The Android Open Source Project | cfb3b27 | 2009-03-03 19:29:20 -0800 | [diff] [blame] | 1 | |
| 2 | This is the README for bzip2/libzip2. |
| 3 | This version is fully compatible with the previous public releases. |
| 4 | |
| 5 | ------------------------------------------------------------------ |
| 6 | This file is part of bzip2/libbzip2, a program and library for |
| 7 | lossless, block-sorting data compression. |
| 8 | |
Nick Kralevich | 172b266 | 2010-09-20 17:21:30 -0700 | [diff] [blame] | 9 | bzip2/libbzip2 version 1.0.6 of 6 September 2010 |
| 10 | Copyright (C) 1996-2010 Julian Seward <jseward@bzip.org> |
The Android Open Source Project | cfb3b27 | 2009-03-03 19:29:20 -0800 | [diff] [blame] | 11 | |
| 12 | Please read the WARNING, DISCLAIMER and PATENTS sections in this file. |
| 13 | |
| 14 | This program is released under the terms of the license contained |
| 15 | in the file LICENSE. |
| 16 | ------------------------------------------------------------------ |
| 17 | |
| 18 | Complete documentation is available in Postscript form (manual.ps), |
| 19 | PDF (manual.pdf) or html (manual.html). A plain-text version of the |
| 20 | manual page is available as bzip2.txt. |
| 21 | |
| 22 | |
| 23 | HOW TO BUILD -- UNIX |
| 24 | |
| 25 | Type 'make'. This builds the library libbz2.a and then the programs |
| 26 | bzip2 and bzip2recover. Six self-tests are run. If the self-tests |
| 27 | complete ok, carry on to installation: |
| 28 | |
| 29 | To install in /usr/local/bin, /usr/local/lib, /usr/local/man and |
| 30 | /usr/local/include, type |
| 31 | |
| 32 | make install |
| 33 | |
| 34 | To install somewhere else, eg, /xxx/yyy/{bin,lib,man,include}, type |
| 35 | |
| 36 | make install PREFIX=/xxx/yyy |
| 37 | |
| 38 | If you are (justifiably) paranoid and want to see what 'make install' |
| 39 | is going to do, you can first do |
| 40 | |
| 41 | make -n install or |
| 42 | make -n install PREFIX=/xxx/yyy respectively. |
| 43 | |
| 44 | The -n instructs make to show the commands it would execute, but not |
| 45 | actually execute them. |
| 46 | |
| 47 | |
| 48 | HOW TO BUILD -- UNIX, shared library libbz2.so. |
| 49 | |
| 50 | Do 'make -f Makefile-libbz2_so'. This Makefile seems to work for |
| 51 | Linux-ELF (RedHat 7.2 on an x86 box), with gcc. I make no claims |
| 52 | that it works for any other platform, though I suspect it probably |
| 53 | will work for most platforms employing both ELF and gcc. |
| 54 | |
| 55 | bzip2-shared, a client of the shared library, is also built, but not |
| 56 | self-tested. So I suggest you also build using the normal Makefile, |
| 57 | since that conducts a self-test. A second reason to prefer the |
| 58 | version statically linked to the library is that, on x86 platforms, |
| 59 | building shared objects makes a valuable register (%ebx) unavailable |
| 60 | to gcc, resulting in a slowdown of 10%-20%, at least for bzip2. |
| 61 | |
| 62 | Important note for people upgrading .so's from 0.9.0/0.9.5 to version |
| 63 | 1.0.X. All the functions in the library have been renamed, from (eg) |
| 64 | bzCompress to BZ2_bzCompress, to avoid namespace pollution. |
| 65 | Unfortunately this means that the libbz2.so created by |
| 66 | Makefile-libbz2_so will not work with any program which used an older |
| 67 | version of the library. I do encourage library clients to make the |
| 68 | effort to upgrade to use version 1.0, since it is both faster and more |
| 69 | robust than previous versions. |
| 70 | |
| 71 | |
| 72 | HOW TO BUILD -- Windows 95, NT, DOS, Mac, etc. |
| 73 | |
| 74 | It's difficult for me to support compilation on all these platforms. |
| 75 | My approach is to collect binaries for these platforms, and put them |
| 76 | on the master web site (http://www.bzip.org). Look there. However |
| 77 | (FWIW), bzip2-1.0.X is very standard ANSI C and should compile |
| 78 | unmodified with MS Visual C. If you have difficulties building, you |
| 79 | might want to read README.COMPILATION.PROBLEMS. |
| 80 | |
| 81 | At least using MS Visual C++ 6, you can build from the unmodified |
| 82 | sources by issuing, in a command shell: |
| 83 | |
| 84 | nmake -f makefile.msc |
| 85 | |
| 86 | (you may need to first run the MSVC-provided script VCVARS32.BAT |
| 87 | so as to set up paths to the MSVC tools correctly). |
| 88 | |
| 89 | |
| 90 | VALIDATION |
| 91 | |
| 92 | Correct operation, in the sense that a compressed file can always be |
| 93 | decompressed to reproduce the original, is obviously of paramount |
| 94 | importance. To validate bzip2, I used a modified version of Mark |
| 95 | Nelson's churn program. Churn is an automated test driver which |
| 96 | recursively traverses a directory structure, using bzip2 to compress |
| 97 | and then decompress each file it encounters, and checking that the |
| 98 | decompressed data is the same as the original. |
| 99 | |
| 100 | |
| 101 | |
| 102 | Please read and be aware of the following: |
| 103 | |
| 104 | WARNING: |
| 105 | |
| 106 | This program and library (attempts to) compress data by |
| 107 | performing several non-trivial transformations on it. |
| 108 | Unless you are 100% familiar with *all* the algorithms |
| 109 | contained herein, and with the consequences of modifying them, |
| 110 | you should NOT meddle with the compression or decompression |
| 111 | machinery. Incorrect changes can and very likely *will* |
| 112 | lead to disastrous loss of data. |
| 113 | |
| 114 | |
| 115 | DISCLAIMER: |
| 116 | |
| 117 | I TAKE NO RESPONSIBILITY FOR ANY LOSS OF DATA ARISING FROM THE |
| 118 | USE OF THIS PROGRAM/LIBRARY, HOWSOEVER CAUSED. |
| 119 | |
| 120 | Every compression of a file implies an assumption that the |
| 121 | compressed file can be decompressed to reproduce the original. |
| 122 | Great efforts in design, coding and testing have been made to |
| 123 | ensure that this program works correctly. However, the complexity |
| 124 | of the algorithms, and, in particular, the presence of various |
| 125 | special cases in the code which occur with very low but non-zero |
| 126 | probability make it impossible to rule out the possibility of bugs |
| 127 | remaining in the program. DO NOT COMPRESS ANY DATA WITH THIS |
| 128 | PROGRAM UNLESS YOU ARE PREPARED TO ACCEPT THE POSSIBILITY, HOWEVER |
| 129 | SMALL, THAT THE DATA WILL NOT BE RECOVERABLE. |
| 130 | |
| 131 | That is not to say this program is inherently unreliable. |
| 132 | Indeed, I very much hope the opposite is true. bzip2/libbzip2 |
| 133 | has been carefully constructed and extensively tested. |
| 134 | |
| 135 | |
| 136 | PATENTS: |
| 137 | |
| 138 | To the best of my knowledge, bzip2/libbzip2 does not use any |
| 139 | patented algorithms. However, I do not have the resources |
| 140 | to carry out a patent search. Therefore I cannot give any |
| 141 | guarantee of the above statement. |
| 142 | |
| 143 | |
| 144 | |
| 145 | WHAT'S NEW IN 0.9.0 (as compared to 0.1pl2) ? |
| 146 | |
| 147 | * Approx 10% faster compression, 30% faster decompression |
| 148 | * -t (test mode) is a lot quicker |
| 149 | * Can decompress concatenated compressed files |
| 150 | * Programming interface, so programs can directly read/write .bz2 files |
| 151 | * Less restrictive (BSD-style) licensing |
| 152 | * Flag handling more compatible with GNU gzip |
| 153 | * Much more documentation, i.e., a proper user manual |
| 154 | * Hopefully, improved portability (at least of the library) |
| 155 | |
| 156 | WHAT'S NEW IN 0.9.5 ? |
| 157 | |
| 158 | * Compression speed is much less sensitive to the input |
| 159 | data than in previous versions. Specifically, the very |
| 160 | slow performance caused by repetitive data is fixed. |
| 161 | * Many small improvements in file and flag handling. |
| 162 | * A Y2K statement. |
| 163 | |
| 164 | WHAT'S NEW IN 1.0.0 ? |
| 165 | |
| 166 | See the CHANGES file. |
| 167 | |
| 168 | WHAT'S NEW IN 1.0.2 ? |
| 169 | |
| 170 | See the CHANGES file. |
| 171 | |
| 172 | WHAT'S NEW IN 1.0.3 ? |
| 173 | |
| 174 | See the CHANGES file. |
| 175 | |
| 176 | WHAT'S NEW IN 1.0.4 ? |
| 177 | |
| 178 | See the CHANGES file. |
| 179 | |
| 180 | WHAT'S NEW IN 1.0.5 ? |
| 181 | |
| 182 | See the CHANGES file. |
| 183 | |
Nick Kralevich | 172b266 | 2010-09-20 17:21:30 -0700 | [diff] [blame] | 184 | WHAT'S NEW IN 1.0.6 ? |
| 185 | |
| 186 | See the CHANGES file. |
| 187 | |
The Android Open Source Project | cfb3b27 | 2009-03-03 19:29:20 -0800 | [diff] [blame] | 188 | |
| 189 | I hope you find bzip2 useful. Feel free to contact me at |
| 190 | jseward@bzip.org |
| 191 | if you have any suggestions or queries. Many people mailed me with |
| 192 | comments, suggestions and patches after the releases of bzip-0.15, |
| 193 | bzip-0.21, and bzip2 versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0, 1.0.1, |
| 194 | 1.0.2 and 1.0.3, and the changes in bzip2 are largely a result of this |
| 195 | feedback. I thank you for your comments. |
| 196 | |
| 197 | bzip2's "home" is http://www.bzip.org/ |
| 198 | |
| 199 | Julian Seward |
| 200 | jseward@bzip.org |
| 201 | Cambridge, UK. |
| 202 | |
| 203 | 18 July 1996 (version 0.15) |
| 204 | 25 August 1996 (version 0.21) |
| 205 | 7 August 1997 (bzip2, version 0.1) |
| 206 | 29 August 1997 (bzip2, version 0.1pl2) |
| 207 | 23 August 1998 (bzip2, version 0.9.0) |
| 208 | 8 June 1999 (bzip2, version 0.9.5) |
| 209 | 4 Sept 1999 (bzip2, version 0.9.5d) |
| 210 | 5 May 2000 (bzip2, version 1.0pre8) |
| 211 | 30 December 2001 (bzip2, version 1.0.2pre1) |
| 212 | 15 February 2005 (bzip2, version 1.0.3) |
| 213 | 20 December 2006 (bzip2, version 1.0.4) |
| 214 | 10 December 2007 (bzip2, version 1.0.5) |
Nick Kralevich | 172b266 | 2010-09-20 17:21:30 -0700 | [diff] [blame] | 215 | 6 Sept 2010 (bzip2, version 1.0.6) |