Question

Assuming I’m trying to automate the installation of something on windows and I want to try to test whether another installation is in progress before attempting install. I don’t have control over the installer and have to do this in the automation framework. Is there a better way to do this, some win32 api?, than just testing if msiexec is running?

[Update 2]

Improved the previous code I had been using to just access the mutex directly, this is a lot more reliable:

using System.Threading;  [...]  /// <summary> /// Wait (up to a timeout) for the MSI installer service to become free. /// </summary> /// <returns> /// Returns true for a successful wait, when the installer service has become free. /// Returns false when waiting for the installer service has exceeded the timeout. /// </returns> public static bool WaitForInstallerServiceToBeFree(TimeSpan maxWaitTime) {     // The _MSIExecute mutex is used by the MSI installer service to serialize installations     // and prevent multiple MSI based installations happening at the same time.     // For more info: http://msdn.microsoft.com/en-us/library/aa372909(VS.85).aspx     const string installerServiceMutexName = 'Global\\_MSIExecute';      try     {         Mutex MSIExecuteMutex = Mutex.OpenExisting(installerServiceMutexName,              System.Security.AccessControl.MutexRights.Synchronize | System.Security.AccessControl.MutexRights.Modify);         bool waitSuccess = MSIExecuteMutex.WaitOne(maxWaitTime, false);         MSIExecuteMutex.ReleaseMutex();         return waitSuccess;     }     catch (WaitHandleCannotBeOpenedException)     {         // Mutex doesn't exist, do nothing     }     catch (ObjectDisposedException)     {         // Mutex was disposed between opening it and attempting to wait on it, do nothing     }     return true; } 

Answer 1

See the description of the _MSIExecute Mutex on MSDN.