Unable to read %LOCALAPPDATA% on Windows service accounts

[AlexAltea]

After the merging of #12091 (cc @ras0219), the instances of vcpkg running in our Windows CI exited reporting that %LOCALAPPDATA% cannot be read. This environment variable is undefined as the CI jobs are running on a Windows service account (running as SYSTEM).

As a hacky workaround, $Env:LOCALAPPDATA = $Env:TEMP solves the problem, but a proper fix would be much appreciated.

Environment

• OS: Windows Server 2019
• Compiler: MSVC 14.26
• Relevant environment variables (some have been redacted to [...])

> Get-ChildItem Env:

Name                           Value
----                           -----
ALLUSERSPROFILE                C:\ProgramData
APPDATA                        C:\Windows\system32\config\systemprofile\AppData\Roaming
[...]
HOME                           C:\Windows\TEMP\drone-[...]\home\drone
HOMEPATH                       C:\Windows\TEMP\drone-[...]\home\drone
OS                             Windows_NT
Path                           C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;...
[...]
PSMODULEPATH                   WindowsPowerShell\Modules;C:\Program Files\WindowsPowerShell\Modules;...
PUBLIC                         C:\Users\Public
SystemDrive                    C:
SystemRoot                     C:\Windows
TEMP                           C:\Windows\TEMP
TMP                            C:\Windows\TEMP
USERNAME                       [...]$
USERPROFILE                    C:\Windows\TEMP\drone-[...]\home\drone
VCPKG_ROOT                     C:\vcpkg
windir                         C:\Windows

To reproduce

Steps to reproduce the behavior:

1. Run vcpkg install on a Windows service account.

2. See error below:

   > vcpkg install
   
   Failed at [C:\vcpkg\toolsrc\src\vcpkg\userconfig.cpp(14)] with message:
   unable to read %LOCALAPPDATA%
   

Expected behavior

The command should succeed on service accounts. If %LOCALAPPDATA% is undefined, maybe it should fallback to one of the following directories:

• C:\Windows\System32\config\systemprofile\AppData\Local
• C:\Windows\SysWOW64\config\systemprofile\AppData\Local

[JackBoosY]

@BillyONeal @ras0219 @ras0219-msft Can you take a look?

Thanks.