I need to preface this feature request by mentioning that, currently, the default BINPKG_COMPRESS is set to zstd, which trumps every other compression format by a landslide, when it comes to being used in the context of portage. I'm not sure if the other compression formats are left around as a legacy, or if they're intended to be supported to their fullest extent. This feature request concerns the latter case. There currently exist a few alternative implementations to some of the supported binpkg compression formats: - app-arch/bzip2: app-arch/lbzip2 app-arch/pbzip2 - app-arch/gzip: app-arch/pigz - app-arch/lzip: app-arch/plzip There's currently two ways to use any of these alternatives: - Using app-alternatives (gzip and bzip2) - Using PORTAGE_BZIP2_COMMAND However, neither of these solutions seems to be meant to change the compressor used for creating and extracting binpkgs. The app-alternatives solution isn't supported for all commands, and affects everything on the system, which may be undesireable. The PORTAGE_BZIP2_COMMAND solution is exclusive to bzip2, and has other side-effects across the portage codebase: - It's used in unpack() in bin/phase-helpers.sh to unpack any bzip2 archive - It's used to compress and decompress environment.bz2, across the ebuild phases and the python code This feature feels a bit legacy, and I'm not sure what its intended use was. I'm not sure what to propose as a solution, as there's no obvious *good* way to solve this, but depending on preferences, one of these solutions may be chosen: - Add PORTAGE_comp_COMMAND for each of the supported compressors, and similarly replace any use in unpack() and similar, to make it consistent with PORTAGE_BZIP2_COMMAND. - Add a new BINPKG_COMPRESS_COMMAND, overriding the compression command for the current BINPKG_COMPRESS method. Wouldn't allow choosing a decompressor, however. - Implement support for the parallel compressors by picking them over the default implementation if available. I've seen more and more programs do this lately, and it'd provide a nice default speed boost by simply having them installed. Not great for reproducible builds, however.
> However, neither of these solutions seems to be meant to change the compressor used for creating and extracting binpkgs. Does switching the default via app-alternatives not allow you to affect what Portage uses as `bzip2`, `gzip`, etc?
They do, but they also change the system-wide defaults, which may be undesireable. In my case, I just don't want to deviate from the secure and well-tested reference implementations where I don't have a reason to fully trust the archive, or don't want to risk data loss.
