Issue #12695 - don't return ByteBuffer from .toMappedBuffer if FS reports as UnsupportedOperationException.

jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpTester.java

@@ -262,17 +262,25 @@ public static Response parseResponse(Input input) throws IOException
         return parseResponse(input, false);
     }
 
+    public static Response parseResponse(Input input, Response response) throws IOException
+    {
+        return parseResponse(input, response, false);
+    }
+
     public static Response parseResponse(Input input, boolean head) throws IOException
     {
-        Response response;
+        return parseResponse(input, new Response(), head);
+    }
+
+    public static Response parseResponse(Input input, Response response, boolean head) throws IOException
+    {
         HttpParser parser = input.takeHttpParser();
         if (parser != null)
         {
             response = (Response)parser.getHandler();
         }
         else
         {
-            response = new Response();
             parser = new HttpParser(response);
         }
         parser.setHeadResponse(head);

jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/content/FileMappingHttpContentFactory.java

@@ -101,6 +101,8 @@ private SingleBufferFileMappedHttpContent(HttpContent content) throws IOExceptio
             if (path == null)
                 throw new IOException("Cannot memory map Content whose Resource is not backed by a Path: " + content.getResource());
             _buffer = BufferUtil.toMappedBuffer(path);
+            if (_buffer == null)
+                throw new IOException("Cannot memory map Content (not supported by underlying FileSystem): " + content.getResource());
             _contentLength = new HttpField(HttpHeader.CONTENT_LENGTH, Integer.toString(_buffer.remaining()));
             _lastModified = content.getLastModified();
             _lastModifiedInstant = content.getLastModifiedInstant();
@@ -176,6 +178,8 @@ private MultiBufferFileMappedHttpContent(HttpContent content, int maxBufferSize)
             {
                 long len = Math.min(contentLength - currentPos, maxBufferSize);
                 _buffers[i] = BufferUtil.toMappedBuffer(path, currentPos, len);
+                if (_buffers[i] == null)
+                    throw new IOException("Cannot memory map Content (not supported by underlying FileSystem): " + content.getResource());
                 currentPos += len;
                 total += _buffers[i].remaining();
             }

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/BufferUtil.java

@@ -17,6 +17,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
 import java.nio.Buffer;
 import java.nio.BufferOverflowException;
 import java.nio.ByteBuffer;
@@ -1166,19 +1167,48 @@ public static ByteBuffer toDirectBuffer(String s, Charset charset)
         return buf;
     }
 
+    /**
+     * Attempt to return a ByteBuffer created via {@link FileChannel#map} call.
+     *
+     * @param path the path to map
+     * @return the mapped bytebuffer, or null if unable to map the {@link FileChannel}
+     * @throws IOException if unable to open mapped byte buffer
+     */
     public static ByteBuffer toMappedBuffer(Path path) throws IOException
     {
         return toMappedBuffer(path, 0, Files.size(path));
     }
 
+    /**
+     * Attempt to return a ByteBuffer created via {@link FileChannel#map} call.
+     *
+     * @param filePath the path to map
+     * @param pos the position to start from
+     * @param len the length to support
+     * @return the mapped bytebuffer, or null if unable to map the {@link FileChannel}
+     * @throws IOException if unable to open mapped byte buffer
+     */
     public static ByteBuffer toMappedBuffer(Path filePath, long pos, long len) throws IOException
     {
         try (FileChannel channel = FileChannel.open(filePath, StandardOpenOption.READ))
         {
             return channel.map(MapMode.READ_ONLY, pos, len);
         }
+        catch (UnsupportedEncodingException e)
+        {
+            if (LOG.isTraceEnabled())
+                LOG.trace("Ignored exception", e);
+            return null;
+        }
     }
 
+    /**
+     * Attempt to return a ByteBuffer created via {@link FileChannel#map} call.
+     *
+     * @param resource the resource to map
+     * @return the mapped bytebuffer, or null if unable to map the {@link FileChannel} (usually due to Resource not supporting memory mapped files)
+     * @throws IOException if unable to open mapped byte buffer
+     */
     public static ByteBuffer toMappedBuffer(Resource resource) throws IOException
     {
         Path path = resource.getPath();
@@ -1187,6 +1217,15 @@ public static ByteBuffer toMappedBuffer(Resource resource) throws IOException
         return toMappedBuffer(path);
     }
 
+    /**
+     * Attempt to return a ByteBuffer created via {@link FileChannel#map} call.
+     *
+     * @param resource the resource to map
+     * @param pos the position to start from
+     * @param len the length to support
+     * @return the mapped bytebuffer, or null if unable to map the {@link FileChannel} (usually due to Resource not supporting memory mapped files)
+     * @throws IOException if unable to open mapped byte buffer
+     */
     public static ByteBuffer toMappedBuffer(Resource resource, long pos, long len) throws IOException
     {
         Path path = resource.getPath();

jetty-ee9/jetty-ee9-nested/src/main/java/org/eclipse/jetty/ee9/nested/FileBufferedResponseHandler.java

@@ -17,6 +17,7 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
+import java.nio.channels.SeekableByteChannel;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
@@ -72,7 +73,7 @@ protected BufferedInterceptor newBufferedInterceptor(HttpChannel httpChannel, In
 
     class FileBufferedInterceptor implements BufferedResponseHandler.BufferedInterceptor
     {
-        private static final int MAX_MAPPED_BUFFER_SIZE = Integer.MAX_VALUE / 2;
+        private static final int MAX_BUFFER_SIZE = Integer.MAX_VALUE / 2;
 
         private final Interceptor _next;
         private final HttpChannel _channel;
@@ -205,9 +206,9 @@ protected Action process() throws Exception
                     if (_last)
                         return Action.SUCCEEDED;
 
-                    long len = Math.min(MAX_MAPPED_BUFFER_SIZE, fileLength - _pos);
+                    long len = Math.min(MAX_BUFFER_SIZE, fileLength - _pos);
                     _last = (_pos + len == fileLength);
-                    ByteBuffer buffer = BufferUtil.toMappedBuffer(_filePath, _pos, len);
+                    ByteBuffer buffer = readByteBuffer(_filePath, _pos, len);
                     getNextInterceptor().write(buffer, _last, this);
                     _pos += len;
                     return Action.SCHEDULED;
@@ -229,5 +230,23 @@ protected void onFailure(Throwable cause)
             };
             icb.iterate();
         }
+
+        private ByteBuffer readByteBuffer(Path path, long pos, long len) throws IOException
+        {
+            ByteBuffer buffer = BufferUtil.toMappedBuffer(path, pos, len);
+            if (buffer != null)
+                return buffer;
+
+            // if we reached here, then file mapped byte buffers is not supported.
+            // we fall back to using traditional I/O instead.
+            try (SeekableByteChannel channel = Files.newByteChannel(path))
+            {
+                channel.position(pos);
+                buffer = ByteBuffer.allocate((int)len);
+                channel.read(buffer);
+                buffer.flip();
+                return buffer;
+            }
+        }
     }
 }