Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/winpr/libwinpr/utils/collections/CountdownEvent.c

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+/**
+ * WinPR: Windows Portable Runtime
+ * Countdown Event
+ *
+ * Copyright 2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <winpr/config.h>
+#include <winpr/assert.h>
+
+#include <winpr/crt.h>
+
+#include <winpr/collections.h>
+
+struct CountdownEvent
+{
+	size_t count;
+	CRITICAL_SECTION lock;
+	HANDLE event;
+	size_t initialCount;
+};
+
+/**
+ * C equivalent of the C# CountdownEvent Class
+ * http://msdn.microsoft.com/en-us/library/dd235708/
+ */
+
+/**
+ * Properties
+ */
+
+/**
+ * Gets the number of remaining signals required to set the event.
+ */
+
+size_t CountdownEvent_CurrentCount(wCountdownEvent* countdown)
+{
+	WINPR_ASSERT(countdown);
+	EnterCriticalSection(&countdown->lock);
+	const size_t rc = countdown->count;
+	LeaveCriticalSection(&countdown->lock);
+	return rc;
+}
+
+/**
+ * Gets the numbers of signals initially required to set the event.
+ */
+
+size_t CountdownEvent_InitialCount(wCountdownEvent* countdown)
+{
+	WINPR_ASSERT(countdown);
+	EnterCriticalSection(&countdown->lock);
+	const size_t rc = countdown->initialCount;
+	LeaveCriticalSection(&countdown->lock);
+	return rc;
+}
+
+/**
+ * Determines whether the event is set.
+ */
+
+BOOL CountdownEvent_IsSet(wCountdownEvent* countdown)
+{
+	BOOL status = FALSE;
+
+	WINPR_ASSERT(countdown);
+	if (WaitForSingleObject(countdown->event, 0) == WAIT_OBJECT_0)
+		status = TRUE;
+
+	return status;
+}
+
+/**
+ * Gets a WaitHandle that is used to wait for the event to be set.
+ */
+
+HANDLE CountdownEvent_WaitHandle(wCountdownEvent* countdown)
+{
+	WINPR_ASSERT(countdown);
+	return countdown->event;
+}
+
+/**
+ * Methods
+ */
+
+/**
+ * Increments the CountdownEvent's current count by a specified value.
+ */
+
+void CountdownEvent_AddCount(wCountdownEvent* countdown, size_t signalCount)
+{
+	WINPR_ASSERT(countdown);
+	EnterCriticalSection(&countdown->lock);
+
+	const BOOL signalSet = countdown->count == 0;
+	countdown->count += signalCount;
+
+	if (signalSet)
+		(void)ResetEvent(countdown->event);
+
+	LeaveCriticalSection(&countdown->lock);
+}
+
+/**
+ * Registers multiple signals with the CountdownEvent, decrementing the value of CurrentCount by the
+ * specified amount.
+ */
+
+BOOL CountdownEvent_Signal(wCountdownEvent* countdown, size_t signalCount)
+{
+	BOOL status = FALSE;
+	BOOL newStatus = FALSE;
+	BOOL oldStatus = FALSE;
+
+	WINPR_ASSERT(countdown);
+
+	EnterCriticalSection(&countdown->lock);
+
+	if (WaitForSingleObject(countdown->event, 0) == WAIT_OBJECT_0)
+		oldStatus = TRUE;
+
+	if (signalCount <= countdown->count)
+		countdown->count -= signalCount;
+	else
+		countdown->count = 0;
+
+	if (countdown->count == 0)
+		newStatus = TRUE;
+
+	if (newStatus && (!oldStatus))
+	{
+		(void)SetEvent(countdown->event);
+		status = TRUE;
+	}
+
+	LeaveCriticalSection(&countdown->lock);
+
+	return status;
+}
+
+/**
+ * Resets the InitialCount property to a specified value.
+ */
+
+void CountdownEvent_Reset(wCountdownEvent* countdown, size_t count)
+{
+	WINPR_ASSERT(countdown);
+	countdown->initialCount = count;
+}
+
+/**
+ * Construction, Destruction
+ */
+
+wCountdownEvent* CountdownEvent_New(size_t initialCount)
+{
+	wCountdownEvent* countdown = (wCountdownEvent*)calloc(1, sizeof(wCountdownEvent));
+
+	if (!countdown)
+		return nullptr;
+
+	countdown->count = initialCount;
+	countdown->initialCount = initialCount;
+
+	if (!InitializeCriticalSectionAndSpinCount(&countdown->lock, 4000))
+		goto fail;
+
+	countdown->event = CreateEvent(nullptr, TRUE, FALSE, nullptr);
+	if (!countdown->event)
+		goto fail;
+
+	if (countdown->count == 0)
+	{
+		if (!SetEvent(countdown->event))
+			goto fail;
+	}
+
+	return countdown;
+
+fail:
+	WINPR_PRAGMA_DIAG_PUSH
+	WINPR_PRAGMA_DIAG_IGNORED_MISMATCHED_DEALLOC
+	CountdownEvent_Free(countdown);
+	WINPR_PRAGMA_DIAG_POP
+	return nullptr;
+}
+
+void CountdownEvent_Free(wCountdownEvent* countdown)
+{
+	if (!countdown)
+		return;
+
+	DeleteCriticalSection(&countdown->lock);
+	(void)CloseHandle(countdown->event);
+
+	free(countdown);
+}