Provided by: libarchive-dev_3.0.3-6ubuntu1_amd64 bug


     libarchive — functions for reading and writing streaming archives


     Reading and Writing Streaming Archives Library (libarchive, -larchive)


     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.
     The library automatically detects archives compressed with gzip(1), bzip2(1), xz(1), or
     compress(1) and decompresses them transparently.

     When writing an archive, you can specify the compression to be used and the format to use.
     The library can write
     ·   POSIX-standard “ustar” archives,
     ·   POSIX “pax interchange format” archives,
     ·   POSIX octet-oriented cpio archives,
     ·   Zip archive,
     ·   two different variants of shar 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

     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.


     See libarchive_read(3).


     See libarchive_write(3).


     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.


     The archive_read_disk(3) provides some support for populating archive_entry(3) objects from
     information in the filesystem.


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

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

     The 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


     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
     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.


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


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


     The libarchive library first appeared in FreeBSD 5.3.


     The libarchive library was written by Tim Kientzle <>.


     Some archive formats support information that is not supported by 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 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 archive_read_disk(3) API should support iterating over filesystems; that would make it
     possible to share code among disk-to-archive, archive-to-archive, archive-to-disk, and disk-
     to-disk operations.  Currently, it only supports reading the information for a single file.
     (Which is still quite useful, as it hides a lot of system-specific details.)