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<p>LIBARCHIVE(3) BSD Library Functions Manual

<p style="margin-top: 1em"><b>NAME</b></p>

<p style="margin-left:6%;"><b>libarchive</b> &mdash;
functions for reading and writing streaming archives</p>

<p style="margin-top: 1em"><b>OVERVIEW</b></p>

<p style="margin-left:6%;">The <b>libarchive</b> library
provides a flexible interface for reading and writing
archives in various formats such as tar and cpio.
<b>libarchive</b> 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.</p>

<p style="margin-left:6%; margin-top: 1em">When reading an
archive, the library automatically detects the format and
the compression. The library currently has read support


<p style="margin-left:12%;">old-style tar archives,</p>


<p style="margin-left:12%;">most variants of the POSIX
&rsquo;&rsquo;ustar&rsquo;&rsquo; format,</p>


<p style="margin-left:12%;">the POSIX &rsquo;&rsquo;pax
interchange&rsquo;&rsquo; format,</p>


<p style="margin-left:12%;">GNU-format tar archives,</p>


<p style="margin-left:12%;">most common cpio archive


<p style="margin-left:12%;">ISO9660 CD images (including
RockRidge and Joliet extensions),</p>


<p style="margin-left:12%;">Zip archives,</p>


<p style="margin-left:12%;">ar archives (including GNU/SysV
and BSD extensions),</p>


<p style="margin-left:12%;">Microsoft CAB archives,</p>


<p style="margin-left:12%;">LHA archives,</p>


<p style="margin-left:12%;">mtree file tree


<p style="margin-left:12%;">RAR archives,</p>


<p style="margin-left:12%;">XAR archives.</p>

<p style="margin-left:6%;">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.</p>

<p style="margin-left:6%; margin-top: 1em">When writing an
archive, you can specify the compression to be used and the
format to use. The library can write</p>


<p style="margin-left:12%;">POSIX-standard
&rsquo;&rsquo;ustar&rsquo;&rsquo; archives,</p>


<p style="margin-left:12%;">POSIX &rsquo;&rsquo;pax
interchange format&rsquo;&rsquo; archives,</p>


<p style="margin-left:12%;">POSIX octet-oriented cpio


<p style="margin-left:12%;">Zip archive,</p>


<p style="margin-left:12%;">two different variants of shar


<p style="margin-left:12%;">ISO9660 CD images,</p>


<p style="margin-left:12%;">7-Zip archives,</p>


<p style="margin-left:12%;">ar archives,</p>


<p style="margin-left:12%;">mtree file tree


<p style="margin-left:12%;">XAR archives.</p>

<p style="margin-left:6%;">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.</p>

<p style="margin-left:6%; margin-top: 1em">The read and
write APIs are accessed through the
<b>archive_read_XXX</b>() functions and the
<b>archive_write_XXX</b>() functions, respectively, and
either can be used independently of the other.</p>

<p style="margin-left:6%; margin-top: 1em">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.</p>

<p style="margin-top: 1em"><b>READING AN ARCHIVE</b></p>

<p style="margin-left:6%;">See archive_read(3).</p>

<p style="margin-top: 1em"><b>WRITING AN ARCHIVE</b></p>

<p style="margin-left:6%;">See archive_write(3).</p>

<p style="margin-top: 1em"><b>WRITING ENTRIES TO

<p style="margin-left:6%;">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
<b>archive_read_extract</b>(); 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

<p style="margin-top: 1em"><b>READING ENTRIES FROM

<p style="margin-left:6%;">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)

<p style="margin-top: 1em"><b>DESCRIPTION</b></p>

<p style="margin-left:6%;">Detailed descriptions of each
function are provided by the corresponding manual pages.</p>

<p style="margin-left:6%; margin-top: 1em">All of the
functions utilize an opaque struct archive datatype that
provides access to the archive contents.</p>

<p style="margin-left:6%; margin-top: 1em">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).</p>

<p style="margin-left:6%; margin-top: 1em">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 <i>PATH_MAX</i>.</p>

<p style="margin-top: 1em"><b>RETURN VALUES</b></p>

<p style="margin-left:6%;">Most functions return
<b>ARCHIVE_OK</b> (zero) on success, non-zero on error. The
return value indicates the general severity of the error,
ranging from <b>ARCHIVE_WARN</b>, which indicates a minor
problem that should probably be reported to the user, to
<b>ARCHIVE_FATAL</b>, which indicates a serious problem that
will prevent any further operations on this archive. On
error, the <b>archive_errno</b>() function can be used to
retrieve a numeric error code (see errno(2)). The
<b>archive_error_string</b>() returns a textual error
message suitable for display.</p>

<p style="margin-left:6%; margin-top: 1em"><b>archive_read_new</b>()
and <b>archive_write_new</b>() return pointers to an
allocated and initialized struct archive object.</p>

<p style="margin-left:6%; margin-top: 1em"><b>archive_read_data</b>()
and <b>archive_write_data</b>() 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 <b>archive_errno</b>()
and <b>archive_error_string</b>() functions can be used to
obtain more information.</p>

<p style="margin-top: 1em"><b>ENVIRONMENT</b></p>

<p style="margin-left:6%;">There are character set
conversions within the archive_entry(3) functions that are
impacted by the currently-selected locale.</p>

<p style="margin-top: 1em"><b>SEE ALSO</b></p>

<p style="margin-left:6%;">tar(1), archive_entry(3),
archive_read(3), archive_util(3), archive_write(3),

<p style="margin-top: 1em"><b>HISTORY</b></p>

<p style="margin-left:6%;">The <b>libarchive</b> library
first appeared in FreeBSD&nbsp;5.3.</p>

<p style="margin-top: 1em"><b>AUTHORS</b></p>

<p style="margin-left:6%;">The <b>libarchive</b> library
was originally written by Tim Kientzle

<p style="margin-top: 1em"><b>BUGS</b></p>

<p style="margin-left:6%;">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.</p>

<p style="margin-left:6%; margin-top: 1em">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.</p>

<p style="margin-left:6%; margin-top: 1em">The ISO9660
reader cannot yet read all ISO9660 images; it should learn
how to seek.</p>

<p style="margin-left:6%; margin-top: 1em">The AR writer
requires the client program to use two passes, unlike all
other libarchive writers.</p>

<p style="margin-left:6%; margin-top: 1em">BSD
March&nbsp;18, 2012 BSD</p>