Avoid NullPointerException in ProxyInputStream.markSupported() when the

underlying input stream is null

Javadoc

src/changes/changes.xml

@@ -65,6 +65,7 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">PathUtils.isPosix(Path, LinkOption...) should return false on null input.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">AutoCloseInputStream(InputStream) uses ClosedInputStream.INSTANCE when its input is null.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">Avoid NullPointerException in ProxyInputStream.available() when the underlying input stream is null.</action>
+      <action dev="ggregory" type="fix"                due-to="Gary Gregory">Avoid NullPointerException in ProxyInputStream.markSupported() when the underlying input stream is null.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">BufferedFileChannelInputStream.available() returns 0 before any reads.</action>
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">BufferedFileChannelInputStream.available() should return 0 when the stream is closed instead of throwing an exception.</action>      
       <action dev="ggregory" type="fix"                due-to="Gary Gregory">CharSequenceInputStream.available() should return 0 after the stream is closed.</action>

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

@@ -102,9 +102,9 @@ protected void afterRead(final int n) throws IOException {
     }
 
     /**
-     * Invokes the delegate's {@code available()} method.
+     * Invokes the delegate's {@link InputStream#available()} method.
      *
-     * @return the number of available bytes
+     * @return the number of available bytes, 0 if the stream is closed.
      * @throws IOException if an I/O error occurs.
      */
     @Override
@@ -145,7 +145,7 @@ protected void beforeRead(final int n) throws IOException {
     }
 
     /**
-     * Invokes the delegate's {@code close()} method.
+     * Invokes the delegate's {@link InputStream#close()} method.
      *
      * @throws IOException if an I/O error occurs.
      */
@@ -180,7 +180,7 @@ boolean isClosed() {
     }
 
     /**
-     * Invokes the delegate's {@code mark(int)} method.
+     * Invokes the delegate's {@link InputStream#mark(int)} method.
      *
      * @param readLimit read ahead limit
      */
@@ -190,17 +190,17 @@ public synchronized void mark(final int readLimit) {
     }
 
     /**
-     * Invokes the delegate's {@code markSupported()} method.
+     * Invokes the delegate's {@link InputStream#markSupported()} method.
      *
      * @return true if mark is supported, otherwise false
      */
     @Override
     public boolean markSupported() {
-        return in.markSupported();
+        return in != null && in.markSupported();
     }
 
     /**
-     * Invokes the delegate's {@code read()} method unless the stream is closed.
+     * Invokes the delegate's {@link InputStream#read()} method unless the stream is closed.
      *
      * @return the byte read or -1 if the end of stream
      * @throws IOException if an I/O error occurs.
@@ -222,7 +222,7 @@ public int read() throws IOException {
     }
 
     /**
-     * Invokes the delegate's {@code read(byte[])} method.
+     * Invokes the delegate's {@link InputStream#read(byte[])} method.
      *
      * @param b the buffer to read the bytes into
      * @return the number of bytes read or EOF if the end of stream
@@ -242,7 +242,7 @@ public int read(final byte[] b) throws IOException {
     }
 
     /**
-     * Invokes the delegate's {@code read(byte[], int, int)} method.
+     * Invokes the delegate's {@link InputStream#read(byte[], int, int)} method.
      *
      * @param b the buffer to read the bytes into
      * @param off The start offset
@@ -264,7 +264,7 @@ public int read(final byte[] b, final int off, final int len) throws IOException
     }
 
     /**
-     * Invokes the delegate's {@code reset()} method.
+     * Invokes the delegate's {@link InputStream#reset()} method.
      *
      * @throws IOException if an I/O error occurs.
      */
@@ -278,7 +278,16 @@ public synchronized void reset() throws IOException {
     }
 
     /**
-     * Invokes the delegate's {@code skip(long)} method.
+     * Package-private for testing.
+     *
+     * @param in The input stream to set.
+     */
+    void setIn(final InputStream in) {
+        this.in = in;
+    }
+
+    /**
+     * Invokes the delegate's {@link InputStream#skip(long)} method.
      *
      * @param n the number of bytes to skip
      * @return the actual number of bytes skipped

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

@@ -10,7 +10,7 @@
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * WITHOUProxyInputStreamFixture WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
@@ -20,6 +20,7 @@
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.Mockito.spy;
@@ -47,10 +48,6 @@ private static final class ProxyInputStreamFixture extends ProxyInputStream {
         ProxyInputStreamFixture(final InputStream proxy) {
             super(proxy);
         }
-
-        void setIn(final InputStream proxy) {
-            in = proxy;
-        }
     }
 
     @SuppressWarnings("resource")
@@ -69,12 +66,23 @@ static void testCloseHandleIOException(final ProxyInputStream inputStream) throw
         assertFalse(spy.isClosed(), "closed");
     }
 
-    @SuppressWarnings({ "resource", "unused" }) // For subclasses
+    /**
+     * Asserts that a ProxyInputStream's markSupported() equals the proxied value.
+     *
+     * @param inputStream The stream to test.
+     */
+    @SuppressWarnings("resource") // unwrap() is a getter
+    protected void assertMarkSupportedEquals(final ProxyInputStream inputStream) {
+        assertNotNull(inputStream, "inputStream");
+        assertEquals(inputStream.unwrap().markSupported(), inputStream.markSupported());
+    }
+
+    @SuppressWarnings({ "resource", "unused", "unchecked" }) // For subclasses
     protected T createFixture() throws IOException {
-        return (T) new ProxyInputStreamFixture(createProxySource());
+        return (T) new ProxyInputStreamFixture(createOriginInputStream());
     }
 
-    protected InputStream createProxySource() {
+    protected InputStream createOriginInputStream() {
         return CharSequenceInputStream.builder().setCharSequence("abc").get();
     }
 
@@ -121,6 +129,32 @@ protected void testEos(final T inputStream) {
         // empty
     }
 
+    @Test
+    public void testMarkSupported() throws IOException {
+        try (T inputStream = createFixture()) {
+            assertMarkSupportedEquals(inputStream);
+        }
+    }
+
+    @SuppressWarnings("resource")
+    @Test
+    public void testMarkSupportedAfterClose() throws IOException {
+        final T shadow;
+        try (T inputStream = createFixture()) {
+            shadow = inputStream;
+        }
+        assertMarkSupportedEquals(shadow);
+    }
+
+    @Test
+    public void testMarkSupportedOnNull() throws IOException {
+        try (ProxyInputStream fixture = createFixture()) {
+            assertMarkSupportedEquals(fixture);
+            fixture.setIn(null);
+            assertFalse(fixture.markSupported());
+        }
+    }
+
     @Test
     public void testRead() throws IOException {
         try (T inputStream = createFixture()) {
@@ -132,7 +166,7 @@ public void testRead() throws IOException {
             assertEquals('c', found);
             found = inputStream.read();
             assertEquals(-1, found);
-            testEos(inputStream);
+            testEos((T) inputStream);
         }
     }
 
@@ -159,7 +193,7 @@ public void testReadArrayAtMiddleFully() throws IOException {
             assertArrayEquals(new byte[] { 0, 0, 'a', 'b', 'c' }, dest);
             found = inputStream.read(dest, 2, 3);
             assertEquals(-1, found);
-            testEos(inputStream);
+            testEos((T) inputStream);
         }
     }
 
@@ -172,7 +206,7 @@ public void testReadArrayAtStartFully() throws IOException {
             assertArrayEquals(new byte[] { 'a', 'b', 'c', 0, 0 }, dest);
             found = inputStream.read(dest, 0, 5);
             assertEquals(-1, found);
-            testEos(inputStream);
+            testEos((T) inputStream);
         }
     }
 
@@ -189,7 +223,7 @@ public void testReadArrayAtStartPartial() throws IOException {
             assertArrayEquals(new byte[] { 'c', 0, 0, 0, 0 }, dest);
             found = inputStream.read(dest, 0, 2);
             assertEquals(-1, found);
-            testEos(inputStream);
+            testEos((T) inputStream);
         }
     }
 
@@ -202,7 +236,7 @@ public void testReadArrayFully() throws IOException {
             assertArrayEquals(new byte[] { 'a', 'b', 'c', 0, 0 }, dest);
             found = inputStream.read(dest);
             assertEquals(-1, found);
-            testEos(inputStream);
+            testEos((T) inputStream);
         }
     }
 
@@ -219,7 +253,7 @@ public void testReadArrayPartial() throws IOException {
             assertArrayEquals(new byte[] { 'c', 0 }, dest);
             found = inputStream.read(dest);
             assertEquals(-1, found);
-            testEos(inputStream);
+            testEos((T) inputStream);
         }
     }
 

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

@@ -30,9 +30,9 @@
 public class ThrottledInputStreamTest extends ProxyInputStreamTest<ThrottledInputStream> {
 
     @Override
-    @SuppressWarnings("resource")
+    @SuppressWarnings({ "resource" })
     protected ThrottledInputStream createFixture() throws IOException {
-        return ThrottledInputStream.builder().setInputStream(createProxySource()).get();
+        return ThrottledInputStream.builder().setInputStream(createOriginInputStream()).get();
     }
 
     @Test