test/hotspot/jtreg/runtime/LoadClass/TestSymlinkLoad.java

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/*
 * @test
 * @summary JVM should be able to handle loading class via symlink on windows
 * @requires vm.flagless
 * @library /test/lib
 * @run testng/othervm TestSymlinkLoad
 */

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import jdk.test.lib.compiler.CompilerUtils;
import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import jdk.test.lib.util.FileUtils;
import org.testng.SkipException;
import org.testng.annotations.Test;

public class TestSymlinkLoad {

    @Test
    public void testSymlinkClassLoading() throws Exception {
        Path sourceDir = Paths.get(System.getProperty("test.src"), "test-classes");

        String subPath = "compiled";
        Path destDir = Paths.get(System.getProperty("test.classes"), subPath);

        CompilerUtils.compile(sourceDir, destDir);

        String bootCP = "-Xbootclasspath/a:" + destDir.toString();

        String className = "Hello";

        // try to load a class itself directly, i.e. not via a symlink
        ProcessBuilder pb = ProcessTools.createLimitedTestJavaProcessBuilder(
                bootCP, className);

        // make sure it runs as expected
        OutputAnalyzer output = new OutputAnalyzer(pb.start());
        output.shouldContain("Hello World")
              .shouldHaveExitValue(0);

        // create a symlink to the classfile in a subdir with a given name
        Path classFile = Path.of(destDir + File.separator + className + ".class");
        final String subdir = "remote";
        final String pathToFolderForSymlink = destDir + File.separator + subdir + File.separator;
        createLinkInSeparateFolder(pathToFolderForSymlink, classFile, className);

        // try to load class via its symlink, which is in a different directory
        pb = ProcessTools.createLimitedTestJavaProcessBuilder(
                bootCP + File.separator + subdir, className);
        output = new OutputAnalyzer(pb.start());
        output.shouldContain("Hello World")
              .shouldHaveExitValue(0);

        // remove the subdir
        FileUtils.deleteFileTreeWithRetry(Path.of(pathToFolderForSymlink));
    }

    public static void createLinkInSeparateFolder(final String pathToFolderForSymlink, final Path target, final String className) throws IOException {
        File theDir = new File(pathToFolderForSymlink);
        if (!theDir.exists()) {
            theDir.mkdirs();
        }
        Path link = Paths.get(pathToFolderForSymlink, className + ".class");
        if (Files.exists(link)) {
            Files.delete(link);
        }
        try {
            Files.createSymbolicLink(link, target);
        } catch (UnsupportedOperationException uoe) {
            throw new SkipException("Symbolic link creation not supported.", uoe);
        } catch (IOException ioe) {
            throw new SkipException("Probably insufficient privileges to create symbolic links (Windows)", ioe);
        }
    }
}