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Merging upstream version 0.21.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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doc/tarlz.info
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@ -11,7 +11,7 @@ File: tarlz.info, Node: Top, Next: Introduction, Up: (dir)
Tarlz Manual
************
This manual is for Tarlz (version 0.19, 8 January 2021).
This manual is for Tarlz (version 0.21, 14 June 2021).
* Menu:
@ -102,7 +102,7 @@ The format for running tarlz is:
tarlz [OPTIONS] [FILES]
All operations except '--concatenate' operate on whole trees if any FILE is
a directory.
a directory. Tarlz overwrites output files without warning.
On archive creation or appending tarlz archives the files specified, but
removes from member names any leading and trailing slashes and any file name
@ -119,7 +119,7 @@ member names in the archive or given in the command line, so that
If several compression levels or '--*solid' options are given, the last
setting is used. For example '-9 --solid --uncompressed -1' is equivalent
to '-1 --solid'
to '-1 --solid'.
tarlz supports the following options: *Note Argument syntax:
(arg_parser)Argument syntax.
@ -134,16 +134,17 @@ to '-1 --solid'
'-A'
'--concatenate'
Append one or more archives to the end of an archive. All the archives
involved must be regular (seekable) files, and must be either all
compressed or all uncompressed. Compressed and uncompressed archives
can't be mixed. Compressed archives must be multimember lzip files
with the two end-of-file blocks plus any zero padding contained in the
last lzip member of each archive. The intermediate end-of-file blocks
are removed as each new archive is concatenated. If the archive is
uncompressed, tarlz parses and skips tar headers until it finds the
end-of-file blocks. Exit with status 0 without modifying the archive
if no FILES have been specified.
Append one or more archives to the end of an archive. If no archive is
specified with the option '-f', the input archives are concatenated to
standard output. All the archives involved must be regular (seekable)
files, and must be either all compressed or all uncompressed.
Compressed and uncompressed archives can't be mixed. Compressed
archives must be multimember lzip files with the two end-of-file
blocks plus any zero padding contained in the last lzip member of each
archive. The intermediate end-of-file blocks are removed as each new
archive is concatenated. If the archive is uncompressed, tarlz parses
and skips tar headers until it finds the end-of-file blocks. Exit with
status 0 without modifying the archive if no FILES have been specified.
'-B BYTES'
'--data-size=BYTES'
@ -249,6 +250,12 @@ to '-1 --solid'
and during decompression to the number of lzip members in the tar.lz
archive, which you can find by running 'lzip -lv archive.tar.lz'.
'-o FILE'
'--output=FILE'
Write the compressed output to FILE. '-o -' writes the compressed
output to standard output. Currently '--output' only works with
'--compress'.
'-p'
'--preserve-permissions'
On extraction, set file permissions as they appear in the archive.
@ -295,11 +302,35 @@ to '-1 --solid'
example, extracting a link over a directory will usually fail.
(Principle of least surprise).
'-z'
'--compress'
Compress existing POSIX tar archives aligning the lzip members to the
tar members with choice of granularity (--bsolid by default, --dsolid
works like --asolid). The input archives are kept unchanged. Existing
compressed archives are not overwritten. A hyphen '-' used as the name
of an input archive reads from standard input and writes to standard
output (unless the option '--output' is used). Tarlz can be used as
compressor for GNU tar using a command like
'tar -c -Hustar foo | tarlz -z -o foo.tar.lz'. Note that tarlz only
works reliably on archives without global headers, or with global
headers whose content can be ignored.
The compression is reversible, including any garbage present after the
EOF blocks. Tarlz stops parsing after the first EOF block is found,
and then compresses the rest of the archive. Unless solid compression
is requested, the EOF blocks are compressed in a lzip member separated
from the preceding members and from any non-zero garbage following the
EOF blocks. '--compress' implies plzip argument style, not tar style.
Each input archive is compressed to a file with the extension '.lz'
added unless the option '--output' is used. When '--output' is used,
only one input archive can be specified. '-f' can't be used with
'--compress'.
'-0 .. -9'
Set the compression level for '--create' and '--append'. The default
compression level is '-6'. Like lzip, tarlz also minimizes the
dictionary size of the lzip members it creates, reducing the amount of
memory required for decompression.
Set the compression level for '--create', '--append', and
'--compress'. The default compression level is '-6'. Like lzip, tarlz
also minimizes the dictionary size of the lzip members it creates,
reducing the amount of memory required for decompression.
Level Dictionary size Match length limit
-0 64 KiB 16 bytes
@ -408,11 +439,20 @@ to '-1 --solid'
the version of lzlib being used and the value of 'LZ_API_VERSION' (if
defined). *Note Library version: (lzlib)Library version.
'--warn-newer'
During archive creation, warn if any file being archived has a
modification time newer than the archive creation time. This option
may slow archive creation somewhat because it makes an extra call to
'stat' after archiving each file, but it guarantees that file contents
were not modified during the creation of the archive. Note that the
file must be at least one second newer than the archive for it to be
detected as newer.
Exit status: 0 for a normal exit, 1 for environmental problems (file not
found, files differ, invalid flags, I/O errors, etc), 2 to indicate a
corrupt or invalid input file, 3 for an internal consistency error (eg, bug)
which caused tarlz to panic.
corrupt or invalid input file, 3 for an internal consistency error (e.g.
bug) which caused tarlz to panic.

File: tarlz.info, Node: Portable character set, Next: File format, Prev: Invoking tarlz, Up: Top
@ -430,7 +470,9 @@ The set of characters from which portable file names are constructed.
characters, respectively.
File names are identifiers. Therefore, archiving works better when file
names use only the portable character set without spaces added.
names use only the portable character set without spaces added. Unicode is
for human consumption. It should be avoided in computing environments,
specially in file names. *Note why not Unicode: (moe)why not Unicode.

File: tarlz.info, Node: File format, Next: Amendments to pax format, Prev: Portable character set, Up: Top
@ -718,8 +760,9 @@ integrity checking of lzip may not be able to detect the corruption before
the metadata has been used, for example, to create a new file in the wrong
place.
Because of the above, tarlz protects the extended records with a CRC in a
way compatible with standard tar tools. *Note key_crc32::.
Because of the above, tarlz protects the extended records with a Cyclic
Redundancy Check (CRC) in a way compatible with standard tar tools. *Note
key_crc32::.
5.2 Remove flawed backward compatibility
@ -740,7 +783,9 @@ to extract a file with a truncated file name.
zeroed except size, chksum, typeflag, magic and version. This prevents old
tar programs from extracting the extended records as a file in the wrong
place. Tarlz also sets to zero those fields of the ustar header overridden
by extended records.
by extended records. Finally, tarlz skips members without name when decoding
except when listing. This is needed to detect certain format violations
during parallel extraction.
If an extended header is required for any reason (for example a file size
larger than 8 GiB or a link name longer than 100 bytes), tarlz moves the
@ -860,11 +905,20 @@ File: tarlz.info, Node: Multi-threaded decoding, Next: Minimum archive sizes,
7 Limitations of parallel tar decoding
**************************************
Safely decoding an arbitrary tar archive in parallel is impossible. For
example, if a tar archive containing another tar archive is decoded starting
from some position other than the beginning, there is no way to know if the
first header found there belongs to the outer tar archive or to the inner
tar archive. Tar is a format inherently serial; it was designed for tapes.
Safely decoding an arbitrary tar archive in parallel is only possible if one
decodes the headers sequentially first. For example, if a tar archive
containing another tar archive is decoded starting from some position other
than the beginning, there is no way to know if the first header found there
belongs to the outer tar archive or to the inner tar archive. Tar is a
format inherently serial; it was designed for tapes.
The pax format is even more serial than the ustar format. Two headers
need to be decoded sequentially for each file. The extended header may even
need parsing to reveal something as basic as file size. If a thread decodes
the ustar header skipping the preceding extended header, it may extract a
file of incorrect size at the wrong place. Moreover, a pax archive with
global headers can't be decoded in parallel because each thread can't know
about the global headers decoded by other threads.
In the case of compressed tar archives, the start of each compressed
block determines one point through which the tar archive can be decoded in
@ -1026,6 +1080,14 @@ Example 8: Copy the contents of directory 'sourcedir' to the directory
tarlz -C sourcedir -c . | tarlz -C destdir -x
Example 9: Compress the existing POSIX archive 'archive.tar' and write the
output to 'archive.tar.lz'. Compress each member individually for maximum
availability. (If one member in the compressed archive gets damaged, the
other members can still be extracted).
tarlz -z --no-solid archive.tar

File: tarlz.info, Node: Problems, Next: Concept index, Prev: Examples, Up: Top
@ -1069,22 +1131,22 @@ Concept index

Tag Table:
Node: Top223
Node: Introduction1214
Node: Invoking tarlz4022
Ref: --data-size6233
Ref: --bsolid14593
Node: Portable character set18852
Node: File format19495
Ref: key_crc3224420
Node: Amendments to pax format30021
Ref: crc3230685
Ref: flawed-compat31970
Node: Program design34615
Node: Multi-threaded decoding38540
Node: Minimum archive sizes42482
Node: Examples44620
Node: Problems46335
Node: Concept index46863
Node: Introduction1212
Node: Invoking tarlz4020
Ref: --data-size6389
Ref: --bsolid16341
Node: Portable character set21079
Node: File format21874
Ref: key_crc3226799
Node: Amendments to pax format32400
Ref: crc3233064
Ref: flawed-compat34375
Node: Program design37176
Node: Multi-threaded decoding41101
Node: Minimum archive sizes45590
Node: Examples47728
Node: Problems49744
Node: Concept index50272

End Tag Table