Class CheckClassAdapter
- java.lang.Object
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- org.objectweb.asm.ClassVisitor
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- org.objectweb.asm.util.CheckClassAdapter
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public class CheckClassAdapter extends org.objectweb.asm.ClassVisitor
AClassVisitor
that checks that its methods are properly used. More precisely this class adapter checks each method call individually, based only on its arguments, but does not check the sequence of method calls. For example, the invalid sequencevisitField(ACC_PUBLIC, "i", "I", null)
visitField(ACC_PUBLIC, "i", "D", null)
will not be detected by this class adapter.CheckClassAdapter
can be also used to verify bytecode transformations in order to make sure that the transformed bytecode is sane. For example:InputStream inputStream = ...; // get bytes for the source class ClassReader classReader = new ClassReader(inputStream); ClassWriter classWriter = new ClassWriter(classReader, ClassWriter.COMPUTE_MAXS); ClassVisitor classVisitor = new MyClassAdapter(new CheckClassAdapter(classWriter, true)); classReader.accept(classVisitor, 0); StringWriter stringWriter = new StringWriter(); PrintWriter printWriter = new PrintWriter(stringWriter); CheckClassAdapter.verify(new ClassReader(classWriter.toByteArray()), false, printWriter); assertTrue(stringWriter.toString().isEmpty());
The above code pass the transformed bytecode through a
CheckClassAdapter
, with data flow checks enabled. These checks are not exactly the same as the JVM verification, but provide some basic type checking for each method instruction. If the bytecode has errors, the output text shows the erroneous instruction number, and a dump of the failed method with information about the type of the local variables and of the operand stack slots for each instruction. For example (format is - insnNumber locals : stack):org.objectweb.asm.tree.analysis.AnalyzerException: Error at instruction 71: Expected I, but found . at org.objectweb.asm.tree.analysis.Analyzer.analyze(Analyzer.java:...) at org.objectweb.asm.util.CheckClassAdapter.verify(CheckClassAdapter.java:...) ... remove()V 00000 LinkedBlockingQueue$Itr . . . . . . . . : ICONST_0 00001 LinkedBlockingQueue$Itr . . . . . . . . : I ISTORE 2 00001 LinkedBlockingQueue$Itr . I . . . . . . : ... 00071 LinkedBlockingQueue$Itr . I . . . . . . : ILOAD 1 00072 ? INVOKESPECIAL java/lang/Integer.<init> (I)V ...
The above output shows that the local variable 1, loaded by the
ILOAD 1
instruction at position00071
is not initialized, whereas the local variable 2 is initialized and contains an int value.- Author:
- Eric Bruneton
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Constructor Summary
Constructors Modifier Constructor Description protected
CheckClassAdapter(int api, org.objectweb.asm.ClassVisitor classVisitor, boolean checkDataFlow)
Constructs a newCheckClassAdapter
.CheckClassAdapter(org.objectweb.asm.ClassVisitor classVisitor)
Constructs a newCheckClassAdapter
.CheckClassAdapter(org.objectweb.asm.ClassVisitor classVisitor, boolean checkDataFlow)
Constructs a newCheckClassAdapter
.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static void
checkClassSignature(java.lang.String signature)
Checks a class signature.static void
checkFieldSignature(java.lang.String signature)
Checks a field signature.static void
checkMethodSignature(java.lang.String signature)
Checks a method signature.static void
main(java.lang.String[] args)
Checks the given class.static void
verify(org.objectweb.asm.ClassReader classReader, boolean printResults, java.io.PrintWriter printWriter)
Checks the given class.static void
verify(org.objectweb.asm.ClassReader classReader, java.lang.ClassLoader loader, boolean printResults, java.io.PrintWriter printWriter)
Checks the given class.void
visit(int version, int access, java.lang.String name, java.lang.String signature, java.lang.String superName, java.lang.String[] interfaces)
org.objectweb.asm.AnnotationVisitor
visitAnnotation(java.lang.String descriptor, boolean visible)
void
visitAttribute(org.objectweb.asm.Attribute attribute)
void
visitEnd()
org.objectweb.asm.FieldVisitor
visitField(int access, java.lang.String name, java.lang.String descriptor, java.lang.String signature, java.lang.Object value)
void
visitInnerClass(java.lang.String name, java.lang.String outerName, java.lang.String innerName, int access)
org.objectweb.asm.MethodVisitor
visitMethod(int access, java.lang.String name, java.lang.String descriptor, java.lang.String signature, java.lang.String[] exceptions)
org.objectweb.asm.ModuleVisitor
visitModule(java.lang.String name, int access, java.lang.String version)
void
visitNestHost(java.lang.String nestHost)
void
visitNestMember(java.lang.String nestMember)
void
visitOuterClass(java.lang.String owner, java.lang.String name, java.lang.String descriptor)
void
visitSource(java.lang.String file, java.lang.String debug)
org.objectweb.asm.AnnotationVisitor
visitTypeAnnotation(int typeRef, org.objectweb.asm.TypePath typePath, java.lang.String descriptor, boolean visible)
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Constructor Detail
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CheckClassAdapter
public CheckClassAdapter(org.objectweb.asm.ClassVisitor classVisitor)
Constructs a newCheckClassAdapter
. Subclasses must not use this constructor. Instead, they must use theCheckClassAdapter(int, ClassVisitor, boolean)
version.- Parameters:
classVisitor
- the class visitor to which this adapter must delegate calls.
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CheckClassAdapter
public CheckClassAdapter(org.objectweb.asm.ClassVisitor classVisitor, boolean checkDataFlow)
Constructs a newCheckClassAdapter
. Subclasses must not use this constructor. Instead, they must use theCheckClassAdapter(int, ClassVisitor, boolean)
version.- Parameters:
classVisitor
- the class visitor to which this adapter must delegate calls.checkDataFlow
- whether to perform basic data flow checks. This option requires valid maxLocals and maxStack values.- Throws:
java.lang.IllegalStateException
- If a subclass calls this constructor.
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CheckClassAdapter
protected CheckClassAdapter(int api, org.objectweb.asm.ClassVisitor classVisitor, boolean checkDataFlow)
Constructs a newCheckClassAdapter
.- Parameters:
api
- the ASM API version implemented by this visitor. Must be one ofOpcodes.ASM4
,Opcodes.ASM5
,Opcodes.ASM6
orOpcodes.ASM7
.classVisitor
- the class visitor to which this adapter must delegate calls.checkDataFlow
- true to perform basic data flow checks, or false to not perform any data flow check (seeCheckMethodAdapter
). This option requires valid maxLocals and maxStack values.
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Method Detail
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visit
public void visit(int version, int access, java.lang.String name, java.lang.String signature, java.lang.String superName, java.lang.String[] interfaces)
- Overrides:
visit
in classorg.objectweb.asm.ClassVisitor
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visitSource
public void visitSource(java.lang.String file, java.lang.String debug)
- Overrides:
visitSource
in classorg.objectweb.asm.ClassVisitor
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visitModule
public org.objectweb.asm.ModuleVisitor visitModule(java.lang.String name, int access, java.lang.String version)
- Overrides:
visitModule
in classorg.objectweb.asm.ClassVisitor
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visitNestHost
public void visitNestHost(java.lang.String nestHost)
- Overrides:
visitNestHost
in classorg.objectweb.asm.ClassVisitor
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visitNestMember
public void visitNestMember(java.lang.String nestMember)
- Overrides:
visitNestMember
in classorg.objectweb.asm.ClassVisitor
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visitOuterClass
public void visitOuterClass(java.lang.String owner, java.lang.String name, java.lang.String descriptor)
- Overrides:
visitOuterClass
in classorg.objectweb.asm.ClassVisitor
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visitInnerClass
public void visitInnerClass(java.lang.String name, java.lang.String outerName, java.lang.String innerName, int access)
- Overrides:
visitInnerClass
in classorg.objectweb.asm.ClassVisitor
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visitField
public org.objectweb.asm.FieldVisitor visitField(int access, java.lang.String name, java.lang.String descriptor, java.lang.String signature, java.lang.Object value)
- Overrides:
visitField
in classorg.objectweb.asm.ClassVisitor
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visitMethod
public org.objectweb.asm.MethodVisitor visitMethod(int access, java.lang.String name, java.lang.String descriptor, java.lang.String signature, java.lang.String[] exceptions)
- Overrides:
visitMethod
in classorg.objectweb.asm.ClassVisitor
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visitAnnotation
public org.objectweb.asm.AnnotationVisitor visitAnnotation(java.lang.String descriptor, boolean visible)
- Overrides:
visitAnnotation
in classorg.objectweb.asm.ClassVisitor
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visitTypeAnnotation
public org.objectweb.asm.AnnotationVisitor visitTypeAnnotation(int typeRef, org.objectweb.asm.TypePath typePath, java.lang.String descriptor, boolean visible)
- Overrides:
visitTypeAnnotation
in classorg.objectweb.asm.ClassVisitor
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visitAttribute
public void visitAttribute(org.objectweb.asm.Attribute attribute)
- Overrides:
visitAttribute
in classorg.objectweb.asm.ClassVisitor
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visitEnd
public void visitEnd()
- Overrides:
visitEnd
in classorg.objectweb.asm.ClassVisitor
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checkClassSignature
public static void checkClassSignature(java.lang.String signature)
Checks a class signature.- Parameters:
signature
- a string containing the signature that must be checked.
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checkMethodSignature
public static void checkMethodSignature(java.lang.String signature)
Checks a method signature.- Parameters:
signature
- a string containing the signature that must be checked.
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checkFieldSignature
public static void checkFieldSignature(java.lang.String signature)
Checks a field signature.- Parameters:
signature
- a string containing the signature that must be checked.
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main
public static void main(java.lang.String[] args) throws java.io.IOException
Checks the given class.Usage: CheckClassAdapter <binary class name or class file name>
- Parameters:
args
- the command line arguments.- Throws:
java.io.IOException
- if the class cannot be found, or if an IO exception occurs.
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verify
public static void verify(org.objectweb.asm.ClassReader classReader, boolean printResults, java.io.PrintWriter printWriter)
Checks the given class.- Parameters:
classReader
- the class to be checked.printResults
- whether to print the results of the bytecode verification.printWriter
- where the results (or the stack trace in case of error) must be printed.
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verify
public static void verify(org.objectweb.asm.ClassReader classReader, java.lang.ClassLoader loader, boolean printResults, java.io.PrintWriter printWriter)
Checks the given class.- Parameters:
classReader
- the class to be checked.loader
- aClassLoader
which will be used to load referenced classes. May be null.printResults
- whether to print the results of the bytecode verification.printWriter
- where the results (or the stack trace in case of error) must be printed.
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