-Welcome to libarchive!
+# Welcome to libarchive!
The libarchive project develops a portable, efficient C library that
can read and write streaming archives in a variety of formats. It
also includes implementations of the common `tar`, `cpio`, and `zcat`
command-line tools that use the libarchive library.
-Questions? Issues?
-* http://www.libarchive.org is the home for ongoing libarchive development, including documentation, and links to the libarchive mailing lists.
-* To report an issue, use the issue tracker at https://github.com/libarchive/libarchive/issues
-* To submit an enhancement to libarchive, please submit a pull request via GitHub: https://github.com/libarchive/libarchive/pulls
+## Questions? Issues?
+
+* http://www.libarchive.org is the home for ongoing
+ libarchive development, including documentation,
+ and links to the libarchive mailing lists.
+* To report an issue, use the issue tracker at
+ https://github.com/libarchive/libarchive/issues
+* To submit an enhancement to libarchive, please
+ submit a pull request via GitHub: https://github.com/libarchive/libarchive/pulls
+
+## Contents of the Distribution
+
+This distribution bundle includes the following major components:
-This distribution bundle includes the following components:
* **libarchive**: a library for reading and writing streaming archives
* **tar**: the 'bsdtar' program is a full-featured 'tar' implementation built on libarchive
* **cpio**: the 'bsdcpio' program is a different interface to essentially the same functionality
* **contrib**: Various items sent to me by third parties; please contact the authors with any questions.
The top-level directory contains the following information files:
+
* **NEWS** - highlights of recent changes
* **COPYING** - what you can do with this
* **INSTALL** - installation instructions
* **README** - this file
-* **configure** - configuration script, see INSTALL for details.
* **CMakeLists.txt** - input for "cmake" build tool, see INSTALL
+* **configure** - configuration script, see INSTALL for details. If your copy of the source lacks a `configure` script, you can try to construct it by running the script in `build/autogen.sh` (or use `cmake`).
-The following files in the top-level directory are used by the
-'configure' script:
- * Makefile.am, aclocal.m4, configure.ac
- - used to build this distribution, only needed by maintainers
- * Makefile.in, config.h.in
- - templates used by configure script
+The following files in the top-level directory are used by the 'configure' script:
+* `Makefile.am`, `aclocal.m4`, `configure.ac` - used to build this distribution, only needed by maintainers
+* `Makefile.in`, `config.h.in` - templates used by configure script
+
+## Documentation
+
+In addition to the informational articles and documentation
+in the online [libarchive Wiki](https://github.com/libarchive/libarchive/wiki),
+the distribution also includes a number of manual pages:
-Guide to Documentation installed by this system:
* bsdtar.1 explains the use of the bsdtar program
* bsdcpio.1 explains the use of the bsdcpio program
* bsdcat.1 explains the use of the bsdcat program
* cpio.5, mtree.5, and tar.5 provide detailed information about these
popular archive formats, including hard-to-find details about
modern cpio and tar variants.
+
The manual pages above are provided in the 'doc' directory in
a number of different formats.
-You should also read the copious comments in "archive.h" and the
+You should also read the copious comments in `archive.h` and the
source code for the sample programs for more details. Please let us
know about any errors or omissions you find.
+## Supported Formats
+
Currently, the library automatically detects and reads the following fomats:
- * GNU tar format (including GNU long filenames, long link names, and sparse files)
- * Solaris 9 extended tar format (including ACLs)
* Old V7 tar archives
* POSIX ustar
+ * GNU tar format (including GNU long filenames, long link names, and sparse files)
+ * Solaris 9 extended tar format (including ACLs)
* POSIX pax interchange format
* POSIX octet-oriented cpio
* SVR4 ASCII cpio
* POSIX octet-oriented cpio
* Binary cpio (big-endian or little-endian)
* ISO9660 CD-ROM images (with optional Rockridge or Joliet extensions)
- * ZIP archives (with uncompressed or "deflate" compressed entries)
+ * ZIP archives (with uncompressed or "deflate" compressed entries, including support for encrypted Zip archives)
* GNU and BSD 'ar' archives
* 'mtree' format
* 7-Zip archives
* Microsoft CAB format
* LHA and LZH archives
- * RAR archives
+ * RAR archives (with some limitations due to RAR's proprietary status)
* XAR archives
The library also detects and handles any of the following before evaluating the archive:
* lz4 compression
* lzop compression
-Notes about the library architecture:
-
- * This is a heavily stream-oriented system. There is no direct
- support for in-place modification or random access.
-
- * The library is designed to be extended with new compression and
- archive formats. The only requirement is that the format be
- readable or writable as a stream and that each archive entry be
- independent. There are articles on the libarchive Wiki explaining
- how to extend libarchive.
-
- * On read, compression and format are always detected automatically.
-
- * I've attempted to minimize static link pollution. If you don't
- explicitly invoke a particular feature (such as support for a
- particular compression or format), it won't get pulled in to
- statically-linked programs. In particular, if you don't explicitly
- enable a particular compression or decompression support, you won't
- need to link against the corresponding compression or decompression
- libraries. This also reduces the size of statically-linked
- binaries in environments where that matters.
-
- * On read, the library accepts whatever blocks you hand it.
- Your read callback is free to pass the library a byte at a time
- or mmap the entire archive and give it to the library at once.
- On write, the library always produces correctly-blocked output.
-
- * The object-style approach allows you to have multiple archive streams
- open at once. bsdtar uses this in its "@archive" extension.
-
- * The archive itself is read/written using callback functions.
- You can read an archive directly from an in-memory buffer or
- write it to a socket, if you wish. There are some utility
- functions to provide easy-to-use "open file," etc, capabilities.
-
- * The read/write APIs are designed to allow individual entries
- to be read or written to any data source: You can create
- a block of data in memory and add it to a tar archive without
- first writing a temporary file. You can also read an entry from
- an archive and write the data directly to a socket. If you want
- to read/write entries to disk, there are convenience functions to
- make this especially easy.
-
- * Note: "pax interchange format" is really an extended tar format,
- despite what the name says.
+## Notes about the Library Design
+
+* This is a heavily stream-oriented system. That means that
+ it is optimized to read or write the archive in a single
+ pass from beginning to end. For example, this allows
+ libarchive to process archives too large to store on disk
+ by processing them on-the-fly as they are read from or
+ written to a network or tape drive. Conversely, libarchive
+ does not support in-place modification or random access.
+
+* The library is designed to be extended with new compression and
+ archive formats. The only requirement is that the format be
+ readable or writable as a stream and that each archive entry be
+ independent. There are articles on the libarchive Wiki explaining
+ how to extend libarchive.
+
+* On read, compression and format are always detected automatically.
+
+* The same API is used for all formats; in particular, it's very
+ easy for software using libarchive to transparently handle
+ any of libarchive's archiving formats.
+
+* Libarchive's automatic support for decompression can be used
+ without archiving by explicitly selecting the "raw" and "empty"
+ formats.
+
+* I've attempted to minimize static link pollution. If you don't
+ explicitly invoke a particular feature (such as support for a
+ particular compression or format), it won't get pulled in to
+ statically-linked programs. In particular, if you don't explicitly
+ enable a particular compression or decompression support, you won't
+ need to link against the corresponding compression or decompression
+ libraries. This also reduces the size of statically-linked
+ binaries in environments where that matters.
+
+* On read, the library accepts whatever blocks you hand it.
+ Your read callback is free to pass the library a byte at a time
+ or mmap the entire archive and give it to the library at once.
+ On write, the library always produces correctly-blocked output.
+
+* The object-style approach allows you to have multiple archive streams
+ open at once. bsdtar uses this in its "@archive" extension.
+
+* The archive itself is read/written using callback functions.
+ You can read an archive directly from an in-memory buffer or
+ write it to a socket, if you wish. There are some utility
+ functions to provide easy-to-use "open file," etc, capabilities.
+
+* The read/write APIs are designed to allow individual entries
+ to be read or written to any data source: You can create
+ a block of data in memory and add it to a tar archive without
+ first writing a temporary file. You can also read an entry from
+ an archive and write the data directly to a socket. If you want
+ to read/write entries to disk, there are convenience functions to
+ make this especially easy.
+
+* Note: "pax interchange format" is really an extended tar format,
+ despite what the name says.
projects / thirdparty / libarchive.git / commitdiff
