Fix dangling handles resulting from actively closing a file.

source/eventcore/driver.d

@@ -371,6 +371,14 @@ interface EventDriverFiles {
 @safe: /*@nogc:*/ nothrow:
 	FileFD open(string path, FileOpenMode mode);
 	FileFD adopt(int system_file_handle);
+
+	/** Disallows any reads/writes and removes any exclusive locks.
+
+		Note that this function may not actually close the file handle. The
+		handle is only guaranteed to be closed one the reference count drops
+		to zero. However, the remaining effects of calling this function will
+		be similar to actually closing the file.
+	*/
 	void close(FileFD file);
 
 	ulong getSize(FileFD file);

source/eventcore/drivers/threadedfile.d

@@ -101,6 +101,7 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
 		static struct FileInfo {
 			IOInfo read;
 			IOInfo write;
+			bool open = true;
 
 			int refCount;
 			DataInitializer userDataDestructor;
@@ -175,7 +176,11 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
 
 	void close(FileFD file)
 	{
-		() @trusted { .close(cast(int)file); } ();
+		// NOTE: The file descriptor itself must stay open until the reference
+		//       count drops to zero, or this would result in dangling handles.
+		//       In case of an exclusive file lock, the lock should be lifted
+		//       here.
+		m_files[file].open = false;
 	}
 
 	ulong getSize(FileFD file)
@@ -193,11 +198,17 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
 	final override void write(FileFD file, ulong offset, const(ubyte)[] buffer, IOMode, FileIOCallback on_write_finish)
 	{
 		//assert(this.writable);
-		auto f = &m_files[file].write;
+		auto f = () @trusted { return &m_files[file]; } ();
-		if (!safeCAS(f.status, ThreadedFileStatus.idle, ThreadedFileStatus.initiated))
+
+		if (!f.open) {
+			on_write_finish(file, IOStatus.disconnected, 0);
+			return;
+		}
+
+		if (!safeCAS(f.write.status, ThreadedFileStatus.idle, ThreadedFileStatus.initiated))
 			assert(false, "Concurrent file writes are not allowed.");
-		assert(f.callback is null, "Concurrent file writes are not allowed.");
+		assert(f.write.callback is null, "Concurrent file writes are not allowed.");
-		f.callback = on_write_finish;
+		f.write.callback = on_write_finish;
 		m_activeWrites.insert(file);
 		threadSetup();
 		log("start write task");
@@ -224,11 +235,17 @@ final class ThreadedFileEventDriver(Events : EventDriverEvents) : EventDriverFil
 
 	final override void read(FileFD file, ulong offset, ubyte[] buffer, IOMode, FileIOCallback on_read_finish)
 	{
-		auto f = &m_files[file].read;
+		auto f = () @trusted { return &m_files[file]; } ();
-		if (!safeCAS(f.status, ThreadedFileStatus.idle, ThreadedFileStatus.initiated))
+
+		if (!f.open) {
+			on_read_finish(file, IOStatus.disconnected, 0);
+			return;
+		}
+
+		if (!safeCAS(f.read.status, ThreadedFileStatus.idle, ThreadedFileStatus.initiated))
 			assert(false, "Concurrent file reads are not allowed.");
-		assert(f.callback is null, "Concurrent file reads are not allowed.");
+		assert(f.read.callback is null, "Concurrent file reads are not allowed.");
-		f.callback = on_read_finish;
+		f.read.callback = on_read_finish;
 		m_activeReads.insert(file);
 		threadSetup();
 		log("start read task");

source/eventcore/drivers/winapi/files.d

@@ -27,7 +27,7 @@ final class WinAPIEventDriverFiles : EventDriverFiles {
 
 		auto access = mode == FileOpenMode.readWrite || mode == FileOpenMode.createTrunc ? (GENERIC_WRITE | GENERIC_READ) :
 						mode == FileOpenMode.append ? GENERIC_WRITE : GENERIC_READ;
-		auto shareMode = mode == FileOpenMode.read ? FILE_SHARE_READ : 0;
+		auto shareMode = FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE;
 		auto creation = mode == FileOpenMode.createTrunc ? CREATE_ALWAYS : mode == FileOpenMode.append? OPEN_ALWAYS : OPEN_EXISTING;
 
 		auto handle = () @trusted {
@@ -76,7 +76,7 @@ final class WinAPIEventDriverFiles : EventDriverFiles {
 		auto h = idToHandle(file);
 		auto slot = () @trusted { return &m_core.m_handles[h].file(); } ();
 		if (slot.read.overlapped.hEvent != INVALID_HANDLE_VALUE) {
-			CloseHandle(h);
+
 			slot.read.overlapped.hEvent = slot.write.overlapped.hEvent = INVALID_HANDLE_VALUE;
 		}
 	}
@@ -92,13 +92,19 @@ final class WinAPIEventDriverFiles : EventDriverFiles {
 
 	override void write(FileFD file, ulong offset, const(ubyte)[] buffer, IOMode mode, FileIOCallback on_write_finish)
 	{
+		auto h = idToHandle(file);
+		auto slot = &m_core.m_handles[h].file.write;
+
+		if (slot.overlapped.hEvent == INVALID_HANDLE_VALUE) {
+			on_write_finish(file, IOStatus.disconnected, 0);
+			return;
+		}
+
 		if (!buffer.length) {
 			on_write_finish(file, IOStatus.ok, 0);
 			return;
 		}
 
-		auto h = idToHandle(file);
-		auto slot = &m_core.m_handles[h].file.write;
 		slot.bytesTransferred = 0;
 		slot.offset = offset;
 		slot.buffer = buffer;
@@ -110,13 +116,19 @@ final class WinAPIEventDriverFiles : EventDriverFiles {
 
 	override void read(FileFD file, ulong offset, ubyte[] buffer, IOMode mode, FileIOCallback on_read_finish)
 	{
+		auto h = idToHandle(file);
+		auto slot = &m_core.m_handles[h].file.read;
+
+		if (slot.overlapped.hEvent == INVALID_HANDLE_VALUE) {
+			on_read_finish(file, IOStatus.disconnected, 0);
+			return;
+		}
+
 		if (!buffer.length) {
 			on_read_finish(file, IOStatus.ok, 0);
 			return;
 		}
 
-		auto h = idToHandle(file);
-		auto slot = &m_core.m_handles[h].file.read;
 		slot.bytesTransferred = 0;
 		slot.offset = offset;
 		slot.buffer = buffer;