install/57782: sysinst doesn't quote paths properly in shell commands

[campbell+netbsd%mumble.net@localhost]

>Number:         57782
>Category:       install
>Synopsis:       sysinst doesn't quote paths properly in shell commands
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    install-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 18 16:15:00 +0000 2023
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The NetBSD Sysinstallation
>Environment:
>Description:
Whenever sysinst passes user-specified paths through run_program with %s, any shell metacharacters such as spaces are interpreted by the shell rather than as part of the path.
>How-To-Repeat:
1. Start an install.
2. In the partition manager, create a mount point with a space in it.
3. Watch sysinst get confused.

(This will probably proceed to trigger a bug in programs that interpret fstab even if we fix sysinst, but let's take it one step at a time and open another bug for that if it comes to it.)
>Fix:
Yes, please!