1 /*

     2  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package indify;

    27 

    28 import java.util.*;

    29 import java.io.*;

    30 import java.lang.reflect.Modifier;

    31 import java.util.regex.*;

    32 

    33 /**

    34  * Transform one or more class files to incorporate JSR 292 features,

    35  * such as {@code invokedynamic}.

    36  * <p>

    37  * This is a standalone program in a single source file.

    38  * In this form, it may be useful for test harnesses, small experiments, and javadoc examples.

    39  * Copies of this file may show up in multiple locations for standalone usage.

    40  * The primary maintained location of this file is as follows:

    41  * <a href="http://kenai.com/projects/ninja/sources/indify-repo/content/src/indify/Indify.java">

    42  * http://kenai.com/projects/ninja/sources/indify-repo/content/src/indify/Indify.java</a>

    43  * <p>

    44  * Static private methods named MH_x and MT_x (where x is arbitrary)

    45  * must be stereotyped generators of MethodHandle and MethodType

    46  * constants.  All calls to them are transformed to {@code CONSTANT_MethodHandle}

    47  * and {@code CONSTANT_MethodType} "ldc" instructions.

    48  * The stereotyped code must create method types by calls to {@code methodType} or

    49  * {@code fromMethodDescriptorString}.  The "lookup" argument must be created

    50  * by calls to {@code java.dyn.MethodHandles#lookup MethodHandles.lookup}.

    51  * The class and string arguments must be constant.

    52  * The following methods of {@code java.dyn.MethodHandle.Lookup Lookup} are

    53  * allowed for method handle creation: {@code findStatic}, {@code findVirtual},

    54  * {@code findConstructor}, {@code findSpecial},

    55  * {@code findGetter}, {@code findSetter},

    56  * {@code findStaticGetter}, or {@code findStaticSetter}.

    57  * The call to one of these methods must be followed immediately

    58  * by an {@code areturn} instruction.

    59  * The net result of the call to the MH_x or MT_x method must be

    60  * the creation of a constant method handle.  Thus, replacing calls

    61  * to MH_x or MT_x methods by {@code ldc} instructions should leave

    62  * the meaning of the program unchanged.

    63  * <p>

    64  * Static private methods named INDY_x must be stereotyped generators

    65  * of {@code invokedynamic} call sites.

    66  * All calls to them must be immediately followed by

    67  * {@code invokeExact} calls.

    68  * All such pairs of calls are transformed to {@code invokedynamic}

    69  * instructions.  Each INDY_x method must begin with a call to a

    70  * MH_x method, which is taken to be its bootstrap method.

    71  * The method must be immediately invoked (via {@code invokeGeneric}

    72  * on constant lookup, name, and type arguments.  An object array of

    73  * constants may also be appended to the {@code invokeGeneric call}.

    74  * This call must be cast to {@code CallSite}, and the result must be

    75  * immediately followed by a call to {@code dynamicInvoker}, with the

    76  * resulting method handle returned.

    77  * <p>

    78  * The net result of all of these actions is equivalent to the JVM's

    79  * execution of an {@code invokedynamic} instruction in the unlinked state.

    80  * Running this code once should produce the same results as running

    81  * the corresponding {@code invokedynamic} instruction.

    82  * In order to model the caching behavior, the code of an INDY_x

    83  * method is allowed to begin with getstatic, aaload, and if_acmpne

    84  * instructions which load a static method handle value and return it

    85  * if the value is non-null.

    86  * <p>

    87  * Example usage:

    88  * <blockquote><pre>

    89 $ JAVA_HOME=(some recent OpenJDK 7 build)

    90 $ ant

    91 $ $JAVA_HOME/bin/java -cp build/classes indify.Indify --overwrite --dest build/testout build/classes/indify/Example.class

    92 $ $JAVA_HOME/bin/java -XX:+UnlockExperimentalVMOptions -XX:+EnableInvokeDynamic -cp build/classes indify.Example

    93 MT = (java.lang.Object)java.lang.Object

    94 MH = adder(int,int)java.lang.Integer

    95 adder(1,2) = 3

    96 calling indy:  42

    97 $ $JAVA_HOME/bin/java -XX:+UnlockExperimentalVMOptions -XX:+EnableInvokeDynamic -cp build/testout indify.Example

    98 (same output as above)

    99  * </pre></blockquote>

   100  * <p>

   101  * Before OpenJDK build b123, the format of {@code CONSTANT_InvokeDynamic} is in transition,

   102  * and the switch {@code --transitionalJSR292=yes} is recommended.

   103  * It is turned <em>off</em> by default, but users of earlier builds may need to turn it on.

   104  * <p>

   105  * A version of this transformation built on top of <a href="http://asm.ow2.org/">http://asm.ow2.org/</a> would be welcome.

   106  * @author John Rose

   107  */

   108 public class Indify {

   109     public static void main(String... av) throws IOException {

   110         new Indify().run(av);

   111     }

   112 

   113     public File dest;

   114     public String[] classpath = {"."};

   115     public boolean keepgoing = false;

   116     public boolean expandProperties = false;

   117     public boolean overwrite = false;

   118     public boolean quiet = false;

   119     public boolean verbose = false;

   120     public boolean transitionalJSR292 = false;  // final version is distributed

   121     public boolean all = false;

   122     public int verifySpecifierCount = -1;

   123 

   124     public void run(String... av) throws IOException {

   125         List<String> avl = new ArrayList<>(Arrays.asList(av));

   126         parseOptions(avl);

   127         if (avl.isEmpty())

   128             throw new IllegalArgumentException("Usage: indify [--dest dir] [option...] file...");

   129         if ("--java".equals(avl.get(0))) {

   130             avl.remove(0);

   131             try {

   132                 runApplication(avl.toArray(new String[0]));

   133             } catch (Exception ex) {

   134                 if (ex instanceof RuntimeException)  throw (RuntimeException) ex;

   135                 throw new RuntimeException(ex);

   136             }

   137             return;

   138         }

   139         Exception err = null;

   140         for (String a : avl) {

   141             try {

   142                 indify(a);

   143             } catch (Exception ex) {

   144                 if (err == null)  err = ex;

   145                 System.err.println("failure on "+a);

   146                 if (!keepgoing)  break;

   147             }

   148         }

   149         if (err != null) {

   150             if (err instanceof IOException)  throw (IOException) err;

   151             throw (RuntimeException) err;

   152         }

   153     }

   154 

   155     /** Execute the given application under a class loader which indifies all application classes. */

   156     public void runApplication(String... av) throws Exception {

   157         List<String> avl = new ArrayList<>(Arrays.asList(av));

   158         String mainClassName = avl.remove(0);

   159         av = avl.toArray(new String[0]);

   160         Class<?> mainClass = Class.forName(mainClassName, true, makeClassLoader());

   161         java.lang.reflect.Method main = mainClass.getMethod("main", String[].class);

   162         try { main.setAccessible(true); } catch (SecurityException ex) { }

   163         main.invoke(null, (Object) av);

   164     }

   165 

   166     public void parseOptions(List<String> av) throws IOException {

   167         for (; !av.isEmpty(); av.remove(0)) {

   168             String a = av.get(0);

   169             if (a.startsWith("-")) {

   170                 String a2 = null;

   171                 int eq = a.indexOf('=');

   172                 if (eq > 0) {

   173                     a2 = maybeExpandProperties(a.substring(eq+1));

   174                     a = a.substring(0, eq+1);

   175                 }

   176                 switch (a) {

   177                 case "--java":

   178                     return;  // keep this argument

   179                 case "-d": case "--dest": case "-d=": case "--dest=":

   180                     dest = new File(a2 != null ? a2 : maybeExpandProperties(av.remove(1)));

   181                     break;

   182                 case "-cp": case "--classpath":

   183                     classpath = maybeExpandProperties(av.remove(1)).split("["+File.pathSeparatorChar+"]");

   184                     break;

   185                 case "-k": case "--keepgoing": case "--keepgoing=":

   186                     keepgoing = booleanOption(a2);  // print errors but keep going

   187                     break;

   188                 case "--expand-properties": case "--expand-properties=":

   189                     expandProperties = booleanOption(a2);  // expand property references in subsequent arguments

   190                     break;

   191                 case "--verify-specifier-count": case "--verify-specifier-count=":

   192                     verifySpecifierCount = Integer.valueOf(a2);

   193                     break;

   194                 case "--overwrite": case "--overwrite=":

   195                     overwrite = booleanOption(a2);  // overwrite output files

   196                     break;

   197                 case "--all": case "--all=":

   198                     all = booleanOption(a2);  // copy all classes, even if no patterns

   199                     break;

   200                 case "-q": case "--quiet": case "--quiet=":

   201                     quiet = booleanOption(a2);  // less output

   202                     break;

   203                 case "-v": case "--verbose": case "--verbose=":

   204                     verbose = booleanOption(a2);  // more output

   205                     break;

   206                 case "--transitionalJSR292": case "--transitionalJSR292=":

   207                     transitionalJSR292 = booleanOption(a2);  // use older invokedynamic format

   208                     break;

   209                 default:

   210                     throw new IllegalArgumentException("unrecognized flag: "+a);

   211                 }

   212                 continue;

   213             } else {

   214                 break;

   215             }

   216         }

   217         if (dest == null && !overwrite)

   218             throw new RuntimeException("no output specified; need --dest d or --overwrite");

   219         if (expandProperties) {

   220             for (int i = 0; i < av.size(); i++)

   221                 av.set(i, maybeExpandProperties(av.get(i)));

   222         }

   223     }

   224 

   225     private boolean booleanOption(String s) {

   226         if (s == null)  return true;

   227         switch (s) {

   228         case "true":  case "yes": case "on":  case "1": return true;

   229         case "false": case "no":  case "off": case "0": return false;

   230         }

   231         throw new IllegalArgumentException("unrecognized boolean flag="+s);

   232     }

   233 

   234     private String maybeExpandProperties(String s) {

   235         if (!expandProperties)  return s;

   236         Set<String> propsDone = new HashSet<>();

   237         while (s.contains("${")) {

   238             int lbrk = s.indexOf("${");

   239             int rbrk = s.indexOf('}', lbrk);

   240             if (rbrk < 0)  break;

   241             String prop = s.substring(lbrk+2, rbrk);

   242             if (!propsDone.add(prop))  break;

   243             String value = System.getProperty(prop);

   244             if (verbose)  System.err.println("expanding ${"+prop+"} => "+value);

   245             if (value == null)  break;

   246             s = s.substring(0, lbrk) + value + s.substring(rbrk+1);

   247         }

   248         return s;

   249     }

   250 

   251     public void indify(String a) throws IOException {

   252         File f = new File(a);

   253         String fn = f.getName();

   254         if (fn.endsWith(".class") && f.isFile())

   255             indifyFile(f, dest);

   256         else if (fn.endsWith(".jar") && f.isFile())

   257             indifyJar(f, dest);

   258         else if (f.isDirectory())

   259             indifyTree(f, dest);

   260         else if (!keepgoing)

   261             throw new RuntimeException("unrecognized file: "+a);

   262     }

   263 

   264     private void ensureDirectory(File dir) {

   265         if (dir.mkdirs() && !quiet)

   266             System.err.println("created "+dir);

   267     }

   268 

   269     public void indifyFile(File f, File dest) throws IOException {

   270         if (verbose)  System.err.println("reading "+f);

   271         ClassFile cf = new ClassFile(f);

   272         Logic logic = new Logic(cf);

   273         boolean changed = logic.transform();

   274         logic.reportPatternMethods(quiet, keepgoing);

   275         if (changed || all) {

   276             File outfile;

   277             if (dest != null) {

   278                 ensureDirectory(dest);

   279                 outfile = classPathFile(dest, cf.nameString());

   280             } else {

   281                 outfile = f;  // overwrite input file, no matter where it is

   282             }

   283             cf.writeTo(outfile);

   284             if (!quiet)  System.err.println("wrote "+outfile);

   285         }

   286     }

   287 

   288     File classPathFile(File pathDir, String className) {

   289         String qualname = className.replace('.','/')+".class";

   290         qualname = qualname.replace('/', File.separatorChar);

   291         return new File(pathDir, qualname);

   292     }

   293 

   294     public void indifyJar(File f, Object dest) throws IOException {

   295         throw new UnsupportedOperationException("Not yet implemented");

   296     }

   297 

   298     public void indifyTree(File f, File dest) throws IOException {

   299         if (verbose)  System.err.println("reading directory: "+f);

   300         for (File f2 : f.listFiles(new FilenameFilter() {

   301                 public boolean accept(File dir, String name) {

   302                     if (name.endsWith(".class"))  return true;

   303                     if (name.contains("."))  return false;

   304                     // return true if it might be a package name:

   305                     return Character.isJavaIdentifierStart(name.charAt(0));

   306                 }})) {

   307             if (f2.getName().endsWith(".class"))

   308                 indifyFile(f2, dest);

   309             else if (f2.isDirectory())

   310                 indifyTree(f2, dest);

   311         }

   312     }

   313 

   314     public ClassLoader makeClassLoader() {

   315         return new Loader();

   316     }

   317     private class Loader extends ClassLoader {

   318         Loader() {

   319             this(Indify.class.getClassLoader());

   320         }

   321         Loader(ClassLoader parent) {

   322             super(parent);

   323         }

   324         public Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {

   325             File f = findClassInPath(name);

   326             if (f != null) {

   327                 try {

   328                     Class<?> c = transformAndLoadClass(f);

   329                     if (c != null) {

   330                         if (resolve)  resolveClass(c);

   331                         return c;

   332                     }

   333                 } catch (Exception ex) {

   334                     if (ex instanceof IllegalArgumentException)

   335                         // pass error from reportPatternMethods

   336                         throw (IllegalArgumentException) ex;

   337                 }

   338             }

   339             return super.loadClass(name, resolve);

   340         }

   341         private File findClassInPath(String name) {

   342             for (String s : classpath) {

   343                 File f = classPathFile(new File(s), name);

   344                 //System.out.println("Checking for "+f);

   345                 if (f.exists() && f.canRead()) {

   346                     return f;

   347                 }

   348             }

   349             return null;

   350         }

   351         protected Class<?> findClass(String name) throws ClassNotFoundException {

   352             try {

   353                 return transformAndLoadClass(findClassInPath(name));

   354             } catch (IOException ex) {

   355                 throw new ClassNotFoundException("IO error", ex);

   356             }

   357         }

   358         private Class<?> transformAndLoadClass(File f) throws ClassNotFoundException, IOException {

   359             if (verbose)  System.err.println("Loading class from "+f);

   360             ClassFile cf = new ClassFile(f);

   361             Logic logic = new Logic(cf);

   362             boolean changed = logic.transform();

   363             if (verbose && !changed)  System.err.println("(no change)");

   364             logic.reportPatternMethods(!verbose, keepgoing);

   365             byte[] bytes = cf.toByteArray();

   366             return defineClass(null, bytes, 0, bytes.length);

   367         }

   368     }

   369 

   370     private class Logic {

   371         // Indify logic, per se.

   372         ClassFile cf;

   373         final char[] poolMarks;

   374         final Map<Method,Constant> constants = new HashMap<>();

   375         final Map<Method,String> indySignatures = new HashMap<>();

   376         Logic(ClassFile cf) {

   377             this.cf = cf;

   378             poolMarks = new char[cf.pool.size()];

   379         }

   380         boolean transform() {

   381             if (!initializeMarks())  return false;

   382             if (!findPatternMethods())  return false;

   383             Pool pool = cf.pool;

   384             //for (Constant c : cp)  System.out.println("  # "+c);

   385             for (Method m : cf.methods) {

   386                 if (constants.containsKey(m))  continue;  // don't bother

   387                 // Transform references.

   388                 int blab = 0;

   389                 for (Instruction i = m.instructions(); i != null; i = i.next()) {

   390                     if (i.bc != opc_invokestatic)  continue;

   391                     int methi = i.u2At(1);

   392                     if (poolMarks[methi] == 0)  continue;

   393                     Short[] ref = pool.getMemberRef((short)methi);

   394                     Method conm = findMember(cf.methods, ref[1], ref[2]);

   395                     if (conm == null)  continue;

   396                     Constant con = constants.get(conm);

   397                     if (con == null)  continue;

   398                     if (blab++ == 0 && !quiet)

   399                         System.err.println("patching "+cf.nameString()+"."+m);

   400                     //if (blab == 1) { for (Instruction j = m.instructions(); j != null; j = j.next()) System.out.println("  |"+j); }

   401                     if (con.tag == CONSTANT_InvokeDynamic ||

   402                         con.tag == CONSTANT_InvokeDynamic_17) {

   403                         // need to patch the following instruction too,

   404                         // but there are usually intervening argument pushes too

   405                         Instruction i2 = findPop(i);

   406                         Short[] ref2 = null;

   407                         short ref2i = 0;

   408                         if (i2 != null && i2.bc == opc_invokevirtual &&

   409                                 poolMarks[(char)(ref2i = (short) i2.u2At(1))] == 'D')

   410                             ref2 = pool.getMemberRef(ref2i);

   411                         if (ref2 == null || !"invokeExact".equals(pool.getString(ref2[1]))) {

   412                             System.err.println(m+": failed to create invokedynamic at "+i.pc);

   413                             continue;

   414                         }

   415                         String invType = pool.getString(ref2[2]);

   416                         String bsmType = indySignatures.get(conm);

   417                         if (!invType.equals(bsmType)) {

   418                             System.err.println(m+": warning: "+conm+" call type and local invoke type differ: "

   419                                     +bsmType+", "+invType);

   420                         }

   421                         assert(i.len == 3 || i2.len == 3);

   422                         if (!quiet)  System.err.println(i+" "+conm+";...; "+i2+" => invokedynamic "+con);

   423                         int start = i.pc + 3, end = i2.pc;

   424                         System.arraycopy(i.codeBase, start, i.codeBase, i.pc, end-start);

   425                         i.forceNext(0);  // force revisit of new instruction

   426                         i2.u1AtPut(-3, opc_invokedynamic);

   427                         i2.u2AtPut(-2, con.index);

   428                         i2.u2AtPut(0, (short)0);

   429                         i2.u1AtPut(2, opc_nop);

   430                         //System.out.println(new Instruction(i.codeBase, i2.pc-3));

   431                     } else {

   432                         if (!quiet)  System.err.println(i+" "+conm+" => ldc "+con);

   433                         assert(i.len == 3);

   434                         i.u1AtPut(0, opc_ldc_w);

   435                         i.u2AtPut(1, con.index);

   436                     }

   437                 }

   438                 //if (blab >= 1) { for (Instruction j = m.instructions(); j != null; j = j.next()) System.out.println("    |"+j); }

   439             }

   440             cf.methods.removeAll(constants.keySet());

   441             return true;

   442         }

   443 

   444         // Scan forward from the instruction to find where the stack p

   445         // below the current sp at the instruction.

   446         Instruction findPop(Instruction i) {

   447             //System.out.println("findPop from "+i);

   448             Pool pool = cf.pool;

   449             JVMState jvm = new JVMState();

   450         decode:

   451             for (i = i.clone().next(); i != null; i = i.next()) {

   452                 String pops = INSTRUCTION_POPS[i.bc];

   453                 //System.out.println("  "+i+" "+jvm.stack+" : "+pops.replace("$", " => "));

   454                 if (pops == null)  break;

   455                 if (jvm.stackMotion(i.bc))  continue decode;

   456                 if (pops.indexOf('Q') >= 0) {

   457                     Short[] ref = pool.getMemberRef((short) i.u2At(1));

   458                     String type = simplifyType(pool.getString(CONSTANT_Utf8, ref[2]));

   459                     switch (i.bc) {

   460                     case opc_getstatic:

   461                     case opc_getfield:

   462                     case opc_putstatic:

   463                     case opc_putfield:

   464                         pops = pops.replace("Q", type);

   465                         break;

   466                     default:

   467                         if (!type.startsWith("("))

   468                             throw new InternalError(i.toString());

   469                         pops = pops.replace("Q$Q", type.substring(1).replace(")","$"));

   470                         break;

   471                     }

   472                     //System.out.println("special type: "+type+" => "+pops);

   473                 }

   474                 int npops = pops.indexOf('$');

   475                 if (npops < 0)  throw new InternalError();

   476                 if (npops > jvm.sp())  return i;

   477                 List<Object> args = jvm.args(npops);

   478                 int k = 0;

   479                 for (Object x : args) {

   480                     char have = (Character) x;

   481                     char want = pops.charAt(k++);

   482                     if (have == 'X' || want == 'X')  continue;

   483                     if (have != want)  break decode;

   484                 }

   485                 if (pops.charAt(k++) != '$')  break decode;

   486                 args.clear();

   487                 while (k < pops.length())

   488                     args.add(pops.charAt(k++));

   489             }

   490             System.err.println("*** bailout on jvm: "+jvm.stack+" "+i);

   491             return null;

   492         }

   493 

   494         boolean findPatternMethods() {

   495             boolean found = false;

   496             for (char mark : "THI".toCharArray()) {

   497                 for (Method m : cf.methods) {

   498                     if (!Modifier.isPrivate(m.access))  continue;

   499                     if (!Modifier.isStatic(m.access))  continue;

   500                     if (nameAndTypeMark(m.name, m.type) == mark) {

   501                         Constant con = scanPattern(m, mark);

   502                         if (con == null)  continue;

   503                         constants.put(m, con);

   504                         found = true;

   505                     }

   506                 }

   507             }

   508             return found;

   509         }

   510 

   511         void reportPatternMethods(boolean quietly, boolean allowMatchFailure) {

   512             if (!quietly && !constants.keySet().isEmpty())

   513                 System.err.println("pattern methods removed: "+constants.keySet());

   514             for (Method m : cf.methods) {

   515                 if (nameMark(cf.pool.getString(m.name)) != 0 &&

   516                     constants.get(m) == null) {

   517                     String failure = "method has special name but fails to match pattern: "+m;

   518                     if (!allowMatchFailure)

   519                         throw new IllegalArgumentException(failure);

   520                     else if (!quietly)

   521                         System.err.println("warning: "+failure);

   522                 }

   523             }

   524             if (verifySpecifierCount >= 0) {

   525                 List<Object[]> specs = bootstrapMethodSpecifiers(false);

   526                 int specsLen = (specs == null ? 0 : specs.size());

   527                 if (specsLen != verifySpecifierCount) {

   528                     throw new IllegalArgumentException("BootstrapMethods length is "+specsLen+" but should be "+verifySpecifierCount);

   529                 }

   530             }

   531             if (!quiet)  System.err.flush();

   532         }

   533 

   534         // mark constant pool entries according to participation in patterns

   535         boolean initializeMarks() {

   536             boolean changed = false;

   537             for (;;) {

   538                 boolean changed1 = false;

   539                 int cpindex = -1;

   540                 for (Constant e : cf.pool) {

   541                     ++cpindex;

   542                     if (e == null)  continue;

   543                     char mark = poolMarks[cpindex];

   544                     if (mark != 0)  continue;

   545                     switch (e.tag) {

   546                     case CONSTANT_Utf8:

   547                         mark = nameMark(e.itemString()); break;

   548                     case CONSTANT_NameAndType:

   549                         mark = nameAndTypeMark(e.itemIndexes()); break;

   550                     case CONSTANT_Class: {

   551                         int n1 = e.itemIndex();

   552                         char nmark = poolMarks[(char)n1];

   553                         if ("DJ".indexOf(nmark) >= 0)

   554                             mark = nmark;

   555                         break;

   556                     }

   557                     case CONSTANT_Field:

   558                     case CONSTANT_Method: {

   559                         Short[] n12 = e.itemIndexes();

   560                         short cl = n12[0];

   561                         short nt = n12[1];

   562                         char cmark = poolMarks[(char)cl];

   563                         if (cmark != 0) {

   564                             mark = cmark;  // it is a java.dyn.* or java.lang.* method

   565                             break;

   566                         }

   567                         String cls = cf.pool.getString(CONSTANT_Class, cl);

   568                         if (cls.equals(cf.nameString())) {

   569                             switch (poolMarks[(char)nt]) {

   570                             // it is a private MH/MT/INDY method

   571                             case 'T': case 'H': case 'I':

   572                                 mark = poolMarks[(char)nt];

   573                                 break;

   574                             }

   575                         }

   576                         break;

   577                     }

   578                     default:  break;

   579                     }

   580                     if (mark != 0) {

   581                         poolMarks[cpindex] = mark;

   582                         changed1 = true;

   583                     }

   584                 }

   585                 if (!changed1)

   586                     break;

   587                 changed = true;

   588             }

   589             return changed;

   590         }

   591         char nameMark(String s) {

   592             if (s.startsWith("MT_"))                return 'T';

   593             else if (s.startsWith("MH_"))           return 'H';

   594             else if (s.startsWith("INDY_"))         return 'I';

   595             else if (s.startsWith("java/dyn/"))     return 'D';

   596             else if (s.startsWith("java/lang/"))    return 'J';

   597             return 0;

   598         }

   599         char nameAndTypeMark(Short[] n12) {

   600             return nameAndTypeMark(n12[0], n12[1]);

   601         }

   602         char nameAndTypeMark(short n1, short n2) {

   603             char mark = poolMarks[(char)n1];

   604             if (mark == 0)  return 0;

   605             String descr = cf.pool.getString(CONSTANT_Utf8, n2);

   606             String requiredType;

   607             switch (poolMarks[(char)n1]) {

   608             case 'H': requiredType = "()Ljava/dyn/MethodHandle;";  break;

   609             case 'T': requiredType = "()Ljava/dyn/MethodType;";    break;

   610             case 'I': requiredType = "()Ljava/dyn/MethodHandle;";  break;

   611             default:  return 0;

   612             }

   613             if (descr.equals(requiredType))  return mark;

   614             return 0;

   615         }

   616 

   617         private class JVMState {

   618             final List<Object> stack = new ArrayList<>();

   619             int sp() { return stack.size(); }

   620             void push(Object x) { stack.add(x); }

   621             void push2(Object x) { stack.add(EMPTY_SLOT); stack.add(x); }

   622             void pushAt(int pos, Object x) { stack.add(stack.size()+pos, x); }

   623             Object pop() { return stack.remove(sp()-1); }

   624             Object top() { return stack.get(sp()-1); }

   625             List<Object> args(boolean hasRecv, String type) {

   626                 return args(argsize(type) + (hasRecv ? 1 : 0));

   627             }

   628             List<Object> args(int argsize) {

   629                 return stack.subList(sp()-argsize, sp());

   630             }

   631             boolean stackMotion(int bc) {

   632                 switch (bc) {

   633                 case opc_pop:    pop();             break;

   634                 case opc_pop2:   pop(); pop();      break;

   635                 case opc_swap:   pushAt(-1, pop()); break;

   636                 case opc_dup:    push(top());       break;

   637                 case opc_dup_x1: pushAt(-2, top()); break;

   638                 case opc_dup_x2: pushAt(-3, top()); break;

   639                 // ? also: dup2{,_x1,_x2}

   640                 default:  return false;

   641                 }

   642                 return true;

   643             }

   644         }

   645         private final String EMPTY_SLOT = "_";

   646         private void removeEmptyJVMSlots(List<Object> args) {

   647             for (;;) {

   648                 int i = args.indexOf(EMPTY_SLOT);

   649                 if (i >= 0 && i+1 < args.size()

   650                     && (isConstant(args.get(i+1), CONSTANT_Long) ||

   651                         isConstant(args.get(i+1), CONSTANT_Double)))

   652                     args.remove(i);

   653                 else  break;

   654             }

   655         }

   656 

   657         private Constant scanPattern(Method m, char patternMark) {

   658             if (verbose)  System.err.println("scan "+m+" for pattern="+patternMark);

   659             int wantTag;

   660             switch (patternMark) {

   661             case 'T': wantTag = CONSTANT_MethodType; break;

   662             case 'H': wantTag = CONSTANT_MethodHandle; break;

   663             case 'I': wantTag = CONSTANT_InvokeDynamic; break;

   664             default: throw new InternalError();

   665             }

   666             Instruction i = m.instructions();

   667             JVMState jvm = new JVMState();

   668             Pool pool = cf.pool;

   669             int branchCount = 0;

   670             Object arg;

   671             List<Object> args;

   672             List<Object> bsmArgs = null;  // args to invokeGeneric

   673         decode:

   674             for (; i != null; i = i.next()) {

   675                 //System.out.println(jvm.stack+" "+i);

   676                 int bc = i.bc;

   677                 switch (bc) {

   678                 case opc_ldc:           jvm.push(pool.get(i.u1At(1)));   break;

   679                 case opc_ldc_w:         jvm.push(pool.get(i.u2At(1)));   break;

   680                 case opc_ldc2_w:        jvm.push2(pool.get(i.u2At(1)));  break;

   681                 case opc_aconst_null:   jvm.push(null);                  break;

   682                 case opc_bipush:        jvm.push((int)(byte) i.u1At(1)); break;

   683                 case opc_sipush:        jvm.push((int)(short)i.u2At(1)); break;

   684 

   685                 // these support creation of a restarg array

   686                 case opc_anewarray:

   687                     arg = jvm.pop();

   688                     if (!(arg instanceof Integer))  break decode;

   689                     arg = Arrays.asList(new Object[(Integer)arg]);

   690                     jvm.push(arg);

   691                     break;

   692                 case opc_dup:

   693                     jvm.push(jvm.top()); break;

   694                 case opc_aastore:

   695                     args = jvm.args(3);  // array, index, value

   696                     if (args.get(0) instanceof List &&

   697                         args.get(1) instanceof Integer) {

   698                         ((List<Object>)args.get(0)).set( (Integer)args.get(1), args.get(2) );

   699                     }

   700                     args.clear();

   701                     break;

   702 

   703                 case opc_new:

   704                 {

   705                     String type = pool.getString(CONSTANT_Class, (short)i.u2At(1));

   706                     //System.out.println("new "+type);

   707                     switch (type) {

   708                     case "java/lang/StringBuilder":

   709                         jvm.push("StringBuilder");

   710                         continue decode;  // go to next instruction

   711                     }

   712                     break decode;  // bail out

   713                 }

   714 

   715                 case opc_getstatic:

   716                 {

   717                     // int.class compiles to getstatic Integer.TYPE

   718                     int fieldi = i.u2At(1);

   719                     char mark = poolMarks[fieldi];

   720                     //System.err.println("getstatic "+fieldi+Arrays.asList(pool.getStrings(pool.getMemberRef((short)fieldi)))+mark);

   721                     if (mark == 'J') {

   722                         Short[] ref = pool.getMemberRef((short) fieldi);

   723                         String name = pool.getString(CONSTANT_Utf8, ref[1]);

   724                         if ("TYPE".equals(name)) {

   725                             String wrapperName = pool.getString(CONSTANT_Class, ref[0]).replace('/', '.');

   726                             // a primitive type descriptor

   727                             Class<?> primClass;

   728                             try {

   729                                 primClass = (Class<?>) Class.forName(wrapperName).getField(name).get(null);

   730                             } catch (Exception ex) {

   731                                 throw new InternalError("cannot load "+wrapperName+"."+name);

   732                             }

   733                             jvm.push(primClass);

   734                             break;

   735                         }

   736                     }

   737                     // unknown field; keep going...

   738                     jvm.push(UNKNOWN_CON);

   739                     break;

   740                 }

   741                 case opc_putstatic:

   742                 {

   743                     if (patternMark != 'I')  break decode;

   744                     jvm.pop();

   745                     // unknown field; keep going...

   746                     break;

   747                 }

   748 

   749                 case opc_invokestatic:

   750                 case opc_invokevirtual:

   751                 case opc_invokespecial:

   752                 {

   753                     boolean hasRecv = (bc != opc_invokestatic);

   754                     int methi = i.u2At(1);

   755                     char mark = poolMarks[methi];

   756                     Short[] ref = pool.getMemberRef((short)methi);

   757                     String type = pool.getString(CONSTANT_Utf8, ref[2]);

   758                     //System.out.println("invoke "+pool.getString(CONSTANT_Utf8, ref[1])+" "+Arrays.asList(ref)+" : "+type);

   759                     args = jvm.args(hasRecv, type);

   760                     String intrinsic = null;

   761                     Constant con;

   762                     if (mark == 'D' || mark == 'J') {

   763                         intrinsic = pool.getString(CONSTANT_Utf8, ref[1]);

   764                         if (mark == 'J') {

   765                             String cls = pool.getString(CONSTANT_Class, ref[0]);

   766                             cls = cls.substring(1+cls.lastIndexOf('/'));

   767                             intrinsic = cls+"."+intrinsic;

   768                         }

   769                         //System.out.println("recognized intrinsic "+intrinsic);

   770                         byte refKind = -1;

   771                         switch (intrinsic) {

   772                         case "findGetter":          refKind = REF_getField;         break;

   773                         case "findStaticGetter":    refKind = REF_getStatic;        break;

   774                         case "findSetter":          refKind = REF_putField;         break;

   775                         case "findStaticSetter":    refKind = REF_putStatic;        break;

   776                         case "findVirtual":         refKind = REF_invokeVirtual;    break;

   777                         case "findStatic":          refKind = REF_invokeStatic;     break;

   778                         case "findSpecial":         refKind = REF_invokeSpecial;    break;

   779                         case "findConstructor":     refKind = REF_newInvokeSpecial; break;

   780                         }

   781                         if (refKind >= 0 && (con = parseMemberLookup(refKind, args)) != null) {

   782                             args.clear(); args.add(con);

   783                             continue;

   784                         }

   785                     }

   786                     Method ownMethod = null;

   787                     if (mark == 'T' || mark == 'H' || mark == 'I') {

   788                         ownMethod = findMember(cf.methods, ref[1], ref[2]);

   789                     }

   790                     //if (intrinsic != null)  System.out.println("intrinsic = "+intrinsic);

   791                     switch (intrinsic == null ? "" : intrinsic) {

   792                     case "fromMethodDescriptorString":

   793                         con = makeMethodTypeCon(args.get(0));

   794                         args.clear(); args.add(con);

   795                         continue;

   796                     case "methodType": {

   797                         flattenVarargs(args);  // there are several overloadings, some with varargs

   798                         StringBuilder buf = new StringBuilder();

   799                         String rtype = null;

   800                         for (Object typeArg : args) {

   801                             if (typeArg instanceof Class) {

   802                                 Class<?> argClass = (Class<?>) typeArg;

   803                                 if (argClass.isPrimitive()) {

   804                                     char tchar;

   805                                     switch (argClass.getName()) {

   806                                     case "void":    tchar = 'V'; break;

   807                                     case "boolean": tchar = 'Z'; break;

   808                                     case "byte":    tchar = 'B'; break;

   809                                     case "char":    tchar = 'C'; break;

   810                                     case "short":   tchar = 'S'; break;

   811                                     case "int":     tchar = 'I'; break;

   812                                     case "long":    tchar = 'J'; break;

   813                                     case "float":   tchar = 'F'; break;

   814                                     case "double":  tchar = 'D'; break;

   815                                     default:  throw new InternalError(argClass.toString());

   816                                     }

   817                                     buf.append(tchar);

   818                                 } else {

   819                                     // should not happen, but...

   820                                     buf.append('L').append(argClass.getName().replace('.','/')).append(';');

   821                                 }

   822                             } else if (typeArg instanceof Constant) {

   823                                 Constant argCon = (Constant) typeArg;

   824                                 if (argCon.tag == CONSTANT_Class) {

   825                                     String cn = pool.get(argCon.itemIndex()).itemString();

   826                                     if (cn.endsWith(";"))

   827                                         buf.append(cn);

   828                                     else

   829                                         buf.append('L').append(cn).append(';');

   830                                 } else {

   831                                     break decode;

   832                                 }

   833                             } else {

   834                                 break decode;

   835                             }

   836                             if (rtype == null) {

   837                                 // first arg is treated differently

   838                                 rtype = buf.toString();

   839                                 buf.setLength(0);

   840                                 buf.append('(');

   841                             }

   842                         }

   843                         buf.append(')').append(rtype);

   844                         con = con = makeMethodTypeCon(buf.toString());

   845                         args.clear(); args.add(con);

   846                         continue;

   847                     }

   848                     case "lookup":

   849                     case "dynamicInvoker":

   850                         args.clear(); args.add(intrinsic);

   851                         continue;

   852                     case "lookupClass":

   853                         if (args.equals(Arrays.asList("lookup"))) {

   854                             // fold lookup().lookupClass() to the enclosing class

   855                             args.clear(); args.add(pool.get(cf.thisc));

   856                             continue;

   857                         }

   858                         break;

   859                     case "invokeGeneric":

   860                     case "invokeWithArguments":

   861                         if (patternMark != 'I')  break decode;

   862                         if ("invokeWithArguments".equals(intrinsic))

   863                             flattenVarargs(args);

   864                         bsmArgs = new ArrayList(args);

   865                         args.clear(); args.add("invokeGeneric");

   866                         continue;

   867                     case "Integer.valueOf":

   868                     case "Float.valueOf":

   869                     case "Long.valueOf":

   870                     case "Double.valueOf":

   871                         removeEmptyJVMSlots(args);

   872                         if (args.size() == 1) {

   873                             arg = args.remove(0);

   874                             assert(3456 == (CONSTANT_Integer*1000 + CONSTANT_Float*100 + CONSTANT_Long*10 + CONSTANT_Double));

   875                             if (isConstant(arg, CONSTANT_Integer + "IFLD".indexOf(intrinsic.charAt(0)))

   876                                 || arg instanceof Number) {

   877                                 args.add(arg); continue;

   878                             }

   879                         }

   880                         break decode;

   881                     case "StringBuilder.append":

   882                         // allow calls like ("value = "+x)

   883                         removeEmptyJVMSlots(args);

   884                         args.subList(1, args.size()).clear();

   885                         continue;

   886                     case "StringBuilder.toString":

   887                         args.clear();

   888                         args.add(intrinsic);

   889                         continue;

   890                     }

   891                     if (!hasRecv && ownMethod != null && patternMark != 0) {

   892                         con = constants.get(ownMethod);

   893                         if (con == null)  break decode;

   894                         args.clear(); args.add(con);

   895                         continue;

   896                     } else if (type.endsWith(")V")) {

   897                         // allow calls like println("reached the pattern method")

   898                         args.clear();

   899                         continue;

   900                     }

   901                     break decode;  // bail out for most calls

   902                 }

   903                 case opc_areturn:

   904                 {

   905                     ++branchCount;

   906                     if (bsmArgs != null) {

   907                         // parse bsmArgs as (MH, lookup, String, MT, [extra])

   908                         Constant indyCon = makeInvokeDynamicCon(bsmArgs);

   909                         if (indyCon != null) {

   910                             Constant typeCon = (Constant) bsmArgs.get(3);

   911                             indySignatures.put(m, pool.getString(typeCon.itemIndex()));

   912                             return indyCon;

   913                         }

   914                         System.err.println(m+": inscrutable bsm arguments: "+bsmArgs);

   915                         break decode;  // bail out

   916                     }

   917                     arg = jvm.pop();

   918                     if (branchCount == 2 && UNKNOWN_CON.equals(arg))

   919                         break;  // merge to next path

   920                     if (isConstant(arg, wantTag))

   921                         return (Constant) arg;

   922                     break decode;  // bail out

   923                 }

   924                 default:

   925                     if (jvm.stackMotion(i.bc))  break;

   926                     if (bc >= opc_nconst_MIN && bc <= opc_nconst_MAX)

   927                         { jvm.push(INSTRUCTION_CONSTANTS[bc - opc_nconst_MIN]); break; }

   928                     if (patternMark == 'I') {

   929                         // these support caching paths in INDY_x methods

   930                         if (bc == opc_aload || bc >= opc_aload_0 && bc <= opc_aload_MAX)

   931                             { jvm.push(UNKNOWN_CON); break; }

   932                         if (bc == opc_astore || bc >= opc_astore_0 && bc <= opc_astore_MAX)

   933                             { jvm.pop(); break; }

   934                         switch (bc) {

   935                         case opc_getfield:

   936                         case opc_aaload:

   937                             jvm.push(UNKNOWN_CON); break;

   938                         case opc_ifnull:

   939                         case opc_ifnonnull:

   940                             // ignore branch target

   941                             if (++branchCount != 1)  break decode;

   942                             jvm.pop();

   943                             break;

   944                         case opc_checkcast:

   945                             arg = jvm.top();

   946                             if ("invokeWithArguments".equals(arg) ||

   947                                 "invokeGeneric".equals(arg))

   948                                 break;  // assume it is a helpful cast

   949                             break decode;

   950                         default:

   951                             break decode;  // bail out

   952                         }

   953                         continue decode; // go to next instruction

   954                     }

   955                     break decode;  // bail out

   956                 } //end switch

   957             }

   958             System.err.println(m+": bailout on "+i+" jvm stack: "+jvm.stack);

   959             return null;

   960         }

   961         private final String UNKNOWN_CON = "<unknown>";

   962 

   963         private void flattenVarargs(List<Object> args) {

   964             int size = args.size();

   965             if (size > 0 && args.get(size-1) instanceof List)

   966                 args.addAll((List<Object>) args.remove(size-1));

   967         }

   968 

   969         private boolean isConstant(Object x, int tag) {

   970             return x instanceof Constant && ((Constant)x).tag == tag;

   971         }

   972         private Constant makeMethodTypeCon(Object x) {

   973             short utfIndex;

   974             if (x instanceof String)

   975                 utfIndex = (short) cf.pool.addConstant(CONSTANT_Utf8, x).index;

   976             else if (isConstant(x, CONSTANT_String))

   977                 utfIndex = ((Constant)x).itemIndex();

   978             else  return null;

   979             return cf.pool.addConstant(CONSTANT_MethodType, utfIndex);

   980         }

   981         private Constant parseMemberLookup(byte refKind, List<Object> args) {

   982             // E.g.: lookup().findStatic(Foo.class, "name", MethodType)

   983             if (args.size() != 4)  return null;

   984             int argi = 0;

   985             if (!"lookup".equals(args.get(argi++)))  return null;

   986             short refindex, cindex, ntindex, nindex, tindex;

   987             Object con;

   988             if (!isConstant(con = args.get(argi++), CONSTANT_Class))  return null;

   989             cindex = (short)((Constant)con).index;

   990             if (!isConstant(con = args.get(argi++), CONSTANT_String))  return null;

   991             nindex = ((Constant)con).itemIndex();

   992             if (isConstant(con = args.get(argi++), CONSTANT_MethodType) ||

   993                 isConstant(con, CONSTANT_Class)) {

   994                 tindex = ((Constant)con).itemIndex();

   995             } else return null;

   996             ntindex = (short) cf.pool.addConstant(CONSTANT_NameAndType,

   997                     new Short[]{ nindex, tindex }).index;

   998             byte reftag = CONSTANT_Method;

   999             if (refKind <= REF_putStatic)

  1000                 reftag = CONSTANT_Field;

  1001             else if (refKind == REF_invokeInterface)

  1002                 reftag = CONSTANT_InterfaceMethod;

  1003             Constant ref = cf.pool.addConstant(reftag, new Short[]{ cindex, ntindex });

  1004             return cf.pool.addConstant(CONSTANT_MethodHandle, new Object[]{ refKind, (short)ref.index });

  1005         }

  1006         private Constant makeInvokeDynamicCon(List<Object> args) {

  1007             // E.g.: MH_bsm.invokeGeneric(lookup(), "name", MethodType, "extraArg")

  1008             removeEmptyJVMSlots(args);

  1009             if (args.size() != 4 && args.size() != 5)  return null;

  1010             int argi = 0;

  1011             short nindex, tindex, ntindex, bsmindex;

  1012             Object con;

  1013             if (!isConstant(con = args.get(argi++), CONSTANT_MethodHandle))  return null;

  1014             bsmindex = (short) ((Constant)con).index;

  1015             if (!"lookup".equals(args.get(argi++)))  return null;

  1016             if (!isConstant(con = args.get(argi++), CONSTANT_String))  return null;

  1017             nindex = ((Constant)con).itemIndex();

  1018             if (!isConstant(con = args.get(argi++), CONSTANT_MethodType))  return null;

  1019             tindex = ((Constant)con).itemIndex();

  1020             ntindex = (short) cf.pool.addConstant(CONSTANT_NameAndType,

  1021                                                   new Short[]{ nindex, tindex }).index;

  1022             if (transitionalJSR292) {

  1023                 if (argi != args.size()) {

  1024                     System.err.println("BSM specifier has extra arguments but transitionalJSR292=1");

  1025                     return null;

  1026                 }

  1027                 return cf.pool.addConstant(CONSTANT_InvokeDynamic_17,

  1028                         new Short[]{ bsmindex, ntindex });

  1029             }

  1030             List<Object> extraArgs = Collections.emptyList();

  1031             if (argi < args.size()) {

  1032                 Object arg = args.get(argi);

  1033                 if (arg instanceof List)

  1034                     extraArgs = (List<Object>) arg;

  1035                 else

  1036                     extraArgs = Arrays.asList(arg);

  1037                 removeEmptyJVMSlots(args);

  1038             }

  1039             List<Short> extraArgIndexes = new CountedList<>(Short.class);

  1040             for (Object x : extraArgs) {

  1041                 if (x instanceof Number) {

  1042                     Object num = null; byte numTag = 0;

  1043                     if (x instanceof Integer) { num = x; numTag = CONSTANT_Integer; }

  1044                     if (x instanceof Float)   { num = Float.floatToRawIntBits((Float)x); numTag = CONSTANT_Float; }

  1045                     if (x instanceof Long)    { num = x; numTag = CONSTANT_Long; }

  1046                     if (x instanceof Double)  { num = Double.doubleToRawLongBits((Double)x); numTag = CONSTANT_Double; }

  1047                     if (num != null)  x = cf.pool.addConstant(numTag, x);

  1048                 }

  1049                 if (!(x instanceof Constant))  return null;

  1050                 extraArgIndexes.add((short) ((Constant)x).index);

  1051             }

  1052             List<Object[]> specs = bootstrapMethodSpecifiers(true);

  1053             int specindex = -1;

  1054             Object[] spec = new Object[]{ bsmindex, extraArgIndexes };

  1055             for (Object[] spec1 : specs) {

  1056                 if (Arrays.equals(spec1, spec)) {

  1057                     specindex = specs.indexOf(spec1);

  1058                     if (verbose)  System.err.println("reusing BSM specifier: "+spec1[0]+spec1[1]);

  1059                     break;

  1060                 }

  1061             }

  1062             if (specindex == -1) {

  1063                 specindex = (short) specs.size();

  1064                 specs.add(spec);

  1065                 if (verbose)  System.err.println("adding BSM specifier: "+spec[0]+spec[1]);

  1066             }

  1067             return cf.pool.addConstant(CONSTANT_InvokeDynamic,

  1068                         new Short[]{ (short)specindex, ntindex });

  1069         }

  1070 

  1071         List<Object[]> bootstrapMethodSpecifiers(boolean createIfNotFound) {

  1072             Attr bsms = cf.findAttr("BootstrapMethods");

  1073             if (bsms == null) {

  1074                 if (!createIfNotFound)  return null;

  1075                 bsms = new Attr(cf, "BootstrapMethods", new byte[]{0,0});

  1076                 assert(bsms == cf.findAttr("BootstrapMethods"));

  1077             }

  1078             if (bsms.item instanceof byte[]) {

  1079                 // unflatten

  1080                 List<Object[]> specs = new CountedList<>(Object[].class);

  1081                 DataInputStream in = new DataInputStream(new ByteArrayInputStream((byte[]) bsms.item));

  1082                 try {

  1083                     int len = (char) in.readShort();

  1084                     for (int i = 0; i < len; i++) {

  1085                         short bsm = in.readShort();

  1086                         int argc = (char) in.readShort();

  1087                         List<Short> argv = new CountedList<>(Short.class);

  1088                         for (int j = 0; j < argc; j++)

  1089                             argv.add(in.readShort());

  1090                         specs.add(new Object[]{ bsm, argv });

  1091                     }

  1092                 } catch (IOException ex) { throw new InternalError(); }

  1093                 bsms.item = specs;

  1094             }

  1095             return (List<Object[]>) bsms.item;

  1096         }

  1097     }

  1098 

  1099     private DataInputStream openInput(File f) throws IOException {

  1100         return new DataInputStream(new BufferedInputStream(new FileInputStream(f)));

  1101     }

  1102 

  1103     private DataOutputStream openOutput(File f) throws IOException {

  1104         if (!overwrite && f.exists())

  1105             throw new IOException("file already exists: "+f);

  1106         ensureDirectory(f.getParentFile());

  1107         return new DataOutputStream(new BufferedOutputStream(new FileOutputStream(f)));

  1108     }

  1109 

  1110     static byte[] readRawBytes(DataInputStream in, int size) throws IOException {

  1111         byte[] bytes = new byte[size];

  1112         int nr = in.read(bytes);

  1113         if (nr != size)

  1114             throw new InternalError("wrong size: "+nr);

  1115         return bytes;

  1116     }

  1117 

  1118     private interface Chunk {

  1119         void readFrom(DataInputStream in) throws IOException;

  1120         void writeTo(DataOutputStream out) throws IOException;

  1121     }

  1122 

  1123     private static class CountedList<T> extends ArrayList<T> implements Chunk {

  1124         final Class<? extends T> itemClass;

  1125         final int rowlen;

  1126         CountedList(Class<? extends T> itemClass, int rowlen) {

  1127             this.itemClass = itemClass;

  1128             this.rowlen = rowlen;

  1129         }

  1130         CountedList(Class<? extends T> itemClass) { this(itemClass, -1); }

  1131         public void readFrom(DataInputStream in) throws IOException {

  1132             int count = in.readUnsignedShort();

  1133             while (size() < count) {

  1134                 if (rowlen < 0) {