minstall: rework root elevation prompt for extensibility and behavior

There's a couple issues with the current approach:
- pkexec is an unusual elevation method, the standard is sudo
- it tries to elevate even in automated workflows
- the user may not want to automatically rerun as root, that might be
  badly behaved

Do some upfront checks instead, first to make sure it even makes sense
to try becoming root, and then to ask the user "do you really want
this". Also check for a couple common approaches to root elevation,
including doas.

Fixes #7345
Fixes #7809

1 files changed, 14 insertions, 0 deletions

diff --git a/docs/markdown/Installing.md b/docs/markdown/Installing.md
index a692afe7d..0bc9a4744 100644
--- a/docs/markdown/Installing.md
+++ b/docs/markdown/Installing.md
@@ -102,6 +102,20 @@ Telling Meson to run this script at install time is a one-liner.
 The argument is the name of the script file relative to the current
 subdirectory.
 
+## Installing as the superuser
+
+When building as a non-root user, but installing to root-owned locations via
+e.g. `sudo ninja install`, ninja will attempt to rebuild any out of date
+targets as root. This results in various bad behaviors due to build outputs and
+ninja internal files being owned by root.
+
+Running `meson install` is preferred for several reasons. It can rebuild out of
+date targets and then re-invoke itself as root.
+
+*(since 1.1.0)* Re-invoking as root will try to guess the user's preferred method for
+re-running commands as root. The order of precedence is: sudo, doas, pkexec
+(polkit). An elevation tool can be forced by setting `$MESON_ROOT_CMD`.
+
 ## DESTDIR support
 
 Sometimes you need to install to a different directory than the