How to determine the \Temporary ASP.NET Files\root\{site hash} with PowerShell?

Question

ASP.NET makes use of a temporary files directory to store files for Shadow Copying and Dynamic Compilation. A typical path will look like this. Note the hash on the end of the p

Answer 1

Well, a few moments with Reflector, searching all members within System.Web for the word "Temporary" shows this call gets me here:

string str2 = AppManagerAppDomainFactory.ConstructSimpleAppName(AppDomainAppVirtualPath);

But then I remember that the source code is available for all of .NET, so I move to the actual code, rather than the reflectored code: https://referencesource.microsoft.com/#System.Web/HttpRuntime.cs,870

Later in that method "SetupCodeGenDirectory" the path appears to be built on top of with

 this._codegenDir = Thread.GetDomain().DynamicDirectory;

So, looks like that hash is from DynamicDirectory. That's over here at http://referencesource.microsoft.com/#mscorlib/system/appdomain.cs#2792 which looks like an extern that is inside some COM Fusion Loader stuff:

[ComImport,InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("7c23ff90-33af-11d3-95da-00a024a85b51")]

But that GUID leads me here http://referencesource.microsoft.com/#mscorlib/microsoft/win32/fusionwrap.cs#94

which implies it's a public key token part:

     public const uint HASH_VALUE            = PUBLIC_KEY_TOKEN + 1;
     public const uint NAME                  = HASH_VALUE + 1;

That perhaps it's NAME? I'm guessing it's yourAssembly.GetPublicKeyToken();

OR, just change the folder that your temporary ASP.NET files go to in config section http://msdn.microsoft.com/en-us/library/system.web.configuration.compilationsection.tempdirectory%28VS.80%29.aspx in system.web in web.config

<compilation tempDirectory="D:\MoveThemHere">

Answer 2

I know this is an old question, but in case someone still need it, this is the C# code that makes the trick. I guess it's not that hard to port to powershell.

        string siteId = "/LM/W3SVC/3/ROOT"; // This can be composed by getting the site ID using the ServerManager (Microsoft.Web.Administration)
        string physicalPath = "E:\\home\\mysite\\web\\";

        string v_app_name = HashCode.GetString32((siteId + physicalPath).ToLower(CultureInfo.InvariantCulture)).ToString("x", CultureInfo.InvariantCulture);

        string dir_name_32_bits_app = HashCode.GetString32(v_app_name).ToString("x8");
        string dir_name_64_bits_app = HashCode.GetString64(v_app_name).ToString("x8");

        Console.WriteLine("32 bits: " + dir_name_32_bits_app);
        Console.WriteLine("64 bits: " + dir_name_64_bits_app);

The HashCode class:

public class HashCode
{        
    public static unsafe int GetString32(string s)
    {
        fixed (char* str = s)
        {
            char* chPtr = str;
            int num = 0x15051505;
            int num2 = num;
            int* numPtr = (int*)chPtr;
            for (int i = s.Length; i > 0; i -= 4)
            {
                num = (((num << 5) + num) + (num >> 0x1b)) ^ numPtr[0];
                if (i <= 2)
                {
                    break;
                }
                num2 = (((num2 << 5) + num2) + (num2 >> 0x1b)) ^ numPtr[1];
                numPtr += 2;
            }
            return (num + (num2 * 0x5d588b65));
        }
    }


    public static unsafe int GetString64(string s)
    {
        fixed (char* str = s)
        {
            int num3;
            char* chPtr = str;
            int num = 0x1505;
            int num2 = num;
            for (char* chPtr2 = chPtr; (num3 = chPtr2[0]) != '\0'; chPtr2 += 2)
            {
                num = ((num << 5) + num) ^ num3;
                num3 = chPtr2[1];
                if (num3 == 0)
                {
                    break;
                }
                num2 = ((num2 << 5) + num2) ^ num3;
            }
            return (num + (num2 * 0x5d588b65));
        }
    }
}