Wrap GZIPInputStream with a ConsumingInputStream to drain on close

google-http-client/src/main/java/com/google/api/client/http/HttpResponse.java

@@ -331,7 +331,8 @@ public InputStream getContent() throws IOException {
           if (!returnRawInputStream
               && contentEncoding != null
               && contentEncoding.contains("gzip")) {
-            lowLevelResponseContent = new GZIPInputStream(lowLevelResponseContent);
+            lowLevelResponseContent = new ConsumingInputStream(
+                new GZIPInputStream(lowLevelResponseContent));
           }
           // logging (wrap content with LoggingInputStream)
           Logger logger = HttpTransport.LOGGER;
@@ -356,6 +357,44 @@ public InputStream getContent() throws IOException {
     return content;
   }
 
+  static class ConsumingInputStream extends InputStream {
+    private InputStream inputStream;
+    private boolean closed = false;
+
+    private ConsumingInputStream(InputStream inputStream) {
+      this.inputStream = Preconditions.checkNotNull(inputStream);
+    }
+
+    @Override
+    public int read() throws IOException {
+      return inputStream.read();
+    }
+
+    @Override
+    public int read(byte[] b, int off, int len) throws IOException {
+      return inputStream.read(b, off, len);
+    }
+
+    @Override
+    public void close() throws IOException {
+      if (!closed && inputStream != null) {
+        try {
+          drainInputStream(this);
+          inputStream.close();
+        } finally {
+          this.closed = true;
+        }
+      }
+    }
+
+    static void drainInputStream(final InputStream inputStream) throws IOException {
+      byte buffer[] = new byte[1024];
+      while (inputStream.read(buffer) >= 0) {
+        // do nothing
+      }
+    }
+  }
+
   /**
    * Writes the content of the HTTP response into the given destination output stream.
    *

google-http-client/src/test/java/com/google/api/client/http/HttpResponseTest.java

@@ -26,10 +26,12 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.lang.reflect.Type;
+import java.nio.charset.StandardCharsets;
 import java.text.NumberFormat;
 import java.util.Arrays;
 import java.util.logging.Level;
 import java.util.zip.GZIPInputStream;
+import java.util.zip.GZIPOutputStream;
 import junit.framework.TestCase;
 
 /**
@@ -457,4 +459,40 @@ public LowLevelHttpResponse execute() throws IOException {
         "it should not decompress stream",
         request.execute().getContent() instanceof GZIPInputStream);
   }
+
+  public void testGetContent_gzipEncoding_finishReading() throws IOException {
+    byte[] dataToCompress = "abcd".getBytes(StandardCharsets.UTF_8);
+    byte[] mockBytes;
+    try (ByteArrayOutputStream byteStream = new ByteArrayOutputStream(dataToCompress.length)) {
+      GZIPOutputStream zipStream = new GZIPOutputStream((byteStream));
+      zipStream.write(dataToCompress);
+      zipStream.close();
+      mockBytes = byteStream.toByteArray();
+    }
+    final MockLowLevelHttpResponse mockResponse = new MockLowLevelHttpResponse();
+    mockResponse.setContent(mockBytes);
+    mockResponse.setContentEncoding("gzip");
+    mockResponse.setContentType("text/plain");
+
+    HttpTransport transport =
+        new MockHttpTransport() {
+          @Override
+          public LowLevelHttpRequest buildRequest(String method, final String url)
+              throws IOException {
+            return new MockLowLevelHttpRequest() {
+              @Override
+              public LowLevelHttpResponse execute() throws IOException {
+                return mockResponse;
+              }
+            };
+          }
+        };
+    HttpRequest request =
+        transport.createRequestFactory().buildHeadRequest(HttpTesting.SIMPLE_GENERIC_URL);
+    HttpResponse response = request.execute();
+    TestableByteArrayInputStream output = (TestableByteArrayInputStream) mockResponse.getContent();
+    assertFalse(output.isClosed());
+    assertEquals("abcd", response.parseAsString());
+    assertTrue(output.isClosed());
+  }
 }