216 lines
7.4 KiB
Plaintext
216 lines
7.4 KiB
Plaintext
|
|
This is the README for bzip2/libzip2.
|
|
This version is fully compatible with the previous public releases.
|
|
|
|
------------------------------------------------------------------
|
|
This file is part of bzip2/libbzip2, a program and library for
|
|
lossless, block-sorting data compression.
|
|
|
|
bzip2/libbzip2 version 1.0.6 of 6 September 2010
|
|
Copyright (C) 1996-2010 Julian Seward <jseward@bzip.org>
|
|
|
|
Please read the WARNING, DISCLAIMER and PATENTS sections in this file.
|
|
|
|
This program is released under the terms of the license contained
|
|
in the file LICENSE.
|
|
------------------------------------------------------------------
|
|
|
|
Complete documentation is available in Postscript form (manual.ps),
|
|
PDF (manual.pdf) or html (manual.html). A plain-text version of the
|
|
manual page is available as bzip2.txt.
|
|
|
|
|
|
HOW TO BUILD -- UNIX
|
|
|
|
Type 'make'. This builds the library libbz2.a and then the programs
|
|
bzip2 and bzip2recover. Six self-tests are run. If the self-tests
|
|
complete ok, carry on to installation:
|
|
|
|
To install in /usr/local/bin, /usr/local/lib, /usr/local/man and
|
|
/usr/local/include, type
|
|
|
|
make install
|
|
|
|
To install somewhere else, eg, /xxx/yyy/{bin,lib,man,include}, type
|
|
|
|
make install PREFIX=/xxx/yyy
|
|
|
|
If you are (justifiably) paranoid and want to see what 'make install'
|
|
is going to do, you can first do
|
|
|
|
make -n install or
|
|
make -n install PREFIX=/xxx/yyy respectively.
|
|
|
|
The -n instructs make to show the commands it would execute, but not
|
|
actually execute them.
|
|
|
|
|
|
HOW TO BUILD -- UNIX, shared library libbz2.so.
|
|
|
|
Do 'make -f Makefile-libbz2_so'. This Makefile seems to work for
|
|
Linux-ELF (RedHat 7.2 on an x86 box), with gcc. I make no claims
|
|
that it works for any other platform, though I suspect it probably
|
|
will work for most platforms employing both ELF and gcc.
|
|
|
|
bzip2-shared, a client of the shared library, is also built, but not
|
|
self-tested. So I suggest you also build using the normal Makefile,
|
|
since that conducts a self-test. A second reason to prefer the
|
|
version statically linked to the library is that, on x86 platforms,
|
|
building shared objects makes a valuable register (%ebx) unavailable
|
|
to gcc, resulting in a slowdown of 10%-20%, at least for bzip2.
|
|
|
|
Important note for people upgrading .so's from 0.9.0/0.9.5 to version
|
|
1.0.X. All the functions in the library have been renamed, from (eg)
|
|
bzCompress to BZ2_bzCompress, to avoid namespace pollution.
|
|
Unfortunately this means that the libbz2.so created by
|
|
Makefile-libbz2_so will not work with any program which used an older
|
|
version of the library. I do encourage library clients to make the
|
|
effort to upgrade to use version 1.0, since it is both faster and more
|
|
robust than previous versions.
|
|
|
|
|
|
HOW TO BUILD -- Windows 95, NT, DOS, Mac, etc.
|
|
|
|
It's difficult for me to support compilation on all these platforms.
|
|
My approach is to collect binaries for these platforms, and put them
|
|
on the master web site (http://www.bzip.org). Look there. However
|
|
(FWIW), bzip2-1.0.X is very standard ANSI C and should compile
|
|
unmodified with MS Visual C. If you have difficulties building, you
|
|
might want to read README.COMPILATION.PROBLEMS.
|
|
|
|
At least using MS Visual C++ 6, you can build from the unmodified
|
|
sources by issuing, in a command shell:
|
|
|
|
nmake -f makefile.msc
|
|
|
|
(you may need to first run the MSVC-provided script VCVARS32.BAT
|
|
so as to set up paths to the MSVC tools correctly).
|
|
|
|
|
|
VALIDATION
|
|
|
|
Correct operation, in the sense that a compressed file can always be
|
|
decompressed to reproduce the original, is obviously of paramount
|
|
importance. To validate bzip2, I used a modified version of Mark
|
|
Nelson's churn program. Churn is an automated test driver which
|
|
recursively traverses a directory structure, using bzip2 to compress
|
|
and then decompress each file it encounters, and checking that the
|
|
decompressed data is the same as the original.
|
|
|
|
|
|
|
|
Please read and be aware of the following:
|
|
|
|
WARNING:
|
|
|
|
This program and library (attempts to) compress data by
|
|
performing several non-trivial transformations on it.
|
|
Unless you are 100% familiar with *all* the algorithms
|
|
contained herein, and with the consequences of modifying them,
|
|
you should NOT meddle with the compression or decompression
|
|
machinery. Incorrect changes can and very likely *will*
|
|
lead to disastrous loss of data.
|
|
|
|
|
|
DISCLAIMER:
|
|
|
|
I TAKE NO RESPONSIBILITY FOR ANY LOSS OF DATA ARISING FROM THE
|
|
USE OF THIS PROGRAM/LIBRARY, HOWSOEVER CAUSED.
|
|
|
|
Every compression of a file implies an assumption that the
|
|
compressed file can be decompressed to reproduce the original.
|
|
Great efforts in design, coding and testing have been made to
|
|
ensure that this program works correctly. However, the complexity
|
|
of the algorithms, and, in particular, the presence of various
|
|
special cases in the code which occur with very low but non-zero
|
|
probability make it impossible to rule out the possibility of bugs
|
|
remaining in the program. DO NOT COMPRESS ANY DATA WITH THIS
|
|
PROGRAM UNLESS YOU ARE PREPARED TO ACCEPT THE POSSIBILITY, HOWEVER
|
|
SMALL, THAT THE DATA WILL NOT BE RECOVERABLE.
|
|
|
|
That is not to say this program is inherently unreliable.
|
|
Indeed, I very much hope the opposite is true. bzip2/libbzip2
|
|
has been carefully constructed and extensively tested.
|
|
|
|
|
|
PATENTS:
|
|
|
|
To the best of my knowledge, bzip2/libbzip2 does not use any
|
|
patented algorithms. However, I do not have the resources
|
|
to carry out a patent search. Therefore I cannot give any
|
|
guarantee of the above statement.
|
|
|
|
|
|
|
|
WHAT'S NEW IN 0.9.0 (as compared to 0.1pl2) ?
|
|
|
|
* Approx 10% faster compression, 30% faster decompression
|
|
* -t (test mode) is a lot quicker
|
|
* Can decompress concatenated compressed files
|
|
* Programming interface, so programs can directly read/write .bz2 files
|
|
* Less restrictive (BSD-style) licensing
|
|
* Flag handling more compatible with GNU gzip
|
|
* Much more documentation, i.e., a proper user manual
|
|
* Hopefully, improved portability (at least of the library)
|
|
|
|
WHAT'S NEW IN 0.9.5 ?
|
|
|
|
* Compression speed is much less sensitive to the input
|
|
data than in previous versions. Specifically, the very
|
|
slow performance caused by repetitive data is fixed.
|
|
* Many small improvements in file and flag handling.
|
|
* A Y2K statement.
|
|
|
|
WHAT'S NEW IN 1.0.0 ?
|
|
|
|
See the CHANGES file.
|
|
|
|
WHAT'S NEW IN 1.0.2 ?
|
|
|
|
See the CHANGES file.
|
|
|
|
WHAT'S NEW IN 1.0.3 ?
|
|
|
|
See the CHANGES file.
|
|
|
|
WHAT'S NEW IN 1.0.4 ?
|
|
|
|
See the CHANGES file.
|
|
|
|
WHAT'S NEW IN 1.0.5 ?
|
|
|
|
See the CHANGES file.
|
|
|
|
WHAT'S NEW IN 1.0.6 ?
|
|
|
|
See the CHANGES file.
|
|
|
|
|
|
I hope you find bzip2 useful. Feel free to contact me at
|
|
jseward@bzip.org
|
|
if you have any suggestions or queries. Many people mailed me with
|
|
comments, suggestions and patches after the releases of bzip-0.15,
|
|
bzip-0.21, and bzip2 versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0, 1.0.1,
|
|
1.0.2 and 1.0.3, and the changes in bzip2 are largely a result of this
|
|
feedback. I thank you for your comments.
|
|
|
|
bzip2's "home" is http://www.bzip.org/
|
|
|
|
Julian Seward
|
|
jseward@bzip.org
|
|
Cambridge, UK.
|
|
|
|
18 July 1996 (version 0.15)
|
|
25 August 1996 (version 0.21)
|
|
7 August 1997 (bzip2, version 0.1)
|
|
29 August 1997 (bzip2, version 0.1pl2)
|
|
23 August 1998 (bzip2, version 0.9.0)
|
|
8 June 1999 (bzip2, version 0.9.5)
|
|
4 Sept 1999 (bzip2, version 0.9.5d)
|
|
5 May 2000 (bzip2, version 1.0pre8)
|
|
30 December 2001 (bzip2, version 1.0.2pre1)
|
|
15 February 2005 (bzip2, version 1.0.3)
|
|
20 December 2006 (bzip2, version 1.0.4)
|
|
10 December 2007 (bzip2, version 1.0.5)
|
|
6 Sept 2010 (bzip2, version 1.0.6)
|