Merging upstream version 1.21.
Signed-off-by: Daniel Baumann <daniel@debian.org>
This commit is contained in:
parent
4b818dc40b
commit
29d9f35b61
GPG key ID:
FBB4F0E80A80222F
42 changed files with 2853 additions and 1586 deletions
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@ -6,8 +6,8 @@
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@finalout
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@c %**end of header
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@set UPDATED 12 February 2018
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@set VERSION 1.20
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@set UPDATED 4 January 2019
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@set VERSION 1.21
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@dircategory Data Compression
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@direntry
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@ -40,6 +40,7 @@ This manual is for Lziprecover (version @value{VERSION}, @value{UPDATED}).
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* Data safety:: Protecting data from accidental loss
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* Repairing files:: Fixing bit flips and similar errors
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* Merging files:: Fixing several damaged copies
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* Tarlz:: Options supporting the tar.lz format
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* File names:: Names of the files produced by lziprecover
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* File format:: Detailed format of the compressed file
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* Trailing data:: Extra data appended to the file
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@ -50,7 +51,7 @@ This manual is for Lziprecover (version @value{VERSION}, @value{UPDATED}).
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@end menu
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@sp 1
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Copyright @copyright{} 2009-2018 Antonio Diaz Diaz.
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Copyright @copyright{} 2009-2019 Antonio Diaz Diaz.
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This manual is free documentation: you have unlimited permission
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to copy, distribute and modify it.
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@ -60,15 +61,22 @@ to copy, distribute and modify it.
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@chapter Introduction
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@cindex introduction
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Lziprecover is a data recovery tool and decompressor for files in the
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lzip compressed data format (.lz). Lziprecover is able to repair
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slightly damaged files, produce a correct file by merging the good parts
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of two or more damaged copies, extract data from damaged files,
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decompress files and test integrity of files.
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@uref{http://www.nongnu.org/lzip/lziprecover.html,,Lziprecover} is a
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data recovery tool and decompressor for files in the lzip compressed
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data format (.lz). Lziprecover is able to repair slightly damaged files,
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produce a correct file by merging the good parts of two or more damaged
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copies, extract data from damaged files, decompress files and test
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integrity of files.
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Lziprecover can remove the damaged members from multimember files, for
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example multimember tar.lz archives.
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Lziprecover provides random access to the data in multimember files; it
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only decompresses the members containing the desired data.
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Lziprecover facilitates the management of metadata stored as trailing
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data in lzip files.
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Lziprecover is not a replacement for regular backups, but a last line of
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defense for the case where the backups are also damaged.
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@ -126,7 +134,7 @@ lziprecover -D0 -i -o file -q file.lz
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When recovering data, lziprecover takes as arguments the names of the
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damaged files and writes zero or more recovered files depending on the
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operation selected and whether the recovery succeeded or not. The
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damaged files themselves are never modified.
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damaged files themselves are kept unchanged.
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When decompressing or testing file integrity, lziprecover behaves like
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lzip or lunzip.
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@ -164,6 +172,7 @@ Print an informative help message describing the options and exit.
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@item -V
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@itemx --version
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Print the version number of lziprecover on the standard output and exit.
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This version number should be included in all bug reports.
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@anchor{--trailing-error}
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@item -a
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@ -227,12 +236,15 @@ Force overwrite of output files.
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@item -i
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@itemx --ignore-errors
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Make @samp{--range-decompress} ignore data errors and continue
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decompressing the remaining members in the file. For example,
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Make @samp{--range-decompress} ignore errors and continue decompressing
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the remaining members in the file. For example,
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@w{@samp{lziprecover -D0 -i file.lz > file}} decompresses all the
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recoverable data in all members of @samp{file.lz} without having to
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split it first.
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Make @samp{--list}, @samp{--dump}, @samp{--remove} and @samp{--strip}
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ignore format errors.
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@item -k
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@itemx --keep
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Keep (don't delete) input files during decompression.
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@ -246,18 +258,22 @@ final line containing the cumulative sizes is printed. With @samp{-v},
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the dictionary size, the number of members in the file, and the amount
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of trailing data (if any) are also printed. With @samp{-vv}, the
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positions and sizes of each member in multimember files are also
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printed. @samp{-lq} can be used to verify quickly (without
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decompressing) the structural integrity of the specified files. (Use
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@samp{--test} to verify the data integrity). @samp{-alq} additionally
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verifies that none of the specified files contain trailing data.
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printed. With @samp{-i}, format errors are ignored, and with
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@samp{-ivv}, gaps between members are shown. The member numbers shown
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coincide with the file numbers produced by @samp{--split}.
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|
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@samp{-lq} can be used to verify quickly (without decompressing) the
|
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structural integrity of the specified files. (Use @samp{--test} to
|
||||
verify the data integrity). @samp{-alq} additionally verifies that none
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of the specified files contain trailing data.
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@item -m
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@itemx --merge
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Try to produce a correct file by merging the good parts of two or more
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damaged copies. If successful, a repaired copy is written to the file
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@samp{@var{file}_fixed.lz}. The exit status is 0 if a correct file could
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be produced, 2 otherwise. See the chapter @samp{Merging files}
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(@pxref{Merging files}) for a complete description of the merge mode.
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be produced, 2 otherwise. @xref{Merging files}, for a complete
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description of the merge mode.
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|
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@item -o @var{file}
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@itemx --output=@var{file}
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@ -280,16 +296,21 @@ Quiet operation. Suppress all messages.
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Try to repair a file with small errors (up to one single-byte error per
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member). If successful, a repaired copy is written to the file
|
||||
@samp{@var{file}_fixed.lz}. @samp{@var{file}} is not modified at all.
|
||||
The exit status is 0 if the file could be repaired, 2 otherwise. See the
|
||||
chapter @samp{Repairing files} (@pxref{Repairing files}) for a complete
|
||||
description of the repair mode.
|
||||
The exit status is 0 if the file could be repaired, 2 otherwise.
|
||||
@xref{Repairing files}, for a complete description of the repair mode.
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|
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@item -s
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@itemx --split
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Search for members in @samp{@var{file}} and write each member in its own
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@samp{.lz} file. You can then use @samp{lziprecover -t} to test the
|
||||
integrity of the resulting files, decompress those which are undamaged,
|
||||
and try to repair or partially decompress those which are damaged.
|
||||
file. Gaps between members are detected and each gap is saved in its own
|
||||
file. Trailing data (if any) are saved alone in the last file. You can
|
||||
then use @samp{lziprecover -t} to test the integrity of the resulting
|
||||
files, decompress those which are undamaged, and try to repair or
|
||||
partially decompress those which are damaged. Gaps may contain garbage
|
||||
or may be members with corrupt headers or trailers. If other lziprecover
|
||||
functions fail to work on a multimember @var{file} because of damage in
|
||||
headers or trailers, try to split @var{file} and then work on each
|
||||
member individually.
|
||||
|
||||
The names of the files produced are in the form @samp{rec01@var{file}},
|
||||
@samp{rec02@var{file}}, etc, and are designed so that the use of
|
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|
@ -326,33 +347,75 @@ 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 corrupt header.
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|
||||
@item --dump-tdata
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||||
Dump the trailing data (if any) of one or more regular files to standard
|
||||
@item --dump=[@var{member_list}][:damaged][:tdata]
|
||||
Dump the members listed, the damaged members (if any), or the trailing
|
||||
data (if any) of one or more regular multimember files to standard
|
||||
output, or to a file if the @samp{--output} option is used. If more than
|
||||
one file is given, the trailing data of all files are concatenated. If a
|
||||
file does not exist, can't be opened, or is not regular, lziprecover
|
||||
continues processing the rest of the files. If the dump fails in one
|
||||
file, lziprecover exits immediately without processing the rest of the
|
||||
files.
|
||||
|
||||
@item --remove-tdata
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||||
Remove the trailing data from regular files in place. The date of each
|
||||
file is preserved if possible. If the removal fails in one file,
|
||||
lziprecover continues processing the rest of the files. This option may
|
||||
be dangerous if the file is corrupt or if the trailing data contain a
|
||||
forbidden combination of characters. @xref{Trailing data}. Verify that
|
||||
@w{@samp{lzip -cd file.lz | wc -c}} and the uncompressed size shown by
|
||||
@w{@samp{lzip -l file.lz}} match before attempting the removal.
|
||||
|
||||
@item --strip-tdata
|
||||
Copy one or more regular files to standard output (or to a file if the
|
||||
@samp{--output} option is used), stripping the trailing data (if any)
|
||||
from each file. If more than one file is given, the files are
|
||||
concatenated. If a file does not exist, can't be opened, or is not
|
||||
regular, lziprecover continues processing the rest of the files. If a
|
||||
file fails to copy, lziprecover exits immediately without processing the
|
||||
one file is given, the elements dumped from all files are concatenated.
|
||||
If a file does not exist, can't be opened, or is not regular,
|
||||
lziprecover continues processing the rest of the files. If the dump
|
||||
fails in one file, lziprecover exits immediately without processing the
|
||||
rest of the files.
|
||||
|
||||
The argument to @samp{--dump} is a colon-separated list of the following
|
||||
element specifiers; a member list (1,3-6), a reverse member list
|
||||
(r1,3-6), and the strings "damaged" and "tdata" (which may be shortened
|
||||
to 'd' and 't' respectively). A member list selects the members (or
|
||||
gaps) listed, whose numbers coincide with those shown by @samp{--list}.
|
||||
A reverse member list selects the members listed counting from the last
|
||||
member in the file (r1). Negated versions of both kinds of lists exist
|
||||
(^1,3-6:r^1,3-6) which selects all the members except those in the list.
|
||||
The strings "damaged" and "tdata" select the damaged members and the
|
||||
trailing data respectively. If the same member is selected more than
|
||||
once, for example by @code{1:r1} in a single-member file, it is dumped
|
||||
just once. See the following examples:
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||||
|
||||
@multitable {@code{3,12:damaged:tdata}} {members 3, 12, damaged members, trailing data}
|
||||
@headitem @code{--dump} argument @tab Elements dumped
|
||||
@item @code{1,3-6} @tab members 1, 3, 4, 5 and 6
|
||||
@item @code{r1-3} @tab last 3 members in file
|
||||
@item @code{^13,15} @tab all but 13th and 15th members in file
|
||||
@item @code{r^1} @tab all but last member in file
|
||||
@item @code{damaged} @tab all damaged members in file
|
||||
@item @code{tdata} @tab trailing data
|
||||
@item @code{1-5:r1:tdata} @tab members 1 to 5, last member, trailing data
|
||||
@item @code{damaged:tdata} @tab damaged members, trailing data
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||||
@item @code{3,12:damaged:tdata} @tab members 3, 12, damaged members, trailing data
|
||||
@end multitable
|
||||
|
||||
@item --remove=[@var{member_list}][:damaged][:tdata]
|
||||
Remove the members listed, the damaged members (if any), or the trailing
|
||||
data (if any) from regular multimember files in place. The date of each
|
||||
file is preserved if possible. If all members in a file are selected to
|
||||
be removed, the file is left unchanged and the exit status is set to 2.
|
||||
If a file does not exist, can't be opened, is not regular, or is left
|
||||
unchanged, lziprecover continues processing the rest of the files. In
|
||||
case of I/O error, lziprecover exits immediately without processing the
|
||||
rest of the files. See @samp{--dump} above for a description of the
|
||||
argument.
|
||||
|
||||
This option may be dangerous even if only the trailing data is being
|
||||
removed because the file may be corrupt or the trailing data may contain
|
||||
a forbidden combination of characters. @xref{Trailing data}. It is
|
||||
advisable to make a backup before attempting the removal. At least
|
||||
verify that @w{@samp{lzip -cd file.lz | wc -c}} and the uncompressed
|
||||
size shown by @w{@samp{lzip -l file.lz}} match before attempting the
|
||||
removal of trailing data.
|
||||
|
||||
@item --strip=[@var{member_list}][:damaged][:tdata]
|
||||
Copy one or more regular multimember files to standard output (or to a
|
||||
file if the @samp{--output} option is used), stripping the members
|
||||
listed, the damaged members (if any), or the trailing data (if any) from
|
||||
each file. If all members in a file are selected to be stripped, the
|
||||
trailing data (if any) are also stripped even if @samp{tdata} is not
|
||||
specified. If more than one file is given, the files are concatenated.
|
||||
In this case the trailing data are also stripped from all but the last
|
||||
file even if @samp{tdata} is not specified. If a file does not exist,
|
||||
can't be opened, or is not regular, lziprecover continues processing the
|
||||
rest of the files. If a file fails to copy, lziprecover exits
|
||||
immediately without processing the rest of the files. See @samp{--dump}
|
||||
above for a description of the argument.
|
||||
|
||||
@end table
|
||||
|
||||
Numbers given as arguments to options may be followed by a multiplier
|
||||
|
|
@ -521,6 +584,80 @@ than the number of corrupt bytes (3104) because contiguous corrupt bytes
|
|||
are counted as a single multibyte error.
|
||||
|
||||
|
||||
@node Tarlz
|
||||
@chapter Options supporting the tar.lz format
|
||||
@cindex tarlz
|
||||
|
||||
@uref{http://www.nongnu.org/lzip/manual/tarlz_manual.html,,Tarlz} is an
|
||||
implementation of the tar archiver which by default creates archives
|
||||
compressed with lzip on a per file basis. Tarlz can append files to the
|
||||
end of such compressed archives because each tar member is compressed in
|
||||
its own lzip member, as well as the end-of-file blocks. Thus tarlz
|
||||
archives are multimember lzip files, which has some safety advantages
|
||||
over solidly compressed tar.lz archives. For example, in case of
|
||||
corruption, tarlz can extract all the undamaged members from the tar.lz
|
||||
archive, skipping over the damaged members, just like the standard
|
||||
(uncompressed) tar. In this chapter we'll explain the ways in which
|
||||
lziprecover can recover and process multimember tar.lz archives.
|
||||
@ifnothtml
|
||||
@xref{Top,tarlz manual,,tarlz}.
|
||||
@end ifnothtml
|
||||
|
||||
@sp 1
|
||||
@section Recovering damaged multimember tar.lz archives
|
||||
|
||||
If you have several copies of the damaged archive, try merging
|
||||
them first because merging has a high probability of success. If the
|
||||
command below prints something like
|
||||
@w{@code{Input files merged successfully.}} you are done and
|
||||
@code{archive.tar.lz} now contains the recovered archive:
|
||||
|
||||
@example
|
||||
lziprecover -m -v -o archive.tar.lz a/archive.tar.lz b/archive.tar.lz
|
||||
@end example
|
||||
|
||||
If you only have one copy of the damaged archive, you may try to repair
|
||||
the archive, but this has a lower probability of success. If the command
|
||||
below prints something like
|
||||
@w{@code{Copy of input file repaired successfully.}} you are done and
|
||||
@code{archive_fixed.tar.lz} now contains the recovered archive:
|
||||
|
||||
@example
|
||||
lziprecover -v -R archive.tar.lz
|
||||
@end example
|
||||
|
||||
If all the above fails, you may save the damaged members for later and
|
||||
then copy the good members to another archive. If the two commands below
|
||||
succeed, @code{bad_members.tar.lz} will contain all the damaged members
|
||||
and @code{archive_cleaned.tar.lz} will contain a good archive with the
|
||||
damaged members removed:
|
||||
|
||||
@example
|
||||
lziprecover -v --dump=damaged -o bad_members.tar.lz archive.tar.lz
|
||||
lziprecover -v --strip=damaged -o archive_cleaned.tar.lz archive.tar.lz
|
||||
@end example
|
||||
|
||||
You can then use @code{tarlz --keep-damaged} to recover as much data as
|
||||
possible from each damaged member in @samp{bad_members.tar.lz}:
|
||||
|
||||
@example
|
||||
mkdir tmp
|
||||
cd tmp
|
||||
tarlz --keep-damaged -xvf ../bad_members.tar.lz
|
||||
@end example
|
||||
|
||||
@sp 1
|
||||
@section Processing multimember tar.lz archives
|
||||
|
||||
Lziprecover is able to copy a list of members from a file to another.
|
||||
For example the command
|
||||
@w{@code{lziprecover --dump=1-10:r1:tdata archive.tar.lz > subarch.tar.lz}}
|
||||
creates a subset archive containing the first ten members, the
|
||||
end-of-file blocks, and the trailing data (if any) of
|
||||
@code{archive.tar.lz}. The @code{r1} part selects the last member, which
|
||||
in an appendable tar.lz archive contains the end-of-file blocks.
|
||||
|
||||
|
||||
@node File names
|
||||
@chapter Names of the files produced by lziprecover
|
||||
@cindex file names
|
||||
|
|
@ -581,10 +718,10 @@ Just in case something needs to be modified in the future. 1 for now.
|
|||
|
||||
@item DS (coded dictionary size, 1 byte)
|
||||
The dictionary size is calculated by taking a power of 2 (the base size)
|
||||
and substracting from it a fraction between 0/16 and 7/16 of the base
|
||||
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 substract
|
||||
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.
|
||||
|
|
@ -675,11 +812,11 @@ Example 1: Add a comment or description to a compressed file.
|
|||
# First append the comment as trailing data to a lzip file
|
||||
echo 'This file contains this and that' >> file.lz
|
||||
# This command prints the comment to standard output
|
||||
lziprecover --dump-tdata file.lz
|
||||
lziprecover --dump=tdata file.lz
|
||||
# This command outputs file.lz without the comment
|
||||
lziprecover --strip-tdata file.lz
|
||||
lziprecover --strip=tdata file.lz
|
||||
# This command removes the comment from file.lz
|
||||
lziprecover --remove-tdata file.lz
|
||||
lziprecover --remove=tdata file.lz
|
||||
@end example
|
||||
|
||||
@sp 1
|
||||
|
|
@ -690,8 +827,8 @@ to guarantee that both file and hash have not been maliciously replaced).
|
|||
|
||||
@example
|
||||
sha256sum < file.lz >> file.lz
|
||||
lziprecover --strip-tdata file.lz | sha256sum -c \
|
||||
<(lziprecover --dump-tdata file.lz)
|
||||
lziprecover --strip=tdata file.lz | sha256sum -c \
|
||||
<(lziprecover --dump=tdata file.lz)
|
||||
@end example
|
||||
|
||||
|
||||
|
|
@ -727,6 +864,10 @@ Don't do this
|
|||
cat file1.lz file2.lz file3.lz | lziprecover -d
|
||||
Do this instead
|
||||
lziprecover -cd file1.lz file2.lz file3.lz
|
||||
You may also concatenate the compressed files like this
|
||||
lziprecover --strip=tdata file1.lz file2.lz file3.lz > file123.lz
|
||||
Or keeping the trailing data of the last file like this
|
||||
lziprecover --strip=damaged file1.lz file2.lz file3.lz > file123.lz
|
||||
@end example
|
||||
|
||||
@sp 1
|
||||
|
|
@ -777,13 +918,13 @@ lziprecover -tv rec*file.lz
|
|||
Example 8: Recover a compressed backup from two copies on CD-ROM with
|
||||
error-checked merging of copies.
|
||||
@ifnothtml
|
||||
(@xref{Top,GNU ddrescue manual,,ddrescue},
|
||||
@xref{Top,GNU ddrescue manual,,ddrescue},
|
||||
@end ifnothtml
|
||||
@ifhtml
|
||||
(See the
|
||||
See the
|
||||
@uref{http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html,,ddrescue manual}
|
||||
@end ifhtml
|
||||
for details about ddrescue).
|
||||
for details about ddrescue.
|
||||
|
||||
@example
|
||||
ddrescue -d -r1 -b2048 /dev/cdrom cdimage1 mapfile1
|
||||
|
|
@ -862,15 +1003,15 @@ after the last byte of a member, producing a shorter but valid
|
|||
compressed file. Except in this latter case, please, report any false
|
||||
negative as a bug.
|
||||
|
||||
In order to compare the outputs, unzcrash needs a @samp{zcmp} program
|
||||
able to understand the format being tested. For example the one provided
|
||||
In order to compare the outputs, unzcrash needs a @samp{zcmp} program able
|
||||
to understand the format being tested. For example the @samp{zcmp} provided
|
||||
by @samp{zutils}.
|
||||
@ifnothtml
|
||||
@xref{Zcmp,,,zutils},
|
||||
@xref{Zcmp,,,zutils}.
|
||||
@end ifnothtml
|
||||
@ifhtml
|
||||
See
|
||||
@uref{http://www.nongnu.org/zutils/manual/zutils_manual.html#Zcmp,,zcmp}
|
||||
@uref{http://www.nongnu.org/zutils/manual/zutils_manual.html#Zcmp,,zcmp}.
|
||||
@end ifhtml
|
||||
|
||||
The format for running unzcrash is:
|
||||
|
|
@ -879,6 +1020,10 @@ The format for running unzcrash is:
|
|||
unzcrash [@var{options}] 'lzip -t' @var{file}.lz
|
||||
@end example
|
||||
|
||||
@noindent
|
||||
@var{file}.lz must not contain errors and must be correctly decompressed
|
||||
by the decompressor being tested for the comparisons to work.
|
||||
|
||||
unzcrash supports the following options:
|
||||
|
||||
@table @code
|
||||
|
|
@ -889,6 +1034,7 @@ Print an informative help message describing the options and exit.
|
|||
@item -V
|
||||
@itemx --version
|
||||
Print the version number of unzcrash on the standard output and exit.
|
||||
This version number should be included in all bug reports.
|
||||
|
||||
@item -b @var{range}
|
||||
@itemx --bits=@var{range}
|
||||
|
|
@ -966,7 +1112,10 @@ Verbose mode.
|
|||
@item -z
|
||||
@itemx --zcmp=<command>
|
||||
Set zcmp command name and options. Defaults to @code{zcmp}. Use
|
||||
@code{--zcmp=false} to disable comparisons.
|
||||
@code{--zcmp=false} to disable comparisons. If testing a decompressor
|
||||
different from the one used by default by zcmp, it is needed to force
|
||||
unzcrash and zcmp to use the same decompressor with a command like
|
||||
@w{@code{unzcrash --zcmp='zcmp --lz=plzip' 'plzip -t' @var{file}.lz}}
|
||||
|
||||
@end table
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue