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.
- An array of TarEntry's for this entry's children.
getFile
public File getFile()
Get this entry's file.
getFileTarHeader
public void getFileTarHeader(TarHeader hdr,
File file)
throws InvalidHeaderException
Fill in a TarHeader with information from a File.
hdr
- The TarHeader to fill in.file
- The file from which to get the header information.
getGroupId
public int getGroupId()
Get this entry's group id.
getGroupName
public String getGroupName()
Get this entry's group name.
getHeader
public TarHeader getHeader()
Get this entry's header.
getModTime
public Date getModTime()
Set this entry's modification time.
getName
public String getName()
Get this entry's name.
getSize
public long getSize()
Get this entry's file size.
getUserId
public int getUserId()
Get this entry's user id.
getUserName
public String getUserName()
Get this entry's user name.
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.
desc
- Entry to be checked as a descendent of this.
- True if entry is a descendant of this.
isDirectory
public boolean isDirectory()
Return whether or not this entry represents a directory.
- True if this entry is a directory.
isGNUTarFormat
public boolean isGNUTarFormat()
Returns true if this entry's header is in the GNU 'ustar' format.
- True if the entry's header is in the GNU 'ustar' format.
isUSTarFormat
public boolean isUSTarFormat()
Returns true if this entry's header is in "ustar" format.
- True if the entry's header is in "ustar" format.
isUnixTarFormat
public boolean isUnixTarFormat()
Returns true if this entry's header is in the old "unix-tar" format.
- True if the entry's header is in the old "unix-tar" format.
nameTarHeader
public void nameTarHeader(TarHeader hdr,
String name)
Fill in a TarHeader given only the entry's name.
hdr
- The TarHeader to fill in.name
- The tar entry name.
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 <dmehring@astro.uiuc.edu>.
hdr
- The TarHeader to fill in from the buffer information.
setGNUTarFormat
public void setGNUTarFormat()
Sets this entry's header format to GNU "ustar".
setGroupId
public void setGroupId(int groupId)
Set this entry's group id.
groupId
- This entry's new group id.
setGroupName
public void setGroupName(String groupName)
Set this entry's group name.
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.
userId
- This entry's new user id.groupId
- This entry's new group id.
setModTime
public void setModTime(Date time)
Set this entry's modification time.
time
- This entry's new modification time.
setModTime
public void setModTime(long time)
Set this entry's modification time. The parameter passed
to this method is in "Java time".
time
- This entry's new modification time.
setName
public void setName(String name)
Set this entry's name.
name
- This entry's new name.
setNames
public void setNames(String userName,
String groupName)
Convenience method to set this entry's group and user names.
userName
- This entry's new user name.groupName
- This entry's new group name.
setSize
public void setSize(long size)
Set this entry's file size.
size
- This entry's new file size.
setUSTarFormat
public void setUSTarFormat()
Sets this entry's header format to "ustar".
setUnixTarFormat
public void setUnixTarFormat()
Sets this entry's header format to "unix-style".
setUserId
public void setUserId(int userId)
Set this entry's user id.
userId
- This entry's new user id.
setUserName
public void setUserName(String userName)
Set this entry's user name.
userName
- This entry's new user name.
toString
public String toString()
writeEntryHeader
public void writeEntryHeader(byte[] outbuf)
throws InvalidHeaderException
Write an entry's header information to a header buffer.
This method can throw an InvalidHeaderException
outbuf
- The tar entry header buffer to fill in.