From 368bc15964d9580eb6f6a875c25280d8a6f4c504 Mon Sep 17 00:00:00 2001
From: Joe Downing <joedow@google.com>
Date: Mon, 31 Aug 2026 14:28:54 -0700
Subject: [PATCH] [remoting] Truncate client username in Linux disconnect window

In Chrome Remote Desktop on Linux, the disconnect dialog displays the
connecting client's identity in an unwrapped, un-ellipsized GtkLabel.
When an authenticated remote user connects with an oversized email address,
the window can expand beyond the screen boundary, pushing the disconnect
button off-screen.

This change collapses whitespace and safely truncates the username to
50 UTF-16 characters at a valid character boundary before formatting
IDS_MESSAGE_SHARED, preserving localized punctuation. It also configures
the message label with PANGO_ELLIPSIZE_MIDDLE and max_width_chars, and
clamps window placement within screen boundaries.

Fixed: 553921181

TAG=workflow

TAG=agy

CONV=180927ee-f343-45e4-a0ce-c2b7b7f11b75

Change-Id: Ie6088bc4d1e5d4dc48b9fb87efe3f4547868dc07
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8315589
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Commit-Queue: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1689275}
---
diff --git a/remoting/host/disconnect_window_linux.cc b/remoting/host/disconnect_window_linux.cc
index dd48ea8..687e36a 100644
--- a/remoting/host/disconnect_window_linux.cc
+++ b/remoting/host/disconnect_window_linux.cc
@@ -4,6 +4,7 @@
 
 #include <gtk/gtk.h>
 
+#include <algorithm>
 #include <memory>
 #include <numbers>
 #include <vector>
@@ -11,6 +12,7 @@
 #include "base/check_op.h"
 #include "base/compiler_specific.h"
 #include "base/functional/bind.h"
+#include "base/i18n/char_iterator.h"
 #include "base/location.h"
 #include "base/memory/raw_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ -32,6 +34,9 @@
 // The amount of time to wait before allowing another position toggle.
 constexpr base::TimeDelta kToggleCooldown = base::Seconds(3);
 
+// Maximum length of the username / client identity in UTF-16 characters.
+constexpr size_t kMaxUsernameLength = 50;
+
 // Margins from screen edges to ensure the dialog is not obscured by the top bar
 // or an auto-hiding dock/panel at the bottom.
 constexpr int kTopMargin = 40;
@@ -250,10 +255,13 @@
           &DisconnectWindowGtk::OnToggleClicked);
 
   message_ = gtk_label_new(nullptr);
+  gtk_label_set_ellipsize(GTK_LABEL(message_.get()), PANGO_ELLIPSIZE_MIDDLE);
+  gtk_label_set_max_width_chars(GTK_LABEL(message_.get()), 30);
 #if GTK_CHECK_VERSION(3, 90, 0)
   gtk_box_pack_start(GTK_BOX(button_row), message_.get());
+  gtk_widget_set_hexpand(message_.get(), TRUE);
 #else
-  gtk_box_pack_start(GTK_BOX(button_row), message_.get(), FALSE, FALSE, 0);
+  gtk_box_pack_start(GTK_BOX(button_row), message_.get(), TRUE, TRUE, 0);
 #endif
 
   button_ = gtk_button_new_with_label(
@@ -296,9 +304,21 @@
   std::string client_jid = client_session_control_->client_jid();
   std::u16string username =
       base::UTF8ToUTF16(client_jid.substr(0, client_jid.find('/')));
-  gtk_label_set_text(
-      GTK_LABEL(message_.get()),
-      l10n_util::GetStringFUTF8(IDS_MESSAGE_SHARED, username).c_str());
+  username = base::CollapseWhitespace(username,
+                                      /*trim_sequences_with_line_breaks=*/true);
+  // Truncate username safely at a Unicode character boundary so that
+  // truncation does not split UTF-16 surrogate pairs. Truncating before
+  // formatting ensures localized punctuation and grammar in IDS_MESSAGE_SHARED
+  // (e.g. trailing periods) are preserved.
+  if (username.length() > kMaxUsernameLength) {
+    username.erase(
+        base::i18n::UTF16CharIterator::LowerBound(username, kMaxUsernameLength)
+            .array_pos());
+  }
+
+  std::string message_text =
+      l10n_util::GetStringFUTF8(IDS_MESSAGE_SHARED, username);
+  gtk_label_set_text(GTK_LABEL(message_.get()), message_text.c_str());
   SetDialogPosition();
   gtk_window_present(window);
 }
@@ -405,7 +425,7 @@
     height = requisition.height;
   }
 
-  int left = geometry.x + (geometry.width - width) / 2;
+  int left = geometry.x + std::max(0, (geometry.width - width) / 2);
   int top = (g_current_anchor == WindowAnchor::kTop)
                 ? (geometry.y + kTopMargin)
                 : (geometry.y + geometry.height - height - kBottomMargin);
diff --git a/remoting/host/disconnect_window_linux_unittest.cc b/remoting/host/disconnect_window_linux_unittest.cc
new file mode 100644
index 0000000..3b398b4
--- /dev/null
+++ b/remoting/host/disconnect_window_linux_unittest.cc
@@ -0,0 +1,180 @@
+// Copyright 2026 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <gtk/gtk.h>
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/memory/ref_counted_memory.h"
+#include "base/memory/weak_ptr.h"
+#include "base/test/task_environment.h"
+#include "remoting/base/string_resources.h"
+#include "remoting/host/client_session_control.h"
+#include "remoting/host/host_mock_objects.h"
+#include "remoting/host/host_window.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/base/resource/resource_scale_factor.h"
+
+namespace remoting {
+
+namespace {
+
+class FakeClientSessionControl : public MockClientSessionControl {
+ public:
+  explicit FakeClientSessionControl(std::string client_jid)
+      : client_jid_(std::move(client_jid)) {
+    EXPECT_CALL(*this, client_jid())
+        .WillRepeatedly(testing::ReturnRef(client_jid_));
+  }
+
+  ~FakeClientSessionControl() override = default;
+
+  base::WeakPtr<ClientSessionControl> GetWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
+ private:
+  std::string client_jid_;
+  base::WeakPtrFactory<FakeClientSessionControl> weak_factory_{this};
+};
+
+class TestResourceBundleDelegate : public ui::ResourceBundle::Delegate {
+ public:
+  TestResourceBundleDelegate() = default;
+  ~TestResourceBundleDelegate() override = default;
+
+  base::FilePath GetPathForResourcePack(
+      const base::FilePath& pack_path,
+      ui::ResourceScaleFactor scale_factor) override {
+    return base::FilePath();
+  }
+  gfx::Image GetImageNamed(int resource_id) override { return gfx::Image(); }
+  gfx::Image GetNativeImageNamed(int resource_id) override {
+    return gfx::Image();
+  }
+  bool HasDataResource(int resource_id) const override { return false; }
+  scoped_refptr<base::RefCountedMemory> LoadDataResourceBytes(
+      int resource_id,
+      ui::ResourceScaleFactor scale_factor) override {
+    return nullptr;
+  }
+  std::optional<std::string> LoadDataResourceString(int resource_id) override {
+    return std::nullopt;
+  }
+  bool GetRawDataResource(int resource_id,
+                          ui::ResourceScaleFactor scale_factor,
+                          std::string_view* value) const override {
+    return false;
+  }
+  bool GetLocalizedString(int message_id,
+                          std::u16string* value) const override {
+    if (message_id == IDS_MESSAGE_SHARED) {
+      *value = u"Your desktop is shared with $1.";
+      return true;
+    }
+    if (message_id == IDS_PRODUCT_NAME) {
+      *value = u"Chrome Remote Desktop";
+      return true;
+    }
+    if (message_id == IDS_STOP_SHARING_BUTTON) {
+      *value = u"Stop Sharing";
+      return true;
+    }
+    return false;
+  }
+};
+
+bool InitializeGtk() {
+#if GTK_CHECK_VERSION(3, 90, 0)
+  return gtk_init_check();
+#else
+  return gtk_init_check(nullptr, nullptr);
+#endif
+}
+
+}  // namespace
+
+class DisconnectWindowLinuxTest : public testing::Test {
+ public:
+  DisconnectWindowLinuxTest()
+      : task_environment_(base::test::TaskEnvironment::MainThreadType::UI),
+        resource_bundle_(&resource_delegate_),
+        resource_swapper_(&resource_bundle_) {}
+  ~DisconnectWindowLinuxTest() override = default;
+
+  void TearDown() override {
+    // Pump the event loop to ensure GTK widget destruction and cleanup is
+    // processed.
+    task_environment_.RunUntilIdle();
+  }
+
+ protected:
+  base::test::TaskEnvironment task_environment_;
+  TestResourceBundleDelegate resource_delegate_;
+  ui::ResourceBundle resource_bundle_;
+  ui::ResourceBundle::SharedInstanceSwapperForTesting resource_swapper_;
+};
+
+TEST_F(DisconnectWindowLinuxTest, NormalEmailDoesNotCrash) {
+  if (!InitializeGtk()) {
+    GTEST_SKIP() << "No display available for GTK.";
+  }
+
+  FakeClientSessionControl session_control(
+      "john.smith@gmail.com/chromoting_ftl");
+  std::unique_ptr<HostWindow> window = HostWindow::CreateDisconnectWindow();
+  ASSERT_TRUE(window);
+  window->Start(session_control.GetWeakPtr());
+  EXPECT_TRUE(session_control.GetWeakPtr());
+
+  window.reset();
+  task_environment_.RunUntilIdle();
+}
+
+TEST_F(DisconnectWindowLinuxTest, LongEmailDoesNotCrash) {
+  if (!InitializeGtk()) {
+    GTEST_SKIP() << "No display available for GTK.";
+  }
+
+  const std::string kLongEmail =
+      "it-support-desk-remote-assistance-session-verification-operators@"
+      "secure-remote-support-verification-and-customer-protection-desk."
+      "assistance-operations-center-for-workspace-hosted-accounts-team."
+      "example-corporation-global-technical-services-departments.com/"
+      "chromoting_ftl";
+
+  FakeClientSessionControl session_control(kLongEmail);
+  std::unique_ptr<HostWindow> window = HostWindow::CreateDisconnectWindow();
+  ASSERT_TRUE(window);
+  window->Start(session_control.GetWeakPtr());
+  EXPECT_TRUE(session_control.GetWeakPtr());
+
+  window.reset();
+  task_environment_.RunUntilIdle();
+}
+
+TEST_F(DisconnectWindowLinuxTest, WhitespaceAndUnicodeEmailDoesNotCrash) {
+  if (!InitializeGtk()) {
+    GTEST_SKIP() << "No display available for GTK.";
+  }
+
+  // Multi-byte Unicode with whitespace formatting
+  const std::string kUnicodeEmail =
+      "  \t\n  user_with_unicode_测试_🚀@example.com  \n/chromoting_ftl";
+
+  FakeClientSessionControl session_control(kUnicodeEmail);
+  std::unique_ptr<HostWindow> window = HostWindow::CreateDisconnectWindow();
+  ASSERT_TRUE(window);
+  window->Start(session_control.GetWeakPtr());
+  EXPECT_TRUE(session_control.GetWeakPtr());
+
+  window.reset();
+  task_environment_.RunUntilIdle();
+}
+
+}  // namespace remoting
diff --git a/remoting/host/BUILD.gn b/remoting/host/BUILD.gn
index a234f50..c9e5a15 100644
--- a/remoting/host/BUILD.gn
+++ b/remoting/host/BUILD.gn
@@ -1031,6 +1031,7 @@
 
   if (is_linux) {
     sources += [
+      "disconnect_window_linux_unittest.cc",
       "pairing_registry_delegate_linux_unittest.cc",
       "terminal_process_monitor_linux_unittest.cc",
     ]

diff --git a/remoting/host/disconnect_window_linux_unittest.cc b/remoting/host/disconnect_window_linux_unittest.cc
new file mode 100644
index 0000000..3b398b4
--- /dev/null
+++ b/remoting/host/disconnect_window_linux_unittest.cc
@@ -0,0 +1,180 @@
+// Copyright 2026 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <gtk/gtk.h>
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "base/memory/ref_counted_memory.h"
+#include "base/memory/weak_ptr.h"
+#include "base/test/task_environment.h"
+#include "remoting/base/string_resources.h"
+#include "remoting/host/client_session_control.h"
+#include "remoting/host/host_mock_objects.h"
+#include "remoting/host/host_window.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/base/resource/resource_bundle.h"
+#include "ui/base/resource/resource_scale_factor.h"
+
+namespace remoting {
+
+namespace {
+
+class FakeClientSessionControl : public MockClientSessionControl {
+ public:
+  explicit FakeClientSessionControl(std::string client_jid)
+      : client_jid_(std::move(client_jid)) {
+    EXPECT_CALL(*this, client_jid())
+        .WillRepeatedly(testing::ReturnRef(client_jid_));
+  }
+
+  ~FakeClientSessionControl() override = default;
+
+  base::WeakPtr<ClientSessionControl> GetWeakPtr() {
+    return weak_factory_.GetWeakPtr();
+  }
+
+ private:
+  std::string client_jid_;
+  base::WeakPtrFactory<FakeClientSessionControl> weak_factory_{this};
+};
+
+class TestResourceBundleDelegate : public ui::ResourceBundle::Delegate {
+ public:
+  TestResourceBundleDelegate() = default;
+  ~TestResourceBundleDelegate() override = default;
+
+  base::FilePath GetPathForResourcePack(
+      const base::FilePath& pack_path,
+      ui::ResourceScaleFactor scale_factor) override {
+    return base::FilePath();
+  }
+  gfx::Image GetImageNamed(int resource_id) override { return gfx::Image(); }
+  gfx::Image GetNativeImageNamed(int resource_id) override {
+    return gfx::Image();
+  }
+  bool HasDataResource(int resource_id) const override { return false; }
+  scoped_refptr<base::RefCountedMemory> LoadDataResourceBytes(
+      int resource_id,
+      ui::ResourceScaleFactor scale_factor) override {
+    return nullptr;
+  }
+  std::optional<std::string> LoadDataResourceString(int resource_id) override {
+    return std::nullopt;
+  }
+  bool GetRawDataResource(int resource_id,
+                          ui::ResourceScaleFactor scale_factor,
+                          std::string_view* value) const override {
+    return false;
+  }
+  bool GetLocalizedString(int message_id,
+                          std::u16string* value) const override {
+    if (message_id == IDS_MESSAGE_SHARED) {
+      *value = u"Your desktop is shared with $1.";
+      return true;
+    }
+    if (message_id == IDS_PRODUCT_NAME) {
+      *value = u"Chrome Remote Desktop";
+      return true;
+    }
+    if (message_id == IDS_STOP_SHARING_BUTTON) {
+      *value = u"Stop Sharing";
+      return true;
+    }
+    return false;
+  }
+};
+
+bool InitializeGtk() {
+#if GTK_CHECK_VERSION(3, 90, 0)
+  return gtk_init_check();
+#else
+  return gtk_init_check(nullptr, nullptr);
+#endif
+}
+
+}  // namespace
+
+class DisconnectWindowLinuxTest : public testing::Test {
+ public:
+  DisconnectWindowLinuxTest()
+      : task_environment_(base::test::TaskEnvironment::MainThreadType::UI),
+        resource_bundle_(&resource_delegate_),
+        resource_swapper_(&resource_bundle_) {}
+  ~DisconnectWindowLinuxTest() override = default;
+
+  void TearDown() override {
+    // Pump the event loop to ensure GTK widget destruction and cleanup is
+    // processed.
+    task_environment_.RunUntilIdle();
+  }
+
+ protected:
+  base::test::TaskEnvironment task_environment_;
+  TestResourceBundleDelegate resource_delegate_;
+  ui::ResourceBundle resource_bundle_;
+  ui::ResourceBundle::SharedInstanceSwapperForTesting resource_swapper_;
+};
+
+TEST_F(DisconnectWindowLinuxTest, NormalEmailDoesNotCrash) {
+  if (!InitializeGtk()) {
+    GTEST_SKIP() << "No display available for GTK.";
+  }
+
+  FakeClientSessionControl session_control(
+      "john.smith@gmail.com/chromoting_ftl");
+  std::unique_ptr<HostWindow> window = HostWindow::CreateDisconnectWindow();
+  ASSERT_TRUE(window);
+  window->Start(session_control.GetWeakPtr());
+  EXPECT_TRUE(session_control.GetWeakPtr());
+
+  window.reset();
+  task_environment_.RunUntilIdle();
+}
+
+TEST_F(DisconnectWindowLinuxTest, LongEmailDoesNotCrash) {
+  if (!InitializeGtk()) {
+    GTEST_SKIP() << "No display available for GTK.";
+  }
+
+  const std::string kLongEmail =
+      "it-support-desk-remote-assistance-session-verification-operators@"
+      "secure-remote-support-verification-and-customer-protection-desk."
+      "assistance-operations-center-for-workspace-hosted-accounts-team."
+      "example-corporation-global-technical-services-departments.com/"
+      "chromoting_ftl";
+
+  FakeClientSessionControl session_control(kLongEmail);
+  std::unique_ptr<HostWindow> window = HostWindow::CreateDisconnectWindow();
+  ASSERT_TRUE(window);
+  window->Start(session_control.GetWeakPtr());
+  EXPECT_TRUE(session_control.GetWeakPtr());
+
+  window.reset();
+  task_environment_.RunUntilIdle();
+}
+
+TEST_F(DisconnectWindowLinuxTest, WhitespaceAndUnicodeEmailDoesNotCrash) {
+  if (!InitializeGtk()) {
+    GTEST_SKIP() << "No display available for GTK.";
+  }
+
+  // Multi-byte Unicode with whitespace formatting
+  const std::string kUnicodeEmail =
+      "  \t\n  user_with_unicode_测试_🚀@example.com  \n/chromoting_ftl";
+
+  FakeClientSessionControl session_control(kUnicodeEmail);
+  std::unique_ptr<HostWindow> window = HostWindow::CreateDisconnectWindow();
+  ASSERT_TRUE(window);
+  window->Start(session_control.GetWeakPtr());
+  EXPECT_TRUE(session_control.GetWeakPtr());
+
+  window.reset();
+  task_environment_.RunUntilIdle();
+}
+
+}  // namespace remoting