From 4099a5b084043e71669a6e38ee4a61ad22fc53e8 Mon Sep 17 00:00:00 2001
From: Tyler Gregg <greggt@amazon.com>
Date: Mon, 30 Oct 2023 17:15:33 -0700
Subject: [PATCH] Fixes a bug that prevented early step-out of a container when
 positioned on a large scalar value in certain cases.

---
 src/com/amazon/ion/impl/IonCursorBinary.java  |  2 +-
 ...onReaderContinuableTopLevelBinaryTest.java | 28 +++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/com/amazon/ion/impl/IonCursorBinary.java b/src/com/amazon/ion/impl/IonCursorBinary.java
index 2548dd0372..07e89cdb0f 100644
--- a/src/com/amazon/ion/impl/IonCursorBinary.java
+++ b/src/com/amazon/ion/impl/IonCursorBinary.java
@@ -1470,7 +1470,7 @@ private Event slowStepOutOfContainer() {
             if (slowSeek(parent.endIndex - offset)) {
                 return event;
             }
-            peekIndex = parent.endIndex;
+            peekIndex = offset;
         }
         setCheckpointBeforeUnannotatedTypeId();
         if (--containerIndex >= 0) {
diff --git a/test/com/amazon/ion/impl/IonReaderContinuableTopLevelBinaryTest.java b/test/com/amazon/ion/impl/IonReaderContinuableTopLevelBinaryTest.java
index 0543df8bb3..e710f9db78 100644
--- a/test/com/amazon/ion/impl/IonReaderContinuableTopLevelBinaryTest.java
+++ b/test/com/amazon/ion/impl/IonReaderContinuableTopLevelBinaryTest.java
@@ -34,6 +34,7 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
 import org.junit.jupiter.params.provider.ValueSource;
 
 import java.io.ByteArrayInputStream;
@@ -1723,6 +1724,33 @@ public void reallyLargeString(boolean constructFromBytes) throws Exception {
         closeAndCount();
     }
 
+    @ParameterizedTest
+    @CsvSource({
+        "true, true",
+        "true, false",
+        "false, true",
+        "false, false"
+    })
+    public void skipReallyLargeStringInContainer(boolean constructFromBytes, boolean incremental) throws Exception {
+        StringBuilder sb = new StringBuilder();
+        // 70000 is greater than twice the default buffer size of 32768. This ensures that the string, when skipped,
+        // will not be fully contained in the buffer.
+        for (int i = 0; i < 70000; i++) {
+            sb.append('a');
+        }
+        String string = sb.toString();
+        readerBuilder = readerBuilder.withIncrementalReadingEnabled(incremental);
+        reader = readerFor("{foo: \"" + string + "\"}", constructFromBytes);
+        assertSequence(
+            container(IonType.STRUCT,
+                next(IonType.STRING)
+                // This is an early-step out that causes the string value to be skipped.
+            ),
+            next(null)
+        );
+        closeAndCount();
+    }
+
     @ParameterizedTest(name = "constructFromBytes={0}")
     @ValueSource(booleans = {true, false})
     public void nopPadInAnnotationWrapperFails(boolean constructFromBytes) throws Exception {