| 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 1.0.8 of 13 July 2019 | |
| Copyright (C) 1996-2019 Julian Seward <jseward@acm.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 (https://sourceware.org/bzip2/). 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.x ? | |
| See the CHANGES file. | |
| I hope you find bzip2 useful. Feel free to contact the developers at | |
| bzip2-devel@sourceware.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 https://sourceware.org/bzip2/ | |
| Julian Seward | |
| jseward@acm.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) | |
| 27 June 2019 (bzip2, version 1.0.7) | |
| 13 July 2019 (bzip2, version 1.0.8) |