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7-Zip 9.13 beta | Lempel-Zip-ENOENT 2010 (Announce)

posted by Rugxulo Homepage, Usono, 08.05.2010, 13:46

> > 7-Zip 9.12 beta
>
> 9.13 beta is out (2010-04-15)
>
> Changes: virtually nothing :-|
>
> I didn't test yet, but I tested the "other compressy thing"

LZMA SDK is still at 9.12, though, and (as I mentioned) now 7zdec can optionally unpack PPMD in addition to LZMA or LZMA2. This adds approx. 4k to the .EXE (for most cases). I'm pretty finished updating my compiles to 9.12 if anybody wants 'em "right now, today!" and can't wait.

> > Latest news
> > 04 April 2010
> > added Lzip version 1.9 to Ports & builds page
I noticed that 1.10 is already out.

http://www.nongnu.org/lzip/lzip.html

> There are many BUG's (see ^^^ shot):
>
> 1. It doesn't work - an attempt to compress "XXX.TAR" without any
> commandline parameters except the source name ends up in an ENOENT
> (1.) (not sure whether I possibly already had reported this type of BUG at
> some time, multiple times or even unreasonably many times in the past
Yes, it needs LFNs for tempfile, that's probably a legit misfeature for the DOS port.

> 2. ... not a single letter of information, no progress indicator (3.)
The *nix philosophy seems to be "stay silent unless something goes wrong" (e.g. NASM, GCC).

> 3. After silent exit, the compressed file seems to be there (and smaller
> :-) !!!), but the source file is gone (4.) !!! This is a criminal BUG,
> considering the file was Read-Only (5.) (IIRC some DGJPP binary of
> BZIP2 had the very same bug when I tested such centuries ago, maybe there
> are even more ...)
That's the correct behavior. I agree it can sometimes be surprising, but it's not a huge deal. Actually, it seems to also support "-k" like Bzip2, so you may wish to use that (or set the appropriate env. var.).

> 5. System requirements are not documented at all, I just tested in
> FreeDOS, it is undeterminable whether it is supposed to work or not (seems
> I even missed the infamous "Error: no DPMI get CWSDPMI"-BUG :confused:
http://www.nongnu.org/lzip/manual/lzip_manual.html#Invoking-Lzip

"The amount of memory required for compression is about 5 MiB plus 1 or 2 times the dictionary size limit (1 if input file size is less than dictionary size limit, else 2) plus 8 times the dictionary size really used. For decompression it is a little more than the dictionary size really used."

Dictionary seems to need 1 MB (-1) through 32 MB (-9), depending on input file size.

> 6. There are too many competing and incompatible LZMA-based attempts to
> replace GZIP/BZIP2: LZIP, XZ, original Igor's LZMA, new Igor's LZMA (???),
> original full 7-ZIP format, ...
LZMA isn't a real file format, nor is LZMA2. 7-Zip is, but even that ignores *nix permissions, which probably is why .xz and .lz exist (both used by some GNU projects).

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