10 Who it installs for, and a guarded folder
Goal: let a user without administrator rights install Hello for themselves, while an administrator can still install it for everyone - and refuse an install folder that someone else prepared.
10.1 Three scopes#
So far every package installed per machine: into Program Files, for every user of the computer, which needs administrator rights (the User Account Control prompt). scope in [package] changes that:
scope | Installs for | Needs administrator | $(ProgramFiles)/Hello becomes | Start menu, desktop | Registry HKMU |
|---|---|---|---|---|---|
machine (default) | everyone | yes | C:\Program Files\Hello | all users' | HKLM |
user | the current user | no | %LOCALAPPDATA%\Programs\Hello | the user's | HKCU |
dual | the user by default, or everyone when chosen | only for everyone | either of the above | either | either |
%LOCALAPPDATA% is the user's own C:\Users\<name>\AppData\Local. A per-user installation needs no permission and is invisible to other users of the computer - often right for small tools.
Some things only exist per machine and need scope = "machine": services, fonts, permissions, and the folders $(SystemRoot), $(System), $(Fonts) and $(ProgramData). rubrapack refuses them in a user or dual package.
10.2 The source#
# tutorial 10: hello.toml
format = 1
[package]
name = "Hello"
manufacturer = "Example Software"
version = "$(VERSION)"
arch = "x64"
upgrade-code = "{3F2A6C1D-8B4E-4F7A-9C2D-5E6F7A8B9C0D}"
scope = "dual"
ui = "installdir"
[define]
VERSION = "1.8.0"
[dir.INSTALLDIR]
path = "$(ProgramFiles)/Hello"
guard = true
[file.Hello]
dir = "INSTALLDIR"
source = "dist/hello.exe"
[shortcut.StartMenu]
dir = "Programs"
name = "Hello"
target = "file:Hello"10.3 A dual package#
With scope = "dual" and dialogs, a page after the license asks:
( ) Just me (the default)
( ) Everyone on this computer"Everyone" asks for administrator rights; the install folder, the Start menu entry and the Installed apps entry follow the choice. Without dialogs, a dual package installs for the current user; from an administrator's terminal it installs for everyone with
msiexec /i hello.msi ALLUSERS=1 MSIINSTALLPERUSER=""(MSIINSTALLPERUSER="" means "empty": the property is cleared.) A user package refuses to install for everyone.
10.4 A guarded install folder: guard#
Some programs are loaded by other programs or run with high rights - an input method, a shell extension, a service. For them an install folder that already exists is a risk: whoever created it may have left files in it (a planted DLL would be loaded with the program's rights). guard = true on a dir makes a first installation stop, before any file is placed, when that folder
- already exists and is not owned by SYSTEM, Administrators or TrustedInstaller, or
- is reached through a junction or another link (the folder itself or any folder above it).
A folder that does not exist yet passes - the installer creates it. Repair, removal and an upgrade into the folder the earlier version created are not affected. The installation ends with the message DirGuardText (in the language chosen in the dialogs), also in a silent installation, and the log names the owner it found. The check is done by a small helper DLL of rubrapack's that the package then carries.
10.5 Try it#
As a normal user (not an administrator), double-click hello.msi and keep "Just me": no permission prompt; Hello lands in %LOCALAPPDATA%\Programs\Hello, and only you see it in the Start menu and in Installed apps. Remove it, and install again choosing "Everyone": Windows asks for administrator rights and installs into Program Files.
To see the guard: as a normal user, create the folder C:\Users\Public\Hello (its owner is then that user). From an administrator's terminal, install for everyone into it:
msiexec /i hello.msi ALLUSERS=1 MSIINSTALLPERUSER="" INSTALLDIR="C:\Users\Public\Hello\"The installation stops with the guard's message and installs nothing. Delete the folder and run the same command again: now the installer creates the folder itself, and the installation goes through.
10.6 What happened inside#
C:\work\hello> rubrapack inspect hello.msi Property
...
ALLUSERS 2
MSIINSTALLPERUSER 1
RP_GUARD INSTALLDIR
...ALLUSERS = 2 together with MSIINSTALLPERUSER = 1 is Windows Installer's "single package for both": per user unless asked otherwise. A per-machine package has ALLUSERS = 1. RP_GUARD lists the guarded dirs for the helper DLL. The page that asks is RpScopeDlg in the Dialog table.