8365467: Fix multiple issues in ExplodedImage #26757

david-beaumont · 2025-08-13T12:20:23Z

This PR addresses several issues found while adding unit tests for ExplodedImage.
I have added review comments for changes (some of which are a little preferential, but bring the code into line with things like ImageReader in terms of the name choices for variables).
Later it is likely that this code will be adapted for the up-coming preview mode support in Valhalla, so having it unit-testable is important.

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JDK-8365467: Fix multiple issues in ExplodedImage (Bug - P4)

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* tweaking tests for readability * Address issues and add unit tests

bridgekeeper · 2025-08-13T12:21:24Z

👋 Welcome back david-beaumont! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2025-08-13T12:21:35Z

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See the Progress checklist in the description for automated requirements.

openjdk · 2025-08-13T12:22:48Z

@david-beaumont The following label will be automatically applied to this pull request:

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mlbridge · 2025-08-13T12:26:54Z

Webrevs

00: Full (1408def0)

david-beaumont

Adding explanatory notes for the non-test changes/fixes.

david-beaumont · 2025-08-13T12:21:42Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java


-    private final FileSystem defaultFS;
+    private final Path modulesDir;


Needed to make this class actually testable and avoid just using the static field from SystemImage.

david-beaumont · 2025-08-13T12:22:11Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java

    private final BasicFileAttributes modulesDirAttrs;

    ExplodedImage(Path modulesDir) throws IOException {
-        defaultFS = FileSystems.getDefault();
-        String str = defaultFS.getSeparator();
+        this.modulesDir = modulesDir;


Avoid unnecessary assumptions about file systems.

david-beaumont · 2025-08-13T12:23:33Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java

@@ -94,6 +92,11 @@ private final class PathNode extends Node {
            this.children = children;
        }

+        @Override


Discovered this method was missing during testing. I think this logic is what's needed here, but I would like someone to just double check.

david-beaumont · 2025-08-13T12:24:30Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java

@@ -126,7 +129,7 @@ public Stream<String> getChildNames() {
                List<Node> list = new ArrayList<>();
                try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
                    for (Path p : stream) {
-                        p = explodedModulesDir.relativize(p);
+                        p = modulesDir.relativize(p);


Avoid using static field.

david-beaumont · 2025-08-13T12:25:29Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java

@@ -152,7 +155,7 @@ public long size() {
    }

    @Override
-    public void close() throws IOException {
+    public synchronized void close() throws IOException {


The nodes map is always accessed synchronised except here, so by synchronizing this we can stop using ConcurrentHashMap.

david-beaumont · 2025-08-13T12:32:18Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java

@@ -275,8 +273,8 @@ private void initNodes() throws IOException {
        }
        // create "/modules" directory
        // "nodes" map contains only /modules/<foo> nodes only so far and so add all as children of /modules
-        PathNode modulesDir = new PathNode("/modules", new ArrayList<>(nodes.values()));
-        nodes.put(modulesDir.getName(), modulesDir);
+        PathNode modulesRootNode = new PathNode("/modules", new ArrayList<>(nodes.values()));


Renamed because there's already "modulesDir" elsewhere.

david-beaumont · 2025-08-13T12:32:58Z

src/java.base/share/classes/jdk/internal/jrtfs/SystemImage.java

@@ -78,13 +78,13 @@ void close() throws IOException {
        return new ExplodedImage(explodedModulesDir);
    }

-    static final String RUNTIME_HOME;
+    private static final String RUNTIME_HOME;


Hiding these prevents unwanted use by other classes (which would make them effectively untestable).

david-beaumont · 2025-08-13T12:33:55Z

test/jdk/jdk/internal/jrtfs/whitebox/ExplodedImageTestDriver.java

+ * @modules java.base/jdk.internal.jrtfs java.base/jdk.internal.jimage
+ * @run junit/othervm java.base/jdk.internal.jrtfs.ExplodedImageTest
+ */
+public class ExplodedImageTestDriver {}


Not 100% sure if a class declaration is needed here. It seems to work fine, but I've seen a case where there wasn't one (but that felt odd). Happy to remove if not wanted.

david-beaumont · 2025-08-13T12:34:32Z

test/jdk/jdk/internal/jrtfs/whitebox/TEST.properties

@@ -0,0 +1,4 @@
+modules = \


Cargo-culted without a true understand of what's going on. This seems to be what's needed for module access.

david-beaumont · 2025-08-13T12:36:40Z

src/java.base/share/classes/jdk/internal/jrtfs/ExplodedImage.java

+     * path does not reference a file.
+     */
+    Path underlyingModulesPath(String name) {
+        if (name.startsWith(MODULES) && name.length() > MODULES.length()) {


The extra length test avoids issues when "/modules/" is given, since that should be invalid but otherwise gets turned into a path to the parent dir.

Provisional fixes for ExplodedImage issues.

1408def

* tweaking tests for readability * Address issues and add unit tests

openjdk bot added core-libs [email protected] rfr Pull request is ready for review labels Aug 13, 2025

david-beaumont commented Aug 13, 2025

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8365467: Fix multiple issues in ExplodedImage #26757

8365467: Fix multiple issues in ExplodedImage #26757

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		private final FileSystem defaultFS;
		private final Path modulesDir;

8365467: Fix multiple issues in ExplodedImage #26757

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david-beaumont commented Aug 13, 2025 •

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