C++ – Avoiding UAC in vista

cuacwindows-vista

im writing an application that downloads and installs addons for programs which needs to save the data to program files (for the programs in question). Now this works fine on xp and vista with uac disabled however it is failing on normal vista due to the virtual folders.

How would one get around this with out needing to request admin rights every time the app started?

P.s. Program is written in c++, vis 2005

Edit: File system virtual folders: http://www.codeproject.com/KB/vista-security/MakingAppsUACAware.aspx

Best Answer

Only write to Program Files during installation. After that, write to the user folders.

You can elevate the apps privileges later, but you'll just be delaying the prompt. The whole point of UAC is to prevent random apps from writing to folders that require admin privileges. (ok, not the whole point, but a large portion of it.)

You could create a service with admin privileges and send commands to it to move the downloaded files into the desired target directories, but this opens up a user's system to being abused by other apps if you don't design it very carefully.

This article talks about getting apps to work nicely with UAC. Also, see this article here.

Related Solutions

How to detect whether Vista UAC is enabled

This registry key should tell you:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System

Value EnableLUA (DWORD)

1 enabled / 0 or missing disabled

But that assumes you have the rights to read it.

Programmatically you can try to read the user's token and guess if it's an admin running with UAC enabled (see here). Not foolproof, but it may work.

The issue here is more of a "why do you need to know" - it has bearing on the answer. Really, there is no API because from a OS behavior point of view, what matters is if the user is an administrator or not - how they choose to protect themselves as admin is their problem.

Windows 7 (UAC) doesn’t allow the program to write down inside data file owned by another program. How to do

You can use either an external manifest file (myapp.exe.manifest) or use a tool to include a manfiest in your exe and a Resource.

There is a ton of content available, just google it. From here I grabbed a sample manifest:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
    <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
        <security>
            <requestedPrivileges>
                <requestedExecutionLevel level="asInvoker" uiAccess="false"/>
            </requestedPrivileges>
        </security>
    </trustInfo>
</assembly>

You need to change the level to "requireAdministrator", which will prompt the user for permission when they launch the application (depending on their UAC settings).

Best Answer

Related Solutions

How to detect whether Vista UAC is enabled

Windows 7 (UAC) doesn’t allow the program to write down inside data file owned by another program. How to do

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