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Adding upstream version 0.21.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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Daniel Baumann 2025-02-17 21:15:58 +01:00
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122
doc/tarlz.texi
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@ -6,8 +6,8 @@
@finalout
@c %**end of header
@set UPDATED 8 January 2021
@set VERSION 0.19
@set UPDATED 14 June 2021
@set VERSION 0.21
@dircategory Data Compression
@direntry
@ -138,7 +138,7 @@ tarlz [@var{options}] [@var{files}]
@noindent
All operations except @samp{--concatenate} operate on whole trees if any
@var{file} is a directory.
@var{file} is 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
@ -155,7 +155,7 @@ member names in the archive or given in the command line, so that
If several compression levels or @samp{--*solid} options are given, the last
setting is used. For example @w{@samp{-9 --solid --uncompressed -1}} is
equivalent to @samp{-1 --solid}
equivalent to @w{@samp{-1 --solid}}.
tarlz supports the following
@uref{http://www.nongnu.org/arg-parser/manual/arg_parser_manual.html#Argument-syntax,,options}:
@ -174,15 +174,17 @@ This version number should be included in all bug reports.
@item -A
@itemx --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 @var{files} have been specified.
Append one or more archives to the end of an archive. If no archive is
specified with the option @samp{-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 @var{files} have been specified.
@anchor{--data-size}
@item -B @var{bytes}
@ -285,6 +287,12 @@ Note that the number of usable threads is limited during compression to
and during decompression to the number of lzip members in the tar.lz
archive, which you can find by running @w{@samp{lzip -lv archive.tar.lz}}.
@item -o @var{file}
@itemx --output=@var{file}
Write the compressed output to @var{file}. @w{@samp{-o -}} writes the
compressed output to standard output. Currently @samp{--output} only works
with @samp{--compress}.
@item -p
@itemx --preserve-permissions
On extraction, set file permissions as they appear in the archive. This is
@ -331,11 +339,34 @@ special effort to extract a file over an incompatible type of file. For
example, extracting a link over a directory will usually fail. (Principle of
least surprise).
@item -z
@itemx --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 @samp{-} used as the name of an input
archive reads from standard input and writes to standard output (unless the
option @samp{--output} is used). Tarlz can be used as compressor for GNU tar
using a command like @w{@samp{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.
@samp{--compress} implies plzip argument style, not tar style. Each input
archive is compressed to a file with the extension @samp{.lz} added unless
the option @samp{--output} is used. When @samp{--output} is used, only one
input archive can be specified. @samp{-f} can't be used with
@samp{--compress}.
@item -0 .. -9
Set the compression level for @samp{--create} and @samp{--append}. The
default compression level is @samp{-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 @samp{--create}, @samp{--append}, and
@samp{--compress}. The default compression level is @samp{-6}. Like lzip,
tarlz also minimizes the dictionary size of the lzip members it creates,
reducing the amount of memory required for decompression.
@multitable {Level} {Dictionary size} {Match length limit}
@item Level @tab Dictionary size @tab Match length limit
@ -446,6 +477,14 @@ the value of @samp{LZ_API_VERSION} (if defined).
@xref{Library version,,,lzlib}.
@end ifnothtml
@item --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 @samp{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.
@ignore
@item --permissive
Allow some violations of the archive format, like consecutive extended
@ -457,7 +496,7 @@ keyword appearing in the same block of extended records.
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)
corrupt or invalid input file, 3 for an internal consistency error (e.g. bug)
which caused tarlz to panic.
@ -477,7 +516,13 @@ The last three characters are the period, underscore, and hyphen-minus
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
@uref{http://www.gnu.org/software/moe/manual/moe_manual.html#why-not-Unicode,,avoided}
in computing environments, specially in file names.
@ifnothtml
@xref{why not Unicode,,,moe}.
@end ifnothtml
@node File format
@ -796,8 +841,9 @@ 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. @xref{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.
@xref{key_crc32}.
@sp 1
@anchor{flawed-compat}
@ -818,7 +864,9 @@ To avoid this problem, tarlz writes extended headers with all fields 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.
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 @w{8 GiB} or a link name longer than 100 bytes), tarlz moves the
@ -940,11 +988,20 @@ error be avoided.
@chapter Limitations of parallel tar decoding
@cindex 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
@ -1131,6 +1188,17 @@ directory @samp{destdir}.
tarlz -C sourcedir -c . | tarlz -C destdir -x
@end example
@sp 1
@noindent
Example 9: Compress the existing POSIX archive @samp{archive.tar} and write
the output to @samp{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).
@example
tarlz -z --no-solid archive.tar
@end example
@node Problems
@chapter Reporting bugs