Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
LIBARCHIVE(3)	       FreeBSD Library Functions Manual		 LIBARCHIVE(3)

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 com-
     pression 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 modifi-
     cation.

     When reading an archive, the library automatically	detects	the format and
     the compression.  The library currently has read support for:
     +o	 old-style tar archives,
     +o	 most variants of the POSIX ``ustar'' format,
     +o	 the POSIX ``pax interchange'' format,
     +o	 GNU-format tar	archives,
     +o	 most common cpio archive formats,
     +o	 ISO9660 CD images (including RockRidge	and Joliet extensions),
     +o	 Zip archives,
     +o	 ar archives (including	GNU/SysV and BSD extensions),
     +o	 Microsoft CAB archives,
     +o	 LHA archives,
     +o	 mtree file tree descriptions,
     +o	 RAR archives,
     +o	 XAR archives.
     The library automatically detects archives	compressed with	gzip(1),
     bzip2(1), xz(1), lzip(1), or compress(1) and decompresses them transpar-
     ently.  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
     +o	 POSIX-standard	``ustar'' archives,
     +o	 POSIX ``pax interchange format'' archives,
     +o	 POSIX octet-oriented cpio archives,
     +o	 Zip archive,
     +o	 two different variants	of shar	archives,
     +o	 ISO9660 CD images,
     +o	 7-Zip archives,
     +o	 ar archives,
     +o	 mtree file tree descriptions,
     +o	 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) implemen-
     tations 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() func-
     tions 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 opera-
     tion.  More detailed information can be found in the individual manual
     pages for each API	or utility function.

READING	AN ARCHIVE
     See libarchive_read(3).

WRITING	AN ARCHIVE
     See libarchive_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	writ-
     ten to disk.  This	API also makes it possible to share code between ar-
     chive-to-archive copy and archive-to-disk extraction operations.

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	acces-
     sible 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 struct archive datatype that pro-
     vides 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 docu-
     mented in archive_entry(3).

     Users familiar with historic formats should be aware that the newer vari-
     ants 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 allo-
     cated 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.

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

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

BUGS
     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 sup-
     port 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.

FreeBSD	9.3			March 18, 2012			   FreeBSD 9.3

NAME | OVERVIEW | READING AN ARCHIVE | WRITING AN ARCHIVE | WRITING ENTRIES TO DISK | READING ENTRIES FROM DISK | DESCRIPTION | RETURN VALUES | ENVIRONMENT | SEE ALSO | HISTORY | AUTHORS | BUGS

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=archive&sektion=3&manpath=FreeBSD+10.0-RELEASE>

home | help