[IO-717] Infinite loop in ReaderInputStream instead of throwing

exception for CodingErrorAction.REPORT.

Author: Gary Gregory

src/changes/changes.xml

@@ -92,6 +92,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action issue="IO-721" dev="ggregory" type="fix" due-to="Dirk Heinrichs, Gary Gregory">
         Wrong exception message in FileUtils.setLastModified(File, File).
       </action>
+      <action issue="IO-717" dev="ggregory" type="fix" due-to="Marcono1234, Gary Gregory">
+        Infinite loop in ReaderInputStream instead of throwing exception for CodingErrorAction.REPORT.
+      </action>
       <!-- ADD -->
       <action dev="ggregory" type="add" due-to="Gary Gregory">
         Add BrokenReader.INSTANCE.

src/main/java/org/apache/commons/io/input/ReaderInputStream.java

@@ -228,6 +228,9 @@ private void fillBuffer() throws IOException {
         }
         encoderOut.compact();
         lastCoderResult = encoder.encode(encoderIn, encoderOut, endOfInput);
+        if (lastCoderResult.isError()) {
+            lastCoderResult.throwException();
+        }
         encoderOut.flip();
     }
 

src/test/java/org/apache/commons/io/input/ReaderInputStreamTest.java

@@ -18,23 +18,30 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.CharArrayReader;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.StringReader;
+import java.nio.charset.CharacterCodingException;
 import java.nio.charset.Charset;
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.CodingErrorAction;
 import java.nio.charset.StandardCharsets;
 import java.util.Random;
+import java.util.concurrent.TimeUnit;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
 
 public class ReaderInputStreamTest {
     private static final String TEST_STRING = "\u00e0 peine arriv\u00e9s nous entr\u00e2mes dans sa chambre";
     private static final String LARGE_TEST_STRING;
 
     static {
         final StringBuilder buffer = new StringBuilder();
-        for (int i=0; i<100; i++) {
+        for (int i = 0; i < 100; i++) {
             buffer.append(TEST_STRING);
         }
         LARGE_TEST_STRING = buffer.toString();
@@ -48,7 +55,7 @@ public class ReaderInputStreamTest {
     @Test
     public void testCharsetMismatchInfiniteLoop() throws IOException {
         // Input is UTF-8 bytes: 0xE0 0xB2 0xA0
-        final char[] inputChars = { (char) 0xE0, (char) 0xB2, (char) 0xA0 };
+        final char[] inputChars = {(char) 0xE0, (char) 0xB2, (char) 0xA0};
         // Charset charset = Charset.forName("UTF-8"); // works
         final Charset charset = StandardCharsets.US_ASCII; // infinite loop
         try (ReaderInputStream stream = new ReaderInputStream(new CharArrayReader(inputChars), charset)) {
@@ -57,6 +64,20 @@ public void testCharsetMismatchInfiniteLoop() throws IOException {
         }
     }
 
+    /**
+     * Tests IO-717 to avoid infinite loops.
+     *
+     * ReaderInputStream does not throw exception with {@link CodingErrorAction#REPORT}.
+     */
+    @Test
+    @Timeout(value = 500, unit = TimeUnit.MILLISECONDS)
+    public void testCodingErrorAction() throws IOException {
+        CharsetEncoder encoder = StandardCharsets.UTF_8.newEncoder().onMalformedInput(CodingErrorAction.REPORT);
+        try (InputStream in = new ReaderInputStream(new StringReader("\uD800aa"), encoder, 2)) {
+            assertThrows(CharacterCodingException.class, in::read);
+        }
+    }
+
     @Test
     public void testLargeUTF8WithBufferedRead() throws IOException {
         testWithBufferedRead(LARGE_TEST_STRING, "UTF-8");