/// <summary>
/// Allocates memory that satisfies a set size constraint and proximity to a set address.
/// </summary>
/// <param name="size">The minimum size of the memory to be allocated.</param>
/// <param name="minimumAddress">The minimum absolute address to allocate in.</param>
/// <param name="maximumAddress">The maximum absolute address to allocate in.</param>
/// <param name="retryCount">In the case the memory allocation fails; the amount of times memory allocation is to be retried.</param>
/// <exception cref="System.Exception">Memory allocation failure due to possible race condition with other process/process itself/Windows scheduling.</exception>
/// <remarks>
/// This function is virtually the same to running <see cref="FindBufferLocation"/> and then running Windows'
/// VirtualAlloc yourself. Except for the extra added safety of mutual exclusion (Mutex).
/// The memory is allocated with the PAGE_EXECUTE_READWRITE permissions.
/// </remarks>
public BufferAllocationProperties Allocate(int size, int minimumAddress = 0x10000, int maximumAddress = 0x7FFFFFFF, int retryCount = 3)
{
if (minimumAddress <= 0)
{
throw new ArgumentException("Please do not set the minimum address to 0 or negative. It collides with the return values of Windows API functions" +
"where e.g. 0 is returned on failure but you can also allocate successfully on 0.");
}
// Keep retrying memory allocation.
_allocateMemoryMutex.WaitOne();
try
{
return(Run(retryCount, () =>
{
var memoryLocation = FindBufferLocation(size, minimumAddress, maximumAddress, true);
var virtualAllocFunction = VirtualAllocUtility.GetVirtualAllocFunction(Process);
var result = virtualAllocFunction(Process.Handle, memoryLocation.MemoryAddress, (ulong)memoryLocation.Size);
if (result == IntPtr.Zero)
{
throw new Exception("Failed to allocate memory using VirtualAlloc/VirtualAllocEx");
}
_allocateMemoryMutex.ReleaseMutex();
return memoryLocation;
}));
}
catch (Exception)
{
_allocateMemoryMutex.ReleaseMutex();
throw;
}
}
/// <summary>
/// Allocates memory to store a <see cref="MemoryBuffer"/>s inside the target process/
/// </summary>
internal static void AllocateBuffer(Process process, nuint bufferAddress, int bufferSize)
{
// Get the function, commit the pages and check.
var virtualAllocFunction = VirtualAllocUtility.GetVirtualAllocFunction(process);
var address = virtualAllocFunction(process.Handle, bufferAddress, (uint)bufferSize);
if (address == UIntPtr.Zero)
{
throw new Exception($"Failed to allocate MemoryBuffer of size {bufferSize} at address {bufferAddress}. Last Win32 Error: {Marshal.GetLastWin32Error()}");
}
}
