#2411 ERROR: Unsupported Method on some DMGs

[jacek szymanski]

7zip fails to unpack (and test) some DMGs (e.g. https://desktop.docker.com/mac/main/amd64/120376/Docker.dmg) with output like this:

7-Zip (z) 23.01 (x64) : Copyright (c) 1999-2023 Igor Pavlov : 2023-06-20
 64-bit locale=en_US.UTF-8 Threads:4 OPEN_MAX:256

Scanning the drive for archives:
1 file, 656801294 bytes (627 MiB)

Testing archive: Docker.dmg
--
Path = Docker.dmg
Type = Dmg
Physical Size = 656801294
Method = Zero0 Zero2 2147483656 CRC
Blocks = 2143
Comment = Docker

ERROR: Unsupported Method : 0.MBR
ERROR: Unsupported Method : 1.Primary GPT Header
ERROR: Unsupported Method : 2.Primary GPT Table
ERROR: Unsupported Method : 4.efi_sys
ERROR: Unsupported Method : 5.hfs
ERROR: Unsupported Method : 7.Backup GPT Table
ERROR: Unsupported Method : 8.Backup GPT Header

Sub items Errors: 7

Archives with Errors: 1

Sub items Errors: 7

I'm using 7zz on MacOS Monterey Intel.

[jacek szymanski]

FWIW, the Docker.dmg image is in ULMO format, after converting to UDBZ 7zz unpacks it just fine.

[Igor Pavlov]

Yes, it's lzma compressed.
I try to implement support for it now.

[Igor Pavlov]

It turned out this ULMO-DMG is not pure LZMA compression, but it's xz compression instead.
xz uses LZMA2 that is lzma based, but xz has another container format and another headers.
I've updated the code. So next version of 7-zip will unpack such ULMO-DMG archives.

Is there official name for that compression method (ULMO or LZMA) in dmg from Apple?
Or it's some suggested name from some third-party (non-Apple) dmg program?

[jacek szymanski]

hdiutil imageinfo identified the Docker.dmg image format as ULMO.