Bug fixes and reorganization of code.

native_query.h

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+#pragma once
+#include <windows.h>
+#include <cstddef>
+#include <cstdint>
+
+namespace native_control {
+inline bool query(HWND window, UINT message, WPARAM wp, LPARAM lp, DWORD_PTR *result) {
+  return SendMessageTimeoutW(window, message, wp, lp, SMTO_ABORTIFHUNG,
+                             100, result) != 0;
+}
+
+// Common-control messages above WM_USER do not marshal embedded pointers.
+// Own the target allocation and process handle together, including failures.
+class RemoteBuffer {
+public:
+  RemoteBuffer(HWND window, size_t size) {
+    DWORD processId = 0;
+    GetWindowThreadProcessId(window, &processId);
+    process_ = OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_READ |
+                           PROCESS_VM_WRITE | PROCESS_QUERY_LIMITED_INFORMATION,
+                           FALSE, processId);
+    if (!process_ || !IsWow64Process(process_, &wow64_)) return;
+    memory_ = VirtualAllocEx(process_, nullptr, size,
+                             MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
+    // Every byte of the allocation must be addressable by the target.
+    if (memory_ && wow64_ &&
+        (address() > UINT32_MAX || size - 1 > UINT32_MAX - address())) {
+      VirtualFreeEx(process_, memory_, 0, MEM_RELEASE);
+      memory_ = nullptr;
+    }
+  }
+  ~RemoteBuffer() {
+    if (memory_) VirtualFreeEx(process_, memory_, 0, MEM_RELEASE);
+    if (process_) CloseHandle(process_);
+  }
+  RemoteBuffer(const RemoteBuffer &) = delete;
+  RemoteBuffer &operator=(const RemoteBuffer &) = delete;
+
+  explicit operator bool() const { return memory_ != nullptr; }
+  bool is32Bit() const { return wow64_ != FALSE; }
+  uintptr_t address(size_t offset = 0) const {
+    return reinterpret_cast<uintptr_t>(memory_) + offset;
+  }
+  bool write(const void *buffer, size_t size) const {
+    return WriteProcessMemory(process_, memory_, buffer, size, nullptr) != 0;
+  }
+  bool read(void *buffer, size_t size, size_t offset = 0) const {
+    return ReadProcessMemory(process_, reinterpret_cast<const void *>(address(offset)),
+                              buffer, size, nullptr) != 0;
+  }
+
+private:
+  HANDLE process_ = nullptr;
+  void *memory_ = nullptr;
+  BOOL wow64_ = FALSE;
+};
+} // namespace native_control