Question

I have written a small util in an app that syncs the time from a time server, which uses the Windows API functions GetSystemTime and SetSystemTime. It was all working fine, but now every time I call Get/SetSystemTime I get an error:

FatalExecutionEngineError was detected  
Message:  
The runtime has encountered a fatal error.  
The address of the error was at 0x792bee10, on thread 0x48c.  
The error code is 0xc0000005. This error may be a bug in the CLR  
or in the unsafe or non-verifiable portions of user code.  
Common sources of this bug include user marshaling errors for COM-interop
or PInvoke, which may corrupt the stack.

Now as the only unsafe code is a call to the Win32 functions (is that even unsafe??) it seems it cant be in my code – that and i havent changed anythig since it was actually working…

Any ideas what might be going on here?

The Win32 calls are made using:

public class SystemTime
        {
            public ushort Year;
            public ushort Month;
            public ushort DayOfWeek;
            public ushort Day;
            public ushort Hour;
            public ushort Minute;
            public ushort Second;
            public ushort Millisecond;

            public static implicit operator SystemTime(DateTime dt)
            {
                SystemTime rval = new SystemTime();
                rval.Year = (ushort)dt.Year;
                rval.Month = (ushort)dt.Month;
                rval.Day = (ushort)dt.Day;
                rval.DayOfWeek = (ushort)dt.DayOfWeek;
                rval.Hour = (ushort)dt.Hour;
                rval.Minute = (ushort)dt.Minute;
                rval.Second = (ushort)dt.Second;
                rval.Millisecond = (ushort)dt.Millisecond;
                return rval;
            }

            public static implicit operator DateTime(SystemTime st)
            {
                return new DateTime(st.Year, st.Month, st.Day, st.Hour, st.Minute, st.Second, st.Millisecond);
            }
        }; 

        [DllImport("kernel32.dll", EntryPoint = "GetSystemTime")]
        public extern static void Win32GetSystemTime(ref SystemTime sysTime); 
        [DllImport("kernel32.dll", EntryPoint = "SetSystemTime")]
        public extern static bool Win32SetSystemTime(ref SystemTime sysTime);

EDIT: Now the very same code (unmodified) is giving me an AccessViolation ???

Attempted to read or write protected memory.  
This is often an indication that other memory is corrupt.

Answer 1

Since you are defining SYSTEMTIME as a class, when you pass it by reference you are actually passing a pointer to a pointer but on the unmanaged side it is expecting a pointer to a SYSTEMTIME structure.

Either change your definition of SYSTEMTIME to a struct and pass it by reference as you are doing now. Or leave it as a class and change your declares to:

[DllImport("kernel32.dll")]
static extern void GetSystemTime([Out] SYSTEMTIME systemTime);

[DllImport("kernel32.dll")]
public extern static uint SetSystemTime([In] SYSTEMTIME systemTime);

Personally, I would change it to a struct.