Fix virtual memory allocation and access (#193)

* Fix virtual memory allocation and access * Update test dependency lock file
2026-07-22 19:06:15 +08:00 · 2026-07-14 21:50:54 -06:00
parent 373100a6b0
commit 9d88542efd
9 changed files with 626 additions and 40 deletions
@@ -0,0 +1,87 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using SharpEmu.Core.Loader;
+using SharpEmu.Core.Memory;
+using Xunit;
+
+namespace SharpEmu.Libs.Tests.Memory;
+
+public sealed class VirtualMemoryTests
+{
+    [Fact]
+    public void OutOfOrderMappingsRemainSortedAndResolveAtBoundaries()
+    {
+        var memory = new VirtualMemory();
+        memory.Map(0x3000, 0x100, 0, [3], ProgramHeaderFlags.Read | ProgramHeaderFlags.Write);
+        memory.Map(0x1000, 0x100, 0, [1], ProgramHeaderFlags.Read | ProgramHeaderFlags.Write);
+        memory.Map(0x2000, 0x100, 0, [2], ProgramHeaderFlags.Read | ProgramHeaderFlags.Write);
+
+        Assert.Equal([0x1000UL, 0x2000UL, 0x3000UL], memory.SnapshotRegions().Select(region => region.VirtualAddress));
+
+        Span<byte> value = stackalloc byte[1];
+        Assert.True(memory.TryRead(0x1000, value));
+        Assert.Equal(1, value[0]);
+        Assert.True(memory.TryRead(0x2000, value));
+        Assert.Equal(2, value[0]);
+        Assert.True(memory.TryRead(0x3000, value));
+        Assert.Equal(3, value[0]);
+        Assert.False(memory.TryRead(0x1100, value));
+        Assert.False(memory.TryRead(0x0FFF, value));
+    }
+
+    [Fact]
+    public void MappingRejectsOverlapWithEitherNeighbor()
+    {
+        var memory = new VirtualMemory();
+        memory.Map(0x2000, 0x100, 0, [], ProgramHeaderFlags.Read);
+        memory.Map(0x4000, 0x100, 0, [], ProgramHeaderFlags.Read);
+
+        Assert.Throws<InvalidOperationException>(() =>
+            memory.Map(0x1FFF, 2, 0, [], ProgramHeaderFlags.Read));
+        Assert.Throws<InvalidOperationException>(() =>
+            memory.Map(0x3FFF, 2, 0, [], ProgramHeaderFlags.Read));
+
+        memory.Map(0x2100, 0x1F00, 0, [], ProgramHeaderFlags.Read);
+        Assert.Equal(3, memory.SnapshotRegions().Count);
+    }
+
+    [Fact]
+    public void ReadAndWriteSpanAdjacentRegions()
+    {
+        var memory = new VirtualMemory();
+        const ProgramHeaderFlags protection = ProgramHeaderFlags.Read | ProgramHeaderFlags.Write;
+        memory.Map(0x1000, 4, 0, [1, 2, 3, 4], protection);
+        memory.Map(0x1004, 4, 0, [5, 6, 7, 8], protection);
+
+        Span<byte> read = stackalloc byte[4];
+        Assert.True(memory.TryRead(0x1002, read));
+        Assert.Equal([3, 4, 5, 6], read.ToArray());
+
+        Assert.True(memory.TryWrite(0x1002, [9, 10, 11, 12]));
+        Assert.True(memory.TryRead(0x1000, read));
+        Assert.Equal([1, 2, 9, 10], read.ToArray());
+        Assert.True(memory.TryRead(0x1004, read));
+        Assert.Equal([11, 12, 7, 8], read.ToArray());
+    }
+
+    [Fact]
+    public void AccessRequiresPermissionAcrossEntireRange()
+    {
+        var memory = new VirtualMemory();
+        memory.Map(0x1000, 4, 0, [1, 2, 3, 4], ProgramHeaderFlags.Read | ProgramHeaderFlags.Write);
+        memory.Map(0x1004, 4, 0, [5, 6, 7, 8], ProgramHeaderFlags.Read);
+        memory.Map(0x2000, 4, 0, [1, 2, 3, 4], ProgramHeaderFlags.Execute);
+        memory.Map(0x3000, 4, 0, [], ProgramHeaderFlags.Write);
+
+        Assert.False(memory.TryWrite(0x1002, [9, 9, 9, 9]));
+        Span<byte> unchanged = stackalloc byte[4];
+        Assert.True(memory.TryRead(0x1000, unchanged));
+        Assert.Equal([1, 2, 3, 4], unchanged.ToArray());
+
+        Assert.False(memory.TryRead(0x2000, unchanged));
+        Assert.False(memory.TryWrite(0x2000, [9]));
+        Assert.False(memory.TryRead(0x3000, unchanged));
+        Assert.True(memory.TryWrite(0x3000, [9]));
+    }
+}