BufferedFileChannelInputStream.available() should return 0 when the

stream is closed instead of throwing an exception

Author: garydgregory

src/changes/changes.xml

@@ -63,6 +63,7 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">AutoCloseInputStream(InputStream) uses ClosedInputStream.INSTANCE when its input is null.</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Avoid NullPointerException in ProxyInputStream.available() when the underlying input stream is null.</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">BufferedFileChannelInputStream.available() returns 0 before any reads.</action>
+      <action dev="ggregory" type="add"                due-to="Gary Gregory">BufferedFileChannelInputStream.available() should return 0 when the stream is closed instead of throwing an exception.</action>      
       <!-- UPDATE -->
       <action dev="ggregory" type="update"             due-to="Dependabot">Bump tests commons.bytebuddy.version from 1.14.13 to 1.14.17 #615, #621, #631, #635.</action>
       <action dev="ggregory" type="update"             due-to="Dependabot">Bump tests commons-codec:commons-codec from 1.16.1 to 1.17.0.</action>

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

@@ -169,6 +169,9 @@ public BufferedFileChannelInputStream(final Path path, final int bufferSize) thr
 
     @Override
     public synchronized int available() throws IOException {
+        if (!fileChannel.isOpen()) {
+            return 0;
+        }
         if (!refill()) {
             return EOF;
         }

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

@@ -16,6 +16,7 @@
  */
 package org.apache.commons.io.input;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -53,6 +54,14 @@ public void setUp() throws IOException {
         //@formatter:on
     }
 
+    @Test
+    public void testAvailableAfterClose() throws Exception {
+        for (final InputStream inputStream : inputStreams) {
+            inputStream.close();
+            assertEquals(0, inputStream.available());
+        }
+    }
+
     @Test
     public void testAvailableAfterRead() throws Exception {
         for (final InputStream inputStream : inputStreams) {