Provided by: libarchive-dev_3.0.3-6ubuntu1_i386 bug

NAME

     libarchive -- functions for reading and writing streaming archives

LIBRARY

     library ``libarchive''

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:
     +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.
     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
     +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.
     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 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
     written to disk.  This API also makes it possible to share code between
     archive-to-archive copy and archive-to-disk extraction operations.

READING ENTRIES FROM DISK

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

DESCRIPTION

     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 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 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 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
     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.)