| [9] | 1 |
|
|---|
| 2 | This is the README for bzip2, a block-sorting file compressor, version
|
|---|
| 3 | 1.0.3. This version is fully compatible with the previous public
|
|---|
| 4 | releases, versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0, 1.0.1 and 1.0.2.
|
|---|
| 5 |
|
|---|
| 6 | bzip2-1.0.3 is distributed under a BSD-style license. For details,
|
|---|
| 7 | see the file LICENSE.
|
|---|
| 8 |
|
|---|
| 9 | Complete documentation is available in Postscript form (manual.ps),
|
|---|
| 10 | PDF (manual.pdf) or html (manual.html). A plain-text version of the
|
|---|
| 11 | manual page is available as bzip2.txt. A statement about Y2K issues
|
|---|
| 12 | is now included in the file Y2K_INFO.
|
|---|
| 13 |
|
|---|
| 14 |
|
|---|
| 15 | HOW TO BUILD -- UNIX
|
|---|
| 16 |
|
|---|
| 17 | Type `make'. This builds the library libbz2.a and then the
|
|---|
| 18 | programs bzip2 and bzip2recover. Six self-tests are run.
|
|---|
| 19 | If the self-tests complete ok, carry on to installation:
|
|---|
| 20 |
|
|---|
| 21 | To install in /usr/bin, /usr/lib, /usr/man and /usr/include, type
|
|---|
| 22 | make install
|
|---|
| 23 | To install somewhere else, eg, /xxx/yyy/{bin,lib,man,include}, type
|
|---|
| 24 | make install PREFIX=/xxx/yyy
|
|---|
| 25 | If you are (justifiably) paranoid and want to see what 'make install'
|
|---|
| 26 | is going to do, you can first do
|
|---|
| 27 | make -n install or
|
|---|
| 28 | make -n install PREFIX=/xxx/yyy respectively.
|
|---|
| 29 | The -n instructs make to show the commands it would execute, but
|
|---|
| 30 | not actually execute them.
|
|---|
| 31 |
|
|---|
| 32 |
|
|---|
| 33 | HOW TO BUILD -- UNIX, shared library libbz2.so.
|
|---|
| 34 |
|
|---|
| 35 | Do 'make -f Makefile-libbz2_so'. This Makefile seems to work for
|
|---|
| 36 | Linux-ELF (RedHat 7.2 on an x86 box), with gcc. I make no claims
|
|---|
| 37 | that it works for any other platform, though I suspect it probably
|
|---|
| 38 | will work for most platforms employing both ELF and gcc.
|
|---|
| 39 |
|
|---|
| 40 | bzip2-shared, a client of the shared library, is also built, but not
|
|---|
| 41 | self-tested. So I suggest you also build using the normal Makefile,
|
|---|
| 42 | since that conducts a self-test. A second reason to prefer the
|
|---|
| 43 | version statically linked to the library is that, on x86 platforms,
|
|---|
| 44 | building shared objects makes a valuable register (%ebx) unavailable
|
|---|
| 45 | to gcc, resulting in a slowdown of 10%-20%, at least for bzip2.
|
|---|
| 46 |
|
|---|
| 47 | Important note for people upgrading .so's from 0.9.0/0.9.5 to version
|
|---|
| 48 | 1.0.X. All the functions in the library have been renamed, from (eg)
|
|---|
| 49 | bzCompress to BZ2_bzCompress, to avoid namespace pollution.
|
|---|
| 50 | Unfortunately this means that the libbz2.so created by
|
|---|
| 51 | Makefile-libbz2_so will not work with any program which used an older
|
|---|
| 52 | version of the library. Sorry. I do encourage library clients to
|
|---|
| 53 | make the effort to upgrade to use version 1.0, since it is both faster
|
|---|
| 54 | and more robust than previous versions.
|
|---|
| 55 |
|
|---|
| 56 |
|
|---|
| 57 | HOW TO BUILD -- Windows 95, NT, DOS, Mac, etc.
|
|---|
| 58 |
|
|---|
| 59 | It's difficult for me to support compilation on all these platforms.
|
|---|
| 60 | My approach is to collect binaries for these platforms, and put them
|
|---|
| 61 | on the master web page (http://sources.redhat.com/bzip2). Look there.
|
|---|
| 62 | However (FWIW), bzip2-1.0.X is very standard ANSI C and should compile
|
|---|
| 63 | unmodified with MS Visual C. If you have difficulties building, you
|
|---|
| 64 | might want to read README.COMPILATION.PROBLEMS.
|
|---|
| 65 |
|
|---|
| 66 | At least using MS Visual C++ 6, you can build from the unmodified
|
|---|
| 67 | sources by issuing, in a command shell:
|
|---|
| 68 | nmake -f makefile.msc
|
|---|
| 69 | (you may need to first run the MSVC-provided script VCVARS32.BAT
|
|---|
| 70 | so as to set up paths to the MSVC tools correctly).
|
|---|
| 71 |
|
|---|
| 72 |
|
|---|
| 73 | VALIDATION
|
|---|
| 74 |
|
|---|
| 75 | Correct operation, in the sense that a compressed file can always be
|
|---|
| 76 | decompressed to reproduce the original, is obviously of paramount
|
|---|
| 77 | importance. To validate bzip2, I used a modified version of Mark
|
|---|
| 78 | Nelson's churn program. Churn is an automated test driver which
|
|---|
| 79 | recursively traverses a directory structure, using bzip2 to compress
|
|---|
| 80 | and then decompress each file it encounters, and checking that the
|
|---|
| 81 | decompressed data is the same as the original.
|
|---|
| 82 |
|
|---|
| 83 |
|
|---|
| 84 |
|
|---|
| 85 | Please read and be aware of the following:
|
|---|
| 86 |
|
|---|
| 87 | WARNING:
|
|---|
| 88 |
|
|---|
| 89 | This program (attempts to) compress data by performing several
|
|---|
| 90 | non-trivial transformations on it. Unless you are 100% familiar
|
|---|
| 91 | with *all* the algorithms contained herein, and with the
|
|---|
| 92 | consequences of modifying them, you should NOT meddle with the
|
|---|
| 93 | compression or decompression machinery. Incorrect changes can and
|
|---|
| 94 | very likely *will* lead to disastrous loss of data.
|
|---|
| 95 |
|
|---|
| 96 |
|
|---|
| 97 | DISCLAIMER:
|
|---|
| 98 |
|
|---|
| 99 | I TAKE NO RESPONSIBILITY FOR ANY LOSS OF DATA ARISING FROM THE
|
|---|
| 100 | USE OF THIS PROGRAM, HOWSOEVER CAUSED.
|
|---|
| 101 |
|
|---|
| 102 | Every compression of a file implies an assumption that the
|
|---|
| 103 | compressed file can be decompressed to reproduce the original.
|
|---|
| 104 | Great efforts in design, coding and testing have been made to
|
|---|
| 105 | ensure that this program works correctly. However, the complexity
|
|---|
| 106 | of the algorithms, and, in particular, the presence of various
|
|---|
| 107 | special cases in the code which occur with very low but non-zero
|
|---|
| 108 | probability make it impossible to rule out the possibility of bugs
|
|---|
| 109 | remaining in the program. DO NOT COMPRESS ANY DATA WITH THIS
|
|---|
| 110 | PROGRAM UNLESS YOU ARE PREPARED TO ACCEPT THE POSSIBILITY, HOWEVER
|
|---|
| 111 | SMALL, THAT THE DATA WILL NOT BE RECOVERABLE.
|
|---|
| 112 |
|
|---|
| 113 | That is not to say this program is inherently unreliable. Indeed,
|
|---|
| 114 | I very much hope the opposite is true. bzip2 has been carefully
|
|---|
| 115 | constructed and extensively tested.
|
|---|
| 116 |
|
|---|
| 117 |
|
|---|
| 118 | PATENTS:
|
|---|
| 119 |
|
|---|
| 120 | To the best of my knowledge, bzip2 does not use any patented
|
|---|
| 121 | algorithms. However, I do not have the resources to carry out
|
|---|
| 122 | a patent search. Therefore I cannot give any guarantee of the
|
|---|
| 123 | above statement.
|
|---|
| 124 |
|
|---|
| 125 | End of legalities.
|
|---|
| 126 |
|
|---|
| 127 |
|
|---|
| 128 | WHAT'S NEW IN 0.9.0 (as compared to 0.1pl2) ?
|
|---|
| 129 |
|
|---|
| 130 | * Approx 10% faster compression, 30% faster decompression
|
|---|
| 131 | * -t (test mode) is a lot quicker
|
|---|
| 132 | * Can decompress concatenated compressed files
|
|---|
| 133 | * Programming interface, so programs can directly read/write .bz2 files
|
|---|
| 134 | * Less restrictive (BSD-style) licensing
|
|---|
| 135 | * Flag handling more compatible with GNU gzip
|
|---|
| 136 | * Much more documentation, i.e., a proper user manual
|
|---|
| 137 | * Hopefully, improved portability (at least of the library)
|
|---|
| 138 |
|
|---|
| 139 | WHAT'S NEW IN 0.9.5 ?
|
|---|
| 140 |
|
|---|
| 141 | * Compression speed is much less sensitive to the input
|
|---|
| 142 | data than in previous versions. Specifically, the very
|
|---|
| 143 | slow performance caused by repetitive data is fixed.
|
|---|
| 144 | * Many small improvements in file and flag handling.
|
|---|
| 145 | * A Y2K statement.
|
|---|
| 146 |
|
|---|
| 147 | WHAT'S NEW IN 1.0.0 ?
|
|---|
| 148 |
|
|---|
| 149 | See the CHANGES file.
|
|---|
| 150 |
|
|---|
| 151 | WHAT'S NEW IN 1.0.2 ?
|
|---|
| 152 |
|
|---|
| 153 | See the CHANGES file.
|
|---|
| 154 |
|
|---|
| 155 | WHAT'S NEW IN 1.0.3 ?
|
|---|
| 156 |
|
|---|
| 157 | See the CHANGES file.
|
|---|
| 158 |
|
|---|
| 159 |
|
|---|
| 160 | I hope you find bzip2 useful. Feel free to contact me at
|
|---|
| 161 | jseward@bzip.org
|
|---|
| 162 | if you have any suggestions or queries. Many people mailed me with
|
|---|
| 163 | comments, suggestions and patches after the releases of bzip-0.15,
|
|---|
| 164 | bzip-0.21, and bzip2 versions 0.1pl2, 0.9.0, 0.9.5, 1.0.0, 1.0.1 and
|
|---|
| 165 | 1.0.2, and the changes in bzip2 are largely a result of this feedback.
|
|---|
| 166 | I thank you for your comments.
|
|---|
| 167 |
|
|---|
| 168 | At least for the time being, bzip2's "home" is (or can be reached via)
|
|---|
| 169 | http://www.bzip.org
|
|---|
| 170 |
|
|---|
| 171 | Julian Seward
|
|---|
| 172 | jseward@bzip.org
|
|---|
| 173 |
|
|---|
| 174 | Cambridge, UK.
|
|---|
| 175 |
|
|---|
| 176 | 18 July 1996 (version 0.15)
|
|---|
| 177 | 25 August 1996 (version 0.21)
|
|---|
| 178 | 7 August 1997 (bzip2, version 0.1)
|
|---|
| 179 | 29 August 1997 (bzip2, version 0.1pl2)
|
|---|
| 180 | 23 August 1998 (bzip2, version 0.9.0)
|
|---|
| 181 | 8 June 1999 (bzip2, version 0.9.5)
|
|---|
| 182 | 4 Sept 1999 (bzip2, version 0.9.5d)
|
|---|
| 183 | 5 May 2000 (bzip2, version 1.0pre8)
|
|---|
| 184 | 30 December 2001 (bzip2, version 1.0.2pre1)
|
|---|
| 185 | 15 February 2005 (bzip2, version 1.0.3)
|
|---|
