Opening a Memory Mapped File causes FileNotFoundException when deployed in IIS

Question

Following the code example from this website, I created a windows console application that creates a mapped memory file:

        using (var file = MemoryMapp         


        

Answer 1

Add "Global\\" prefix to the mapName. That is the only way it worked for me. When we try to access shared memory created in the first process it runs in a different security context and shared memory objects are not visible unless they are created in the global namespace.

This is the code that worked for me. I used CreateOrOpen in a WinForm application and I used OpenExisting in an IIS process:

mSec = new MemoryMappedFileSecurity();
mSec.AddAccessRule(new AccessRule(new SecurityIdentifier(WellKnownSidType.WorldSid, null), MemoryMappedFileRights.FullControl, AccessControlType.Allow));

mmf = MemoryMappedFile.CreateOrOpen("Global\\\MmfName", 100, MemoryMappedFileAccess.ReadWrite, MemoryMappedFileOptions.None, mSec, HandleInheritability.Inheritable);

mmf = MemoryMappedFile.OpenExisting("Global\\\MmfName");