1 /*

     2  * Copyright (c) 2008, 2009, 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 sun.dyn.anon;

    27 

    28 import java.io.IOException;

    29 import java.io.OutputStream;

    30 import java.nio.BufferUnderflowException;

    31 import java.nio.ByteBuffer;

    32 

    33 import static sun.dyn.anon.ConstantPoolVisitor.*;

    34 

    35 /** A constant pool parser.

    36  */

    37 public class ConstantPoolParser {

    38     final byte[] classFile;

    39     final byte[] tags;

    40     final char[] firstHeader;  // maghi, maglo, minor, major, cplen

    41 

    42     // these are filled in on first parse:

    43     int endOffset;

    44     char[] secondHeader;       // flags, this_class, super_class, intlen

    45 

    46     // used to decode UTF8 array

    47     private char[] charArray = new char[80];

    48 

    49     /** Creates a constant pool parser.

    50      * @param classFile an array of bytes containing a class.

    51      * @throws InvalidConstantPoolFormatException if the header of the class has errors.

    52      */

    53     public ConstantPoolParser(byte[] classFile) throws InvalidConstantPoolFormatException {

    54         this.classFile = classFile;

    55         this.firstHeader = parseHeader(classFile);

    56         this.tags = new byte[firstHeader[4]];

    57     }

    58 

    59     /** Create a constant pool parser by loading the bytecodes of the

    60      *  class taken as argument.

    61      *

    62      * @param templateClass the class to parse.

    63      *

    64      * @throws IOException raised if an I/O occurs when loading

    65      *  the bytecode of the template class.

    66      * @throws InvalidConstantPoolFormatException if the header of the class has errors.

    67      *

    68      * @see #ConstantPoolParser(byte[])

    69      * @see AnonymousClassLoader#readClassFile(Class)

    70      */

    71     public ConstantPoolParser(Class<?> templateClass) throws IOException, InvalidConstantPoolFormatException {

    72         this(AnonymousClassLoader.readClassFile(templateClass));

    73     }

    74 

    75     /** Creates an empty patch to patch the class file

    76      *  used by the current parser.

    77      * @return a new class patch.

    78      */

    79     public ConstantPoolPatch createPatch() {

    80         return new ConstantPoolPatch(this);

    81     }

    82 

    83     /** Report the tag of the indicated CP entry.

    84      * @param index

    85      * @return one of {@link ConstantPoolVisitor#CONSTANT_Utf8}, etc.

    86      */

    87     public byte getTag(int index) {

    88         getEndOffset();  // trigger an exception if we haven't parsed yet

    89         return tags[index];

    90     }

    91 

    92     /** Report the length of the constant pool. */

    93     public int getLength() {

    94         return firstHeader[4];

    95     }

    96 

    97     /** Report the offset, within the class file, of the start of the constant pool. */

    98     public int getStartOffset() {

    99         return firstHeader.length * 2;

   100     }

   101 

   102     /** Report the offset, within the class file, of the end of the constant pool. */

   103     public int getEndOffset() {

   104         if (endOffset == 0)

   105             throw new IllegalStateException("class file has not yet been parsed");

   106         return endOffset;

   107     }

   108 

   109     /** Report the CP index of this class's own name. */

   110     public int getThisClassIndex() {

   111         getEndOffset();   // provoke exception if not yet parsed

   112         return secondHeader[1];

   113     }

   114 

   115     /** Report the total size of the class file. */

   116     public int getTailLength() {

   117         return classFile.length - getEndOffset();

   118     }

   119 

   120     /** Write the head (header plus constant pool)

   121      *  of the class file to the indicated stream.

   122      */

   123     public void writeHead(OutputStream out) throws IOException {

   124         out.write(classFile, 0, getEndOffset());

   125     }

   126 

   127     /** Write the head (header plus constant pool)

   128      *  of the class file to the indicated stream,

   129      *  incorporating the non-null entries of the given array

   130      *  as patches.

   131      */

   132     void writePatchedHead(OutputStream out, Object[] patchArray) {

   133         // this will be useful to partially emulate the class loader on old JVMs

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

   135     }

   136 

   137     /** Write the tail (everything after the constant pool)

   138      *  of the class file to the indicated stream.

   139      */

   140     public void writeTail(OutputStream out) throws IOException {

   141         out.write(classFile, getEndOffset(), getTailLength());

   142     }

   143 

   144     private static char[] parseHeader(byte[] classFile) throws InvalidConstantPoolFormatException {

   145         char[] result = new char[5];

   146         ByteBuffer buffer = ByteBuffer.wrap(classFile);

   147         for (int i = 0; i < result.length; i++)

   148             result[i] = (char) getUnsignedShort(buffer);

   149         int magic = result[0] << 16 | result[1] << 0;

   150         if (magic != 0xCAFEBABE)

   151             throw new InvalidConstantPoolFormatException("invalid magic number "+magic);

   152         // skip major, minor version

   153         int len = result[4];

   154         if (len < 1)

   155             throw new InvalidConstantPoolFormatException("constant pool length < 1");

   156         return result;

   157     }

   158 

   159     /** Parse the constant pool of the class

   160      *  calling a method visit* each time a constant pool entry is parsed.

   161      *

   162      *  The order of the calls to visit* is not guaranteed to be the same

   163      *  than the order of the constant pool entry in the bytecode array.

   164      *

   165      * @param visitor

   166      * @throws InvalidConstantPoolFormatException

   167      */

   168     public void parse(ConstantPoolVisitor visitor) throws InvalidConstantPoolFormatException {

   169         ByteBuffer buffer = ByteBuffer.wrap(classFile);

   170         buffer.position(getStartOffset()); //skip header

   171 

   172         Object[] values = new Object[getLength()];

   173         try {

   174             parseConstantPool(buffer, values, visitor);

   175         } catch(BufferUnderflowException e) {

   176             throw new InvalidConstantPoolFormatException(e);

   177         }

   178         if (endOffset == 0) {

   179             endOffset = buffer.position();

   180             secondHeader = new char[4];

   181             for (int i = 0; i < secondHeader.length; i++) {

   182                 secondHeader[i] = (char) getUnsignedShort(buffer);

   183             }

   184         }

   185         resolveConstantPool(values, visitor);

   186     }

   187 

   188     private char[] getCharArray(int utfLength) {

   189         if (utfLength <= charArray.length)

   190             return charArray;

   191         return charArray = new char[utfLength];

   192     }

   193 

   194     private void parseConstantPool(ByteBuffer buffer, Object[] values, ConstantPoolVisitor visitor) throws InvalidConstantPoolFormatException {

   195         for (int i = 1; i < tags.length; ) {

   196             byte tag = (byte) getUnsignedByte(buffer);

   197             assert(tags[i] == 0 || tags[i] == tag);

   198             tags[i] = tag;

   199             switch (tag) {

   200                 case CONSTANT_Utf8:

   201                     int utfLen = getUnsignedShort(buffer);

   202                     String value = getUTF8(buffer, utfLen, getCharArray(utfLen));

   203                     visitor.visitUTF8(i, CONSTANT_Utf8, value);

   204                     tags[i] = tag;

   205                     values[i++] = value;

   206                     break;

   207                 case CONSTANT_Integer:

   208                     visitor.visitConstantValue(i, tag, buffer.getInt());

   209                     i++;

   210                     break;

   211                 case CONSTANT_Float:

   212                     visitor.visitConstantValue(i, tag, buffer.getFloat());

   213                     i++;

   214                     break;

   215                 case CONSTANT_Long:

   216                     visitor.visitConstantValue(i, tag, buffer.getLong());

   217                     i+=2;

   218                     break;

   219                 case CONSTANT_Double:

   220                     visitor.visitConstantValue(i, tag, buffer.getDouble());

   221                     i+=2;

   222                     break;

   223 

   224                 case CONSTANT_Class:    // fall through:

   225                 case CONSTANT_String:

   226                     tags[i] = tag;

   227                     values[i++] = new int[] { getUnsignedShort(buffer) };

   228                     break;

   229 

   230                 case CONSTANT_Fieldref:           // fall through:

   231                 case CONSTANT_Methodref:          // fall through:

   232                 case CONSTANT_InterfaceMethodref: // fall through:

   233                 case CONSTANT_NameAndType:

   234                     tags[i] = tag;

   235                     values[i++] = new int[] { getUnsignedShort(buffer), getUnsignedShort(buffer) };

   236                     break;

   237                 default:

   238                     throw new AssertionError("invalid constant "+tag);

   239             }

   240         }

   241     }

   242 

   243     private void resolveConstantPool(Object[] values, ConstantPoolVisitor visitor) {

   244         // clean out the int[] values, which are temporary

   245         for (int beg = 1, end = values.length-1, beg2, end2;

   246              beg <= end;

   247              beg = beg2, end = end2) {

   248              beg2 = end; end2 = beg-1;

   249              //System.out.println("CP resolve pass: "+beg+".."+end);

   250              for (int i = beg; i <= end; i++) {

   251                   Object value = values[i];

   252                   if (!(value instanceof int[]))

   253                       continue;

   254                   int[] array = (int[]) value;

   255                   byte tag = tags[i];

   256                   switch (tag) {

   257                       case CONSTANT_String:

   258                           String stringBody = (String) values[array[0]];

   259                           visitor.visitConstantString(i, tag, stringBody, array[0]);

   260                           values[i] = null;

   261                           break;

   262                       case CONSTANT_Class: {

   263                           String className = (String) values[array[0]];

   264                           // use the external form favored by Class.forName:

   265                           className = className.replace('/', '.');

   266                           visitor.visitConstantString(i, tag, className, array[0]);

   267                           values[i] = className;

   268                           break;

   269                       }

   270                       case CONSTANT_NameAndType: {

   271                           String memberName = (String) values[array[0]];

   272                           String signature  = (String) values[array[1]];

   273                           visitor.visitDescriptor(i, tag, memberName, signature,

   274                                                   array[0], array[1]);

   275                           values[i] = new String[] {memberName, signature};

   276                           break;

   277                       }

   278                       case CONSTANT_Fieldref:           // fall through:

   279                       case CONSTANT_Methodref:          // fall through:

   280                       case CONSTANT_InterfaceMethodref: {

   281                               Object className   = values[array[0]];

   282                               Object nameAndType = values[array[1]];

   283                               if (!(className instanceof String) ||

   284                                   !(nameAndType instanceof String[])) {

   285                                    // one more pass is needed

   286                                    if (beg2 > i)  beg2 = i;

   287                                    if (end2 < i)  end2 = i;

   288                                    continue;

   289                               }

   290                               String[] nameAndTypeArray = (String[]) nameAndType;

   291                               visitor.visitMemberRef(i, tag,

   292                                   (String)className,

   293                                   nameAndTypeArray[0],

   294                                   nameAndTypeArray[1],

   295                                   array[0], array[1]);

   296                               values[i] = null;

   297                           }

   298                           break;

   299                       default:

   300                           continue;

   301                 }

   302             }

   303         }

   304     }

   305 

   306     private static int getUnsignedByte(ByteBuffer buffer) {

   307         return buffer.get() & 0xFF;

   308     }

   309 

   310     private static int getUnsignedShort(ByteBuffer buffer) {

   311         int b1 = getUnsignedByte(buffer);

   312         int b2 = getUnsignedByte(buffer);

   313         return (b1 << 8) + (b2 << 0);

   314     }

   315 

   316     private static String getUTF8(ByteBuffer buffer, int utfLen, char[] charArray) throws InvalidConstantPoolFormatException {

   317       int utfLimit = buffer.position() + utfLen;

   318       int index = 0;

   319       while (buffer.position() < utfLimit) {

   320           int c = buffer.get() & 0xff;

   321           if (c > 127) {

   322               buffer.position(buffer.position() - 1);

   323               return getUTF8Extended(buffer, utfLimit, charArray, index);

   324           }

   325           charArray[index++] = (char)c;

   326       }

   327       return new String(charArray, 0, index);

   328     }

   329 

   330     private static String getUTF8Extended(ByteBuffer buffer, int utfLimit, char[] charArray, int index) throws InvalidConstantPoolFormatException {

   331         int c, c2, c3;

   332         while (buffer.position() < utfLimit) {

   333             c = buffer.get() & 0xff;

   334             switch (c >> 4) {

   335                 case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:

   336                     /* 0xxxxxxx*/

   337                     charArray[index++] = (char)c;

   338                     break;

   339                 case 12: case 13:

   340                     /* 110x xxxx   10xx xxxx*/

   341                     c2 = buffer.get();

   342                     if ((c2 & 0xC0) != 0x80)

   343                         throw new InvalidConstantPoolFormatException(

   344                             "malformed input around byte " + buffer.position());

   345                      charArray[index++] = (char)(((c  & 0x1F) << 6) |

   346                                                   (c2 & 0x3F));

   347                     break;

   348                 case 14:

   349                     /* 1110 xxxx  10xx xxxx  10xx xxxx */

   350                     c2 = buffer.get();

   351                     c3 = buffer.get();

   352                     if (((c2 & 0xC0) != 0x80) || ((c3 & 0xC0) != 0x80))

   353                        throw new InvalidConstantPoolFormatException(

   354                           "malformed input around byte " + (buffer.position()));

   355                     charArray[index++] = (char)(((c  & 0x0F) << 12) |

   356                                                 ((c2 & 0x3F) << 6)  |

   357                                                 ((c3 & 0x3F) << 0));

   358                     break;

   359                 default:

   360                     /* 10xx xxxx,  1111 xxxx */

   361                     throw new InvalidConstantPoolFormatException(

   362                         "malformed input around byte " + buffer.position());

   363             }

   364         }

   365         // The number of chars produced may be less than utflen

   366         return new String(charArray, 0, index);

   367     }

   368 }