Add HOMEBREW_SUDO_THROUGH_SUDO_USER

This environment variable allows telling Homebrew to use the `SUDO_USER`
variable to `sudo` through that user when Homebrew (Cask) attempts to
run `sudo`.

While we're here, clarify in some messaging that we're running `sudo`
and that that's the password we're asking for; the specific password is
configuration dependent and not the specific password for the user.

Similarly, remove the `Package installers may write to any location`
output; it's kinda spammy and doesn't feel like the right place.

Library/Homebrew/cask/artifact/abstract_uninstall.rb

@@ -379,7 +379,7 @@ module Cask
       end
 
       def uninstall_pkgutil(*pkgs, command: nil, **_)
-        ohai "Uninstalling packages; your password may be necessary:"
+        ohai "Uninstalling packages with sudo; the password may be necessary:"
         pkgs.each do |regex|
           ::Cask::Pkg.all_matching(regex, command).each do |pkg|
             puts pkg.package_id

Library/Homebrew/cask/artifact/pkg.rb

@@ -36,8 +36,7 @@ module Cask
       private
 
       def run_installer(command: nil, verbose: false, **_options)
-        ohai "Running installer for #{cask}; your password may be necessary.",
-             "Package installers may write to any location; options such as `--appdir` are ignored."
+        ohai "Running installer for #{cask} with sudo; the password may be necessary."
         unless path.exist?
           pkg = path.relative_path_from(cask.staged_path)
           pkgs = Pathname.glob(cask.staged_path/"**"/"*.pkg").map { |path| path.relative_path_from(cask.staged_path) }

Library/Homebrew/cask/staged.rb

@@ -27,7 +27,7 @@ module Cask
       full_paths = remove_nonexistent(paths)
       return if full_paths.empty?
 
-      ohai "Changing ownership of paths required by #{@cask}; your password may be necessary."
+      ohai "Changing ownership of paths required by #{@cask} with sudo; the password may be necessary."
       @command.run!("/usr/sbin/chown", args: ["-R", "--", "#{user}:#{group}", *full_paths],
                                        sudo: true)
     end

Library/Homebrew/env_config.rb

@@ -373,6 +373,11 @@ module Homebrew
                      "the system-wide environment file will be loaded last to override any prefix or user settings.",
         boolean:     true,
       },
+      HOMEBREW_SUDO_THROUGH_SUDO_USER:           {
+        description: "If set, Homebrew will use the `SUDO_USER` environment variable to define the user to " \
+                     "`sudo`(8) through when running `sudo`(8).",
+        boolean:     true,
+      },
       HOMEBREW_TEMP:                             {
         description:  "Use this path as the temporary directory for building packages. Changing " \
                       "this may be needed if your system temporary directory and Homebrew prefix are on " \

Library/Homebrew/env_config.rbi

@@ -217,6 +217,9 @@ module Homebrew::EnvConfig
   sig { returns(T.nilable(String)) }
   def self.sudo_askpass; end
 
+  sig { returns(T::Boolean) }
+  def self.sudo_through_sudo_user?; end
+
   sig { returns(T.nilable(String)) }
   def self.svn; end
 

Library/Homebrew/system_command.rb

@@ -157,11 +157,25 @@ class SystemCommand
     set_variables
   end
 
+  sig { returns(T.nilable(String)) }
+  def homebrew_sudo_user
+    ENV.fetch("HOMEBREW_SUDO_USER", nil)
+  end
+
   sig { returns(T::Array[String]) }
   def sudo_prefix
-    user_flags = []
-    user_flags += ["-u", "root"] if sudo_as_root?
     askpass_flags = ENV.key?("SUDO_ASKPASS") ? ["-A"] : []
+    user_flags = []
+    if Homebrew::EnvConfig.sudo_through_sudo_user?
+      raise ArgumentError, "HOMEBREW_SUDO_THROUGH_SUDO_USER set but SUDO_USER unset!" if homebrew_sudo_user.blank?
+
+      user_flags += ["--prompt", "Password for %p:", "-u", homebrew_sudo_user,
+                     *askpass_flags,
+                     "-E", *env_args,
+                     "--", "/usr/bin/sudo"]
+    elsif sudo_as_root?
+      user_flags += ["-u", "root"]
+    end
     ["/usr/bin/sudo", *user_flags, *askpass_flags, "-E", *env_args, "--"]
   end
 

docs/Manpage.md

@@ -2362,6 +2362,9 @@ command execution e.g. `$(cat file)`.
 - `HOMEBREW_SYSTEM_ENV_TAKES_PRIORITY`
   <br>If set in Homebrew's system-wide environment file (`/etc/homebrew/brew.env`), the system-wide environment file will be loaded last to override any prefix or user settings.
 
+- `HOMEBREW_SUDO_THROUGH_SUDO_USER`
+  <br>If set, Homebrew will use the `SUDO_USER` environment variable to define the user to `sudo`(8) through when running `sudo`(8).
+
 - `HOMEBREW_TEMP`
   <br>Use this path as the temporary directory for building packages. Changing this may be needed if your system temporary directory and Homebrew prefix are on different volumes, as macOS has trouble moving symlinks across volumes when the target does not yet exist. This issue typically occurs when using FileVault or custom SSD configurations.
 

manpages/brew.1

@@ -3483,6 +3483,12 @@ Use this as the \fBsvn\fR(1) binary\.
 If set in Homebrew\'s system\-wide environment file (\fB/etc/homebrew/brew\.env\fR), the system\-wide environment file will be loaded last to override any prefix or user settings\.
 .
 .TP
+\fBHOMEBREW_SUDO_THROUGH_SUDO_USER\fR
+.
+.br
+If set, Homebrew will use the \fBSUDO_USER\fR environment variable to define the user to \fBsudo\fR(8) through when running \fBsudo\fR(8)\.
+.
+.TP
 \fBHOMEBREW_TEMP\fR
 .
 .br