Fix macOS fixed-address allocation collisions (#246)

2026-07-22 19:06:15 +08:00 · 2026-07-16 09:45:08 -04:00
parent 53d414e096
commit f2d9051358
3 changed files with 136 additions and 13 deletions
@@ -0,0 +1,62 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using System.Runtime.InteropServices;
+using SharpEmu.HLE.Host;
+using SharpEmu.HLE.Host.Posix;
+using Xunit;
+
+namespace SharpEmu.Libs.Tests.Memory;
+
+public sealed unsafe class PosixHostMemoryTests
+{
+    private const int ProtRead = 0x1;
+    private const int ProtWrite = 0x2;
+    private const int MapPrivate = 0x02;
+    private const int MapAnonymousDarwin = 0x1000;
+    private static readonly nint MapFailed = -1;
+
+    [Fact]
+    public void ExactAllocationDoesNotReplaceUntrackedDarwinMapping()
+    {
+        if (!OperatingSystem.IsMacOS())
+        {
+            return;
+        }
+
+        var size = checked((nuint)Environment.SystemPageSize);
+        var externalMapping = mmap(
+            0,
+            size,
+            ProtRead | ProtWrite,
+            MapPrivate | MapAnonymousDarwin,
+            -1,
+            0);
+        Assert.NotEqual(MapFailed, externalMapping);
+
+        try
+        {
+            var sentinel = new Span<byte>((void*)externalMapping, checked((int)size));
+            sentinel.Fill(0xA5);
+
+            var hostMemory = new PosixHostMemory();
+            var result = hostMemory.Allocate(
+                (ulong)externalMapping,
+                (ulong)size,
+                HostPageProtection.ReadWrite);
+
+            Assert.Equal(0UL, result);
+            Assert.All(sentinel.ToArray(), value => Assert.Equal(0xA5, value));
+        }
+        finally
+        {
+            Assert.Equal(0, munmap(externalMapping, size));
+        }
+    }
+
+    [DllImport("libc", SetLastError = true)]
+    private static extern nint mmap(nint addr, nuint length, int prot, int flags, int fd, long offset);
+
+    [DllImport("libc", SetLastError = true)]
+    private static extern int munmap(nint addr, nuint length);
+}