Milestone 5: deliver embedded RDP sessions and lifecycle hardening

third_party/FreeRDP/channels/rdpsnd/client/ios/TPCircularBuffer.c

@@ -0,0 +1,153 @@
+//
+//  TPCircularBuffer.c
+//  Circular/Ring buffer implementation
+//
+//  https://github.com/michaeltyson/TPCircularBuffer
+//
+//  Created by Michael Tyson on 10/12/2011.
+//
+//  Copyright (C) 2012-2013 A Tasty Pixel
+//
+//  This software is provided 'as-is', without any express or implied
+//  warranty.  In no event will the authors be held liable for any damages
+//  arising from the use of this software.
+//
+//  Permission is granted to anyone to use this software for any purpose,
+//  including commercial applications, and to alter it and redistribute it
+//  freely, subject to the following restrictions:
+//
+//  1. The origin of this software must not be misrepresented; you must not
+//     claim that you wrote the original software. If you use this software
+//     in a product, an acknowledgment in the product documentation would be
+//     appreciated but is not required.
+//
+//  2. Altered source versions must be plainly marked as such, and must not be
+//     misrepresented as being the original software.
+//
+//  3. This notice may not be removed or altered from any source distribution.
+//
+
+#include <winpr/wlog.h>
+
+#include "TPCircularBuffer.h"
+#include "rdpsnd_main.h"
+
+#include <mach/mach.h>
+#include <stdio.h>
+
+#define reportResult(result, operation) (_reportResult((result), (operation), __FILE__, __LINE__))
+static inline bool _reportResult(kern_return_t result, const char* operation, const char* file,
+                                 int line)
+{
+	if (result != ERR_SUCCESS)
+	{
+		WLog_DBG(TAG, "%s:%d: %s: %s\n", file, line, operation, mach_error_string(result));
+		return false;
+	}
+	return true;
+}
+
+bool TPCircularBufferInit(TPCircularBuffer* buffer, int length)
+{
+
+	// Keep trying until we get our buffer, needed to handle race conditions
+	int retries = 3;
+	while (true)
+	{
+
+		buffer->length = round_page(length); // We need whole page sizes
+
+		// Temporarily allocate twice the length, so we have the contiguous address space to
+		// support a second instance of the buffer directly after
+		vm_address_t bufferAddress;
+		kern_return_t result = vm_allocate(mach_task_self(), &bufferAddress, buffer->length * 2,
+		                                   VM_FLAGS_ANYWHERE); // allocate anywhere it'll fit
+		if (result != ERR_SUCCESS)
+		{
+			if (retries-- == 0)
+			{
+				reportResult(result, "Buffer allocation");
+				return false;
+			}
+			// Try again if we fail
+			continue;
+		}
+
+		// Now replace the second half of the allocation with a virtual copy of the first half.
+		// Deallocate the second half...
+		result = vm_deallocate(mach_task_self(), bufferAddress + buffer->length, buffer->length);
+		if (result != ERR_SUCCESS)
+		{
+			if (retries-- == 0)
+			{
+				reportResult(result, "Buffer deallocation");
+				return false;
+			}
+			// If this fails somehow, deallocate the whole region and try again
+			vm_deallocate(mach_task_self(), bufferAddress, buffer->length);
+			continue;
+		}
+
+		// Re-map the buffer to the address space immediately after the buffer
+		vm_address_t virtualAddress = bufferAddress + buffer->length;
+		vm_prot_t cur_prot, max_prot;
+		result = vm_remap(mach_task_self(),
+		                  &virtualAddress,  // mirror target
+		                  buffer->length,   // size of mirror
+		                  0,                // auto alignment
+		                  0,                // force remapping to virtualAddress
+		                  mach_task_self(), // same task
+		                  bufferAddress,    // mirror source
+		                  0,                // MAP READ-WRITE, NOT COPY
+		                  &cur_prot,        // unused protection struct
+		                  &max_prot,        // unused protection struct
+		                  VM_INHERIT_DEFAULT);
+		if (result != ERR_SUCCESS)
+		{
+			if (retries-- == 0)
+			{
+				reportResult(result, "Remap buffer memory");
+				return false;
+			}
+			// If this remap failed, we hit a race condition, so deallocate and try again
+			vm_deallocate(mach_task_self(), bufferAddress, buffer->length);
+			continue;
+		}
+
+		if (virtualAddress != bufferAddress + buffer->length)
+		{
+			// If the memory is not contiguous, clean up both allocated buffers and try again
+			if (retries-- == 0)
+			{
+				WLog_DBG(TAG, "Couldn't map buffer memory to end of buffer");
+				return false;
+			}
+
+			vm_deallocate(mach_task_self(), virtualAddress, buffer->length);
+			vm_deallocate(mach_task_self(), bufferAddress, buffer->length);
+			continue;
+		}
+
+		buffer->buffer = (void*)bufferAddress;
+		buffer->fillCount = 0;
+		buffer->head = buffer->tail = 0;
+
+		return true;
+	}
+	return false;
+}
+
+void TPCircularBufferCleanup(TPCircularBuffer* buffer)
+{
+	vm_deallocate(mach_task_self(), (vm_address_t)buffer->buffer, buffer->length * 2);
+	memset(buffer, 0, sizeof(TPCircularBuffer));
+}
+
+void TPCircularBufferClear(TPCircularBuffer* buffer)
+{
+	int32_t fillCount;
+	if (TPCircularBufferTail(buffer, &fillCount))
+	{
+		TPCircularBufferConsume(buffer, fillCount);
+	}
+}