public static extern IntPtr CreateFileMapping(IntPtr hFile, ref SECURITY_ATTRIBUTES lpFileMappingAttributes, PageProtection flProtect, uint dwMaximumSizeHigh, uint dwMaximumSizeLow, string lpName);
public static void Start()
{
if (_listenTask == null) {
lock (typeof (Monitor)) {
_cancellationTokenSource = new CancellationTokenSource();
bool wasCreated;
var ewhSec = new EventWaitHandleSecurity();
ewhSec.AddAccessRule(
new EventWaitHandleAccessRule(
new SecurityIdentifier(WellKnownSidType.WorldSid, null), EventWaitHandleRights.FullControl, AccessControlType.Allow));
var sessionAckEvent = new EventWaitHandle(false, EventResetMode.AutoReset, "DBWIN_BUFFER_READY", out wasCreated, ewhSec);
var sessionReadyEvent = new EventWaitHandle(false, EventResetMode.AutoReset, "DBWIN_DATA_READY", out wasCreated, ewhSec);
var globalAckEvent = new EventWaitHandle(false, EventResetMode.AutoReset, "Global\\DBWIN_BUFFER_READY", out wasCreated, ewhSec);
var globalReadyEvent = new EventWaitHandle(false, EventResetMode.AutoReset, "Global\\DBWIN_DATA_READY", out wasCreated, ewhSec);
var sd = new SECURITY_DESCRIPTOR();
var sa = new SECURITY_ATTRIBUTES();
// Initialize the security descriptor.
if (!Advapi32.InitializeSecurityDescriptor(ref sd, 1)) {
throw new ApplicationException(
string.Format("{0}. Last Win32 Error was {1}", "Failed to initializes the security descriptor.", Marshal.GetLastWin32Error()));
}
// Set information in a discretionary access control list
if (!Advapi32.SetSecurityDescriptorDacl(ref sd, true, IntPtr.Zero, false)) {
throw new ApplicationException(
string.Format("{0}. Last Win32 Error was {1}", "Failed to initializes the security descriptor", Marshal.GetLastWin32Error()));
}
// Create the event for slot 'DBWIN_BUFFER_READY'
sa.nLength = Marshal.SizeOf(sa);
sa.lpSecurityDescriptor = Marshal.AllocHGlobal(Marshal.SizeOf(sd));
Marshal.StructureToPtr(sd, sa.lpSecurityDescriptor, false);
// Get a handle to the readable shared memory at slot 'DBWIN_BUFFER'.
var sessionSharedFileHandle = Kernel32.CreateFileMapping(new IntPtr(-1), ref sa, PageProtection.ReadWrite, 0, 4096, "DBWIN_BUFFER");
if (sessionSharedFileHandle == IntPtr.Zero) {
throw new ApplicationException(
string.Format(
"{0}. Last Win32 Error was {1}", "Failed to create a file mapping to slot 'DBWIN_BUFFER'", Marshal.GetLastWin32Error()));
}
// Create a view for this file mapping so we can access it
var sessionSharedMemoryHandle = Kernel32.MapViewOfFile(sessionSharedFileHandle, /*SECTION_MAP_READ*/ 0x0004, 0, 0, 4096);
if (sessionSharedMemoryHandle == IntPtr.Zero) {
throw new ApplicationException(
string.Format(
"{0}. Last Win32 Error was {1}", "Failed to create a mapping view for slot 'DBWIN_BUFFER'", Marshal.GetLastWin32Error()));
}
// Get a handle to the readable shared memory at slot 'DBWIN_BUFFER'.
var globalSharedFileHandle = Kernel32.CreateFileMapping(new IntPtr(-1), ref sa, PageProtection.ReadWrite, 0, 4096, "Global\\DBWIN_BUFFER");
if (globalSharedFileHandle == IntPtr.Zero) {
throw new ApplicationException(
string.Format(
"{0}. Last Win32 Error was {1}", "Failed to create a file mapping to slot 'Global\\DBWIN_BUFFER'", Marshal.GetLastWin32Error()));
}
// Create a view for this file mapping so we can access it
var globalSharedMemoryHandle = Kernel32.MapViewOfFile(globalSharedFileHandle, /*SECTION_MAP_READ*/ 0x0004, 0, 0, 4096);
if (globalSharedMemoryHandle == IntPtr.Zero) {
throw new ApplicationException(
string.Format(
"{0}. Last Win32 Error was {1}", "Failed to create a mapping view for slot 'Global\\DBWIN_BUFFER'", Marshal.GetLastWin32Error()));
}
var queue = new Queue<Tuple<int, DateTime, string>>();
var dataAvailable = new ManualResetEvent(true);
_listenTask = Task.Factory.StartNew(
() => {
// Everything after the first DWORD is our debugging text
IntPtr sessionStringPointer;
IntPtr globalStringPointer;
if (Environment.Is64BitProcess) {
sessionStringPointer = new IntPtr(sessionSharedMemoryHandle.ToInt64() + Marshal.SizeOf(typeof (int)));
globalStringPointer = new IntPtr(globalSharedMemoryHandle.ToInt64() + Marshal.SizeOf(typeof (int)));
} else {
sessionStringPointer = new IntPtr(sessionSharedMemoryHandle.ToInt32() + Marshal.SizeOf(typeof (int)));
globalStringPointer = new IntPtr(globalSharedMemoryHandle.ToInt32() + Marshal.SizeOf(typeof (int)));
}
while (!_cancellationTokenSource.IsCancellationRequested) {
sessionAckEvent.Set();
globalAckEvent.Set();
try {
var i = WaitHandle.WaitAny(new[] {sessionReadyEvent, globalReadyEvent, _cancellationTokenSource.Token.WaitHandle});
var now = DateTime.Now;
if (i == 0) {
lock (queue) {
queue.Enqueue(new Tuple<int, DateTime, string>(Marshal.ReadInt32(sessionSharedMemoryHandle), now, Marshal.PtrToStringAnsi(sessionStringPointer)));
dataAvailable.Set();
}
}
if (i == 1) {
lock (queue) {
queue.Enqueue(new Tuple<int, DateTime, string>(Marshal.ReadInt32(globalSharedMemoryHandle), now, Marshal.PtrToStringAnsi(globalStringPointer)));
dataAvailable.Set();
}
}
} catch {
// it's over.
_cancellationTokenSource.Cancel();
}
}
_listenTask = null;
// cleanup after stopping.
globalAckEvent.Reset();
globalAckEvent.Dispose();
globalAckEvent = null;
sessionAckEvent.Reset();
sessionAckEvent.Dispose();
sessionAckEvent = null;
globalReadyEvent.Reset();
globalReadyEvent.Dispose();
globalReadyEvent = null;
sessionReadyEvent.Reset();
sessionReadyEvent.Dispose();
sessionReadyEvent = null;
// Close SharedFile
if (sessionSharedFileHandle != IntPtr.Zero) {
if (!Kernel32.CloseHandle(sessionSharedFileHandle)) {
throw new ApplicationException(
string.Format("{0}. Last Win32 Error was {1}", "Failed to close handle for 'SharedFile'", Marshal.GetLastWin32Error()));
}
sessionSharedFileHandle = IntPtr.Zero;
}
// Unmap SharedMem
if (sessionSharedMemoryHandle != IntPtr.Zero) {
if (!Kernel32.UnmapViewOfFile(sessionSharedMemoryHandle)) {
throw new ApplicationException(
string.Format(
"{0}. Last Win32 Error was {1}", "Failed to unmap view for slot 'DBWIN_BUFFER'", Marshal.GetLastWin32Error()));
}
sessionSharedMemoryHandle = IntPtr.Zero;
}
// Close SharedFile
if (globalSharedFileHandle != IntPtr.Zero) {
if (!Kernel32.CloseHandle(globalSharedFileHandle)) {
throw new ApplicationException(
string.Format("{0}. Last Win32 Error was {1}", "Failed to close handle for 'SharedFile'", Marshal.GetLastWin32Error()));
}
globalSharedFileHandle = IntPtr.Zero;
}
// Unmap SharedMem
if (globalSharedMemoryHandle != IntPtr.Zero) {
if (!Kernel32.UnmapViewOfFile(globalSharedMemoryHandle)) {
throw new ApplicationException(
string.Format(
"{0}. Last Win32 Error was {1}", "Failed to unmap view for slot 'Global\\DBWIN_BUFFER'", Marshal.GetLastWin32Error()));
}
globalSharedMemoryHandle = IntPtr.Zero;
}
}, _cancellationTokenSource.Token);
Task.Factory.StartNew(() => {
// handle events on seperate task to minimize the work that is done blocking the handles
Tuple<int, DateTime, string> item = null;
while (WaitHandle.WaitAny(new[] {dataAvailable, _cancellationTokenSource.Token.WaitHandle}) == 0) {
lock (queue) {
if (queue.Count > 0) {
item = queue.Dequeue();
}
if (queue.Count == 0) {
dataAvailable.Reset();
}
}
if (item == null || OnOutputDebugString == null) {
continue;
}
try {
OnOutputDebugString(new OutputDebugStringEventArgs(item.Item1, item.Item2, item.Item3));
} catch {
// if it's taken, good, if not--well too bad!
}
}
}, _cancellationTokenSource.Token);
}
}
}