[GR-62101] Ensure users see final bundle output directories in build-output.

substratevm/src/com.oracle.svm.driver/src/com/oracle/svm/driver/BundleSupport.java

@@ -583,7 +583,7 @@ void complete() {
         }
 
         if (writeOutput) {
-            Path externalOutputDir = bundlePath.resolve(bundleName + "." + outputDir.getFileName());
+            Path externalOutputDir = getExternalOutputDir();
             copyFiles(outputDir, externalOutputDir, true);
             nativeImage.showMessage(BUNDLE_INFO_MESSAGE_PREFIX + "Bundle build output written to " + externalOutputDir);
         }
@@ -598,6 +598,12 @@ void complete() {
         }
     }
 
+    Path getExternalOutputDir() {
+        Objects.requireNonNull(bundlePath);
+        Objects.requireNonNull(bundleName);
+        return bundlePath.resolve(bundleName + '.' + outputDir.getFileName());
+    }
+
     void updateBundleLocation(Path bundleFile, boolean redefine) {
         if (redefine) {
             bundlePath = null;

substratevm/src/com.oracle.svm.driver/src/com/oracle/svm/driver/NativeImage.java

@@ -31,6 +31,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.io.PrintStream;
 import java.lang.module.FindException;
 import java.lang.module.ModuleDescriptor;
 import java.lang.module.ModuleFinder;
@@ -83,6 +84,7 @@
 import com.oracle.svm.common.option.CommonOptions;
 import com.oracle.svm.core.FallbackExecutor;
 import com.oracle.svm.core.FallbackExecutor.Options;
+import com.oracle.svm.core.JavaVersionUtil;
 import com.oracle.svm.core.NativeImageClassLoaderOptions;
 import com.oracle.svm.core.OS;
 import com.oracle.svm.core.SharedConstants;
@@ -111,7 +113,6 @@
 import com.oracle.svm.util.StringUtil;
 
 import jdk.graal.compiler.options.OptionKey;
-import com.oracle.svm.core.JavaVersionUtil;
 import jdk.internal.jimage.ImageReader;
 
 public class NativeImage {
@@ -1865,7 +1866,17 @@ protected int buildImage(List<String> javaArgs, LinkedHashSet<Path> cp, LinkedHa
 
         Process p = null;
         try {
-            p = pb.inheritIO().start();
+            if (!useBundle()) {
+                pb.inheritIO();
+            }
+            p = pb.start();
+            if (useBundle()) {
+                var internalOutputDir = bundleSupport.outputDir.toString();
+                var externalOutputDir = bundleSupport.getExternalOutputDir().toString();
+                Function<String, String> filter = line -> line.replace(internalOutputDir, externalOutputDir);
+                ProcessOutputTransformer.attach(p.getInputStream(), filter, System.out);
+                ProcessOutputTransformer.attach(p.getErrorStream(), filter, System.err);
+            }
             imageBuilderPid = p.pid();
             return p.waitFor();
         } catch (IOException | InterruptedException e) {
@@ -1877,6 +1888,22 @@ protected int buildImage(List<String> javaArgs, LinkedHashSet<Path> cp, LinkedHa
         }
     }
 
+    private record ProcessOutputTransformer(InputStream in, Function<String, String> filter, PrintStream out) implements Runnable {
+
+        static void attach(InputStream in, Function<String, String> filter, PrintStream out) {
+            Thread.ofVirtual().start(new ProcessOutputTransformer(in, filter, out));
+        }
+
+        @Override
+        public void run() {
+            try (BufferedReader reader = new BufferedReader(new InputStreamReader(in))) {
+                reader.lines().map(filter).forEach(out::println);
+            } catch (IOException e) {
+                throw showError("Unable to process stdout/stderr of image builder process", e);
+            }
+        }
+    }
+
     /**
      * Creates a file with name 'fileName' in the {@link NativeImage#driverTempDir temporary
      * directory} and returns the path to the newly created file. Note: the file will be deleted if