Add memory-region query, enumeration, and scoped protection

Implements VirtualQueryEx + MEMORY_BASIC_INFORMATION wrappers, the immutable MemoryRegion record, the ProtectionScope disposable helper, and MemoryBase.QueryRegion/EnumerateRegions/ChangeProtection. Closes section 1 of add-thread-region-finder.
2026-07-22 16:04:15 +02:00
parent e8c84f0ba1
commit f0faca3112
7 changed files with 504 additions and 0 deletions
@@ -0,0 +1,159 @@
+using System;
+using System.Linq;
+using System.Runtime.InteropServices;
+using WhiteMagic;
+using WhiteMagic.Memory;
+using WhiteMagic.Native;
+using Xunit;
+
+namespace WhiteMagicTest.Memory;
+
+/// <summary>
+/// Tests for memory-region query, enumeration and scoped protection (tasks 1.2, 1.4, 1.6, 1.8).
+/// </summary>
+public sealed class MemoryRegionTests
+{
+    [Fact]
+    public void Contains_returns_true_for_addresses_inside_half_open_range()
+    {
+        var region = new MemoryRegion(
+            new IntPtr(0x10000),
+            0x1000,
+            MemoryProtectionType.ReadWrite,
+            MemoryState.Commit,
+            MemoryType.Private,
+            new IntPtr(0x10000),
+            MemoryProtectionType.ReadWrite);
+
+        Assert.True(region.Contains(new IntPtr(0x10000)));
+        Assert.True(region.Contains(new IntPtr(0x10FFF)));
+        Assert.False(region.Contains(new IntPtr(0x11000)));
+        Assert.False(region.Contains(new IntPtr(0x0FFF)));
+    }
+
+    [Fact]
+    public void QueryRegion_returns_region_containing_committed_address()
+    {
+        using var reader = new InProcessReader();
+        nint pageSize = Environment.SystemPageSize;
+
+        IntPtr block = NativeMethods.VirtualAllocEx(
+            reader.Handle,
+            IntPtr.Zero,
+            pageSize,
+            MemoryAllocationType.Commit | MemoryAllocationType.Reserve,
+            MemoryProtectionType.ReadWrite);
+
+        Assert.NotEqual(IntPtr.Zero, block);
+
+        try
+        {
+            MemoryRegion region = reader.QueryRegion(block);
+
+            Assert.Equal(block, region.BaseAddress);
+            Assert.True(region.Contains(block));
+            Assert.True(region.Contains(block + (int)pageSize - 1));
+            Assert.Equal(MemoryState.Commit, region.State);
+            Assert.Equal(MemoryType.Private, region.Type);
+            Assert.Equal(MemoryProtectionType.ReadWrite, region.Protection);
+            Assert.Equal(MemoryProtectionType.ReadWrite, region.AllocationProtect);
+            Assert.Equal(block, region.AllocationBase);
+        }
+        finally
+        {
+            NativeMethods.VirtualFreeEx(reader.Handle, block, 0, MemoryFreeType.Release);
+        }
+    }
+
+    [Fact]
+    public void EnumerateRegions_yields_ascending_non_overlapping_regions()
+    {
+        using var reader = new InProcessReader();
+
+        MemoryRegion[] regions = reader.EnumerateRegions().Take(5).ToArray();
+        Assert.True(regions.Length > 0);
+
+        for (int i = 1; i < regions.Length; i++)
+        {
+            Assert.True(
+                (nuint)regions[i].BaseAddress >=
+                (nuint)regions[i - 1].BaseAddress + regions[i - 1].Size);
+        }
+    }
+
+    [Fact]
+    public void EnumerateRegions_is_lazy_and_stops_early()
+    {
+        using var reader = new InProcessReader();
+
+        // Taking a single item must not force a full address-space walk.
+        MemoryRegion first = reader.EnumerateRegions().First();
+        Assert.True(first.Size > 0);
+    }
+
+    [Fact]
+    public void ChangeProtection_applies_new_protection_inside_scope_and_restores_on_dispose()
+    {
+        using var reader = new InProcessReader();
+        nint pageSize = Environment.SystemPageSize;
+
+        IntPtr block = NativeMethods.VirtualAllocEx(
+            reader.Handle,
+            IntPtr.Zero,
+            pageSize,
+            MemoryAllocationType.Commit | MemoryAllocationType.Reserve,
+            MemoryProtectionType.ReadWrite);
+
+        Assert.NotEqual(IntPtr.Zero, block);
+
+        try
+        {
+            Assert.Equal(MemoryProtectionType.ReadWrite, reader.QueryRegion(block).Protection);
+
+            using (reader.ChangeProtection(block, pageSize, MemoryProtectionType.ExecuteReadWrite))
+            {
+                Assert.Equal(MemoryProtectionType.ExecuteReadWrite, reader.QueryRegion(block).Protection);
+            }
+
+            Assert.Equal(MemoryProtectionType.ReadWrite, reader.QueryRegion(block).Protection);
+        }
+        finally
+        {
+            NativeMethods.VirtualFreeEx(reader.Handle, block, 0, MemoryFreeType.Release);
+        }
+    }
+
+    [Fact]
+    public void ChangeProtection_restores_original_protection_when_body_throws()
+    {
+        using var reader = new InProcessReader();
+        nint pageSize = Environment.SystemPageSize;
+
+        IntPtr block = NativeMethods.VirtualAllocEx(
+            reader.Handle,
+            IntPtr.Zero,
+            pageSize,
+            MemoryAllocationType.Commit | MemoryAllocationType.Reserve,
+            MemoryProtectionType.ReadWrite);
+
+        Assert.NotEqual(IntPtr.Zero, block);
+
+        try
+        {
+            Assert.Throws<InvalidOperationException>(new Action(() =>
+            {
+                using (reader.ChangeProtection(block, pageSize, MemoryProtectionType.ExecuteReadWrite))
+                {
+                    Assert.Equal(MemoryProtectionType.ExecuteReadWrite, reader.QueryRegion(block).Protection);
+                    throw new InvalidOperationException("Intentional failure inside scope.");
+                }
+            }));
+
+            Assert.Equal(MemoryProtectionType.ReadWrite, reader.QueryRegion(block).Protection);
+        }
+        finally
+        {
+            NativeMethods.VirtualFreeEx(reader.Handle, block, 0, MemoryFreeType.Release);
+        }
+    }
+}