Bug 1710887 - Make modal state handling in window.print() more reliable. r=smaug

If afterprint removes the window we're printing, we'd call
LeaveModalState() without a top window, and never leave the modal state.

Differential Revision: https://phabricator.services.mozilla.com/D115007

dom/base/nsGlobalWindowOuter.cpp

@@ -5237,6 +5237,20 @@ void nsGlobalWindowOuter::PrintOuter(ErrorResult& aError) {
 #endif
 }
 
+class MOZ_RAII AutoModalState {
+ public:
+  explicit AutoModalState(nsGlobalWindowOuter& aWin)
+      : mModalStateWin(aWin.EnterModalState()) {}
+
+  ~AutoModalState() {
+    if (mModalStateWin) {
+      mModalStateWin->LeaveModalState();
+    }
+  }
+
+  RefPtr<nsGlobalWindowOuter> mModalStateWin;
+};
+
 Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
     nsIPrintSettings* aPrintSettings, nsIWebProgressListener* aListener,
     nsIDocShell* aDocShellToCloneInto, IsPreview aIsPreview,
@@ -5265,8 +5279,7 @@ Nullable<WindowProxyHolder> nsGlobalWindowOuter::Print(
   }
 
   nsAutoSyncOperation sync(docToPrint, SyncOperationBehavior::eAllowInput);
-  EnterModalState();
-  auto exitModal = MakeScopeExit([&] { LeaveModalState(); });
+  AutoModalState modalState(*this);
 
   nsCOMPtr<nsIContentViewer> cv;
   RefPtr<BrowsingContext> bc;
@@ -6327,14 +6340,14 @@ void nsGlobalWindowOuter::ReallyCloseWindow() {
   CleanUp();
 }
 
-void nsGlobalWindowOuter::EnterModalState() {
+nsGlobalWindowOuter* nsGlobalWindowOuter::EnterModalState() {
   // GetInProcessScriptableTop, not GetInProcessTop, so that EnterModalState
   // works properly with <iframe mozbrowser>.
   nsGlobalWindowOuter* topWin = GetInProcessScriptableTopInternal();
 
   if (!topWin) {
     NS_ERROR("Uh, EnterModalState() called w/o a reachable top window?");
-    return;
+    return nullptr;
   }
 
   // If there is an active ESM in this window, clear it. Otherwise, this can
@@ -6389,33 +6402,38 @@ void nsGlobalWindowOuter::EnterModalState() {
     }
   }
   topWin->mModalStateDepth++;
+  return topWin;
 }
 
 void nsGlobalWindowOuter::LeaveModalState() {
-  nsGlobalWindowOuter* topWin = GetInProcessScriptableTopInternal();
+  {
+    nsGlobalWindowOuter* topWin = GetInProcessScriptableTopInternal();
+    if (!topWin) {
+      NS_WARNING("Uh, LeaveModalState() called w/o a reachable top window?");
+      return;
+    }
 
-  if (!topWin) {
-    NS_WARNING("Uh, LeaveModalState() called w/o a reachable top window?");
-    return;
+    if (topWin != this) {
+      MOZ_ASSERT(IsSuspended());
+      return topWin->LeaveModalState();
+    }
   }
 
-  MOZ_ASSERT(topWin->mModalStateDepth != 0);
+  MOZ_ASSERT(mModalStateDepth != 0);
   MOZ_ASSERT(IsSuspended());
-  MOZ_ASSERT(topWin->IsSuspended());
-  topWin->mModalStateDepth--;
+  mModalStateDepth--;
 
-  nsGlobalWindowInner* inner = topWin->GetCurrentInnerWindowInternal();
-
-  if (topWin->mModalStateDepth == 0) {
+  nsGlobalWindowInner* inner = GetCurrentInnerWindowInternal();
+  if (mModalStateDepth == 0) {
     if (inner) {
       inner->Resume();
     }
 
-    if (topWin->mSuspendedDoc) {
-      nsCOMPtr<Document> currentDoc = topWin->GetExtantDoc();
-      topWin->mSuspendedDoc->UnsuppressEventHandlingAndFireEvents(
-          currentDoc == topWin->mSuspendedDoc);
-      topWin->mSuspendedDoc = nullptr;
+    if (mSuspendedDoc) {
+      nsCOMPtr<Document> currentDoc = GetExtantDoc();
+      mSuspendedDoc->UnsuppressEventHandlingAndFireEvents(currentDoc ==
+                                                          mSuspendedDoc);
+      mSuspendedDoc = nullptr;
     }
   }
 
@@ -6424,12 +6442,12 @@ void nsGlobalWindowOuter::LeaveModalState() {
     inner->mLastDialogQuitTime = TimeStamp::Now();
   }
 
-  if (topWin->mModalStateDepth == 0) {
+  if (mModalStateDepth == 0) {
     RefPtr<Event> event = NS_NewDOMEvent(inner, nullptr, nullptr);
     event->InitEvent(u"endmodalstate"_ns, true, false);
     event->SetTrusted(true);
     event->WidgetEventPtr()->mFlags.mOnlyChromeDispatch = true;
-    topWin->DispatchEvent(*event);
+    DispatchEvent(*event);
   }
 }
 

dom/base/nsGlobalWindowOuter.h

@@ -328,7 +328,7 @@ class nsGlobalWindowOuter final : public mozilla::dom::EventTarget,
   // Outer windows only.
   virtual void EnsureSizeAndPositionUpToDate() override;
 
-  MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual void EnterModalState() override;
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY virtual nsGlobalWindowOuter* EnterModalState() override;
   virtual void LeaveModalState() override;
 
   // Outer windows only.

dom/base/nsPIDOMWindow.h

@@ -913,8 +913,12 @@ class nsPIDOMWindowOuter : public mozIDOMWindowProxy {
   /**
    * Callback for notifying a window about a modal dialog being
    * opened/closed with the window as a parent.
+   *
+   * If any script can run between the enter and leave modal states, and the
+   * window isn't top, the LeaveModalState() should be called on the window
+   * returned by EnterModalState().
    */
-  virtual void EnterModalState() = 0;
+  virtual nsPIDOMWindowOuter* EnterModalState() = 0;
   virtual void LeaveModalState() = 0;
 
   virtual bool CanClose() = 0;

toolkit/components/printing/tests/browser.ini

@@ -45,6 +45,7 @@ support-files =
   file_window_print_delayed_during_load.html
   file_window_print_sandboxed_iframe.html
   file_window_print_another_iframe_and_remove.html
+  file_window_print_iframe_remove_on_afterprint.html
   file_coop_header2.html
   file_coop_header2.html^headers^
 

toolkit/components/printing/tests/browser_window_print.js

@@ -212,6 +212,48 @@ add_task(async function test_window_print_coop_site() {
   }
 });
 
+add_task(async function test_window_print_iframe_remove_on_afterprint() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["print.tab_modal.enabled", true]],
+  });
+  ok(
+    !document.querySelector(".printPreviewBrowser"),
+    "There shouldn't be any print preview browser"
+  );
+  await BrowserTestUtils.withNewTab(
+    `${TEST_PATH}file_window_print_iframe_remove_on_afterprint.html`,
+    async function(browser) {
+      info("Waiting for dialog");
+      await BrowserTestUtils.waitForCondition(
+        () => !!document.querySelector(".printPreviewBrowser")
+      );
+
+      let modalBefore = await SpecialPowers.spawn(browser, [], () => {
+        return content.windowUtils.isInModalState();
+      });
+
+      ok(modalBefore, "The tab should be in modal state");
+
+      // Clear the dialog.
+      gBrowser.getTabDialogBox(browser).abortAllDialogs();
+
+      let [modalAfter, hasIframe] = await SpecialPowers.spawn(
+        browser,
+        [],
+        () => {
+          return [
+            content.windowUtils.isInModalState(),
+            !!content.document.querySelector("iframe"),
+          ];
+        }
+      );
+
+      ok(!modalAfter, "Should've cleared the modal state properly");
+      ok(!hasIframe, "Iframe should've been removed from the DOM");
+    }
+  );
+});
+
 // FIXME(emilio): This test doesn't use window.print(), why is it on this file?
 add_task(async function test_focused_browsing_context() {
   await SpecialPowers.pushPrefEnv({

toolkit/components/printing/tests/file_window_print_iframe_remove_on_afterprint.html

@@ -0,0 +1,30 @@
+<!doctype html>
+<script>
+function closePrint() {
+  document.documentElement.removeChild(this.__container__);
+}
+
+function setPrint() {
+  this.contentWindow.__container__ = this;
+  this.contentWindow.onbeforeunload = closePrint;
+  this.contentWindow.onafterprint = closePrint;
+  this.contentWindow.print();
+}
+
+function printPage(content) {
+  var frame = document.createElement("iframe");
+  frame.onload = setPrint;
+  frame.style.position = "fixed";
+  frame.style.right = "0";
+  frame.style.bottom = "0";
+  frame.style.width = "0";
+  frame.style.height = "0";
+  frame.style.border = "0";
+  frame.srcdoc = content;
+  document.documentElement.appendChild(frame);
+}
+
+onload = function() {
+  printPage("Something");
+}
+</script>