path: root/src/main/java/org/glavo/javah/HeaderGenerator.java

package org.glavo.javah;

import org.objectweb.asm.*;

import java.io.*;
import java.nio.file.*;
import java.util.*;

public final class HeaderGenerator {
    private static final Path[] EMPTY_PATH_ARRAY = new Path[0];
    private static final List<String> THROWABLE_NAME_LIST = Arrays.asList("Ljava/lang/Throwable;", "Ljava/lang/Error;", "Ljava/lang/Exception");
    private static final HeaderGenerator generator = new HeaderGenerator();
    public static final String VERSION = "0.1.1";
    private static final String message = "Usage: \n" +
            "  javah [options] <classes>\n" +
            "where [options] include:\n" +
            "  -o <file>                Output file (only one of -d or -o may be used)\n" +
            "  -d <dir>                 Output directory\n" +
            "  -h  -help --help  -?     Print this message\n" +
            "  -version                 Print version information\n" +
            "  -classpath <path>        Path from which to load classes\n" +
            "  -cp <path>               Path from which to load classes\n" +
            "<classes> are specified with their fully qualified names\n" +
            "(for example, java.lang.Object).";

    private static String escape(String source) {
        StringBuilder builder = new StringBuilder();
        char ch;
        for (int i = 0; i < source.length(); i++) {
            switch (ch = source.charAt(i)) {
                case '_':
                    builder.append("_1");
                    break;
                case ';':
                    builder.append("_2");
                    break;
                case '[':
                    builder.append("_3");
                    break;
                case '/':
                    builder.append('.');
                    break;
                default:
                    if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
                        builder.append(ch);
                    } else {
                        builder.append("_0").append(String.format("%04x", (int) ch));
                    }
            }
        }
        return builder.toString();
    }

    public static void generateFunctionDeclarations(ClassReader reader, PrintWriter output) {
        getGenerator().classGenerateFunctionDeclarations(reader, output);
    }

    public static void generateHeader(ClassReader reader, PrintWriter output) {
        getGenerator().classGenerateHeader(reader, output);
    }

    public static void generateHeader(byte[] classFile, PrintWriter output) {
        getGenerator().classGenerateHeader(classFile, output);
    }

    public static void generateHeader(byte[] classFileBuffer, int classFileOffset, int classFileLength, PrintWriter output) {
        getGenerator().classGenerateHeader(classFileBuffer, classFileOffset, classFileLength, output);
    }

    public static void generateHeader(String className, PrintWriter output) throws IOException {
        getGenerator().classGenerateHeader(className, output);
    }

    public static void generateHeader(InputStream input, PrintWriter output) throws IOException {
        getGenerator().classGenerateHeader(input, output);
    }

    public static HeaderGenerator getGenerator() {
        return generator;
    }

    private Path[] classPaths;
    private boolean useRuntimeClassPath;

    public HeaderGenerator() {
        this(EMPTY_PATH_ARRAY, true);
    }

    public HeaderGenerator(boolean useRuntimeClassPath) {
        this(EMPTY_PATH_ARRAY, useRuntimeClassPath);
    }

    public HeaderGenerator(Path[] classPaths) {
        this(classPaths, true);
    }

    public HeaderGenerator(Path[] classPaths, boolean useRuntimeClassPath) {
        Objects.requireNonNull(classPaths);
        this.classPaths = classPaths;
        this.useRuntimeClassPath = useRuntimeClassPath;
    }

    private boolean isThrowable(Type type) {
        String desc = type.getDescriptor();
        if (!desc.startsWith("L")) {
            return false;
        }
        if (classPaths.length == 0 && !useRuntimeClassPath) {
            return THROWABLE_NAME_LIST.contains(type.getDescriptor());
        }
        String className = type.getInternalName();
        while (true) {
            if (className == null) {
                return false;
            }
            if (className.equals("java/lang/Throwable")) {
                return true;
            }
            try {
                ClassReader reader = findClass(className);
                if (reader == null) {
                    return false;
                }
                className = reader.getSuperName();
            } catch (Exception ignored) {
                return false;
            }
        }
    }

    private String typeToNative(Type tpe) {
        if (tpe == Type.BOOLEAN_TYPE) {
            return "jboolean";
        } else if (tpe == Type.BYTE_TYPE) {
            return "jbyte";
        } else if (tpe == Type.CHAR_TYPE) {
            return "jchar";
        } else if (tpe == Type.SHORT_TYPE) {
            return "jshort";
        } else if (tpe == Type.INT_TYPE) {
            return "jint";
        } else if (tpe == Type.LONG_TYPE) {
            return "jlong";
        } else if (tpe == Type.FLOAT_TYPE) {
            return "jfloat";
        } else if (tpe == Type.DOUBLE_TYPE) {
            return "jdouble";
        } else if (tpe == Type.VOID_TYPE) {
            return "void";
        } else {
            String desc = tpe.getDescriptor();
            if (desc.startsWith("[")) {
                Type elemTpe = tpe.getElementType();
                String descriptor = elemTpe.getDescriptor();
                if (descriptor.startsWith("[") || descriptor.startsWith("L")) {
                    return "jobjectArray";
                }
                return typeToNative(elemTpe) + "Array";
            }
            if (desc.equals("Ljava/lang/String;")) {
                return "jstring";
            }
            if (desc.equals("Ljava/lang/Class;")) {
                return "jclass";
            }
            if (isThrowable(tpe)) {
                return "jthrowable";
            }
            return "jobject";
        }
    }

    private ClassReader findClass(String name) {
        loop:
        for (Path path : classPaths) {
            path = path.toAbsolutePath();
            if (!Files.exists(path)) {
                continue;
            }
            String[] ps = name.split("/|\\.");
            if (ps.length == 0) {
                continue;
            }
            ps[ps.length - 1] += ".class";
            for (String p : ps) {
                path = path.resolve(p);
                if (!Files.exists(path)) {
                    continue loop;
                }
            }
            try {
                return new ClassReader(Files.newInputStream(path));
            } catch (IOException ignored) {
            }
        }
        try {
            return new ClassReader(name.replace('/', '.'));
        } catch (IOException e) {
            return null;
        }
    }

    private void classGenerateFunctionDeclarations(Generator generator, PrintWriter output) {
        String className = escape(generator.getClassName());

        for (Map.Entry<String, Set<MethodDesc>> entry : generator.getMethods().entrySet()) {
            boolean overload = entry.getValue().size() > 1;
            for (MethodDesc desc : entry.getValue()) {
                String methodName = escape(entry.getKey());
                output.println("/*" + "\n" +
                        " * Class:     " + className + "\n" +
                        " * Method:    " + entry.getKey() + "\n" +
                        " * Signature: " + desc.descriptor + "\n" +
                        " */"
                );

                Type[] argTypes = Type.getArgumentTypes(desc.descriptor);
                Type retType = Type.getReturnType(desc.descriptor);

                output.print(
                        "JNIEXPORT " + typeToNative(retType) + " JNICALL Java_" + className + "_" + methodName
                );

                if (overload) {
                    output.print("__");
                    for (Type tpe : argTypes) {
                        output.print(escape(tpe.toString()));
                    }
                }
                output.println();

                output.print("  (JNIEnv *, ");
                if (desc.isStatic) {
                    output.print("jclass");
                } else {
                    output.print("jobject");
                }
                for (Type tpe : argTypes) {
                    output.print(", " + typeToNative(tpe));
                }
                output.println(");\n");
            }

        }
    }

    public void classGenerateFunctionDeclarations(ClassReader reader, PrintWriter output) {
        Generator generator = new Generator();
        reader.accept(generator, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
        classGenerateFunctionDeclarations(generator, output);
    }

    private void classGenerateHeaderWithoutInclude(Generator generator, PrintWriter output) {
        StringBuilder builder = new StringBuilder();
        String className = escape(generator.getClassName());

        output.println("/* Header for class " + className + " */");

        String includeHeader = "_Include_" + className;
        output.println("#ifndef " + includeHeader);
        output.println("#define " + includeHeader);

        output.println("#ifdef __cplusplus\n" +
                "extern \"C\" {\n" +
                "#endif");

        classGenerateFunctionDeclarations(generator, output);

        output.println("#ifdef __cplusplus\n" +
                "}\n" +
                "#endif\n" +
                "#endif\n");
    }

    private void classGenerateHeaderWithoutInclude(ClassReader reader, PrintWriter output) {
        Generator generator = new Generator();
        reader.accept(generator, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
        classGenerateHeaderWithoutInclude(generator, output);
    }

    private void classGenerateHeader(Generator generator, PrintWriter output) {
        output.println("/* DO NOT EDIT THIS FILE - it is machine generated */");
        output.println("#include <jni.h>");

        classGenerateHeaderWithoutInclude(generator, output);
    }

    public void classGenerateHeader(ClassReader reader, PrintWriter output) {
        Generator generator = new Generator();
        reader.accept(generator, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
        classGenerateHeader(generator, output);
    }

    public void classGenerateHeader(byte[] classFile, PrintWriter output) {
        classGenerateHeader(new ClassReader(classFile), output);
    }

    public void classGenerateHeader(byte[] classFileBuffer, int classFileOffset, int classFileLength, PrintWriter output) {
        classGenerateHeader(new ClassReader(classFileBuffer, classFileOffset, classFileLength), output);
    }

    public void classGenerateHeader(String className, PrintWriter output) throws IOException {
        ClassReader reader = findClass(className);
        if (reader == null) {
            throw new IOException();
        }
        classGenerateHeader(reader, output);
    }

    public void classGenerateHeader(InputStream input, PrintWriter output) throws IOException {
        classGenerateHeader(new ClassReader(input), output);
    }

    public Path[] getClassPaths() {
        return classPaths;
    }

    public void setClassPaths(Path[] classPaths) {
        Objects.requireNonNull(classPaths);
        this.classPaths = classPaths;
    }

    public boolean isUseRuntimeClassPath() {
        return useRuntimeClassPath;
    }

    public void setUseRuntimeClassPath(boolean useRuntimeClassPath) {
        this.useRuntimeClassPath = useRuntimeClassPath;
    }

    public static void main(String[] args) throws IOException {
        boolean isWindows = System.getProperty("os.name", "").toLowerCase().contains("windows");
        ArrayList<Path> cps = new ArrayList<>();
        Path outputFile = null;
        Path outputDir = null;
        ArrayList<String> classNames = new ArrayList<>();

        if (args.length == 0) {
            System.out.println(message);
            return;
        }
        for (int i = 0; i < args.length; i++) {
            String arg = args[i];
            if (arg.startsWith("-")) {
                switch (arg) {
                    case "-h":
                    case "-help":
                    case "--help":
                    case "-?":
                        System.out.println(message);
                        return;
                    case "-version":
                        System.out.println();
                        return;
                    case "-cp":
                    case "-classpath":
                        i++;
                        if (i == args.length) {
                            System.err.println("javah: " + arg + " requires an argument.");
                            return;
                        }
                        String[] s = args[i].split(isWindows ? ";" : ":");
                        for (String ss : s) {
                            Path p = Paths.get(ss);
                            if (Files.exists(p)) {
                                if (Files.isDirectory(p)) {
                                    cps.add(p);
                                } else if (ss.toLowerCase().endsWith(".jar") || ss.toLowerCase().endsWith(".zip")) {
                                    try {
                                        cps.add(FileSystems.newFileSystem(p, null).getPath("/"));
                                    } catch (Exception ignored) {
                                    }
                                }
                            }
                        }
                        break;
                    case "-o":
                        i++;
                        if (i == args.length) {
                            System.err.println("javah: " + arg + " requires an argument.");
                            return;
                        }
                        if (outputDir != null) {
                            System.err.println("Error: Can't mix options -d and -o.  Try -help.");
                            return;
                        }
                        outputFile = Paths.get(args[i]);
                        break;

                    case "-d":
                        i++;
                        if (i == args.length) {
                            System.err.println("javah: " + arg + " requires an argument.");
                            return;
                        }
                        if (outputFile != null) {
                            System.err.println("Error: Can't mix options -d and -o.  Try -help.");
                            return;
                        }
                        outputDir = Paths.get(args[i]);

                        break;
                    default:
                        System.err.println("Error: unknown option: " + arg);
                        return;
                }

            } else {
                if (arg.contains("/")) {
                    int idx = arg.indexOf('/');
                    if (idx != arg.lastIndexOf('/')) {
                        System.err.println("Not a valid class name: " + arg);
                    }
                    arg = arg.substring(idx + 1);
                }
                classNames.add(arg);
            }

            if (outputDir == null && outputFile == null) {
                outputDir = Paths.get(System.getProperty("user.dir", "."));
            }
            if (cps.isEmpty()) {
                cps.add(Paths.get(System.getProperty("user.dir", ".")));
            }

            if (outputDir != null && Files.notExists(outputDir)) {
                Files.createDirectories(outputDir);
            }

            if (outputFile != null && Files.notExists(outputFile)) {
                if (Files.notExists(outputFile.getParent())) {
                    Files.createDirectories(outputFile.getParent());
                }
            }

            HeaderGenerator generator = new HeaderGenerator(cps.toArray(new Path[0]));
            if (outputFile != null) {
                if (Files.notExists(outputFile.getParent())) {
                    Files.createDirectories(outputFile.getParent());
                }
                try (PrintWriter writer = new PrintWriter(Files.newBufferedWriter(outputFile, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING))) {
                    boolean first = true;
                    for (String name : classNames) {
                        ClassReader reader = generator.findClass(name);
                        if (reader == null) {
                            System.err.println("Error: Could not find class file for '" + name + "'.");
                            return;
                        }
                        Generator g = new Generator();
                        reader.accept(g, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
                        if (first) {
                            generator.classGenerateHeader(g, writer);
                            first = false;
                        } else {
                            generator.classGenerateHeaderWithoutInclude(g, writer);
                        }
                    }
                }
            }
            if (outputDir != null) {
                if (Files.notExists(outputDir)) {
                    Files.createDirectories(outputDir);
                }
                for (String name : classNames) {
                    ClassReader reader = generator.findClass(name);
                    if (reader == null) {
                        System.err.println("Error: Could not find class file for '" + name + "'.");
                        return;
                    }
                    Generator g = new Generator();
                    reader.accept(g, ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);

                    try (PrintWriter writer = new PrintWriter(Files.newBufferedWriter(outputDir.resolve(name.replace('.', '_') + ".h"), StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING))) {
                        generator.classGenerateHeader(g, writer);
                    }
                }
            }

        }
    }
}

class MethodDesc {
    public final boolean isStatic;
    public final String descriptor;

    public MethodDesc(boolean isStatic, String descriptor) {
        this.isStatic = isStatic;
        this.descriptor = descriptor;
    }
}

class Generator extends ClassVisitor {
    private String className;

    private Map<String, String> constants = new LinkedHashMap<>();
    private Map<String, Set<MethodDesc>> methods = new LinkedHashMap<String, Set<MethodDesc>>();

    public Generator() {
        super(Opcodes.ASM5);
    }

    @Override
    public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
        className = name;
    }

    @Override
    public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
        if ((access & Opcodes.ACC_NATIVE) != 0) {
            if (methods.containsKey(name)) {
                methods.get(name).add(new MethodDesc((access & Opcodes.ACC_STATIC) != 0, descriptor));
            } else {
                LinkedHashSet<MethodDesc> set = new LinkedHashSet<>();
                set.add(new MethodDesc((access & Opcodes.ACC_STATIC) != 0, descriptor));
                methods.put(name, set);
            }
        }
        return null;
    }

    public String getClassName() {
        return className;
    }

    public Map<String, Set<MethodDesc>> getMethods() {
        return methods;
    }
}