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README for libarchive bundle.
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* http://libarchive.googlecode.com/ is the home for ongoing
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libarchive development, including issue tracker, additional
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documentation, and links to the libarchive mailing lists.
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This distribution bundle includes the following components:
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* libarchive: a library for reading and writing streaming archives
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* tar: the 'bsdtar' program is a full-featured 'tar'
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replacement built on libarchive
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* cpio: the 'bsdcpio' program is a different interface to
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essentially the same functionality
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* examples: Some small example programs that you may find useful.
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* examples/minitar: a compact sample demonstrating use of libarchive.
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I use this for testing link pollution; it should produce a very
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small executable file on most systems.
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* contrib: Various items sent to me by third parties;
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please contact the authors with any questions.
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The top-level directory contains the following information files:
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* NEWS - highlights of recent changes
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* COPYING - what you can do with this
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* INSTALL - installation instructions
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* configure - configuration script, see INSTALL for details.
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* CMakeLists.txt - input for "cmake" build tool, see INSTALL
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The following files in the top-level directory are used by the
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* Makefile.am, aclocal.m4, configure.ac
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- used to build this distribution, only needed by maintainers
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* Makefile.in, config.h.in
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- templates used by configure script
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Guide to Documentation installed by this system:
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* bsdtar.1 explains the use of the bsdtar program
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* bsdcpio.1 explains the use of the bsdcpio program
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* libarchive.3 gives an overview of the library as a whole
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* archive_read.3, archive_write.3, archive_write_disk.3, and
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archive_read_disk.3 provide detailed calling sequences for the read
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* archive_entry.3 details the "struct archive_entry" utility class
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* archive_internals.3 provides some insight into libarchive's
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internal structure and operation.
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* libarchive-formats.5 documents the file formats supported by the library
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* cpio.5, mtree.5, and tar.5 provide detailed information about these
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popular archive formats, including hard-to-find details about
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modern cpio and tar variants.
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The manual pages above are provided in the 'doc' directory in
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a number of different formats.
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You should also read the copious comments in "archive.h" and the
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source code for the sample programs for more details. Please let me
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know about any errors or omissions you find.
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Currently, the library automatically detects and reads the following:
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* compress/LZW compression
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* lzma and xz compression
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* GNU tar format (including GNU long filenames, long link names, and
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* Solaris 9 extended tar format (including ACLs)
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* POSIX pax interchange format
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* POSIX octet-oriented cpio
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* POSIX octet-oriented cpio
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* Binary cpio (big-endian or little-endian)
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* ISO9660 CD-ROM images (with optional Rockridge or Joliet extensions)
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* ZIP archives (with uncompressed or "deflate" compressed entries)
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* GNU and BSD 'ar' archives
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The library can write:
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* compress/LZW compression
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* lzma and xz compression
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* POSIX pax interchange format
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* "restricted" pax format, which will create ustar archives except for
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entries that require pax extensions (for long filenames, ACLs, etc).
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* POSIX octet-oriented cpio
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* ZIP archives (with uncompressed or "deflate" compressed entries)
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* GNU and BSD 'ar' archives
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Notes about the library architecture:
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* This is a heavily stream-oriented system. There is no direct
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support for in-place modification or random access.
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* The library is designed to be extended with new compression and
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archive formats. The only requirement is that the format be
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readable or writable as a stream and that each archive entry be
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independent. There are articles on the libarchive Wiki explaining
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how to extend libarchive.
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* On read, compression and format are always detected automatically.
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* I've attempted to minimize static link pollution. If you don't
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explicitly invoke a particular feature (such as support for a
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particular compression or format), it won't get pulled in.
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In particular, if you don't explicitly enable a particular
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compression or decompression support, you won't need to link
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against the corresponding compression or decompression libraries.
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This also reduces the size of statically-linked binaries in
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environments where that matters.
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* On read, the library accepts whatever blocks you hand it.
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Your read callback is free to pass the library a byte at a time
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or mmap the entire archive and give it to the library at once.
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On write, the library always produces correctly-blocked output.
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* The object-style approach allows you to have multiple archive streams
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open at once. bsdtar uses this in its "@archive" extension.
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* The archive itself is read/written using callback functions.
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You can read an archive directly from an in-memory buffer or
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write it to a socket, if you wish. There are some utility
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functions to provide easy-to-use "open file," etc, capabilities.
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* The read/write APIs are designed to allow individual entries
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to be read or written to any data source: You can create
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a block of data in memory and add it to a tar archive without
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first writing a temporary file. You can also read an entry from
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an archive and write the data directly to a socket. If you want
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to read/write entries to disk, there are convenience functions to
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make this especially easy.
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* Note: "pax interchange format" is really an extended tar format,
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despite what the name says.