Finally, see the ???File and Registry Virtualization Explained??? sidebar, next,
for details on the User Account Control: Virtualizes file and registry write
486 | Chapter 8: Users and Security
failures to per-user locations setting, and an explanation of something else
that can break UAC-unaware programs.
File and Registry Virtualization Explained
As described in this chapter??™s ???Control User Account Control??? section, Vista??™s
UAC feature is designed to prevent changes to operating system folders like
Program Files, as well as protected areas of the Registry. If a program wasn??™t
designed with UAC in mind, it won??™t request elevation to administrator-level
access, and its attempt to, say, write to its own application folder in Program
Files will fail.
Microsoft had to come up with a compromise that would allow some of these
older programs to work.
That compromise is virtualization, a system that redirects older (legacy, as
Microsoft puts it) applications to special, protected areas of your hard disk
and Registry. So, if a program with an auto-update feature tries to write files
to C:\Program Files\Acme Update\newversion.dll, Windows will instead send
it to C:\Users\{your_username}\AppData\Local\VirtualStore\Program Files\
Acme Update\newversion.dll.
Likewise, if a program tries to make a change to the Registry, in the HKEY_ LOCAL_
MACHINE\Software\Acme key, the change will be made instead to the HKEY_
CURRENT_USER\Software\Classes\VirtualStore\MACHINE\Software\Acme key.
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