/**
* Auxiliary method to extract the signature associated with the resource. This is fetched from
* the 'Signature_attribute' structure, which has the following format:
*
* <p>[java 8] Signature_attribute { u2 attribute_name_index; u4 attribute_length; u2
* signature_index; }
*
* <p>- signature_index: The value of the 'signature_index' must be a valid index in the
* 'constant_pool' table. The 'constant_pool' entry at that index must be a 'CONSTANT_Utf8_info'
* structure representing a class signature if this 'Signature' is an attribute of a 'ClassFile'
* structure. It is a method signature of this 'Signature' is an attribute of a 'method_info'
* structure. It is a field signature otherwise.
*
* @param dataInputStream The byte stream associated with the resource (aka .class file).
* @param resource The resource associated with the attribute.
* @throws IOException When reading bytes from the stream fails.
*/
public static void extractSignature(
DataInputStream dataInputStream, String location, Resource resource) throws IOException {
int signatureIndex = dataInputStream.readUnsignedShort();
String signature =
ConstantPoolAnalyser.extractStringValueByConstantPoolIndex(
resource.getConstantPool(), signatureIndex);
LOGGER.debug("Class signature: " + signature + " (location: " + location + ")");
// Add signature (when applicable) to the referenced classes
SignatureAnalyser.referencedClasses(resource.getReferencedClasses(), signature);
}
/**
* The structure has the following (general) format:
*
* <p>[java 8] annotation { u2 type_index; u2 num_element_value_pairs; element_value_pairs
* element_value_pair[num_element_value_pairs] }
*
* <p>- type_index: The value of the 'type_index' item must be a valid index in the
* 'constant_pool' table. The 'constant_pool' table entry at that index must be a
* 'CONSTANT_Utf8_info' structure representing a field descriptor. The field descriptor denotes
* the type of the annotation represented by this 'annotation' structure. -
* num_element_value_pairs: The value of 'num_element_value_pairs' item gives the number of
* element-value pairs of the annotation represented by this 'annotation' structure.
*
* @param dataInputStream The byte stream associated with the resource (aka .class file).
* @param index The annotation index, used for precise data logging.
* @param resource The resource associated with the attribute.
* @throws IOException When reading bytes from the stream fails.
*/
protected static void extractAnnotation(
DataInputStream dataInputStream, int index, Resource resource) throws IOException {
StringBuilder buffer = new StringBuilder();
buffer.append("Annotation (index: ").append(index).append(")");
// Read the type index
int typeIndex = dataInputStream.readUnsignedShort();
String descriptor =
ConstantPoolAnalyser.extractStringValueByConstantPoolIndex(
resource.getConstantPool(), typeIndex);
buffer.append(", of type (index: ").append(typeIndex).append("): ").append(descriptor);
LOGGER.debug(buffer.toString());
// Add signature (when applicable) to the referenced classes
SignatureAnalyser.referencedClasses(resource.getReferencedClasses(), descriptor);
// Read the element value pairs
int numberOfElementValuePairs = dataInputStream.readUnsignedShort();
extractElementValuePairs(dataInputStream, numberOfElementValuePairs, resource);
}
/**
* Auxiliary method to extract an 'element_value' from the data input stream. Note that this
* method can be called recursively (in case the value of the element_value is an array with more
* element_value's).
*
* @param dataInputStream The byte stream associated with the resource (aka .class file).
* @param buffer The buffer with relevant text to support (deep and semantic) logging.
* @param resource The resource associated with the attribute.
* @throws IOException When reading bytes from the stream fails.
*/
public static void extractElementValue(
DataInputStream dataInputStream, StringBuilder buffer, Resource resource) throws IOException {
// Read the tag
int tag = dataInputStream.readUnsignedByte();
// Read the element value
switch ((char) tag) {
case 'B':
int constantByteValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo byteValue =
findConstantByIndex(constantByteValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantByteValueIndex)
.append(", type: byte): ")
.append(byteValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'C':
int constantCharValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo charValue =
findConstantByIndex(constantCharValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantCharValueIndex)
.append(", type: char): ")
.append((char) charValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'D':
int constantDoubleValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo doubleValue =
findConstantByIndex(constantDoubleValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantDoubleValueIndex)
.append(", type: double): ")
.append(doubleValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'F':
int constantFloatValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo floatValue =
findConstantByIndex(constantFloatValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantFloatValueIndex)
.append(", type: float): ")
.append(floatValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'I':
// Read the value index
int constantIntegerValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo integerValue =
findConstantByIndex(constantIntegerValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantIntegerValueIndex)
.append(", type: integer): ")
.append(integerValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'J':
// Read the value index
int constantLongValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo longValue =
findConstantByIndex(constantLongValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantLongValueIndex)
.append(", type: long): ")
.append(longValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'S':
// Read the value index
int constantShortValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo shortValue =
findConstantByIndex(constantShortValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantShortValueIndex)
.append(", type: short): ")
.append(shortValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 'Z':
// Read the value index
int constantBooleanValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo booleanValue =
findConstantByIndex(constantBooleanValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantBooleanValueIndex)
.append(", type: boolean): ")
.append(booleanValue.getIntValue());
LOGGER.debug(buffer.toString());
break;
case 's':
// Read the value index
int constantStringValueIndex = dataInputStream.readUnsignedShort();
ConstantInfo stringValue =
findConstantByIndex(constantStringValueIndex, resource.getConstantPool());
buffer
.append(", with value (index: ")
.append(constantStringValueIndex)
.append(", type: String): ")
.append(stringValue.getStringValue());
LOGGER.debug(buffer.toString());
break;
case 'e':
// Read the enum type index
int typeNameIndex = dataInputStream.readUnsignedShort();
// The value of the type_name_index item must be a valid index in the 'constant_pool' table.
// The 'constant_pool'
// entry at that index must be a 'CONSTANT_Utf8_info' structure representing a field
// descriptor.
String typeNameDescriptor =
ConstantPoolAnalyser.extractStringValueByConstantPoolIndex(
resource.getConstantPool(), typeNameIndex);
// Read the constant name index
int constantNameIndex = dataInputStream.readUnsignedShort();
// The value of constant_name_index item must be a valid index in the 'constant_pool' table.
// The 'constant_pool'
// entry at that index must be a 'CONSTANT_Utf8_info' structure.
String enumValue =
ConstantPoolAnalyser.extractStringValueByConstantPoolIndex(
resource.getConstantPool(), constantNameIndex);
buffer
.append(", with type name (index: ")
.append(typeNameIndex)
.append(", type: enum): ")
.append(typeNameDescriptor);
buffer
.append(" and value (index: ")
.append(constantNameIndex)
.append("): ")
.append(enumValue);
LOGGER.debug(buffer.toString());
// Add signature (when applicable) to the referenced classes
SignatureAnalyser.referencedClasses(resource.getReferencedClasses(), typeNameDescriptor);
break;
case 'c':
// Read the class index
int classInfoIndex = dataInputStream.readUnsignedShort();
// The class_info_index denotes a class literal as the value of this element-value pair. The
// class_info_index
// must be a valid index into the 'constant_pool' table. The 'constant_pool' entry at that
// index must be a
// 'CONSTANT_Utf8_info' structure representing a return descriptor. The return descriptor
// give the type
// corresponding to the class literal represented by this 'element_value' structure. Types
// correspond to class
// literals as follows:
//
// - For a class literal C.class, where C is the name of the class, interface, or array
// type, the corresponding
// type is C. The return descriptor in the 'constant_pool' will be an ObjectType or an
// ArrayType.
// Example: the class literal Object.class corresponds to Object, so the 'constant_pool'
// entry is Ljava/lang/Object;
// - For a class literal p.class, where p is the name of a primitive type, the corresponding
// type is p. The
// return descriptor in the 'constant_pool' will be a BaseType character.
// Example: the literal int.class corresponds to the type int, so the 'constant_pool'
// entry is I.
// - For a class literal void.class, the corresponding type is void. The return descriptor
// in the 'constant_pool'
// will be V.
// Example: the literal void.class corresponds to void, so the 'constant_pool' entry is V,
// whereas
// the class literal Void.class corresponds to the type Void, so the 'constant_pool' entry
// is Ljava/lang/Void;
String descriptor =
ConstantPoolAnalyser.extractStringValueByConstantPoolIndex(
resource.getConstantPool(), classInfoIndex);
buffer
.append(", with value (index: ")
.append(classInfoIndex)
.append(", type: Class) with descriptor: ")
.append(descriptor);
LOGGER.debug(buffer.toString());
// Add signature (when applicable) to the referenced classes
SignatureAnalyser.referencedClasses(resource.getReferencedClasses(), descriptor);
break;
case '@':
buffer.append(
", with type annotation -> delegating to extract annotation (with index: -1)...");
LOGGER.debug(buffer.toString());
// Read annotation
extractAnnotation(dataInputStream, -1, resource);
break;
case '[':
int numberOfValues = dataInputStream.readUnsignedShort();
buffer
.append(", with type array (size: ")
.append(numberOfValues)
.append(") entering recursion...");
LOGGER.debug(buffer.toString());
// Read array members, delegate by recursion
LOGGER.debug("Number of nested element-value pairs: " + numberOfValues);
for (int index = 0; index < numberOfValues; index++) {
StringBuilder nestedBuffer = new StringBuilder();
nestedBuffer.append("Nested element-value pair (index: ").append(index).append(")");
extractElementValue(dataInputStream, nestedBuffer, resource);
}
break;
default:
buffer.append(", but tag is unsupported: ").append(tag);
LOGGER.warn(buffer.toString());
}
}