Usage: ps2lrz [-s] [-f] [-i] filename
ps2lrz [-h | -?]
-s size in bytes.
-f force overwrite of file size. CAUTION!!
-i show file info, evaluate Magic Header Bytes, and exit.
If no option, info for filename will be shown.
-h|? (or no argument) show this help message.
Updated magic header is 6 bytes smaller for v0.8 and 4 bytes smaller for v0.9 and v0.10 files.
v0.9 lrzip-next files stores compression levels and any optional comment.
v0.10 lrzip-next files also stores BZIP3 compression block size.
v0.11 Add zstd level and strategy to magic header.
v0.12 LZMA SDK 23.01 Add ARM64 filtering.
ps2lrz is a C program to allow a user to poke an uncompressed
file size into an lrzip version 0.6 or lrzip-next
version 0.6 and later file.
ps2lrz can also decode information stored in the Magic Header
Bytes and present it in an easy to read format.
lrzip version 0.6 files will not store an expected file size
in lrz files when STDIN or STDOUT is used. lrzip-next
will store an expected file size when STDIN is used, but not STDOUT
in most cases.
While not having an expected file size won't impact lrzip/lrzip-next
functionality or effectiveness, it is very useful when using the -i
option because without an expected file size, lrzip/lrzip-next can't
measure net compression.
Rzip compression: 1386443973800.0% 13864439738 / 0
Back end compression: 31.0% 4300751017 / 13864439738
Overall compression: 430075101700.0% 4300751017 / 0
Encrypted files cannot at present store an expected file size. Instead it uses the same Magic Header Bytes for storing hash loops and salt.
After file compression with lrzip or lrzip-next if STDIN or STDOUT
are used, a file size may be presented if using verbose options.
If you know the number of bytes that were fed to the compressor, you
can use ps2lrz.
First, check and see if your lrz file needs a file size.
$ ps2lrz -i filename.lrz
Showing file info only
filename.lrz is an lrzip version 0.7 file
filename.lrz is not encrypted
filename.lrz uncompressed file size is 0 bytes
Dumping magic header 24 bytes
Byte Offset Description/Content
=========== ===================
Magic Bytes 0-3: 4C 52 5A 49 LRZI
Bytes 4-5: LRZIP Major, Minor version: 00, 07
Bytes 6-13: LRZIP Uncompressed Size bytes: 00 00 00 00 00 00 00 00
Bytes 14 and 15: unused
Byte 16: LRZIP Filter 1
Bytes 17-21: LZMA Properties Bytes; 5D 00 00 40 00 lc=3, lp=0, pb=2, Dictionary Size=4194304
Byte 22: MD5 Sum at EOF: yes
Byte 23: File is encrypted: no
Or if you have an lrzip-next version 0.8.x file, the output will resemble this.
$ ps2lrz -i lrzip-next.git.tar.lrz
Showing file info only
lrzip-next.git.tar.lrz is an lrzip version 0.8 file
lrzip-next.git.tar.lrz is not encrypted
lrzip-next.git.tar.lrz uncompressed file size is 0 bytes
Dumping magic header 18 bytes
Byte Offset Description/Content
=========== ===================
Magic Bytes 0-3: 4C 52 5A 49 LRZI
Bytes 4-5: LRZIP Major, Minor version: 00, 08
Bytes 6-13: LRZIP Uncompressed Size bytes: 00 00 00 00 00 00 00 00
Byte 14: MD5 Sum at EOF: yes
Byte 15: File is encrypted: no
Byte 16: LRZIP Filter 0
Byte 17: LZMA Dictionary Size Byte 1A lc=3, lp=0, pb=2, Dictionary Size=33554432
Or, if you have an lrzip-next version 0.9.x or 0.10.x file, the output will resemble this.
$ ./ps2lrz /tmp/words.txt.lrz
/tmp/words.txt.lrz is an lrzip version 0.10 file
/tmp/words.txt.lrz is not encrypted
/tmp/words.txt.lrz uncompressed file size is 1,191,359 bytes
Dumping magic header 20 bytes
Byte Offset Description/Content
=========== ===================
Magic Bytes 0-3: 4C 52 5A 49 LRZI
Bytes 4-5: LRZIP Major, Minor version: 00, 0a
Bytes 6-13: LRZIP Uncompressed Size bytes: BF 2D 12 00 00 00 00 00
Byte 14: Hash Sum at EOF: SHA 256
Byte 15: File is encrypted: NONE
Byte 16: LRZIP Filter 0 - None
Byte 17: BZIP3 Compression and Block Size Size Byte 0xF5 -- BZIP3 Block Size: 5, 201,326,592
Byte 18: Rzip / Lrzip-next Compression Levels 1 / 9
Archive Comment: ps2lrz comment example
filename.lrz uncompressed file size is 0 bytes shows you could use a file size.
This indicates that the lrz file was created with tar -I or a pipe to STDOUT.
Using lrzip -t lrzip-next -t, you can retrieve the uncompressed file size.
$ lrzip-next -tv filename.tar.lrz
...
MD5 being used for integrity testing.
Decompressing...
Average DeCompression Speed: 274.397MB/s
[OK] - 16688998400 bytes
Total time: 00:00:58.21
$ ps2lrz -s 16688998400 filename.tar.lrz
New file size is 16688998400. Magic file size set to: 00 e8 bd e2 03 00 00 00
will add the uncompressed, expected file size to filename.tar.lrz. Now
lrzip/lrzip-next -i will function as expected.
| Before ps2lrz | After ps2lrz -s 16688998400 |
|---|---|
| Rzip compression: 1386443973800.0% 13864439738 / 0 | Rzip compression: 83.1% 13864439738 / 16688998400 |
| Back end compression: 31.0% 4300751017 / 13864439738 | Back end compression: 31.0% 4300751017 / 13864439738 |
| Overall compression: 430075101700.0% 4300751017 / 0 | Overall compression: 25.8% 4300751017 / 16688998400 |
And ps2lrz -i will confirm
ps2lrz -i ilename.tar.lrz
Showing file info only
filename.tar.lrz is an lrzip version 0.7 file
filename.tar.lrz is not encrypted
filename.tar.lrz uncompressed file size is 16688998400 bytes
Dumping magic header 24 bytes
Byte Offset Description/Content
=========== ===================
Magic Bytes 0-3: 4C 52 5A 49 LRZI
Bytes 4-5: LRZIP Major, Minor version: 00, 07
Bytes 6-13: LRZIP Uncompressed Size bytes: 00 E8 BD E2 03 00 00 00
Bytes 14 and 15: unused
Byte 16: LRZIP Filter 1
Bytes 17-21: LZMA Properties Bytes; 5D 00 00 40 00 lc=3, lp=0, pb=2, Dictionary Size=4194304
Byte 22: MD5 Sum at EOF: yes
Byte 23: File is encrypted: no
Or if you have an lrzip-next version 0.8.x file,
$ ./ps2lrz -i lrzip-next.git.tar.lrz
Showing file info only
lrzip-next.git.tar.lrz is an lrzip version 0.8 file
lrzip-next.git.tar.lrz is not encrypted
lrzip-next.git.tar.lrz uncompressed file size is 13342720 bytes
Dumping magic header 18 bytes
Byte Offset Description/Content
=========== ===================
Magic Bytes 0-3: 4C 52 5A 49 LRZI
Bytes 4-5: LRZIP Major, Minor version: 00, 08
Bytes 6-13: LRZIP Uncompressed Size bytes: 00 98 CB 00 00 00 00 00
Byte 14: MD5 Sum at EOF: yes
Byte 15: File is encrypted: no
Byte 16: LRZIP Filter 0
Byte 17: LZMA Dictionary Size Byte 1A lc=3, lp=0, pb=2, Dictionary Size=33554432
One can use ./autogen.sh && ./configure && make
or simply
gcc -o ps2lrz ps2lrz.c
Feeback welcome!
August 2023
Peter Hyman
[email protected]