Implement memory mapper for macOS

BepInEx.IL2CPP/Hook/Allocator/MacOsPageAllocator.cs

@@ -1,24 +1,67 @@
 using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using MonoMod.Utils;
 
 namespace BepInEx.IL2CPP.Allocator
 {
 	internal class MacOsPageAllocator : UnixPageAllocator
 	{
-		protected override IMemoryMapper OpenMemoryMap()
+		protected override IEnumerable<(IntPtr, IntPtr)> MapMemoryAreas()
 		{
-			throw new NotImplementedException();
-		}
+			var size = IntPtr.Zero;
+			var info = new LibSystem.vm_region_basic_info_64();
+			var infoCount = (uint)(Marshal.SizeOf<LibSystem.vm_region_basic_info_64>() / sizeof(int));
+			var objectName = 0u;
+			var address = IntPtr.Zero;
 
-		protected class MacOsMemoryMapper : IMemoryMapper
+			while (LibSystem.vm_region_64(LibSystem.TaskSelf, ref address, ref size, LibSystem.VM_REGION_BASIC_INFO_64, ref info, ref infoCount, ref objectName) == LibSystem.KERN_SUCCESS)
+			{
+				var start = new IntPtr(address.ToInt64());
+				var end = new IntPtr(address.ToInt64() + size.ToInt64());
+				address = end;
+				yield return (start, end);
+			}
+		}
+		
+		private static class LibSystem
 		{
-			public void Dispose()
+			public static readonly IntPtr TaskSelf;
+			public const int VM_REGION_BASIC_INFO_64 = 9;
+			public const int KERN_SUCCESS = 0;
+
+			[StructLayout(LayoutKind.Sequential)]
+			public struct vm_region_basic_info_64
 			{
-				throw new NotImplementedException();
+				public int protection;
+				public int max_protection;
+				public uint inheritance;
+				[MarshalAs(UnmanagedType.I4)]
+				public bool shared;
+				[MarshalAs(UnmanagedType.I4)]
+				public bool reserved;
+				public ulong offset;
+				public int behavior;
+				public ushort user_wired_count;
 			}
 
-			public bool FindNextFree(out IntPtr start, out IntPtr end)
+			public delegate int vm_region_64Delegate(IntPtr target_task, ref IntPtr address, ref IntPtr size, int flavor, ref vm_region_basic_info_64 info, ref uint infoCnt, ref uint object_name);
+
+			[DynDllImport("libSystem")]
+			public static vm_region_64Delegate vm_region_64;
+			
+			static LibSystem()
 			{
-				throw new NotImplementedException();
+				typeof(LibSystem).ResolveDynDllImports(new Dictionary<string, List<DynDllMapping>>
+				{
+					["libSystem"] = new List<DynDllMapping>
+					{
+						"/usr/lib/libSystem.dylib" // OSX POSIX
+					}
+				});
+
+				var libsystem = DynDll.OpenLibrary("/usr/lib/libSystem.dylib");
+				TaskSelf = libsystem.GetFunction("mach_task_self_"); // This isn't a function but rather an exported symbol
 			}
 		}
 	}