Fix non-root unpacking for old systems

[Enchufa2]

@grantmcdermott @philipp-baumann: Could you please try this branch?

Closes #9

[philipp-baumann]

awesome, this PR works on Rocky 8.7 with RPM version 4.14.3. On CentOS like systems with RPM v < 4.12, can cpio be expected to be installed? If no, would a short error message to install help users?

[Enchufa2]

Thanks for testing. Package cpio is expected to be available because the CentOS 7 base image has this installed, even the docker one. And I believe they implemented rpm2archive to avoid providing cpio by default. Anyways, if this is not available, an error would be issued due to https://github.com/Enchufa2/rspm/pull/11/files#diff-da37bec44282a8b2a2f78b5040c8f5d211affb10a0727d08c9a8a784c32dacf2R21

[philipp-baumann]

Thanks for testing. Package cpio is expected to be available because the CentOS 7 base image has this installed, even the docker one. And I believe they implemented rpm2archive to avoid providing cpio by default. Anyways, if this is not available, an error would be issued due to https://github.com/Enchufa2/rspm/pull/11/files#diff-da37bec44282a8b2a2f78b5040c8f5d211affb10a0727d08c9a8a784c32dacf2R21

Excellent, thanks a lot for this! Interesting note on rpm2archive.

[Enchufa2]

I'll merge this later and send it to CRAN. Thanks again for raising this.

[philipp-baumann]

Neat! Quick info maybe before you update on CRAN. Just also tested on Rocky 9.0 on google cloud instance. rspm::os() resolves to "centos9", which is not resolved to correctly in the URL to packagemanager.rstudio.com. Will quickly open a spearate issue, PR should be very minimal.