Merge pull request 'updated ptrguard to use system_info for minimum calculations' (#144) from clr-fix-attempt into 2.0.3

Reviewed-on: #144

LightlessSync/Utils/PtrGuard.cs

@@ -5,19 +5,35 @@ namespace LightlessSync.Utils
 {
     public static partial class PtrGuard
     {
-        private const ulong _minLikelyPtr = 0x0000_0001_0000_0000UL;
-        private const ulong _maxUserPtr = 0x0000_7FFF_FFFF_FFFFUL;
         private const ulong _aligmentPtr = 0x7UL;
+        private static readonly nuint _minAppAddr = (nuint)GetMinAppAddr();
+        private static readonly nuint _maxAppAddr = (nuint)GetMaxAppAddr();
 
-        public static bool LooksLikePtr(nint p)
+        private static nint GetMinAppAddr()
         {
-            if (p == 0) return false;
+            GetSystemInfo(out var si);
-            var u = (ulong)p;
+            return si.lpMinimumApplicationAddress;
-            if (u < _minLikelyPtr) return false;
-            if (u > _maxUserPtr) return false;
-            if ((u & _aligmentPtr) != 0) return false;
-            return true;
         }
+
+        private static nint GetMaxAppAddr()
+        {
+            GetSystemInfo(out var si);
+            return si.lpMaximumApplicationAddress;
+        }
+
+            public static bool LooksLikePtr(nint p)
+            {
+                if (p == 0) return false;
+                nuint u = (nuint)p;
+
+                if (u < _minAppAddr) return false;
+                if (u > _maxAppAddr) return false;
+                if ((u & _aligmentPtr) != 0) return false;
+                if ((uint)u == 0x12345679u) return false;
+
+                return true;
+            }
+
         public static bool TryReadIntPtr(nint addr, out nint value)
         {
             value = 0;

LightlessSync/Utils/PtrGuardMemory.cs

@@ -32,5 +32,24 @@ namespace LightlessSync.Utils
 
         [DllImport("kernel32.dll")]
         internal static extern nint GetCurrentProcess();
+
+        [DllImport("kernel32.dll")]
+        internal static extern void GetSystemInfo(out SYSTEM_INFO lpSystemInfo);
+
+        [StructLayout(LayoutKind.Sequential)]
+        internal struct SYSTEM_INFO
+        {
+            public ushort wProcessorArchitecture;
+            public ushort wReserved;
+            public uint dwPageSize;
+            public nint lpMinimumApplicationAddress;
+            public nint lpMaximumApplicationAddress;
+            public nint dwActiveProcessorMask;
+            public uint dwNumberOfProcessors;
+            public uint dwProcessorType;
+            public uint dwAllocationGranularity;
+            public ushort wProcessorLevel;
+            public ushort wProcessorRevision;
+        }
     }
 }