Merge #7031

7031: Closes #5249: Long URI in the address bar will hang the UI r=pocmo a=csadilek

We've had two cases now where this was a problem. A bookmarklet (see #6985) and a data URI (#5249).

This fix is similar to the one we landed last week for our Awesomebar (csadilek@bba846d), but tapping on long URLs or copying them from the clipboard etc. would still cause the UI to hang. With data URIs I can reproduce seconds/minutes long hangs that are fixed with this.

Took this from Fennec (https://github.com/pocmo/fennec-graveyard/blob/master/mobile/android/chrome/content/browser.js#L4308), and applied to both display and edit toolbar (otherwise the UI would hang once the toolbar is in edit mode).

Co-authored-by: Christian Sadilek <[email protected]>

components/browser/toolbar/src/main/java/mozilla/components/browser/toolbar/BrowserToolbar.kt

@@ -32,6 +32,11 @@ import mozilla.components.ui.autocomplete.InlineAutocompleteEditText
 import mozilla.components.ui.autocomplete.OnFilterListener
 import kotlin.coroutines.CoroutineContext
 
+// This is used for truncating URLs to prevent extreme cases from
+// slowing down UI rendering e.g. in case of a bookmarklet or a data URI.
+// https://github.com/mozilla-mobile/android-components/issues/5249
+const val MAX_URI_LENGTH = 25000
+
 /**
  * A customizable toolbar for browsers.
  *
@@ -99,7 +104,7 @@ class BrowserToolbar @JvmOverloads constructor(
             // We update the display toolbar immediately. We do not do that for the edit toolbar to not
             // mess with what the user is entering. Instead we will remember the value and update the
             // edit toolbar whenever we switch to it.
-            display.url = value
+            display.url = value.take(MAX_URI_LENGTH)
         }
 
     override var siteSecure: Toolbar.SiteSecurity

components/browser/toolbar/src/test/java/mozilla/components/browser/toolbar/BrowserToolbarTest.kt

@@ -22,6 +22,7 @@ import mozilla.components.concept.toolbar.AutocompleteDelegate
 import mozilla.components.concept.toolbar.Toolbar
 import mozilla.components.concept.toolbar.Toolbar.SiteSecurity
 import mozilla.components.concept.toolbar.Toolbar.SiteTrackingProtection
+import mozilla.components.support.test.argumentCaptor
 import mozilla.components.support.test.mock
 import mozilla.components.support.test.robolectric.testContext
 import org.junit.Assert.assertEquals
@@ -121,6 +122,30 @@ class BrowserToolbarTest {
         verify(edit, never()).updateUrl(ArgumentMatchers.anyString(), ArgumentMatchers.anyBoolean(), ArgumentMatchers.anyBoolean())
     }
 
+    @Test
+    fun `displayUrl is truncated to prevent extreme cases from slowing down the UI`() {
+        val toolbar = BrowserToolbar(testContext)
+        val display: DisplayToolbar = mock()
+        val edit: EditToolbar = mock()
+
+        toolbar.display = display
+        toolbar.edit = edit
+
+        toolbar.url = "a".repeat(MAX_URI_LENGTH + 1)
+        toolbar.url = "b".repeat(MAX_URI_LENGTH)
+        toolbar.url = "c".repeat(MAX_URI_LENGTH - 1)
+
+        val urlCaptor = argumentCaptor<String>()
+        verify(display, times(3)).url = urlCaptor.capture()
+
+        val capturedValues = urlCaptor.allValues
+        // Value was too long and should've been truncated
+        assertEquals("a".repeat(MAX_URI_LENGTH), capturedValues[0])
+        // Values should be the same as before
+        assertEquals("b".repeat(MAX_URI_LENGTH), capturedValues[1])
+        assertEquals("c".repeat(MAX_URI_LENGTH - 1), capturedValues[2])
+    }
+
     @Test
     fun `last URL will be forwarded to edit toolbar when switching mode`() {
         val toolbar = BrowserToolbar(testContext)