From e714cb6423d752fc747518c1eccda6652be6be77 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Fri, 15 May 2020 11:11:27 -0400
Subject: [PATCH] Fix potential issues with ConversationDataSource boundaries.

---
 .../conversation/ConversationAdapter.java     |  5 +++-
 .../conversation/ConversationDataSource.java  | 25 ++++++++++++++++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationAdapter.java b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationAdapter.java
index 1cbd7e47e8..af16b65180 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationAdapter.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationAdapter.java
@@ -357,7 +357,7 @@ public class ConversationAdapter<V extends View & BindableConversationItem>
    * Momentarily highlights a row at the requested position.
    */
   void pulseHighlightItem(int position) {
-    if (position < getItemCount()) {
+    if (position >= 0 && position < getItemCount()) {
       recordToPulseHighlight = getItem(position);
       notifyItemChanged(position);
     }
@@ -430,7 +430,10 @@ public class ConversationAdapter<V extends View & BindableConversationItem>
     pool.setMaxRecycledViews(MESSAGE_TYPE_UPDATE, 5);
   }
 
+  @MainThread
   private void cleanFastRecords() {
+    Util.assertMainThread();
+
     synchronized (releasedFastRecords) {
       Iterator<MessageRecord> recordIterator = fastRecords.iterator();
       while (recordIterator.hasNext()) {
diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationDataSource.java b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationDataSource.java
index 4289dd0b8f..fcae9bb23e 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationDataSource.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationDataSource.java
@@ -16,6 +16,7 @@ import org.thoughtcrime.securesms.util.Util;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * Core data source for loading an individual conversation.
@@ -58,7 +59,20 @@ class ConversationDataSource extends PositionalDataSource<MessageRecord> {
       }
     }
 
-    callback.onResult(records, params.requestedStartPosition, db.getConversationCount(threadId));
+    int effectiveCount = records.size() + params.requestedStartPosition;
+    int totalCount     = db.getConversationCount(threadId);
+
+    if (effectiveCount > totalCount) {
+      Log.w(TAG, String.format(Locale.ENGLISH, "Miscalculation! Records: %d, Start Position: %d, Total: %d. Adjusting total.",
+                                               records.size(),
+                                               params.requestedStartPosition,
+                                               totalCount));
+      totalCount = effectiveCount;
+    }
+
+    records = ensureMultipleOfPageSize(records, params.pageSize, totalCount);
+
+    callback.onResult(records, params.requestedStartPosition, totalCount);
     Util.runOnMain(dataUpdateCallback::onDataUpdated);
 
     Log.d(TAG, "[Initial Load] " + (System.currentTimeMillis() - start) + " ms" + (isInvalid() ? " -- invalidated" : ""));
@@ -84,6 +98,15 @@ class ConversationDataSource extends PositionalDataSource<MessageRecord> {
     Log.d(TAG, "[Update] " + (System.currentTimeMillis() - start) + " ms" + (isInvalid() ? " -- invalidated" : ""));
   }
 
+  private static @NonNull List<MessageRecord> ensureMultipleOfPageSize(@NonNull List<MessageRecord> records, int pageSize, int total) {
+    if (records.size() != total && records.size() % pageSize != 0) {
+      int overflow = records.size() % pageSize;
+      return records.subList(0, records.size() - overflow);
+    } else {
+      return records;
+    }
+  }
+
   interface DataUpdatedCallback {
     void onDataUpdated();
   }