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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-11-30 08:55:09 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-11-30 08:55:09 +0000
commit9f81e66fc3db2005d673efb81d752ed166575a4e (patch)
tree48c1ccffb414aa445d17a33b6dd6b2825b367f16 /doc/plzip.info
parentAdding upstream version 1.11. (diff)
downloadplzip-9f81e66fc3db2005d673efb81d752ed166575a4e.tar.xz
plzip-9f81e66fc3db2005d673efb81d752ed166575a4e.zip
Adding upstream version 1.12~rc1.upstream/1.12_rc1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/plzip.info')
-rw-r--r--doc/plzip.info347
1 files changed, 196 insertions, 151 deletions
diff --git a/doc/plzip.info b/doc/plzip.info
index becd133..a12b06a 100644
--- a/doc/plzip.info
+++ b/doc/plzip.info
@@ -11,21 +11,22 @@ File: plzip.info, Node: Top, Next: Introduction, Up: (dir)
Plzip Manual
************
-This manual is for Plzip (version 1.11, 21 January 2024).
+This manual is for Plzip (version 1.12-rc1, 19 November 2024).
* Menu:
-* Introduction:: Purpose and features of plzip
-* Output:: Meaning of plzip's output
-* Invoking plzip:: Command-line interface
-* Program design:: Internal structure of plzip
-* Memory requirements:: Memory required to compress and decompress
-* Minimum file sizes:: Minimum file sizes required for full speed
-* File format:: Detailed format of the compressed file
-* Trailing data:: Extra data appended to the file
-* Examples:: A small tutorial with examples
-* Problems:: Reporting bugs
-* Concept index:: Index of concepts
+* Introduction:: Purpose and features of plzip
+* Output:: Meaning of plzip's output
+* Invoking plzip:: Command-line interface
+* Argument syntax:: By convention, options start with a hyphen
+* File format:: Detailed format of the compressed file
+* Program design:: Internal structure of plzip
+* Memory requirements:: Memory required to compress and decompress
+* Minimum file sizes:: Minimum file sizes required for full speed
+* Trailing data:: Extra data appended to the file
+* Examples:: A small tutorial with examples
+* Problems:: Reporting bugs
+* Concept index:: Index of concepts
Copyright (C) 2009-2024 Antonio Diaz Diaz.
@@ -39,27 +40,27 @@ File: plzip.info, Node: Introduction, Next: Output, Prev: Top, Up: Top
1 Introduction
**************
-Plzip is a massively parallel (multi-threaded) implementation of lzip,
-compatible with lzip 1.4 or newer. Plzip uses the compression library lzlib.
+Plzip is a massively parallel (multi-threaded) implementation of lzip.
+Plzip uses the compression library lzlib.
Lzip is a lossless data compressor with a user interface similar to the
-one of gzip or bzip2. Lzip uses a simplified form of the 'Lempel-Ziv-Markov
-chain-Algorithm' (LZMA) stream format to maximize interoperability. The
-maximum dictionary size is 512 MiB so that any lzip file can be decompressed
-on 32-bit machines. Lzip provides accurate and robust 3-factor integrity
-checking. Lzip can compress about as fast as gzip (lzip -0) or compress most
-files more than bzip2 (lzip -9). Decompression speed is intermediate between
-gzip and bzip2. Lzip is better than gzip and bzip2 from a data recovery
-perspective. Lzip has been designed, written, and tested with great care to
-replace gzip and bzip2 as the standard general-purpose compressed format for
-Unix-like systems.
+one of gzip or bzip2. Lzip uses a simplified form of LZMA (Lempel-Ziv-Markov
+chain-Algorithm) designed to achieve complete interoperability between
+implementations. The maximum dictionary size is 512 MiB so that any lzip
+file can be decompressed on 32-bit machines. Lzip provides accurate and
+robust 3-factor integrity checking. 'lzip -0' compresses about as fast as
+gzip, while 'lzip -9' compresses most files more than bzip2. Decompression
+speed is intermediate between gzip and bzip2. Lzip provides better data
+recovery capabilities than gzip and bzip2. Lzip has been designed, written,
+and tested with great care to replace gzip and bzip2 as general-purpose
+compressed format for Unix-like systems.
Plzip can compress/decompress large files on multiprocessor machines much
faster than lzip, at the cost of a slightly reduced compression ratio (0.4
to 2 percent larger compressed files). Note that the number of usable
threads is limited by file size; on files larger than a few GB plzip can use
-hundreds of processors, but on files of only a few MB plzip is no faster
-than lzip. *Note Minimum file sizes::.
+hundreds of processors, but on files smaller than 1 MiB plzip is no faster
+than lzip (even at compression level -0). *Note Minimum file sizes::.
For creation and manipulation of compressed tar archives tarlz can be
more efficient than using tar and plzip because tarlz is able to keep the
@@ -96,9 +97,9 @@ makes it safer than compressors returning ambiguous warning values (like
gzip) when it is used as a back end for other programs like tar or zutils.
Plzip automatically uses for each file the largest dictionary size that
-does not exceed neither the file size nor the limit given. Keep in mind
-that the decompression memory requirement is affected at compression time
-by the choice of dictionary size limit. *Note Memory requirements::.
+does not exceed neither the file size nor the limit given. The dictionary
+size used for decompression is the same dictionary size used for
+compression. *Note Memory requirements::.
When compressing, plzip replaces every file given in the command line
with a compressed version of itself, with the name "original_name.lz". When
@@ -174,7 +175,7 @@ have been compressed. Decompressed is used to refer to data which have
undergone the process of decompression.

-File: plzip.info, Node: Invoking plzip, Next: Program design, Prev: Output, Up: Top
+File: plzip.info, Node: Invoking plzip, Next: Argument syntax, Prev: Output, Up: Top
3 Invoking plzip
****************
@@ -189,8 +190,7 @@ means standard input. It can be mixed with other FILES and is read just
once, the first time it appears in the command line. Remember to prepend
'./' to any file name beginning with a hyphen, or use '--'.
- plzip supports the following options: *Note Argument syntax:
-(arg_parser)Argument syntax.
+plzip supports the following options: *Note Argument syntax::.
'-h'
'--help'
@@ -235,7 +235,8 @@ once, the first time it appears in the command line. Remember to prepend
status 1. If a file fails to decompress, or is a terminal, plzip exits
immediately with error status 2 without decompressing the rest of the
files. A terminal is considered an uncompressed file, and therefore
- invalid.
+ invalid. A multimember file with one or more empty members is accepted
+ if redirected to standard input.
'-f'
'--force'
@@ -259,7 +260,8 @@ once, the first time it appears in the command line. Remember to prepend
'-v', the dictionary size, the number of members in the file, and the
amount of trailing data (if any) are also printed. With '-vv', the
positions and sizes of each member in multimember files are also
- printed.
+ printed. A multimember file with one or more empty members is accepted
+ if redirected to standard input.
If any file is damaged, does not exist, can't be opened, or is not
regular, the final exit status is > 0. '-lq' can be used to check
@@ -278,8 +280,8 @@ once, the first time it appears in the command line. Remember to prepend
'-n N'
'--threads=N'
Set the maximum number of worker threads, overriding the system's
- default. Valid values range from 1 to "as many as your system can
- support". If this option is not used, plzip tries to detect the number
+ default. Valid values range from 1 to as many as your system can
+ support. If this option is not used, plzip tries to detect the number
of processors in the system and use it as default value. When
compressing on a 32 bit system, plzip tries to limit the memory use to
under 2.22 GiB (4 worker threads at level -9) by reducing the number
@@ -338,7 +340,8 @@ once, the first time it appears in the command line. Remember to prepend
fails the test, does not exist, can't be opened, or is a terminal,
plzip continues testing the rest of the files. A final diagnostic is
shown at verbosity level 1 or higher if any file fails the test when
- testing multiple files.
+ testing multiple files. A multimember file with one or more empty
+ members is accepted if redirected to standard input.
'-v'
'--verbose'
@@ -368,6 +371,7 @@ once, the first time it appears in the command line. Remember to prepend
'-s64MiB -m273'
Level Dictionary size (-s) Match length limit (-m)
+ ------------------------------------------------------
-0 64 KiB 16 bytes
-1 1 MiB 5 bytes
-2 1.5 MiB 6 bytes
@@ -387,7 +391,7 @@ once, the first time it appears in the command line. Remember to prepend
When decompressing, testing, or listing, allow trailing data whose
first bytes are so similar to the magic bytes of a lzip header that
they can be confused with a corrupt header. Use this option if a file
- triggers a "corrupt header" error and the cause is not indeed a
+ triggers a 'corrupt header' error and the cause is not indeed a
corrupt header.
'--in-slots=N'
@@ -421,6 +425,7 @@ and may be followed by a multiplier and an optional 'B' for "byte".
Table of SI and binary prefixes (unit multipliers):
Prefix Value | Prefix Value
+----------------------------------------------------------------------
k kilobyte (10^3 = 1000) | Ki kibibyte (2^10 = 1024)
M megabyte (10^6) | Mi mebibyte (2^20)
G gigabyte (10^9) | Gi gibibyte (2^30)
@@ -439,9 +444,131 @@ corrupt or invalid input file, 3 for an internal consistency error (e.g.,
bug) which caused plzip to panic.

-File: plzip.info, Node: Program design, Next: Memory requirements, Prev: Invoking plzip, Up: Top
+File: plzip.info, Node: Argument syntax, Next: File format, Prev: Invoking plzip, Up: Top
-4 Internal structure of plzip
+4 Syntax of command-line arguments
+**********************************
+
+POSIX recommends these conventions for command-line arguments.
+
+ * A command-line argument is an option if it begins with a hyphen ('-').
+
+ * Option names are single alphanumeric characters.
+
+ * Certain options require an argument.
+
+ * An option and its argument may or may not appear as separate tokens.
+ (In other words, the whitespace separating them is optional, unless the
+ argument is the empty string). Thus, '-o foo' and '-ofoo' are
+ equivalent.
+
+ * One or more options without arguments, followed by at most one option
+ that takes an argument, may follow a hyphen in a single token. Thus,
+ '-abc' is equivalent to '-a -b -c'.
+
+ * Options typically precede other non-option arguments.
+
+ * The argument '--' terminates all options; any following arguments are
+ treated as non-option arguments, even if they begin with a hyphen.
+
+ * A token consisting of a single hyphen character is interpreted as an
+ ordinary non-option argument. By convention, it is used to specify
+ standard input, standard output, or a file named '-'.
+
+GNU adds "long options" to these conventions:
+
+ * A long option consists of two hyphens ('--') followed by a name made
+ of alphanumeric characters and hyphens. Option names are typically one
+ to three words long, with hyphens to separate words. Abbreviations can
+ be used for the long option names as long as the abbreviations are
+ unique.
+
+ * A long option and its argument may or may not appear as separate
+ tokens. In the latter case they must be separated by an equal sign '='.
+ Thus, '--foo bar' and '--foo=bar' are equivalent.
+
+The syntax of options with an optional argument is
+'-<short_option><argument>' (without whitespace), or
+'--<long_option>=<argument>'.
+
+
+File: plzip.info, Node: File format, Next: Program design, Prev: Argument syntax, Up: Top
+
+5 File format
+*************
+
+Perfection is reached, not when there is no longer anything to add, but
+when there is no longer anything to take away.
+-- Antoine de Saint-Exupery
+
+ In the diagram below, a box like this:
+
++---+
+| | <-- the vertical bars might be missing
++---+
+
+ represents one byte; a box like this:
+
++==============+
+| |
++==============+
+
+ represents a variable number of bytes.
+
+A lzip file consists of one or more independent "members" (compressed data
+sets). The members simply appear one after another in the file, with no
+additional information before, between, or after them. Each member can
+encode in compressed form up to 16 EiB - 1 byte of uncompressed data. The
+size of a multimember file is unlimited. Empty members (data size = 0) are
+not allowed in multimember files.
+
+ Each member has the following structure:
+
++--+--+--+--+----+----+=============+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| ID string | VN | DS | LZMA stream | CRC32 | Data size | Member size |
++--+--+--+--+----+----+=============+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ All multibyte values are stored in little endian order.
+
+'ID string (the "magic" bytes)'
+ A four byte string, identifying the lzip format, with the value "LZIP"
+ (0x4C, 0x5A, 0x49, 0x50).
+
+'VN (version number, 1 byte)'
+ Just in case something needs to be modified in the future. 1 for now.
+
+'DS (coded dictionary size, 1 byte)'
+ The dictionary size is calculated by taking a power of 2 (the base
+ size) and subtracting from it a fraction between 0/16 and 7/16 of the
+ base size.
+ Bits 4-0 contain the base 2 logarithm of the base size (12 to 29).
+ Bits 7-5 contain the numerator of the fraction (0 to 7) to subtract
+ from the base size to obtain the dictionary size.
+ Example: 0xD3 = 2^19 - 6 * 2^15 = 512 KiB - 6 * 32 KiB = 320 KiB
+ Valid values for dictionary size range from 4 KiB to 512 MiB.
+
+'LZMA stream'
+ The LZMA stream, terminated by an 'End Of Stream' marker. Uses default
+ values for encoder properties. *Note Stream format: (lzip)Stream
+ format, for a complete description.
+
+'CRC32 (4 bytes)'
+ Cyclic Redundancy Check (CRC) of the original uncompressed data.
+
+'Data size (8 bytes)'
+ Size of the original uncompressed data.
+
+'Member size (8 bytes)'
+ Total size of the member, including header and trailer. This field acts
+ as a distributed index, improves the checking of stream integrity, and
+ facilitates the safe recovery of undamaged members from multimember
+ files. Lzip limits the member size to 2 PiB to prevent the data size
+ field from overflowing.
+
+
+File: plzip.info, Node: Program design, Next: Memory requirements, Prev: File format, Up: Top
+
+6 Internal structure of plzip
*****************************
When compressing, plzip divides the input file into chunks and compresses as
@@ -456,8 +583,8 @@ because lzip usually produces single-member files, which can't be
decompressed in parallel.
For each input file, a splitter thread and several worker threads are
-created, acting the main thread as muxer (multiplexer) thread. A "packet
-courier" takes care of data transfers among threads and limits the maximum
+created, acting the main thread as muxer (multiplexer) thread. A 'packet
+courier' takes care of data transfers among threads and limits the maximum
number of data blocks (packets) being processed simultaneously.
The splitter reads data blocks from the input file, and distributes them
@@ -486,7 +613,7 @@ only limited by the number of processors available and by I/O speed.

File: plzip.info, Node: Memory requirements, Next: Minimum file sizes, Prev: Program design, Up: Top
-5 Memory required to compress and decompress
+7 Memory required to compress and decompress
********************************************
The amount of memory required *per worker thread* for decompression or
@@ -520,6 +647,7 @@ The following table shows the memory required *per thread* for compression
at a given level, using the default data size for each level:
Level Memory required
+------------------------
-0 4.875 MiB
-1 17.75 MiB
-2 26.625 MiB
@@ -532,9 +660,9 @@ Level Memory required
-9 568 MiB

-File: plzip.info, Node: Minimum file sizes, Next: File format, Prev: Memory requirements, Up: Top
+File: plzip.info, Node: Minimum file sizes, Next: Trailing data, Prev: Memory requirements, Up: Top
-6 Minimum file sizes required for full compression speed
+8 Minimum file sizes required for full compression speed
********************************************************
When compressing, plzip divides the input file into chunks and compresses
@@ -569,85 +697,9 @@ Level
-9 128 MiB 256 MiB 512 MiB 1 GiB 4 GiB 16 GiB

-File: plzip.info, Node: File format, Next: Trailing data, Prev: Minimum file sizes, Up: Top
-
-7 File format
-*************
-
-Perfection is reached, not when there is no longer anything to add, but
-when there is no longer anything to take away.
--- Antoine de Saint-Exupery
-
-
- In the diagram below, a box like this:
-
-+---+
-| | <-- the vertical bars might be missing
-+---+
-
- represents one byte; a box like this:
-
-+==============+
-| |
-+==============+
-
- represents a variable number of bytes.
-
-
- A lzip file consists of one or more independent "members" (compressed
-data sets). The members simply appear one after another in the file, with no
-additional information before, between, or after them. Each member can
-encode in compressed form up to 16 EiB - 1 byte of uncompressed data. The
-size of a multimember file is unlimited.
-
- Each member has the following structure:
-
-+--+--+--+--+----+----+=============+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-| ID string | VN | DS | LZMA stream | CRC32 | Data size | Member size |
-+--+--+--+--+----+----+=============+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- All multibyte values are stored in little endian order.
-
-'ID string (the "magic" bytes)'
- A four byte string, identifying the lzip format, with the value "LZIP"
- (0x4C, 0x5A, 0x49, 0x50).
-
-'VN (version number, 1 byte)'
- Just in case something needs to be modified in the future. 1 for now.
+File: plzip.info, Node: Trailing data, Next: Examples, Prev: Minimum file sizes, Up: Top
-'DS (coded dictionary size, 1 byte)'
- The dictionary size is calculated by taking a power of 2 (the base
- size) and subtracting from it a fraction between 0/16 and 7/16 of the
- base size.
- Bits 4-0 contain the base 2 logarithm of the base size (12 to 29).
- Bits 7-5 contain the numerator of the fraction (0 to 7) to subtract
- from the base size to obtain the dictionary size.
- Example: 0xD3 = 2^19 - 6 * 2^15 = 512 KiB - 6 * 32 KiB = 320 KiB
- Valid values for dictionary size range from 4 KiB to 512 MiB.
-
-'LZMA stream'
- The LZMA stream, finished by an "End Of Stream" marker. Uses default
- values for encoder properties. *Note Stream format: (lzip)Stream
- format, for a complete description.
-
-'CRC32 (4 bytes)'
- Cyclic Redundancy Check (CRC) of the original uncompressed data.
-
-'Data size (8 bytes)'
- Size of the original uncompressed data.
-
-'Member size (8 bytes)'
- Total size of the member, including header and trailer. This field acts
- as a distributed index, improves the checking of stream integrity, and
- facilitates the safe recovery of undamaged members from multimember
- files. Lzip limits the member size to 2 PiB to prevent the data size
- field from overflowing.
-
-
-
-File: plzip.info, Node: Trailing data, Next: Examples, Prev: File format, Up: Top
-
-8 Extra data appended to the file
+9 Extra data appended to the file
*********************************
Sometimes extra data are found appended to a lzip file after the last
@@ -657,7 +709,7 @@ member. Such trailing data may be:
example when writing to a tape. It is safe to append any amount of
padding zero bytes to a lzip file.
- * Useful data added by the user; an "End Of File" string (to check that
+ * Useful data added by the user; an 'End Of File' string (to check that
the file has not been truncated), a cryptographically secure hash, a
description of file contents, etc. It is safe to append any amount of
text to a lzip file as long as none of the first four bytes of the
@@ -693,8 +745,8 @@ where a file containing trailing data must be rejected, the option

File: plzip.info, Node: Examples, Next: Problems, Prev: Trailing data, Up: Top
-9 A small tutorial with examples
-********************************
+10 A small tutorial with examples
+*********************************
WARNING! Even if plzip is bug-free, other causes may result in a corrupt
compressed file (bugs in the system libraries, memory errors, etc).
@@ -706,38 +758,32 @@ comparing the compressed file with the original because the corruption
happens before plzip compresses the RAM contents, resulting in a valid
compressed file containing wrong data.
-
Example 1: Extract all the files from archive 'foo.tar.lz'.
tar -xf foo.tar.lz
or
plzip -cd foo.tar.lz | tar -xf -
-
Example 2: Replace a regular file with its compressed version 'file.lz' and
show the compression ratio.
plzip -v file
-
Example 3: Like example 2 but the created 'file.lz' has a block size of
1 MiB. The compression ratio is not shown.
plzip -B 1MiB file
-
Example 4: Restore a regular file from its compressed version 'file.lz'. If
the operation is successful, 'file.lz' is removed.
plzip -d file.lz
-
Example 5: Check the integrity of the compressed file 'file.lz' and show
status.
plzip -tv file.lz
-
Example 6: The right way of concatenating the decompressed output of two or
more compressed files. *Note Trailing data::.
@@ -746,19 +792,16 @@ more compressed files. *Note Trailing data::.
Do this instead
plzip -cd file1.lz file2.lz file3.lz
-
Example 7: Decompress 'file.lz' partially until 10 KiB of decompressed data
are produced.
plzip -cd file.lz | dd bs=1024 count=10
-
Example 8: Decompress 'file.lz' partially from decompressed byte at offset
10000 to decompressed byte at offset 14999 (5000 bytes are produced).
plzip -cd file.lz | dd bs=1000 skip=10 count=5
-
Example 9: Compress a whole device in /dev/sdc and send the output to
'file.lz'.
@@ -769,7 +812,7 @@ Example 9: Compress a whole device in /dev/sdc and send the output to

File: plzip.info, Node: Problems, Next: Concept index, Prev: Examples, Up: Top
-10 Reporting bugs
+11 Reporting bugs
*****************
There are probably bugs in plzip. There are certainly errors and omissions
@@ -790,6 +833,7 @@ Concept index
* Menu:
+* argument syntax: Argument syntax. (line 6)
* bugs: Problems. (line 6)
* examples: Examples. (line 6)
* file format: File format. (line 6)
@@ -809,21 +853,22 @@ Concept index

Tag Table:
Node: Top217
-Node: Introduction1156
-Node: Output5934
-Node: Invoking plzip7497
-Ref: --trailing-error8372
-Ref: --data-size8610
-Node: Program design19519
-Node: Memory requirements21818
-Node: Minimum file sizes23503
-Node: File format25506
-Ref: coded-dict-size26945
-Node: Trailing data28195
-Node: Examples30531
-Ref: concat-example31964
-Node: Problems32721
-Node: Concept index33276
+Node: Introduction1207
+Node: Output5956
+Node: Invoking plzip7519
+Ref: --trailing-error8365
+Ref: --data-size8603
+Node: Argument syntax19941
+Node: File format21886
+Ref: coded-dict-size23386
+Node: Program design24637
+Node: Memory requirements26933
+Node: Minimum file sizes28643
+Node: Trailing data30648
+Node: Examples32991
+Ref: concat-example34420
+Node: Problems35174
+Node: Concept index35729

End Tag Table