From cb81a9f7836c51653b05cb2df6550d5e12b73030 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Wed, 1 Jul 2020 15:30:39 -0400
Subject: [PATCH] Disallow 'visually empty' profile names.

---
 .../profiles/edit/EditProfileViewModel.java   |  3 +-
 .../securesms/util/StringUtil.java            | 33 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/profiles/edit/EditProfileViewModel.java b/app/src/main/java/org/thoughtcrime/securesms/profiles/edit/EditProfileViewModel.java
index b9da8c6d2a..c2de06b4ff 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/profiles/edit/EditProfileViewModel.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/profiles/edit/EditProfileViewModel.java
@@ -12,6 +12,7 @@ import androidx.lifecycle.ViewModelProvider;
 
 import org.thoughtcrime.securesms.groups.GroupId;
 import org.thoughtcrime.securesms.profiles.ProfileName;
+import org.thoughtcrime.securesms.util.StringUtil;
 import org.thoughtcrime.securesms.util.livedata.LiveDataPair;
 import org.whispersystems.libsignal.util.guava.Optional;
 
@@ -27,7 +28,7 @@ class EditProfileViewModel extends ViewModel {
   private final MutableLiveData<byte[]>           originalAvatar      = new MutableLiveData<>();
   private final MutableLiveData<Optional<String>> internalUsername    = new MutableLiveData<>();
   private final MutableLiveData<String>           originalDisplayName = new MutableLiveData<>();
-  private final LiveData<Boolean>                 isFormValid         = Transformations.map(givenName, name -> !name.isEmpty());
+  private final LiveData<Boolean>                 isFormValid         = Transformations.map(givenName, name -> !StringUtil.isVisuallyEmpty(name));
   private final EditProfileRepository             repository;
   private final GroupId                           groupId;
 
diff --git a/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java b/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
index b12cb581c8..addaded2ee 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java
@@ -3,10 +3,17 @@ package org.thoughtcrime.securesms.util;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import com.google.android.collect.Sets;
+
 import java.nio.charset.StandardCharsets;
+import java.util.Set;
 
 public final class StringUtil {
 
+  private static final Set<Character> WHITESPACE = Sets.newHashSet('\u200E',  // left-to-right mark
+                                                                   '\u200F',  // right-to-left mark
+                                                                   '\u2007'); // figure space
+
   private StringUtil() {
   }
 
@@ -28,4 +35,30 @@ public final class StringUtil {
 
     return name;
   }
+
+  /**
+   * @return True if the string is empty, or if it contains nothing but whitespace characters.
+   *         Accounts for various unicode whitespace characters.
+   */
+  public static boolean isVisuallyEmpty(@Nullable String value) {
+    if (value == null || value.length() == 0) {
+      return true;
+    }
+
+    for (int i = 0; i < value.length(); i++) {
+      if (!isVisuallyEmpty(value.charAt(i))) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  /**
+   * @return True if the character is invisible or whitespace. Accounts for various unicode
+   *         whitespace characters.
+   */
+  public static boolean isVisuallyEmpty(char c) {
+    return Character.isWhitespace(c) || WHITESPACE.contains(c);
+  }
 }