org.objectweb.asm.util

Class CheckMethodAdapter

java.lang.Object

org.objectweb.asm.MethodAdapter

org.objectweb.asm.util.CheckMethodAdapter

All Implemented Interfaces:

MethodVisitor

public class CheckMethodAdapter
extends MethodAdapter

A MethodAdapter that checks that its methods are properly used. More precisely this method adapter checks each instruction individually, i.e., each visit method checks some preconditions based only on its arguments - such as the fact that the given opcode is correct for a given visit method. This adapter can also perform some basic data flow checks (more precisely those that can be performed without the full class hierarchy - see BasicVerifier). For instance in a method whose signature is void m (), the invalid instruction IRETURN, or the invalid sequence IADD L2I will be detected if the data flow checks are enabled. These checks are enabled by using the CheckMethodAdapter(int,String,String,MethodVisitor,Map) constructor. They are not performed if any other constructor is used.

Author:

Eric Bruneton

Field Summary

Fields inherited from class org.objectweb.asm.MethodAdapter

mv

Constructor Summary

Constructors

Constructor and Description
CheckMethodAdapter(int access, String name, String desc, MethodVisitor mv, Map labels) Constructs a new CheckMethodAdapter object.
CheckMethodAdapter(MethodVisitor mv) Constructs a new CheckMethodAdapter object.
CheckMethodAdapter(MethodVisitor mv, Map labels) Constructs a new CheckMethodAdapter object.

Method Summary

Methods

Modifier and Type	Method and Description
AnnotationVisitor	visitAnnotation(String desc, boolean visible) Visits an annotation of this method.
AnnotationVisitor	visitAnnotationDefault() Visits the default value of this annotation interface method.
void	visitAttribute(Attribute attr) Visits a non standard attribute of this method.
void	visitCode() Starts the visit of the method's code, if any (i.e.
void	visitEnd() Visits the end of the method.
void	visitFieldInsn(int opcode, String owner, String name, String desc) Visits a field instruction.
void	visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack) Visits the current state of the local variables and operand stack elements.
void	visitIincInsn(int var, int increment) Visits an IINC instruction.
void	visitInsn(int opcode) Visits a zero operand instruction.
void	visitIntInsn(int opcode, int operand) Visits an instruction with a single int operand.
void	visitJumpInsn(int opcode, Label label) Visits a jump instruction.
void	visitLabel(Label label) Visits a label.
void	visitLdcInsn(Object cst) Visits a LDC instruction.
void	visitLineNumber(int line, Label start) Visits a line number declaration.
void	visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index) Visits a local variable declaration.
void	visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels) Visits a LOOKUPSWITCH instruction.
void	visitMaxs(int maxStack, int maxLocals) Visits the maximum stack size and the maximum number of local variables of the method.
void	visitMethodInsn(int opcode, String owner, String name, String desc) Visits a method instruction.
void	visitMultiANewArrayInsn(String desc, int dims) Visits a MULTIANEWARRAY instruction.
AnnotationVisitor	visitParameterAnnotation(int parameter, String desc, boolean visible) Visits an annotation of a parameter this method.
void	visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels) Visits a TABLESWITCH instruction.
void	visitTryCatchBlock(Label start, Label end, Label handler, String type) Visits a try catch block.
void	visitTypeInsn(int opcode, String type) Visits a type instruction.
void	visitVarInsn(int opcode, int var) Visits a local variable instruction.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CheckMethodAdapter

public CheckMethodAdapter(MethodVisitor mv)

Constructs a new CheckMethodAdapter object. This method adapter will not perform any data flow check (see CheckMethodAdapter(int,String,String,MethodVisitor,Map)).

Parameters:

mv - the method visitor to which this adapter must delegate calls.

CheckMethodAdapter

public CheckMethodAdapter(MethodVisitor mv,
                  Map labels)

Constructs a new CheckMethodAdapter object. This method adapter will not perform any data flow check (see CheckMethodAdapter(int,String,String,MethodVisitor,Map)).

Parameters:

mv - the method visitor to which this adapter must delegate calls.

labels - a map of already visited labels (in other methods).

CheckMethodAdapter

public CheckMethodAdapter(int access,
                  String name,
                  String desc,
                  MethodVisitor mv,
                  Map labels)

Constructs a new CheckMethodAdapter object. This method adapter will perform basic data flow checks. For instance in a method whose signature is void m (), the invalid instruction IRETURN, or the invalid sequence IADD L2I will be detected.

Parameters:

access - the method's access flags.

name - the method's name.

desc - the method's descriptor (see Type).

mv - the method visitor to which this adapter must delegate calls.

labels - a map of already visited labels (in other methods).

Method Detail

visitAnnotation

public AnnotationVisitor visitAnnotation(String desc,
                                boolean visible)

Description copied from interface: MethodVisitor

Visits an annotation of this method.

Specified by:

visitAnnotation in interface MethodVisitor

Overrides:

visitAnnotation in class MethodAdapter

Parameters:

desc - the class descriptor of the annotation class.

visible - true if the annotation is visible at runtime.

Returns:

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

visitAnnotationDefault

public AnnotationVisitor visitAnnotationDefault()

Description copied from interface: MethodVisitor

Visits the default value of this annotation interface method.

Specified by:

visitAnnotationDefault in interface MethodVisitor

Overrides:

visitAnnotationDefault in class MethodAdapter

Returns:

a visitor to the visit the actual default value of this annotation interface method, or null if this visitor is not interested in visiting this default value. The 'name' parameters passed to the methods of this annotation visitor are ignored. Moreover, exacly one visit method must be called on this annotation visitor, followed by visitEnd.

visitParameterAnnotation

public AnnotationVisitor visitParameterAnnotation(int parameter,
                                         String desc,
                                         boolean visible)

Description copied from interface: MethodVisitor

Visits an annotation of a parameter this method.

Specified by:

visitParameterAnnotation in interface MethodVisitor

Overrides:

visitParameterAnnotation in class MethodAdapter

Parameters:

parameter - the parameter index.

desc - the class descriptor of the annotation class.

visible - true if the annotation is visible at runtime.

Returns:

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

visitAttribute

public void visitAttribute(Attribute attr)

Description copied from interface: MethodVisitor

Visits a non standard attribute of this method.

Specified by:

visitAttribute in interface MethodVisitor

Overrides:

visitAttribute in class MethodAdapter

Parameters:

attr - an attribute.

visitCode

public void visitCode()

Description copied from interface: MethodVisitor

Starts the visit of the method's code, if any (i.e. non abstract method).

Specified by:

visitCode in interface MethodVisitor

Overrides:

visitCode in class MethodAdapter

visitFrame

public void visitFrame(int type,
              int nLocal,
              Object[] local,
              int nStack,
              Object[] stack)

Description copied from interface: MethodVisitor

Visits the current state of the local variables and operand stack elements. This method must(*) be called just before any instruction i that follows an unconditional branch instruction such as GOTO or THROW, that is the target of a jump instruction, or that starts an exception handler block. The visited types must describe the values of the local variables and of the operand stack elements just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to V1_6.

Packed frames are basically "deltas" from the state of the previous frame (very first frame is implicitly defined by the method's parameters and access flags):

• Opcodes.F_SAME representing frame with exactly the same locals as the previous frame and with the empty stack.
• Opcodes.F_SAME1 representing frame with exactly the same locals as the previous frame and with single value on the stack (nStack is 1 and stack[0] contains value for the type of the stack item).
• Opcodes.F_APPEND representing frame with current locals are the same as the locals in the previous frame, except that additional locals are defined (nLocal is 1, 2 or 3 and local elements contains values representing added types).
• Opcodes.F_CHOP representing frame with current locals are the same as the locals in the previous frame, except that the last 1-3 locals are absent and with the empty stack (nLocals is 1, 2 or 3).
• Opcodes.F_FULL representing complete frame data.

Specified by:

visitFrame in interface MethodVisitor

Overrides:

visitFrame in class MethodAdapter

Parameters:

type - the type of this stack map frame. Must be Opcodes.F_NEW for expanded frames, or Opcodes.F_FULL, Opcodes.F_APPEND, Opcodes.F_CHOP, Opcodes.F_SAME or Opcodes.F_APPEND, Opcodes.F_SAME1 for compressed frames.

nLocal - the number of local variables in the visited frame.

local - the local variable types in this frame. This array must not be modified. Primitive types are represented by Opcodes.TOP, Opcodes.INTEGER, Opcodes.FLOAT, Opcodes.LONG, Opcodes.DOUBLE,Opcodes.NULL or Opcodes.UNINITIALIZED_THIS (long and double are represented by a single element). Reference types are represented by String objects (representing internal names), and uninitialized types by Label objects (this label designates the NEW instruction that created this uninitialized value).

nStack - the number of operand stack elements in the visited frame.

stack - the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.

visitInsn

public void visitInsn(int opcode)

Description copied from interface: MethodVisitor

Visits a zero operand instruction.

Specified by:

visitInsn in interface MethodVisitor

Overrides:

visitInsn in class MethodAdapter

Parameters:

opcode - the opcode of the instruction to be visited. This opcode is either NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1, FCONST_0, FCONST_1, FCONST_2, DCONST_0, DCONST_1, IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE, SASTORE, POP, POP2, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP, IADD, LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV, LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, INEG, LNEG, FNEG, DNEG, ISHL, LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, I2C, I2S, LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, RETURN, ARRAYLENGTH, ATHROW, MONITORENTER, or MONITOREXIT.

visitIntInsn

public void visitIntInsn(int opcode,
                int operand)

Description copied from interface: MethodVisitor

Visits an instruction with a single int operand.

Specified by:

visitIntInsn in interface MethodVisitor

Overrides:

visitIntInsn in class MethodAdapter

Parameters:

opcode - the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY.

operand - the operand of the instruction to be visited.
When opcode is BIPUSH, operand value should be between Byte.MIN_VALUE and Byte.MAX_VALUE.
When opcode is SIPUSH, operand value should be between Short.MIN_VALUE and Short.MAX_VALUE.
When opcode is NEWARRAY, operand value should be one of Opcodes.T_BOOLEAN, Opcodes.T_CHAR, Opcodes.T_FLOAT, Opcodes.T_DOUBLE, Opcodes.T_BYTE, Opcodes.T_SHORT, Opcodes.T_INT or Opcodes.T_LONG.

visitVarInsn

public void visitVarInsn(int opcode,
                int var)

Description copied from interface: MethodVisitor

Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.

Specified by:

visitVarInsn in interface MethodVisitor

Overrides:

visitVarInsn in class MethodAdapter

Parameters:

opcode - the opcode of the local variable instruction to be visited. This opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, LSTORE, FSTORE, DSTORE, ASTORE or RET.

var - the operand of the instruction to be visited. This operand is the index of a local variable.

visitTypeInsn

public void visitTypeInsn(int opcode,
                 String type)

Description copied from interface: MethodVisitor

Visits a type instruction. A type instruction is an instruction that takes the internal name of a class as parameter.

Specified by:

visitTypeInsn in interface MethodVisitor

Overrides:

visitTypeInsn in class MethodAdapter

Parameters:

opcode - the opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.

type - the operand of the instruction to be visited. This operand must be the internal name of an object or array class (see getInternalName).

visitFieldInsn

public void visitFieldInsn(int opcode,
                  String owner,
                  String name,
                  String desc)

Description copied from interface: MethodVisitor

Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.

Specified by:

visitFieldInsn in interface MethodVisitor

Overrides:

visitFieldInsn in class MethodAdapter

Parameters:

opcode - the opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.

owner - the internal name of the field's owner class (see getInternalName).

name - the field's name.

desc - the field's descriptor (see Type).

visitMethodInsn

public void visitMethodInsn(int opcode,
                   String owner,
                   String name,
                   String desc)

Description copied from interface: MethodVisitor

Visits a method instruction. A method instruction is an instruction that invokes a method.

Specified by:

visitMethodInsn in interface MethodVisitor

Overrides:

visitMethodInsn in class MethodAdapter

Parameters:

opcode - the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC, INVOKEINTERFACE or INVOKEDYNAMIC.

owner - the internal name of the method's owner class (see getInternalName) or Opcodes.INVOKEDYNAMIC_OWNER.

name - the method's name.

desc - the method's descriptor (see Type).

visitJumpInsn

public void visitJumpInsn(int opcode,
                 Label label)

Description copied from interface: MethodVisitor

Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.

Specified by:

visitJumpInsn in interface MethodVisitor

Overrides:

visitJumpInsn in class MethodAdapter

Parameters:

opcode - the opcode of the type instruction to be visited. This opcode is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE, GOTO, JSR, IFNULL or IFNONNULL.

label - the operand of the instruction to be visited. This operand is a label that designates the instruction to which the jump instruction may jump.

visitLabel

public void visitLabel(Label label)

Description copied from interface: MethodVisitor

Visits a label. A label designates the instruction that will be visited just after it.

Specified by:

visitLabel in interface MethodVisitor

Overrides:

visitLabel in class MethodAdapter

Parameters:

label - a Label object.

visitLdcInsn

public void visitLdcInsn(Object cst)

Description copied from interface: MethodVisitor

Visits a LDC instruction.

Specified by:

visitLdcInsn in interface MethodVisitor

Overrides:

visitLdcInsn in class MethodAdapter

Parameters:

cst - the constant to be loaded on the stack. This parameter must be a non null Integer, a Float, a Long, a Double a String (or a Type for .class constants, for classes whose version is 49.0 or more).

visitIincInsn

public void visitIincInsn(int var,
                 int increment)

Description copied from interface: MethodVisitor

Visits an IINC instruction.

Specified by:

visitIincInsn in interface MethodVisitor

Overrides:

visitIincInsn in class MethodAdapter

Parameters:

var - index of the local variable to be incremented.

increment - amount to increment the local variable by.

visitTableSwitchInsn

public void visitTableSwitchInsn(int min,
                        int max,
                        Label dflt,
                        Label[] labels)

Description copied from interface: MethodVisitor

Visits a TABLESWITCH instruction.

Specified by:

visitTableSwitchInsn in interface MethodVisitor

Overrides:

visitTableSwitchInsn in class MethodAdapter

Parameters:

min - the minimum key value.

max - the maximum key value.

dflt - beginning of the default handler block.

labels - beginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.

visitLookupSwitchInsn

public void visitLookupSwitchInsn(Label dflt,
                         int[] keys,
                         Label[] labels)

Description copied from interface: MethodVisitor

Visits a LOOKUPSWITCH instruction.

Specified by:

visitLookupSwitchInsn in interface MethodVisitor

Overrides:

visitLookupSwitchInsn in class MethodAdapter

Parameters:

dflt - beginning of the default handler block.

keys - the values of the keys.

labels - beginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.

visitMultiANewArrayInsn

public void visitMultiANewArrayInsn(String desc,
                           int dims)

Description copied from interface: MethodVisitor

Visits a MULTIANEWARRAY instruction.

Specified by:

visitMultiANewArrayInsn in interface MethodVisitor

Overrides:

visitMultiANewArrayInsn in class MethodAdapter

Parameters:

desc - an array type descriptor (see Type).

dims - number of dimensions of the array to allocate.

visitTryCatchBlock

public void visitTryCatchBlock(Label start,
                      Label end,
                      Label handler,
                      String type)

Description copied from interface: MethodVisitor

Visits a try catch block.

Specified by:

visitTryCatchBlock in interface MethodVisitor

Overrides:

visitTryCatchBlock in class MethodAdapter

Parameters:

start - beginning of the exception handler's scope (inclusive).

end - end of the exception handler's scope (exclusive).

handler - beginning of the exception handler's code.

type - internal name of the type of exceptions handled by the handler, or null to catch any exceptions (for "finally" blocks).

visitLocalVariable

public void visitLocalVariable(String name,
                      String desc,
                      String signature,
                      Label start,
                      Label end,
                      int index)

Description copied from interface: MethodVisitor

Visits a local variable declaration.

Specified by:

visitLocalVariable in interface MethodVisitor

Overrides:

visitLocalVariable in class MethodAdapter

Parameters:

name - the name of a local variable.

desc - the type descriptor of this local variable.

signature - the type signature of this local variable. May be null if the local variable type does not use generic types.

start - the first instruction corresponding to the scope of this local variable (inclusive).

end - the last instruction corresponding to the scope of this local variable (exclusive).

index - the local variable's index.

visitLineNumber

public void visitLineNumber(int line,
                   Label start)

Description copied from interface: MethodVisitor

Visits a line number declaration.

Specified by:

visitLineNumber in interface MethodVisitor

Overrides:

visitLineNumber in class MethodAdapter

Parameters:

line - a line number. This number refers to the source file from which the class was compiled.

start - the first instruction corresponding to this line number.

visitMaxs

public void visitMaxs(int maxStack,
             int maxLocals)

Description copied from interface: MethodVisitor

Visits the maximum stack size and the maximum number of local variables of the method.

Specified by:

visitMaxs in interface MethodVisitor

Overrides:

visitMaxs in class MethodAdapter

Parameters:

maxStack - maximum stack size of the method.

maxLocals - maximum number of local variables for the method.

visitEnd

public void visitEnd()

Description copied from interface: MethodVisitor

Visits the end of the method. This method, which is the last one to be called, is used to inform the visitor that all the annotations and attributes of the method have been visited.

Specified by:

visitEnd in interface MethodVisitor

Overrides:

visitEnd in class MethodAdapter