util: Add support for GraalVM Native-Image resource:-URIs and Paths

GraalVM Native-Image makes its classpath resources accessible through an
opaque resource: URL scheme.

Add support for this scheme in URIUtil and PathResource.

Automatically create the NativeImageResourceFileSystem when necessary.
Also add a workaround where converting such Native-Image Paths back to
URI would yield the wrong URI (potentially a bug in GraalVM).

https://github.com/eclipse/jetty.project/issues/9116
https://github.com/oracle/graal/issues/5720

Signed-off-by: Christian Kohlschütter <christian@kohlschutter.com>

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

@@ -19,11 +19,14 @@ import java.net.URI;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.FileSystemNotFoundException;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
@@ -54,6 +57,7 @@ public final class URIUtil
         .with("file:")
         .with("jrt:")
         .with("jar:")
+        .with("resource:")
         .build();
 
     // From https://www.rfc-editor.org/rfc/rfc3986
@@ -211,6 +215,8 @@ public final class URIUtil
 
     private static final boolean[] ENCODE_PATH_NEEDS_ENCODING;
 
+    private static final String URI_BAD_RESOURCE_PREFIX = "file:///resources!";
+
     private URIUtil()
     {
     }
@@ -1735,6 +1741,54 @@ public final class URIUtil
         return query1 + '&' + query2;
     }
 
+    /**
+     * Corrects any bad {@code resource} based URIs, such as those starting with {@code resource:file:///resources!}.
+     * 
+     * @param uri
+     *            The URI to correct.
+     * @return the corrected URI, or the original URI.
+     * @see <a href="https://github.com/oracle/graal/issues/5720">Graal issue 5720</a>
+     */
+    public static URI correctResourceURI(URI uri)
+    {
+        if (uri == null || !"resource".equals(uri.getScheme()))
+            return uri;
+
+        String ssp = uri.getSchemeSpecificPart();
+        if (ssp.startsWith(URI_BAD_RESOURCE_PREFIX))
+        {
+            return URI.create("resource:" + ssp.substring(URI_BAD_RESOURCE_PREFIX.length()));
+        }
+        else
+        {
+            return uri;
+        }
+    }
+
+    /**
+     * A wrapper for {@link Paths#get(URI)} and {@link Path#of(URI)}.
+     * 
+     * It automatically handles custom file systems, such as ZipFileSystem and NativeImageResourceFileSystem.
+     * 
+     * @param uri
+     *            The URI.
+     * @return The path.
+     * @throws IOException
+     *             on error.
+     */
+    public static Path getPath(URI uri) throws IOException
+    {
+        try
+        {
+            return Path.of(uri);
+        }
+        catch (FileSystemNotFoundException e)
+        {
+            FileSystems.newFileSystem(uri, Collections.emptyMap());
+            return Path.of(uri);
+        }
+    }
+
     /**
      * <p>
      * Corrects any bad {@code file} based URIs (even within a {@code jar:file:} based URIs) from the bad out-of-spec

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/resource/PathResource.java

@@ -48,6 +48,7 @@ public class PathResource extends Resource
         .caseSensitive(false)
         .with("file")
         .with("jrt")
+        .with("resource")
         .build();
 
     // The path object represented by this instance
@@ -141,15 +142,16 @@ public class PathResource extends Resource
      * Must be an absolute URI using the <code>file</code> scheme.
      *
      * @param uri the URI to build this PathResource from.
+     * @throws IOException if the path could not be resolved.
      */
-    PathResource(URI uri)
+    PathResource(URI uri) throws IOException
     {
         this(uri, false);
     }
 
-    PathResource(URI uri, boolean bypassAllowedSchemeCheck)
+    PathResource(URI uri, boolean bypassAllowedSchemeCheck) throws IOException
     {
-        this(Paths.get(uri), uri, bypassAllowedSchemeCheck);
+        this(URIUtil.getPath(URIUtil.correctResourceURI(uri)), uri, bypassAllowedSchemeCheck);
     }
 
     PathResource(Path path)
@@ -166,6 +168,7 @@ public class PathResource extends Resource
      */
     PathResource(Path path, URI uri, boolean bypassAllowedSchemeCheck)
     {
+        uri = URIUtil.correctResourceURI(uri);
         if (!uri.isAbsolute())
             throw new IllegalArgumentException("not an absolute uri: " + uri);
         if (!bypassAllowedSchemeCheck && !SUPPORTED_SCHEMES.contains(uri.getScheme()))

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/resource/PathResourceFactory.java

@@ -13,19 +13,46 @@
 
 package org.eclipse.jetty.util.resource;
 
+import java.io.IOException;
 import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
+
+import org.eclipse.jetty.util.URIUtil;
 
 public class PathResourceFactory implements ResourceFactory
 {
     @Override
     public Resource newResource(URI uri)
     {
-        Path path = Paths.get(uri.normalize());
+        Path path = Path.of(uri.normalize());
         if (!Files.exists(path))
             return null;
         return new PathResource(path, uri, false);
     }
+
+    @Override
+    public Resource newResource(Path path)
+    {
+        if (path == null)
+            return null;
+
+        URI uri = path.toUri();
+
+        try
+        {
+            // Validate URI conversion, and trigger FileSystem initialization, if necessary
+            if (URIUtil.getPath(uri) == null)
+                return null;
+        }
+        catch (IOException e)
+        {
+            return null;
+        }
+
+        if (!Files.exists(path))
+            return null;
+
+        return new PathResource(path, uri, false);
+    }
 }

jetty-core/jetty-util/src/main/java/org/eclipse/jetty/util/resource/ResourceFactoryInternals.java

@@ -52,6 +52,7 @@ class ResourceFactoryInternals
         PathResourceFactory pathResourceFactory = new PathResourceFactory();
         RESOURCE_FACTORIES.put("file", pathResourceFactory);
         RESOURCE_FACTORIES.put("jrt", pathResourceFactory);
+        RESOURCE_FACTORIES.put("resource", pathResourceFactory); // GraalVM native-image resource
     }
 
     static ResourceFactory ROOT = new CompositeResourceFactory()