Package org.apache.commons.compress.archivers.ar

Class ArArchiveEntry

java.lang.Object
org.apache.commons.compress.archivers.ar.ArArchiveEntry
All Implemented Interfaces:
ArchiveEntry
public class ArArchiveEntry extends Object implements ArchiveEntry
Represents an archive entry in the "ar" format.

Each AR archive starts with "!<arch>" followed by a LF. After these 8 bytes the archive entries are listed. The format of an entry header is as it follows: 

 START BYTE   END BYTE    NAME                    FORMAT      LENGTH
 0            15          File name               ASCII       16
 16           27          Modification timestamp  Decimal     12
 28           33          Owner ID                Decimal     6
 34           39          Group ID                Decimal     6
 40           47          File mode               Octal       8
 48           57          File size (bytes)       Decimal     10
 58           59          File magic              \140\012    2

This specifies that an ar archive entry header contains 60 bytes.

Due to the limitation of the file name length to 16 bytes GNU and BSD has their own variants of this format. Currently Commons Compress can read but not write the GNU variant. It fully supports the BSD variant.

See Also:

  • Field Details

    • TRAILER

      public static final String TRAILER
      The trailer for each entry 0x60 0x0A
      See Also:

    • DEFAULT_MODE

      private static final int DEFAULT_MODE
      See Also:

    • name

      private final String name
      SVR4/GNU adds a trailing / to names; BSD does not. They also vary in how names longer than 16 characters are represented. (Not yet fully supported by this implementation)

    • userId

      private final int userId

    • groupId

      private final int groupId

    • mode

      private final int mode

    • lastModified

      private final long lastModified

    • length

      private final long length

  • Constructor Details

    • ArArchiveEntry

      public ArArchiveEntry(File inputFile, String entryName)
      Creates a new instance using the attributes of the given file
      Parameters:
      inputFile - the file to create an entry from
      entryName - the name of the entry

    • ArArchiveEntry

      public ArArchiveEntry(Path inputPath, String entryName, LinkOption... options) throws IOException
      Creates a new instance using the attributes of the given file
      Parameters:
      inputPath - the file to create an entry from
      entryName - the name of the entry
      options - options indicating how symbolic links are handled.
      Throws:
      IOException - if an I/O error occurs.
      Since:
      1.21

    • ArArchiveEntry

      public ArArchiveEntry(String name, long length)
      Constructs a new instance using a couple of default values.

      Sets userId and groupId to 0, the octal file mode to 644 and the last modified time to the current time.

      Parameters:
      name - name of the entry
      length - length of the entry in bytes

    • ArArchiveEntry

      public ArArchiveEntry(String name, long length, int userId, int groupId, int mode, long lastModified)
      Constructs a new instance.
      Parameters:
      name - name of the entry
      length - length of the entry in bytes
      userId - numeric user id
      groupId - numeric group id
      mode - file mode
      lastModified - last modified time in seconds since the epoch

  • Method Details

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • getGroupId

      public int getGroupId()
      Gets the group ID.
      Returns:
      the group ID.

    • getLastModified

      public long getLastModified()
      Gets the last modified time in seconds since the epoch.
      Returns:
      the last modified date.

    • getLastModifiedDate

      public Date getLastModifiedDate()
      Description copied from interface: ArchiveEntry
      Gets the last modified date of this entry.
      Specified by:
      getLastModifiedDate in interface ArchiveEntry
      Returns:
      the last modified date of this entry.

    • getLength

      public long getLength()
      Gets the length.
      Returns:
      the length.

    • getMode

      public int getMode()
      Gets the mode.
      Returns:
      the mode.

    • getName

      public String getName()
      Description copied from interface: ArchiveEntry
      Gets the name of the entry in this archive. May refer to a file or directory or other item.

      This method returns the raw name as it is stored inside of the archive.

      Specified by:
      getName in interface ArchiveEntry
      Returns:
      The name of this entry in the archive.

    • getSize

      public long getSize()
      Description copied from interface: ArchiveEntry
      Gets the uncompressed size of this entry. May be -1 (SIZE_UNKNOWN) if the size is unknown
      Specified by:
      getSize in interface ArchiveEntry
      Returns:
      the uncompressed size of this entry.

    • getUserId

      public int getUserId()
      Gets the user ID.
      Returns:
      the user ID.

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • isDirectory

      public boolean isDirectory()
      Description copied from interface: ArchiveEntry
      Tests whether this entry refers to a directory (true).
      Specified by:
      isDirectory in interface ArchiveEntry
      Returns:
      true if this entry refers to a directory.