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 LIBARCHIVE(3)                                                 LIBARCHIVE(3)
                               March 18, 2012



 NAME
      libarchive - functions for reading and writing streaming archives

 OVERVIEW
      The libarchive library provides a flexible interface for reading and
      writing archives in various formats such as tar and cpio.  libarchive
      also supports reading and writing archives compressed using various
      compression filters such as gzip and bzip2.  The library is inherently
      stream-oriented; readers serially iterate through the archive, writers
      serially add things to the archive.  In particular, note that there is
      currently no built-in support for random access nor for in-place
      modification.

      When reading an archive, the library automatically detects the format
      and the compression.  The library currently has read support for:

           +    old-style tar archives,

           +    most variants of the POSIX ``ustar'' format,

           +    the POSIX ``pax interchange'' format,

           +    GNU-format tar archives,

           +    most common cpio archive formats,

           +    ISO9660 CD images (including RockRidge and Joliet
                extensions),

           +    Zip archives,

           +    ar archives (including GNU/SysV and BSD extensions),

           +    Microsoft CAB archives,

           +    LHA archives,

           +    mtree file tree descriptions,

           +    RAR archives,

           +    XAR archives.
      The library automatically detects archives compressed with gzip(1),
      bzip2(1), xz(1), lzip(1), or compress(1) and decompresses them
      transparently.  It can similarly detect and decode archives processed
      with uuencode(1) or which have an rpm(1) header.

      When writing an archive, you can specify the compression to be used
      and the format to use.  The library can write





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 LIBARCHIVE(3)                                                 LIBARCHIVE(3)
                               March 18, 2012



           +    POSIX-standard ``ustar'' archives,

           +    POSIX ``pax interchange format'' archives,

           +    POSIX octet-oriented cpio archives,

           +    Zip archive,

           +    two different variants of shar archives,

           +    ISO9660 CD images,

           +    7-Zip archives,

           +    ar archives,

           +    mtree file tree descriptions,

           +    XAR archives.
      Pax interchange format is an extension of the tar archive format that
      eliminates essentially all of the limitations of historic tar formats
      in a standard fashion that is supported by POSIX-compliant pax(1)
      implementations on many systems as well as several newer
      implementations of tar(1).  Note that the default write format will
      suppress the pax extended attributes for most entries; explicitly
      requesting pax format will enable those attributes for all entries.

      The read and write APIs are accessed through the archive_read_XXX()
      functions and the archive_write_XXX() functions, respectively, and
      either can be used independently of the other.

      The rest of this manual page provides an overview of the library
      operation.  More detailed information can be found in the individual
      manual pages for each API or utility function.

 READING AN ARCHIVE
      See archive_read(3).

 WRITING AN ARCHIVE
      See archive_write(3).

 WRITING ENTRIES TO DISK
      The archive_write_disk(3) API allows you to write archive_entry(3)
      objects to disk using the same API used by archive_write(3).  The
      archive_write_disk(3) API is used internally by
      archive_read_extract(;) using it directly can provide greater control
      over how entries get written to disk.  This API also makes it possible
      to share code between archive-to-archive copy and archive-to-disk
      extraction operations.





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 LIBARCHIVE(3)                                                 LIBARCHIVE(3)
                               March 18, 2012



 READING ENTRIES FROM DISK
      The archive_read_disk(3) supports for populating archive_entry(3)
      objects from information in the filesystem.  This includes the
      information accessible from the stat(2) system call as well as ACLs,
      extended attributes, and other metadata.  The archive_read_disk(3) API
      also supports iterating over directory trees, which allows directories
      of files to be read using an API compatible with the archive_read(3)
      API.

 DESCRIPTION
      Detailed descriptions of each function are provided by the
      corresponding manual pages.

      All of the functions utilize an opaque Tn struct archive datatype that
      provides access to the archive contents.

      The Tn struct archive_entry structure contains a complete description
      of a single archive entry.  It uses an opaque interface that is fully
      documented in archive_entry(3).

      Users familiar with historic formats should be aware that the newer
      variants have eliminated most restrictions on the length of textual
      fields.  Clients should not assume that filenames, link names, user
      names, or group names are limited in length.  In particular, pax
      interchange format can easily accommodate pathnames in arbitrary
      character sets that exceed PATH_MAX.

 RETURN VALUES
      Most functions return ARCHIVE_OK (zero) on success, non-zero on error.
      The return value indicates the general severity of the error, ranging
      from ARCHIVE_WARN, which indicates a minor problem that should
      probably be reported to the user, to ARCHIVE_FATAL, which indicates a
      serious problem that will prevent any further operations on this
      archive.  On error, the archive_errno() function can be used to
      retrieve a numeric error code (see errno(2)).  The
      archive_error_string() returns a textual error message suitable for
      display.

      archive_read_new() and archive_write_new() return pointers to an
      allocated and initialized Tn struct archive object.

      archive_read_data() and archive_write_data() return a count of the
      number of bytes actually read or written.  A value of zero indicates
      the end of the data for this entry.  A negative value indicates an
      error, in which case the archive_errno() and archive_error_string()
      functions can be used to obtain more information.

 ENVIRONMENT
      There are character set conversions within the archive_entry(3)
      functions that are impacted by the currently-selected locale.




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 LIBARCHIVE(3)                                                 LIBARCHIVE(3)
                               March 18, 2012



 SEE ALSO
      tar(1), archive_entry(3), archive_read(3), archive_util(3),
      archive_write(3), tar(5)

 HISTORY
      The libarchive library first appeared in FreeBSD 5.3.

 AUTHORS
      -nosplit The libarchive library was originally written by Tim Kientzle
      <kientzle@acm.org.>

 BUGS
      Some archive formats support information that is not supported by Tn
      struct archive_entry.  Such information cannot be fully archived or
      restored using this library.  This includes, for example, comments,
      character sets, or the arbitrary key/value pairs that can appear in
      pax interchange format archives.

      Conversely, of course, not all of the information that can be stored
      in an Tn struct archive_entry is supported by all formats.  For
      example, cpio formats do not support nanosecond timestamps; old tar
      formats do not support large device numbers.

      The ISO9660 reader cannot yet read all ISO9660 images; it should learn
      how to seek.

      The AR writer requires the client program to use two passes, unlike
      all other libarchive writers.


























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