task 2.3-2.4: implement MemoryBase + ExternalReader with tests

Add abstract MemoryBase base class with typed Read<T>/Write<T>, array IO, string IO, and relative/absolute addressing. Uses MarshalCache<T> to branch between blittable (MemoryMarshal) and marshal-required paths. Add ExternalReader (out-of-process via ReadProcessMemory/WriteProcessMemory) with SafeMemoryHandle lifecycle management. 11 new tests: ImageBase, Read/Write of int/byte/long/struct, byte array, int array, struct array, invalid address, dispose, double-dispose. All passing (total: 30).
2026-07-21 17:05:29 +02:00
parent ccde012e45
commit 6b34e0fab8
3 changed files with 520 additions and 0 deletions
@@ -0,0 +1,86 @@
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using WhiteMagic.Native;
+
+namespace WhiteMagic;
+
+/// <summary>
+/// Out-of-process memory reader that accesses the target's memory through
+/// <see cref="NativeMethods.ReadProcessMemory"/> and
+/// <see cref="NativeMethods.WriteProcessMemory"/>.
+/// </summary>
+public sealed class ExternalReader : MemoryBase
+{
+    private readonly SafeMemoryHandle _handle;
+    private readonly IntPtr _imageBase;
+    private bool _disposed;
+
+    /// <summary>
+    /// Opens a process for external memory access.
+    /// </summary>
+    /// <param name="process">The target process.</param>
+    /// <param name="desiredAccess">The access rights to request. Defaults to
+    /// <see cref="ProcessAccess.AllAccess"/>.</param>
+    public ExternalReader(Process process, ProcessAccess desiredAccess = ProcessAccess.AllAccess)
+    {
+        _handle = NativeMethods.OpenProcess(desiredAccess, false, process.Id);
+        if (_handle.IsInvalid)
+        {
+            int error = Marshal.GetLastPInvokeError();
+            throw new InvalidOperationException(
+                $"OpenProcess failed for PID {process.Id}: error {error}");
+        }
+
+        _imageBase = process.MainModule?.BaseAddress ?? IntPtr.Zero;
+    }
+
+    /// <inheritdoc />
+    public override IntPtr ImageBase => _imageBase;
+
+    /// <inheritdoc />
+    public override SafeMemoryHandle Handle => _handle;
+
+    /// <inheritdoc />
+    public override byte[] ReadBytes(IntPtr address, int count, bool isRelative = false)
+    {
+        if (isRelative)
+            address = GetAbsolute(address);
+
+        byte[] buffer = new byte[count];
+        if (!NativeMethods.ReadProcessMemory(_handle, address, buffer, count, out nint bytesRead))
+        {
+            return [];
+        }
+
+        if ((int)bytesRead != count)
+        {
+            Array.Resize(ref buffer, (int)bytesRead);
+        }
+
+        return buffer;
+    }
+
+    /// <inheritdoc />
+    public override int WriteBytes(IntPtr address, ReadOnlySpan<byte> bytes, bool isRelative = false)
+    {
+        if (isRelative)
+            address = GetAbsolute(address);
+
+        if (!NativeMethods.WriteProcessMemory(_handle, address, bytes, bytes.Length, out nint written))
+        {
+            return 0;
+        }
+
+        return (int)written;
+    }
+
+    /// <inheritdoc />
+    public override void Dispose()
+    {
+        if (!_disposed)
+        {
+            _disposed = true;
+            _handle.Dispose();
+        }
+    }
+}