jdk/test/langtools/tools/javac/SystemFilesClosed.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/*
 * @test
 * @bug 8357249
 * @summary Check that `lib/jrt-fs.jar` and `lib/modules` are properly closed while
 *          javac is invoked with `--system` option.
 * @requires os.family == "mac" | os.family == "linux"
 * @run junit ${test.main.class}
 */

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URI;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import javax.tools.JavaCompiler;
import javax.tools.JavaFileObject;
import javax.tools.SimpleJavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInfo;

public class SystemFilesClosed {

    private Path base;

    @Test
    void testSystemFilesClosed() throws Exception {
        String targetSystem = base.toString();
        int ret = java.util.spi.ToolProvider.findFirst("jlink")
                .orElseThrow()
                .run(System.out, System.err, "--add-modules", "java.base", "--output", targetSystem);
        if (ret != 0) {
            System.out.println("It is most probably an exploded build. Skip testing.");
            return;
        }

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        SimpleJavaFileObject compilationUnit = new SimpleJavaFileObject(URI.create("string:///Test.java"), JavaFileObject.Kind.SOURCE) {
            @Override
            public CharSequence getCharContent(boolean ignoreEncodingErrors) {
                return """
               public class Test {
                    public static void main(String[] args) {
                        System.out.println("Hello, World!");
                    }
               }
               """;
            }
        };

        try (StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null)) {
            Assertions.assertEquals(true,
                    compiler.getTask(null, fileManager, null, List.of("--system", targetSystem), null, List.of(compilationUnit)).call(),
                    "Compilation task failed");
        }

        Process process = new ProcessBuilder()
                .command("lsof", "-p", String.valueOf(ProcessHandle.current().pid()))
                .redirectOutput(ProcessBuilder.Redirect.PIPE)
                .redirectError(ProcessBuilder.Redirect.INHERIT)
                .start();
        List<String> lines;
        String realPath = base.toRealPath().toString();
        try (InputStream stdout = process.getInputStream(); BufferedReader reader = new BufferedReader(new InputStreamReader(stdout))) {
            lines = reader.lines().filter(line -> line.contains(realPath)).toList();
        }
        process.waitFor();
        Assertions.assertEquals(0, lines.size(), "File(s) remain opened: " + lines);
    }

    @BeforeEach
    public void setUp(TestInfo info) {
        base = Paths.get(".")
                    .resolve(info.getTestMethod()
                                 .orElseThrow()
                                 .getName());
    }
}