Revert "Fix bug in SlicedInputStream with zero length (opensearch-pro…

…ject#4863) (opensearch-project#5044)"

This reverts commit 870d13d.

CHANGELOG.md

@@ -133,7 +133,6 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Better plural stemmer than minimal_english ([#4738](https://github.com/opensearch-project/OpenSearch/pull/4738))
 - Fix AbstractStringFieldDataTestCase tests to account for TotalHits lower bound ([4867](https://github.com/opensearch-project/OpenSearch/pull/4867))
 - [Segment Replication] Fix bug of replica shard's translog not purging on index flush when segment replication is enabled ([4975](https://github.com/opensearch-project/OpenSearch/pull/4975))
-- Fix bug in SlicedInputStream with zero length ([#4863](https://github.com/opensearch-project/OpenSearch/pull/4863))
 -
 
 ### Security

server/src/main/java/org/opensearch/index/snapshots/blobstore/SlicedInputStream.java

@@ -35,7 +35,6 @@
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.Objects;
 
 /**
  *  A {@link SlicedInputStream} is a logical
@@ -101,11 +100,6 @@ public final int read() throws IOException {
 
     @Override
     public final int read(byte[] buffer, int offset, int length) throws IOException {
-        Objects.checkFromIndexSize(offset, length, buffer.length);
-        if (length == 0) {
-            return 0;
-        }
-
         final InputStream stream = currentStream();
         if (stream == null) {
             return -1;

server/src/test/java/org/opensearch/index/snapshots/blobstore/SlicedInputStreamTests.java

@@ -32,18 +32,13 @@
 package org.opensearch.index.snapshots.blobstore;
 
 import com.carrotsearch.randomizedtesting.generators.RandomNumbers;
-
-import org.hamcrest.MatcherAssert;
 import org.opensearch.test.OpenSearchTestCase;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
 import java.util.Random;
 
 import static org.hamcrest.Matchers.equalTo;
@@ -91,9 +86,11 @@ protected InputStream openSlice(int slice) throws IOException {
                     assertThat(random.nextInt(Byte.MAX_VALUE), equalTo(input.read()));
                     break;
                 default:
-                    byte[] expectedBytes = randomBytes(random);
-                    byte[] actualBytes = input.readNBytes(expectedBytes.length);
-                    assertArrayEquals(expectedBytes, actualBytes);
+                    byte[] b = randomBytes(random);
+                    byte[] buffer = new byte[b.length];
+                    int read = readFully(input, buffer);
+                    assertThat(b.length, equalTo(read));
+                    assertArrayEquals(b, buffer);
                     break;
             }
         }
@@ -110,45 +107,19 @@ protected InputStream openSlice(int slice) throws IOException {
 
     }
 
-    public void testReadZeroLength() throws IOException {
-        try (InputStream input = createSingleByteStream()) {
-            final byte[] buffer = new byte[100];
-            final int read = input.read(buffer, 0, 0);
-            MatcherAssert.assertThat(read, equalTo(0));
-        }
-    }
-
-    public void testInvalidOffsetAndLength() throws IOException {
-        try (InputStream input = createSingleByteStream()) {
-            final byte[] buffer = new byte[100];
-            expectThrows(NullPointerException.class, () -> input.read(null, 0, 10));
-            expectThrows(IndexOutOfBoundsException.class, () -> input.read(buffer, -1, 10));
-            expectThrows(IndexOutOfBoundsException.class, () -> input.read(buffer, 0, -1));
-            expectThrows(IndexOutOfBoundsException.class, () -> input.read(buffer, 0, buffer.length + 1));
-        }
-    }
-
-    public void testReadAllBytes() throws IOException {
-        final byte[] expectedResults = randomByteArrayOfLength(50_000);
-        final int numSlices = 200;
-        final int slizeSize = expectedResults.length / numSlices;
-
-        final List<byte[]> arraySlices = new ArrayList<>(numSlices);
-        for (int i = 0; i < numSlices; i++) {
-            final int offset = slizeSize * i;
-            arraySlices.add(Arrays.copyOfRange(expectedResults, offset, offset + slizeSize));
-        }
-        // Create a SlicedInputStream that will return the expected result in 2 slices
-        final byte[] actualResults;
-        try (InputStream is = new SlicedInputStream(numSlices) {
-            @Override
-            protected InputStream openSlice(int slice) {
-                return new ByteArrayInputStream(arraySlices.get(slice));
+    private int readFully(InputStream stream, byte[] buffer) throws IOException {
+        for (int i = 0; i < buffer.length;) {
+            int read = stream.read(buffer, i, buffer.length - i);
+            if (read == -1) {
+                if (i == 0) {
+                    return -1;
+                } else {
+                    return i;
+                }
             }
-        }) {
-            actualResults = is.readAllBytes();
+            i += read;
         }
-        assertArrayEquals(expectedResults, actualResults);
+        return buffer.length;
     }
 
     private byte[] randomBytes(Random random) {
@@ -158,15 +129,6 @@ private byte[] randomBytes(Random random) {
         return data;
     }
 
-    private static InputStream createSingleByteStream() {
-        return new SlicedInputStream(1) {
-            @Override
-            protected InputStream openSlice(int slice) {
-                return new ByteArrayInputStream(new byte[] { 1 });
-            }
-        };
-    }
-
     private static final class CheckClosedInputStream extends FilterInputStream {
 
         public boolean closed = false;