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src/java.base/share/classes/jdk/internal/classfile/impl/DirectClassBuilder.java

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 18  * You should have received a copy of the GNU General Public License version
 19  * 2 along with this work; if not, write to the Free Software Foundation,
 20  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 21  *
 22  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 23  * or visit www.oracle.com if you need additional information or have any
 24  * questions.
 25  */
 26 
 27 package jdk.internal.classfile.impl;
 28 
 29 import java.lang.classfile.*;
 30 import java.lang.classfile.constantpool.ClassEntry;
 31 import java.lang.classfile.constantpool.Utf8Entry;
 32 import java.lang.constant.ConstantDescs;
 33 import java.util.Arrays;
 34 import java.util.Collections;
 35 import java.util.List;
 36 import java.util.function.Consumer;
 37 


 38 import static java.util.Objects.requireNonNull;
 39 
 40 public final class DirectClassBuilder
 41         extends AbstractDirectBuilder<ClassModel>
 42         implements ClassBuilder {
 43 
 44     /** The value of default class access flags */
 45     static final int DEFAULT_CLASS_FLAGS = ClassFile.ACC_PUBLIC | ClassFile.ACC_SUPER;
 46     static final Util.Writable[] EMPTY_WRITABLE_ARRAY = {};

 47     static final ClassEntry[] EMPTY_CLASS_ENTRY_ARRAY = {};
 48     final ClassEntry thisClassEntry;
 49     private Util.Writable[] fields = EMPTY_WRITABLE_ARRAY;
 50     private Util.Writable[] methods = EMPTY_WRITABLE_ARRAY;
 51     private int fieldsCount = 0;
 52     private int methodsCount = 0;
 53     private ClassEntry superclassEntry;
 54     private List<ClassEntry> interfaceEntries;
 55     private int majorVersion;
 56     private int minorVersion;
 57     private int flags;
 58     private int sizeHint;
 59 
 60     public DirectClassBuilder(SplitConstantPool constantPool,
 61                               ClassFileImpl context,
 62                               ClassEntry thisClass) {
 63         super(constantPool, context);
 64         this.thisClassEntry = AbstractPoolEntry.maybeClone(constantPool, thisClass);
 65         this.flags = DEFAULT_CLASS_FLAGS;
 66         this.superclassEntry = null;
 67         this.interfaceEntries = Collections.emptyList();
 68         this.majorVersion = ClassFile.latestMajorVersion();
 69         this.minorVersion = ClassFile.latestMinorVersion();

112     public ClassBuilder withMethod(Utf8Entry name,
113                                    Utf8Entry descriptor,
114                                    int flags,
115                                    Consumer<? super MethodBuilder> handler) {
116         return withMethod(new DirectMethodBuilder(constantPool, context, name, descriptor, flags, null)
117                                   .run(handler));
118     }
119 
120     @Override
121     public ClassBuilder transformMethod(MethodModel method, MethodTransform transform) {
122         DirectMethodBuilder builder = new DirectMethodBuilder(constantPool, context, method.methodName(),
123                                                               method.methodType(),
124                                                               method.flags().flagsMask(),
125                                                               method);
126         builder.transform(method, transform);
127         return withMethod(builder);
128     }
129 
130     // internal / for use by elements
131 
132     ClassBuilder withField(Util.Writable field) {
133         if (fieldsCount >= fields.length) {
134             int newCapacity = fieldsCount + 8;
135             this.fields = Arrays.copyOf(fields, newCapacity);
136         }
137         fields[fieldsCount++] = field;
138         return this;
139     }
140 
141     ClassBuilder withMethod(Util.Writable method) {
142         if (methodsCount >= methods.length) {
143             int newCapacity = methodsCount + 8;
144             this.methods = Arrays.copyOf(methods, newCapacity);
145         }
146         methods[methodsCount++] = method;
147         return this;
148     }
149 
150     void setSuperclass(ClassEntry superclassEntry) {
151         this.superclassEntry = superclassEntry;
152     }
153 
154     void setInterfaces(List<ClassEntry> interfaces) {
155         this.interfaceEntries = interfaces;
156     }
157 
158     void setVersion(int major, int minor) {
159         this.majorVersion = major;
160         this.minorVersion = minor;
161     }
162 
163     void setFlags(int flags) {
164         this.flags = flags;
165     }
166 
167     public void setSizeHint(int sizeHint) {
168         this.sizeHint = sizeHint;
169     }
170 
171 
172     public byte[] build() {
173 
174         // The logic of this is very carefully ordered.  We want to avoid
175         // repeated buffer copyings, so we accumulate lists of writers which
176         // all get written later into the same buffer.  But, writing can often
177         // trigger CP / BSM insertions, so we cannot run the CP writer or
178         // BSM writers until everything else is written.
179 
180         // Do this early because it might trigger CP activity
181         var constantPool = this.constantPool;
182         ClassEntry superclass = superclassEntry;
183         if (superclass != null)
184             superclass = AbstractPoolEntry.maybeClone(constantPool, superclass);
185         else if ((flags & ClassFile.ACC_MODULE) == 0 && !"java/lang/Object".equals(thisClassEntry.asInternalName()))
186             superclass = constantPool.classEntry(ConstantDescs.CD_Object);
187         int interfaceEntriesSize = interfaceEntries.size();
188         ClassEntry[] ies = interfaceEntriesSize == 0 ? EMPTY_CLASS_ENTRY_ARRAY : buildInterfaceEnties(interfaceEntriesSize);
189 
190         // We maintain two writers, and then we join them at the end
191         int size = sizeHint == 0 ? 256 : sizeHint;
192         BufWriterImpl head = new BufWriterImpl(constantPool, context, size);
193         BufWriterImpl tail = new BufWriterImpl(constantPool, context, size, thisClassEntry, majorVersion);
194 
195         // The tail consists of fields and methods, and attributes
196         // This should trigger all the CP/BSM mutation
197         Util.writeList(tail, fields, fieldsCount);







198         Util.writeList(tail, methods, methodsCount);
199         int attributesOffset = tail.size();
200         attributes.writeTo(tail);
201 
202         // Now we have to append the BSM, if there is one
203         if (constantPool.writeBootstrapMethods(tail)) {
204             // Update attributes count
205             tail.patchU2(attributesOffset, attributes.size() + 1);
206         }
207 
208         // Now we can make the head
209         head.writeInt(ClassFile.MAGIC_NUMBER);
210         head.writeU2U2(minorVersion, majorVersion);
211         constantPool.writeTo(head);
212         head.writeU2U2U2(flags, head.cpIndex(thisClassEntry), head.cpIndexOrZero(superclass));
213         head.writeU2(interfaceEntriesSize);
214         for (int i = 0; i < interfaceEntriesSize; i++) {
215             head.writeIndex(ies[i]);
216         }
217 

 18  * You should have received a copy of the GNU General Public License version
 19  * 2 along with this work; if not, write to the Free Software Foundation,
 20  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 21  *
 22  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 23  * or visit www.oracle.com if you need additional information or have any
 24  * questions.
 25  */
 26 
 27 package jdk.internal.classfile.impl;
 28 
 29 import java.lang.classfile.*;
 30 import java.lang.classfile.constantpool.ClassEntry;
 31 import java.lang.classfile.constantpool.Utf8Entry;
 32 import java.lang.constant.ConstantDescs;
 33 import java.util.Arrays;
 34 import java.util.Collections;
 35 import java.util.List;
 36 import java.util.function.Consumer;
 37 
 38 import static java.lang.classfile.ClassFile.PREVIEW_MINOR_VERSION;
 39 import static java.lang.classfile.ClassFile.latestMajorVersion;
 40 import static java.util.Objects.requireNonNull;
 41 
 42 public final class DirectClassBuilder
 43         extends AbstractDirectBuilder<ClassModel>
 44         implements ClassBuilder {
 45 
 46     /** The value of default class access flags */
 47     static final int DEFAULT_CLASS_FLAGS = ClassFile.ACC_PUBLIC | ClassFile.ACC_SUPER;
 48     static final Util.Writable[] EMPTY_WRITABLE_ARRAY = {};
 49     static final WritableField[] EMPTY_WRITABLE_FIELD_ARRAY = {};
 50     static final ClassEntry[] EMPTY_CLASS_ENTRY_ARRAY = {};
 51     final ClassEntry thisClassEntry;
 52     private WritableField[] fields = EMPTY_WRITABLE_FIELD_ARRAY;
 53     private Util.Writable[] methods = EMPTY_WRITABLE_ARRAY;
 54     private int fieldsCount = 0;
 55     private int methodsCount = 0;
 56     private ClassEntry superclassEntry;
 57     private List<ClassEntry> interfaceEntries;
 58     private int majorVersion;
 59     private int minorVersion;
 60     private int flags;
 61     private int sizeHint;
 62 
 63     public DirectClassBuilder(SplitConstantPool constantPool,
 64                               ClassFileImpl context,
 65                               ClassEntry thisClass) {
 66         super(constantPool, context);
 67         this.thisClassEntry = AbstractPoolEntry.maybeClone(constantPool, thisClass);
 68         this.flags = DEFAULT_CLASS_FLAGS;
 69         this.superclassEntry = null;
 70         this.interfaceEntries = Collections.emptyList();
 71         this.majorVersion = ClassFile.latestMajorVersion();
 72         this.minorVersion = ClassFile.latestMinorVersion();

115     public ClassBuilder withMethod(Utf8Entry name,
116                                    Utf8Entry descriptor,
117                                    int flags,
118                                    Consumer<? super MethodBuilder> handler) {
119         return withMethod(new DirectMethodBuilder(constantPool, context, name, descriptor, flags, null)
120                                   .run(handler));
121     }
122 
123     @Override
124     public ClassBuilder transformMethod(MethodModel method, MethodTransform transform) {
125         DirectMethodBuilder builder = new DirectMethodBuilder(constantPool, context, method.methodName(),
126                                                               method.methodType(),
127                                                               method.flags().flagsMask(),
128                                                               method);
129         builder.transform(method, transform);
130         return withMethod(builder);
131     }
132 
133     // internal / for use by elements
134 
135     ClassBuilder withField(WritableField field) {
136         if (fieldsCount >= fields.length) {
137             int newCapacity = fieldsCount + 8;
138             this.fields = Arrays.copyOf(fields, newCapacity);
139         }
140         fields[fieldsCount++] = field;
141         return this;
142     }
143 
144     ClassBuilder withMethod(Util.Writable method) {
145         if (methodsCount >= methods.length) {
146             int newCapacity = methodsCount + 8;
147             this.methods = Arrays.copyOf(methods, newCapacity);
148         }
149         methods[methodsCount++] = method;
150         return this;
151     }
152 
153     void setSuperclass(ClassEntry superclassEntry) {
154         this.superclassEntry = superclassEntry;
155     }
156 
157     void setInterfaces(List<ClassEntry> interfaces) {
158         this.interfaceEntries = interfaces;
159     }
160 
161     void setVersion(int major, int minor) {
162         this.majorVersion = major;
163         this.minorVersion = minor;
164     }
165 
166     void setFlags(int flags) {
167         this.flags = flags;
168     }
169 
170     public void setSizeHint(int sizeHint) {
171         this.sizeHint = sizeHint;
172     }
173 

174     public byte[] build() {
175 
176         // The logic of this is very carefully ordered.  We want to avoid
177         // repeated buffer copyings, so we accumulate lists of writers which
178         // all get written later into the same buffer.  But, writing can often
179         // trigger CP / BSM insertions, so we cannot run the CP writer or
180         // BSM writers until everything else is written.
181 
182         // Do this early because it might trigger CP activity
183         var constantPool = this.constantPool;
184         ClassEntry superclass = superclassEntry;
185         if (superclass != null)
186             superclass = AbstractPoolEntry.maybeClone(constantPool, superclass);
187         else if ((flags & ClassFile.ACC_MODULE) == 0 && !"java/lang/Object".equals(thisClassEntry.asInternalName()))
188             superclass = constantPool.classEntry(ConstantDescs.CD_Object);
189         int interfaceEntriesSize = interfaceEntries.size();
190         ClassEntry[] ies = interfaceEntriesSize == 0 ? EMPTY_CLASS_ENTRY_ARRAY : buildInterfaceEnties(interfaceEntriesSize);
191 
192         // We maintain two writers, and then we join them at the end
193         int size = sizeHint == 0 ? 256 : sizeHint;
194         BufWriterImpl head = new BufWriterImpl(constantPool, context, size);
195         BufWriterImpl tail = new BufWriterImpl(constantPool, context, size, thisClassEntry, majorVersion);
196 
197         // The tail consists of fields and methods, and attributes
198         // This should trigger all the CP/BSM mutation
199         Util.writeList(tail, fields, fieldsCount);
200         WritableField.UnsetField[] strictInstanceFields;
201         if (minorVersion == PREVIEW_MINOR_VERSION && majorVersion >= Util.VALUE_OBJECTS_MAJOR) {
202             strictInstanceFields = WritableField.filterStrictInstanceFields(constantPool, fields, fieldsCount);
203         } else {
204             strictInstanceFields = WritableField.UnsetField.EMPTY_ARRAY;
205         }
206         tail.setStrictInstanceFields(strictInstanceFields);
207         Util.writeList(tail, methods, methodsCount);
208         int attributesOffset = tail.size();
209         attributes.writeTo(tail);
210 
211         // Now we have to append the BSM, if there is one
212         if (constantPool.writeBootstrapMethods(tail)) {
213             // Update attributes count
214             tail.patchU2(attributesOffset, attributes.size() + 1);
215         }
216 
217         // Now we can make the head
218         head.writeInt(ClassFile.MAGIC_NUMBER);
219         head.writeU2U2(minorVersion, majorVersion);
220         constantPool.writeTo(head);
221         head.writeU2U2U2(flags, head.cpIndex(thisClassEntry), head.cpIndexOrZero(superclass));
222         head.writeU2(interfaceEntriesSize);
223         for (int i = 0; i < interfaceEntriesSize; i++) {
224             head.writeIndex(ies[i]);
225         }
226 
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