1 /*
  2  * Copyright (c) 2019, 2021, 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 com.sun.tools.javac.jvm;
 27 
 28 import com.sun.tools.javac.code.Kinds.Kind;
 29 import com.sun.tools.javac.code.Symbol;
 30 import com.sun.tools.javac.code.Symbol.ClassSymbol;
 31 import com.sun.tools.javac.code.Symbol.DynamicMethodSymbol;
 32 import com.sun.tools.javac.code.Symbol.MethodHandleSymbol;
 33 import com.sun.tools.javac.code.Symbol.ModuleSymbol;
 34 import com.sun.tools.javac.code.Symbol.PackageSymbol;
 35 import com.sun.tools.javac.code.Type;
 36 import com.sun.tools.javac.code.Types;
 37 import com.sun.tools.javac.jvm.ClassWriter.PoolOverflow;
 38 import com.sun.tools.javac.jvm.ClassWriter.StringOverflow;
 39 import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant;
 40 import com.sun.tools.javac.jvm.PoolConstant.LoadableConstant.BasicConstant;
 41 import com.sun.tools.javac.jvm.PoolConstant.Dynamic;
 42 import com.sun.tools.javac.jvm.PoolConstant.Dynamic.BsmKey;
 43 import com.sun.tools.javac.jvm.PoolConstant.NameAndType;
 44 import com.sun.tools.javac.util.ByteBuffer;
 45 import com.sun.tools.javac.util.InvalidUtfException;
 46 import com.sun.tools.javac.util.List;
 47 import com.sun.tools.javac.util.Name;
 48 import com.sun.tools.javac.util.Names;
 49 
 50 import java.io.IOException;
 51 import java.io.OutputStream;
 52 import java.util.ArrayDeque;
 53 import java.util.HashMap;
 54 import java.util.HashSet;
 55 import java.util.LinkedHashMap;
 56 import java.util.LinkedHashSet;
 57 import java.util.Map;
 58 import java.util.Set;
 59 
 60 import static com.sun.tools.javac.code.Kinds.Kind.TYP;
 61 import static com.sun.tools.javac.code.TypeTag.ARRAY;
 62 import static com.sun.tools.javac.code.TypeTag.CLASS;
 63 import static com.sun.tools.javac.jvm.ClassFile.CONSTANT_Class;
 64 import static com.sun.tools.javac.jvm.ClassFile.CONSTANT_MethodType;
 65 import static com.sun.tools.javac.jvm.ClassFile.externalize;
 66 
 67 /**
 68  * Pool interface towards {@code ClassWriter}. Exposes methods to encode and write javac entities
 69  * into the constant pool.
 70  *
 71  *  <p><b>This is NOT part of any supported API.
 72  *  If you write code that depends on this, you do so at your own risk.
 73  *  This code and its internal interfaces are subject to change or
 74  *  deletion without notice.</b>
 75  */
 76 public class PoolWriter {
 77 
 78     /** Max number of constant pool entries. */
 79     public static final int MAX_ENTRIES = 0xFFFF;
 80 
 81     /** Max number of char in a string constant. */
 82     public static final int MAX_STRING_LENGTH = 0xFFFF;
 83 
 84     private static final int POOL_BUF_SIZE = 0x7fff;
 85 
 86     private final Types types;
 87 
 88     private final Names names;
 89 
 90     /** Pool helper **/
 91     final WriteablePoolHelper pool;
 92 
 93     /** Sole signature generator */
 94     final SharedSignatureGenerator signatureGen;
 95 
 96     /** The inner classes to be written, as an ordered set (enclosing first). */
 97     LinkedHashSet<ClassSymbol> innerClasses = new LinkedHashSet<>();
 98 
 99     Set<Symbol> loadableDescriptors = new HashSet<>();
100 
101     /** The list of entries in the BootstrapMethods attribute. */
102     Map<BsmKey, Integer> bootstrapMethods = new LinkedHashMap<>();
103 
104     public PoolWriter(Types types, Names names) {
105         this.types = types;
106         this.names = names;
107         this.signatureGen = new SharedSignatureGenerator(types);
108         this.pool = new WriteablePoolHelper();
109     }
110 
111     /**
112      * Puts a class symbol into the pool and return its index.
113      */
114     int putClass(ClassSymbol csym) {
115         return putClass(csym.type);
116     }
117 
118     /**
119      * Puts a type into the pool and return its index. The type could be either a class, a type variable
120      * or an array type.
121      */
122     int putClass(Type t) {
123         return pool.writeIfNeeded(types.erasure(t));
124     }
125 
126     /**
127      * Puts a member reference into the constant pool. Valid members are either field or method symbols.
128      */
129     int putMember(Symbol s) {
130         return pool.writeIfNeeded(s);
131     }
132 
133     /**
134      * Puts a dynamic reference into the constant pool and return its index.
135      */
136     int putDynamic(Dynamic d) {
137         return pool.writeIfNeeded(d);
138     }
139 
140     /**
141      * Puts a field or method descriptor into the constant pool and return its index.
142      */
143     int putDescriptor(Type t) {
144         return putName(typeSig(types.erasure(t)));
145     }
146 
147     /**
148      * Puts a field or method descriptor into the constant pool and return its index.
149      */
150     int putDescriptor(Symbol s) {
151         return putDescriptor(descriptorType(s));
152     }
153 
154     /**
155      * Puts a signature (see {@code Signature} attribute in JVMS 4.4) into the constant pool and
156      * return its index.
157      */
158     int putSignature(Symbol s) {
159         if (s.kind == TYP) {
160             return putName(classSig(s.type));
161         } else {
162             return putName(typeSig(s.type));
163         }
164     }
165 
166     /**
167      * Puts a constant value into the pool and return its index. Supported values are int, float, long,
168      * double and String.
169      */
170     int putConstant(Object o) {
171         if (o instanceof Integer intVal) {
172             return putConstant(LoadableConstant.Int(intVal));
173         } else if (o instanceof Float floatVal) {
174             return putConstant(LoadableConstant.Float(floatVal));
175         } else if (o instanceof Long longVal) {
176             return putConstant(LoadableConstant.Long(longVal));
177         } else if (o instanceof Double doubleVal) {
178             return putConstant(LoadableConstant.Double(doubleVal));
179         } else if (o instanceof String strVal) {
180             return putConstant(LoadableConstant.String(strVal));
181         } else {
182             throw new AssertionError("unexpected constant: " + o);
183         }
184     }
185 
186     /**
187      * Puts a constant into the pool and return its index.
188      */
189     int putConstant(LoadableConstant c) {
190         switch (c.poolTag()) {
191             case CONSTANT_Class:
192                 return putClass((Type)c);
193             case CONSTANT_MethodType:
194                 return pool.writeIfNeeded(types.erasure((Type)c));
195             default:
196                 return pool.writeIfNeeded(c);
197         }
198     }
199 
200     int putName(Name name) {
201         return pool.writeIfNeeded(name);
202     }
203 
204     /**
205      * Puts a name and type pair into the pool and returns its index.
206      */
207     int putNameAndType(Symbol s) {
208         return pool.writeIfNeeded(new NameAndType(s.name, descriptorType(s)));
209     }
210 
211     /**
212      * Puts a package entry into the pool and returns its index.
213      */
214     int putPackage(PackageSymbol pkg) {
215         return pool.writeIfNeeded(pkg);
216     }
217 
218     /**
219      * Puts a module entry into the pool and returns its index.
220      */
221     int putModule(ModuleSymbol mod) {
222         return pool.writeIfNeeded(mod);
223     }
224 
225     /**
226      * Enter an inner class into the `innerClasses' set.
227      */
228     void enterInner(ClassSymbol c) {
229         if (c.type.isCompound()) {
230             throw new AssertionError("Unexpected intersection type: " + c.type);
231         }
232         c.complete();
233         if (c.owner.enclClass() != null && !innerClasses.contains(c)) {
234             enterInner(c.owner.enclClass());
235             innerClasses.add(c);
236         }
237     }
238 
239     /** Enter a value class into the `loadableDescriptorsClasses' set.
240      */
241     void enterLoadableDescriptorsClass(Symbol c) {
242         if (c.type.isCompound()) {
243             throw new AssertionError("Unexpected intersection type: " + c.type);
244         }
245         c.complete();
246         loadableDescriptors.add(c);
247     }
248 
249     /**
250      * Create a new Utf8 entry representing a descriptor for given (member) symbol.
251      */
252     private Type descriptorType(Symbol s) {
253         return s.kind == Kind.MTH ? s.externalType(types) : s.erasure(types);
254     }
255 
256     private int makeBootstrapEntry(Dynamic dynamic) {
257         BsmKey bsmKey = dynamic.bsmKey(types);
258 
259         // Figure out the index for existing BSM; create a new BSM if no key
260         Integer index = bootstrapMethods.get(bsmKey);
261         if (index == null) {
262             index = bootstrapMethods.size();
263             bootstrapMethods.put(bsmKey, index);
264         }
265 
266         return index;
267     }
268 
269     /**
270      * Write pool contents into given byte buffer.
271      */
272     void writePool(OutputStream out) throws IOException, PoolOverflow {
273         if (pool.overflowString != null) {
274             throw new StringOverflow(pool.overflowString);
275         }
276         int size = size();
277         if (size > MAX_ENTRIES) {
278             throw new PoolOverflow();
279         }
280         out.write(size >> 8);
281         out.write(size);
282         out.write(pool.poolbuf.elems, 0, pool.poolbuf.length);
283     }
284 
285     /**
286      * Signature Generation
287      */
288     class SharedSignatureGenerator extends Types.SignatureGenerator {
289 
290         /**
291          * An output buffer for type signatures.
292          */
293         ByteBuffer sigbuf = new ByteBuffer();
294 
295         SharedSignatureGenerator(Types types) {
296             super(types);
297         }
298 
299         /**
300          * Assemble signature of given type in string buffer.
301          * Check for uninitialized types before calling the general case.
302          */
303         @Override
304         public void assembleSig(Type type) {
305             switch (type.getTag()) {
306                 case UNINITIALIZED_THIS:
307                 case UNINITIALIZED_OBJECT:
308                     // we don't yet have a spec for uninitialized types in the
309                     // local variable table
310                     assembleSig(types.erasure(((UninitializedType)type).qtype));
311                     break;
312                 default:
313                     super.assembleSig(type);
314             }
315         }
316 
317         @Override
318         protected void append(char ch) {
319             sigbuf.appendByte(ch);
320         }
321 
322         @Override
323         protected void append(byte[] ba) {
324             sigbuf.appendBytes(ba);
325         }
326 
327         @Override
328         protected void append(Name name) {
329             sigbuf.appendName(name);
330         }
331 
332         @Override
333         protected void classReference(ClassSymbol c) {
334             enterInner(c);
335         }
336 
337         protected void reset() {
338             sigbuf.reset();
339         }
340 
341         protected Name toName() {
342             try {
343                 return sigbuf.toName(names);
344             } catch (InvalidUtfException e) {
345                 throw new AssertionError(e);
346             }
347         }
348     }
349 
350     class WriteablePoolHelper {
351 
352         /** Pool entries. */
353         private final Map<Object, Integer> keysToPos = new HashMap<>(64);
354 
355         final ByteBuffer poolbuf = new ByteBuffer(POOL_BUF_SIZE);
356 
357         int currentIndex = 1;
358 
359         ArrayDeque<PoolConstant> todo = new ArrayDeque<>();
360 
361         String overflowString = null;
362 
363         private <P extends PoolConstant> int writeIfNeeded(P p) {
364             Object key = p.poolKey(types);
365             Integer index = keysToPos.get(key);
366             if (index == null) {
367                 keysToPos.put(key, index = currentIndex++);
368                 boolean first = todo.isEmpty();
369                 todo.addLast(p);
370                 if (first) {
371                     while (!todo.isEmpty()) {
372                         writeConstant(todo.peekFirst());
373                         todo.removeFirst();
374                     }
375                 }
376             }
377             return index;
378         }
379 
380         void writeConstant(PoolConstant c) {
381             int tag = c.poolTag();
382             switch (tag) {
383                 case ClassFile.CONSTANT_Class: {
384                     Type ct = (Type)c;
385                     Name name = ct.hasTag(ARRAY) ?
386                             typeSig(ct) :
387                             externalize(ct.tsym.flatName());
388                     poolbuf.appendByte(tag);
389                     poolbuf.appendChar(putName(name));
390                     if (ct.hasTag(CLASS)) {
391                         enterInner((ClassSymbol)ct.tsym);
392                     }
393                     break;
394                 }
395                 case ClassFile.CONSTANT_Utf8: {
396                     Name name = (Name)c;
397                     poolbuf.appendByte(tag);
398                     byte[] bs = name.toUtf();
399                     poolbuf.appendChar(bs.length);
400                     poolbuf.appendBytes(bs, 0, bs.length);
401                     if (overflowString == null && bs.length > MAX_STRING_LENGTH) {
402                         //report error only once
403                         overflowString = new String(bs);
404                     }
405                     break;
406                 }
407                 case ClassFile.CONSTANT_InterfaceMethodref:
408                 case ClassFile.CONSTANT_Methodref:
409                 case ClassFile.CONSTANT_Fieldref: {
410                     Symbol sym = (Symbol)c;
411                     poolbuf.appendByte(tag);
412                     poolbuf.appendChar(putClass((ClassSymbol)sym.owner));
413                     poolbuf.appendChar(putNameAndType(sym));
414                     break;
415                 }
416                 case ClassFile.CONSTANT_Package: {
417                     PackageSymbol pkg = (PackageSymbol)c;
418                     Name pkgName = externalize(pkg.flatName());
419                     poolbuf.appendByte(tag);
420                     poolbuf.appendChar(putName(pkgName));
421                     break;
422                 }
423                 case ClassFile.CONSTANT_Module: {
424                     ModuleSymbol mod = (ModuleSymbol)c;
425                     int modName = putName(mod.name);
426                     poolbuf.appendByte(mod.poolTag());
427                     poolbuf.appendChar(modName);
428                     break;
429                 }
430                 case ClassFile.CONSTANT_Integer:
431                     poolbuf.appendByte(tag);
432                     poolbuf.appendInt((int)((BasicConstant)c).data);
433                     break;
434                 case ClassFile.CONSTANT_Float:
435                     poolbuf.appendByte(tag);
436                     poolbuf.appendFloat((float)((BasicConstant)c).data);
437                     break;
438                 case ClassFile.CONSTANT_Long:
439                     currentIndex++;
440                     poolbuf.appendByte(tag);
441                     poolbuf.appendLong((long)((BasicConstant)c).data);
442                     break;
443                 case ClassFile.CONSTANT_Double:
444                     currentIndex++;
445                     poolbuf.appendByte(tag);
446                     poolbuf.appendDouble((double)((BasicConstant)c).data);
447                     break;
448                 case ClassFile.CONSTANT_MethodHandle: {
449                     MethodHandleSymbol h = (MethodHandleSymbol)c;
450                     poolbuf.appendByte(tag);
451                     poolbuf.appendByte(h.referenceKind());
452                     poolbuf.appendChar(putMember(h.baseSymbol()));
453                     break;
454                 }
455                 case ClassFile.CONSTANT_MethodType: {
456                     Type.MethodType mt = (Type.MethodType)c;
457                     poolbuf.appendByte(tag);
458                     poolbuf.appendChar(putDescriptor(mt.baseType()));
459                     break;
460                 }
461                 case ClassFile.CONSTANT_String: {
462                     Name utf = names.fromString((String)((BasicConstant)c).data);
463                     poolbuf.appendByte(tag);
464                     poolbuf.appendChar(putName(utf));
465                     break;
466                 }
467                 case ClassFile.CONSTANT_NameandType: {
468                     NameAndType nt = (NameAndType)c;
469                     poolbuf.appendByte(tag);
470                     poolbuf.appendChar(putName(nt.name));
471                     poolbuf.appendChar(putDescriptor(nt.type));
472                     break;
473                 }
474                 case ClassFile.CONSTANT_InvokeDynamic: {
475                     DynamicMethodSymbol d = (DynamicMethodSymbol)c;
476                     poolbuf.appendByte(tag);
477                     poolbuf.appendChar(makeBootstrapEntry(d));
478                     poolbuf.appendChar(putNameAndType(d));
479                     break;
480                 }
481                 case ClassFile.CONSTANT_Dynamic: {
482                     Symbol.DynamicVarSymbol d = (Symbol.DynamicVarSymbol)c;
483                     poolbuf.appendByte(tag);
484                     poolbuf.appendChar(makeBootstrapEntry(d));
485                     poolbuf.appendChar(putNameAndType(d));
486                     break;
487                 }
488                 default:
489                     throw new AssertionError("Unexpected constant tag: " + tag);
490             }
491         }
492 
493         void reset() {
494             keysToPos.clear();
495             currentIndex = 1;
496             todo.clear();
497             overflowString = null;
498             poolbuf.reset();
499         }
500     }
501 
502     int size() {
503         return pool.currentIndex;
504     }
505 
506     /**
507      * Return signature of given type
508      */
509     private Name typeSig(Type type) {
510         signatureGen.reset();
511         signatureGen.assembleSig(type);
512         return signatureGen.toName();
513     }
514 
515     private Name classSig(Type t) {
516         signatureGen.reset();
517         List<Type> typarams = t.getTypeArguments();
518         if (typarams.nonEmpty()) {
519             signatureGen.assembleParamsSig(typarams);
520         }
521         signatureGen.assembleSig(types.supertype(t));
522         for (Type i : types.interfaces(t))
523             signatureGen.assembleSig(i);
524         return signatureGen.toName();
525     }
526 
527     void reset() {
528         innerClasses.clear();
529         loadableDescriptors.clear();
530         bootstrapMethods.clear();
531         pool.reset();
532     }
533 }