Chrome Windows Debugger Extension Skeleton

tools/win/chromeexts/chromeexts.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <windows.h>
+#include <dbgeng.h>
+#include <wrl/client.h>
+
+namespace {
+using Microsoft::WRL::ComPtr;
+constexpr size_t kMaxWindowStringLength = 256;
+}  // namespace
+
+HRESULT CALLBACK DebugExtensionInitialize(ULONG* version, ULONG* flags) {
+  *version = DEBUG_EXTENSION_VERSION(0, 1);
+  *flags = 0;
+  return S_OK;
+}
+
+void CALLBACK DebugExtensionUninitialize() {}
+
+HRESULT CALLBACK help(IDebugClient* client, PCSTR args) {
+  ComPtr<IDebugControl> debug_control;
+  HRESULT hr = client->QueryInterface(IID_PPV_ARGS(&debug_control));
+  if (FAILED(hr)) {
+    return hr;
+  }
+
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "Chrome Windows Debugger Extension\n");
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "hwnd       - Displays basic hwnd info.\n");

[scottmg, 2017/01/05 15:53:46]

nit; The number of spaces between hwnd and - seems strange here. Is this to
match alignment from some other output?

[robliao, 2017/01/06 02:31:06]

This was a loose convention in !help for other extensions, but I think I'm going
to favor some sort of unified way of doing this. I'll drop this down to one
space in the meantime.

+  return S_OK;
+}
+
+HRESULT CALLBACK hwnd(IDebugClient* client, PCSTR args) {
+  ComPtr<IDebugControl> debug_control;
+  HRESULT hr = client->QueryInterface(IID_PPV_ARGS(&debug_control));
+  if (FAILED(hr)) {
+    return hr;
+  }
+
+  DEBUG_VALUE value;
+  hr = debug_control->Evaluate(args, DEBUG_VALUE_INT64, &value, nullptr);

[scottmg, 2017/01/05 15:53:46]

I assume this will work on x86?

[scottmg, 2017/01/05 15:53:46]

Is it necessary to call SetExpressionSyntax(DEBUG_EXPR_CPLUSPLUS)? Or better to
leave as default?

[robliao, 2017/01/06 02:31:06]

Yep, this works on x86 and x64. Since the upper-bits for an HWND are ignored,
the number of bits for us are less important here. I'll move the comment below
up here.

As for the expression syntax, I think I'd rather leave it default and let
callers change modes manually as necessary. At least I think that's how it
works, the docs leave much to be desired.

+  if (FAILED(hr)) {
+    debug_control->Output(
+        DEBUG_OUTPUT_ERROR,"Unavailable to evaluate %s\n", args);

[scottmg, 2017/01/05 15:53:46]

nit; "Unavailable" sounds weird, how about "Unable".

[scottmg, 2017/01/05 15:53:46]

Missing space before opening ".

(Run the whole thing though clang-format too).

[robliao, 2017/01/06 02:31:06]

Done and done.

+    return hr;
+  }
+
+  // While sizeof(HWND) can change between 32-bit and 64-bit platforms, Windows
+  // only cares about the lower 32-bits. We evaluate as 64-bit as a convenience
+  // and truncate the displayed hwnds to 32-bit below.
+  // See https://msdn.microsoft.com/en-us/library/aa384203.aspx
+  HWND hwnd = reinterpret_cast<HWND>(value.I64);
+  if (!IsWindow(hwnd)) {
+    debug_control->Output(DEBUG_OUTPUT_NORMAL, "Not a window: %s\n", args);
+    return E_FAIL;
+  }
+
+  wchar_t title[kMaxWindowStringLength];
+  GetWindowText(hwnd, title, ARRAYSIZE(title));
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "Title: %ws\n", title);
+  wchar_t window_class[kMaxWindowStringLength];
+  GetClassName(hwnd, window_class, ARRAYSIZE(window_class));
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "Class: %ws\n", window_class);
+  debug_control->Output(DEBUG_OUTPUT_NORMAL, "Hierarchy: \n");
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "   Owner: %08x Parent: %08x\n",
+      GetWindow(hwnd, GW_OWNER), GetParent(hwnd));
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "   Prev:  %08x Next:   %08x\n",
+      GetNextWindow(hwnd, GW_HWNDPREV), GetNextWindow(hwnd, GW_HWNDNEXT));
+  debug_control->Output(
+      DEBUG_OUTPUT_NORMAL, "Styles: %08x (Ex: %08x)\n",
+      GetWindowLong(hwnd, GWL_STYLE), GetWindowLong(hwnd, GWL_EXSTYLE));
+  RECT window_rect;
+  if (GetWindowRect(hwnd, &window_rect)) {
+    debug_control->Output(
+        DEBUG_OUTPUT_NORMAL, "Bounds: (%d, %d) %dx%d\n",
+        window_rect.left, window_rect.top,
+        window_rect.right - window_rect.left,
+        window_rect.bottom - window_rect.top);
+  } else {
+    DWORD last_error = GetLastError();
+    debug_control->Output(
+        DEBUG_OUTPUT_NORMAL, "Bounds: Unavailable (Last Error = %d)\n",
+        last_error);
+  }
+  return S_OK;
+}
+