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Merging upstream version 1.18~pre2.

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Signed-off-by: Daniel Baumann <daniel@debian.org>
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Daniel Baumann 2025-02-21 11:25:59 +01:00
parent 20207bbadd
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Signed by: daniel
GPG key ID: FBB4F0E80A80222F
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doc/lziprecover.info
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@ -12,7 +12,7 @@ File: lziprecover.info, Node: Top, Next: Introduction, Up: (dir)
Lziprecover Manual
******************
This manual is for Lziprecover (version 1.18-pre1, 30 June 2015).
This manual is for Lziprecover (version 1.18-pre2, 16 September 2015).
* Menu:
@ -23,6 +23,7 @@ This manual is for Lziprecover (version 1.18-pre1, 30 June 2015).
* Merging files:: Fixing several damaged copies
* File names:: Names of the files produced by lziprecover
* File format:: Detailed format of the compressed file
* Trailing data:: Extra data appended to the file
* Examples:: A small tutorial with examples
* Unzcrash:: Testing the robustness of decompressors
* Problems:: Reporting bugs
@ -54,7 +55,7 @@ availability:
recovery means. The lziprecover program can repair bit-flip errors
(one of the most common forms of data corruption) in lzip files,
and provides data recovery capabilities, including error-checked
merging of damaged copies of a file.
merging of damaged copies of a file. *Note Data safety::.
* The lzip format is as simple as possible (but not simpler). The
lzip manual provides the code of a simple decompressor along with
@ -125,6 +126,13 @@ The format for running lziprecover is:
Print the version number of lziprecover on the standard output and
exit.
'-a'
'--trailing-error'
Exit with error status 2 if any remaining input is detected after
decompressing the last member. Such remaining input is usually
trailing garbage that can be safely ignored. *Note
concat-example::.
'-c'
'--stdout'
Decompress to standard output. Needed when reading from a named
@ -133,7 +141,9 @@ The format for running lziprecover is:
'-d'
'--decompress'
Decompress.
Decompress the specified file(s). If a file fails to decompress,
lziprecover exits immediately without decompressing the rest of the
files.
'-D RANGE'
'--range-decompress=RANGE'
@ -220,7 +230,8 @@ The format for running lziprecover is:
Check integrity of the specified file(s), but don't decompress
them. This really performs a trial decompression and throws away
the result. Use it together with '-v' to see information about
the file.
the file(s). If a file fails the test, lziprecover continues
checking the rest of the files.
'-v'
'--verbose'
@ -228,7 +239,7 @@ The format for running lziprecover is:
When decompressing or testing, further -v's (up to 4) increase the
verbosity level, showing status, compression ratio, dictionary
size, trailer contents (CRC, data size, member size), and up to 6
bytes of trailing garbage (if any).
bytes of trailing data (if any).
Numbers given as arguments to options may be followed by a multiplier
@ -387,7 +398,7 @@ original file name ends with one of the extensions '.tar.lz', '.lz' or
'.tlz', the string '_fixed' is inserted before the extension.

File: lziprecover.info, Node: File format, Next: Examples, Prev: File names, Up: Top
File: lziprecover.info, Node: File format, Next: Trailing data, Prev: File names, Up: Top
7 File format
*************
@ -421,7 +432,7 @@ additional information before, between, or after them.
All multibyte values are stored in little endian order.
'ID string'
'ID string (the "magic" bytes)'
A four byte string, identifying the lzip format, with the value
"LZIP" (0x4C, 0x5A, 0x49, 0x50).
@ -458,9 +469,42 @@ additional information before, between, or after them.

File: lziprecover.info, Node: Examples, Next: Unzcrash, Prev: File format, Up: Top
File: lziprecover.info, Node: Trailing data, Next: Examples, Prev: File format, Up: Top
8 A small tutorial with examples
8 Extra data appended to the file
*********************************
Sometimes extra data is found appended to a lzip file after the last
member. Such trailing data may be:
* Padding added to make the file size a multiple of some block size,
for example when writing to a tape.
* Garbage added by some not totally successful copy operation.
* Useful data added by the user; a cryptographically secure hash, a
description of file contents, etc.
* Malicious data added to the file in order to make its total size
and hash value (for a chosen hash) coincide with those of another
file.
* In very rare cases, trailing data could be the corrupt header of
another member. In multi-member or concatenated files the
probability of corruption happening in the magic bytes is 5 times
smaller than the probability of getting a false positive caused by
the corruption of the integrity information itself. Therefore it
can be considered to be below the noise level.
Trailing data can be safely ignored in most cases. In some cases,
like user-added data, it is expected to be ignored. In those cases
where a file containing trailing data must be rejected, the option
'--trailing-error' can be used. *Note --trailing-error::.

File: lziprecover.info, Node: Examples, Next: Unzcrash, Prev: Trailing data, Up: Top
9 A small tutorial with examples
********************************
Example 1: Restore a regular file from its compressed version
@ -475,29 +519,38 @@ show status.
lziprecover -tv file.lz
Example 3: Decompress 'file.lz' partially until 10 KiB of decompressed
Example 3: The right way of concatenating compressed files. *Note
Trailing data::.
Don't do this
cat file1.lz file2.lz file3.lz | lziprecover -d
Do this instead
lziprecover -cd file1.lz file2.lz file3.lz
Example 4: Decompress 'file.lz' partially until 10 KiB of decompressed
data are produced.
lziprecover -D 0,10KiB file.lz
Example 4: Decompress 'file.lz' partially from decompressed byte 10000
Example 5: Decompress 'file.lz' partially from decompressed byte 10000
to decompressed byte 15000 (5000 bytes are produced).
lziprecover -D 10000-15000 file.lz
Example 5: Repair small errors in the file 'file.lz'. (Indented lines
Example 6: Repair small errors in the file 'file.lz'. (Indented lines
are abridged diagnostic messages from lziprecover).
lziprecover -v -R file.lz
Copy of input file repaired successfully.
lziprecover -tv file_fixed.lz
ok
file_fixed.lz: ok
mv file_fixed.lz file.lz
Example 6: Split the multi-member file 'file.lz' and write each member
Example 7: Split the multi-member file 'file.lz' and write each member
in its own 'recXXXfile.lz' file. Then use 'lziprecover -t' to test the
integrity of the resulting files.
@ -505,26 +558,26 @@ integrity of the resulting files.
lziprecover -tv rec*file.lz
Example 7: Recover a compressed backup from two copies on CD-ROM with
error-checked merging of copies (*Note GNU ddrescue manual:
Example 8: Recover a compressed backup from two copies on CD-ROM with
error-checked merging of copies. (*Note GNU ddrescue manual:
(ddrescue)Top, for details about ddrescue).
ddrescue -d -r1 -b2048 /dev/cdrom cdimage1 logfile1
ddrescue -d -r1 -b2048 /dev/cdrom cdimage1 mapfile1
mount -t iso9660 -o loop,ro cdimage1 /mnt/cdimage
cp /mnt/cdimage/backup.tar.lz rescued1.tar.lz
umount /mnt/cdimage
(insert second copy in the CD drive)
ddrescue -d -r1 -b2048 /dev/cdrom cdimage2 logfile2
ddrescue -d -r1 -b2048 /dev/cdrom cdimage2 mapfile2
mount -t iso9660 -o loop,ro cdimage2 /mnt/cdimage
cp /mnt/cdimage/backup.tar.lz rescued2.tar.lz
umount /mnt/cdimage
lziprecover -m -v -o backup.tar.lz rescued1.tar.lz rescued2.tar.lz
Input files merged successfully.
lziprecover -tv backup.tar.lz
ok
backup.tar.lz: ok
Example 8: Recover the first volume of those created with the command
Example 9: Recover the first volume of those created with the command
'lzip -b 32MiB -S 650MB big_db' from two copies, 'big_db1_00001.lz' and
'big_db2_00001.lz', with member 07 damaged in the first copy, member 18
damaged in the second copy, and member 12 damaged in both copies. The
@ -533,13 +586,13 @@ correct file produced is saved in 'big_db_00001.lz'.
lziprecover -m -v -o big_db_00001.lz big_db1_00001.lz big_db2_00001.lz
Input files merged successfully.
lziprecover -tv big_db_00001.lz
ok
big_db_00001.lz: ok

File: lziprecover.info, Node: Unzcrash, Next: Problems, Prev: Examples, Up: Top
9 Testing the robustness of decompressors
*****************************************
10 Testing the robustness of decompressors
******************************************
The lziprecover package also includes unzcrash, a program written to
test robustness to decompression of corrupted data, inspired by
@ -615,7 +668,7 @@ caused unzcrash to panic.

File: lziprecover.info, Node: Problems, Next: Concept index, Prev: Unzcrash, Up: Top
10 Reporting bugs
11 Reporting bugs
*****************
There are probably bugs in lziprecover. There are certainly errors and
@ -646,24 +699,28 @@ Concept index
* invoking: Invoking lziprecover. (line 6)
* merging files: Merging files. (line 6)
* repairing files: Repairing files. (line 6)
* trailing data: Trailing data. (line 6)
* unzcrash: Unzcrash. (line 6)

Tag Table:
Node: Top231
Node: Introduction1214
Node: Invoking lziprecover4310
Node: Data safety9743
Node: Repairing files11667
Node: Merging files13569
Node: File names15410
Node: File format15874
Node: Examples18278
Ref: ddrescue-example19524
Node: Unzcrash20780
Node: Problems23334
Node: Concept index23886
Node: Introduction1278
Node: Invoking lziprecover4395
Ref: --trailing-error4860
Node: Data safety10294
Node: Repairing files12218
Node: Merging files14120
Node: File names15961
Node: File format16425
Node: Trailing data18854
Node: Examples20230
Ref: concat-example20661
Ref: ddrescue-example21725
Node: Unzcrash23015
Node: Problems25571
Node: Concept index26123

End Tag Table