filter bidi isolates in notifications, fixes #60 (#68)

idavydov · web-flow · commit 8a4a394b4ece · 2025-12-19T10:22:58.000-08:00
* stripBidiIsolates in notifications, fixes #60 * add io.rebble.libpebblecommon.util.stripBidiIsolates * test for BidiSanitizer --------- Co-authored-by: Iakov Davydov <idavydov@users.noreply.github.com>
diff --git a/libpebble3/src/androidMain/kotlin/io/rebble/libpebblecommon/notification/LibPebbleNotificationAction.kt b/libpebble3/src/androidMain/kotlin/io/rebble/libpebblecommon/notification/LibPebbleNotificationAction.kt
@@ -9,6 +9,7 @@ import io.rebble.libpebblecommon.NotificationConfig
 import io.rebble.libpebblecommon.database.entity.ChannelItem
 import io.rebble.libpebblecommon.database.entity.NotificationAppItem
 import io.rebble.libpebblecommon.packets.blobdb.TimelineItem
+import io.rebble.libpebblecommon.util.stripBidiIsolates
 
 data class ActionRemoteInput(
     val remoteInput: RemoteInput,
@@ -59,12 +60,12 @@ data class LibPebbleNotificationAction(
             } else {
                 SemanticAction.None
             }
-            val title = action.title?.toString() ?: return null
+            val title = stripBidiIsolates(action.title) ?: return null
             val pendingIntent = action.actionIntent ?: return null
             val input = action.remoteInputs?.firstOrNull {
                 it.allowFreeFormInput
             }
-            val suggestedResponses = input?.choices?.map { it.toString() }
+            val suggestedResponses = input?.choices?.map { stripBidiIsolates(it.toString()) ?: "" }
             return LibPebbleNotificationAction(
                 packageName = packageName,
                 title = title,
diff --git a/libpebble3/src/androidMain/kotlin/io/rebble/libpebblecommon/notification/processor/BasicNotificationProcessor.kt b/libpebble3/src/androidMain/kotlin/io/rebble/libpebblecommon/notification/processor/BasicNotificationProcessor.kt
@@ -25,6 +25,7 @@ import io.rebble.libpebblecommon.notification.NotificationDecision
 import io.rebble.libpebblecommon.packets.blobdb.TimelineIcon
 import io.rebble.libpebblecommon.timeline.TimelineColor
 import io.rebble.libpebblecommon.timeline.argbColor
+import io.rebble.libpebblecommon.util.stripBidiIsolates
 import kotlin.time.Instant
 import kotlin.uuid.Uuid
 
@@ -50,11 +51,13 @@ class BasicNotificationProcessor(
             channel,
             notificationConfigFlow.value
         )
-        val title = sbn.notification.extras.getCharSequence(Notification.EXTRA_TITLE) ?: ""
+        val title = stripBidiIsolates(
+            sbn.notification.extras.getCharSequence(Notification.EXTRA_TITLE)
+        ) ?: ""
         val text = sbn.notification.extras.getCharSequence(Notification.EXTRA_TEXT)
         val bigText = sbn.notification.extras.getCharSequence(Notification.EXTRA_BIG_TEXT)
         val showWhen = sbn.notification.extras.getBoolean(Notification.EXTRA_SHOW_WHEN)
-        val body = bigText ?: text ?: ""
+        val body = stripBidiIsolates(bigText ?: text) ?: ""
         val people = sbn.notification.people()
         val contactKeys = people.asContacts(context.context)
         val contactEntries = contactKeys.mapNotNull {
@@ -70,8 +73,8 @@ class BasicNotificationProcessor(
             uuid = Uuid.random(),
             groupKey = sbn.groupKey,
             key = sbn.key,
-            title = title.toString(),
-            body = body.toString(),
+            title = title,
+            body = body,
             icon = icon,
             timestamp = if (showWhen) {
                 Instant.fromEpochMilliseconds(sbn.notification.`when`)
diff --git a/libpebble3/src/commonMain/kotlin/io/rebble/libpebblecommon/util/BidiSanitizer.kt b/libpebble3/src/commonMain/kotlin/io/rebble/libpebblecommon/util/BidiSanitizer.kt
@@ -0,0 +1,30 @@
+package io.rebble.libpebblecommon.util
+
+/**
+ * Strips Unicode bidi isolate markers that some upstream apps include in notification text.
+ *
+ * These characters are invisible control codes in Unicode, but some downstream renderers
+ * (e.g. Pebble firmware fonts) may display them as tofu/squares.
+ *
+ * Removed range: U+2066..U+2069 (LRI, RLI, FSI, PDI).
+ */
+fun stripBidiIsolates(text: CharSequence?): String? {
+    if (text == null) return null
+
+    // Allocate a StringBuilder only if we actually encounter isolate markers, so the common case
+    // (no markers) stays allocation-free.
+    var out: StringBuilder? = null
+    for (i in 0 until text.length) {
+        val ch = text[i]
+        if (ch >= '\u2066' && ch <= '\u2069') {
+            if (out == null) {
+                out = StringBuilder(text.length)
+                out.append(text, 0, i)
+            }
+            continue
+        }
+        out?.append(ch)
+    }
+
+    return out?.toString() ?: text.toString()
+}
diff --git a/libpebble3/src/commonTest/kotlin/io/rebble/libpebblecommon/util/BidiSanitizerTest.kt b/libpebble3/src/commonTest/kotlin/io/rebble/libpebblecommon/util/BidiSanitizerTest.kt
@@ -0,0 +1,26 @@
+package io.rebble.libpebblecommon.util
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class BidiSanitizerTest {
+    @Test
+    fun stripBidiIsolates_nullInput() {
+        assertNull(stripBidiIsolates(null))
+    }
+
+    @Test
+    fun stripBidiIsolates_removesIsolateMarkers() {
+        val input = "\u2068Юлия\u2069 and \u2066abc\u2069 and \u2067xyz\u2069"
+        val expected = "Юлия and abc and xyz"
+        assertEquals(expected, stripBidiIsolates(input))
+    }
+
+    @Test
+    fun stripBidiIsolates_noopWhenNonePresent() {
+        val input = "Sender Name"
+        assertEquals(input, stripBidiIsolates(input))
+    }
+}
+
