Question

I’m trying to run a piece of code in a sandbox. It failed and the problem comes from the part of the code where cache is used.

Case where it works as expected:

public void Demo()
{
    // Verify that the code is running in a sandbox: the next line is expected to
    // fail, since the sandbox doesn't have enough I/O privileges to access H:\.
    File.WriteAllText(@"H:\Hello.txt", "Hello");
}

works as expected, i.e. an exception is thrown, showing that “Request for the permission […] FileIOPermission […] failed.”.

When I replace the code by a call to the database, again the result is expected: the app is complaining that there are no enough privileges.

If I add the requested privileges, the code is executed with no exception.

Case where it fails:

If I replace the previous method by:

public void Demo()
{
    Cache cache = HttpRuntime.Cache;
    File.WriteAllText(@"H:\Hello.txt", "Hello");
}

it stops working: instead of an expected exception complaining about the insufficient I/O permissions, the one which is thrown is System.Security.SecurityException:

That assembly does not allow partially trusted callers.

Is there something to do with this issue, or the cache is not intended to be used in scenarios other than full-trust?

Answer 1

One of the possible ways to use cache inside code running in partial trust is to move the cache object outside the plug-in. Adapter pattern can be used in order for the plug-in to still be able to read and write data from and in cache, while managing the cache by the caller in a full-trust context.

If other people are interested, I illustrated the original issue and the solution in a project published on CodePlex.