private static ClassMember readClassMember(ClassInvestigator ci, ClassInput in)
throws IOException {
ClassMember member = new ClassMember(ci, in.getU2(), in.getU2(), in.getU2());
int attributeCount = in.getU2();
if (attributeCount != 0) {
member.attribute_info = new Attributes(attributeCount);
for (int i = 0; i < attributeCount; i++)
member.attribute_info.addEntry(new AttributeEntry(in));
}
return member;
}
private static ConstantPoolEntry getConstant(ClassInput in) throws IOException {
ConstantPoolEntry item;
int tag;
tag = in.readUnsignedByte();
switch (tag) {
case VMDescriptor.CONSTANT_Class:
case VMDescriptor.CONSTANT_String:
item = new CONSTANT_Index_info(tag, in.getU2(), 0);
break;
case VMDescriptor.CONSTANT_NameAndType:
case VMDescriptor.CONSTANT_Fieldref:
case VMDescriptor.CONSTANT_Methodref:
case VMDescriptor.CONSTANT_InterfaceMethodref:
item = new CONSTANT_Index_info(tag, in.getU2(), in.getU2());
break;
case VMDescriptor.CONSTANT_Integer:
item = new CONSTANT_Integer_info(in.getU4());
break;
case VMDescriptor.CONSTANT_Float:
item = new CONSTANT_Float_info(in.readFloat());
break;
case VMDescriptor.CONSTANT_Long:
item = new CONSTANT_Long_info(in.readLong());
break;
case VMDescriptor.CONSTANT_Double:
item = new CONSTANT_Double_info(in.readDouble());
break;
case VMDescriptor.CONSTANT_Utf8:
item = new CONSTANT_Utf8_info(in.readUTF());
break;
default:
throw new ClassFormatError();
}
return item;
}
private void processCodeAttribute(ClassMember member, AttributeEntry ae) throws IOException {
ClassInput ci = new ClassInput(new java.io.ByteArrayInputStream(ae.infoIn));
DataInputUtil.skipFully(ci, 4); // puts us at code_length
int len = ci.getU4();
DataInputUtil.skipFully(ci, len); // puts us at exception_table_length
int count = ci.getU2();
if (count != 0) DataInputUtil.skipFully(ci, 8 * count);
int nonAttrLength = 4 + 4 + len + 2 + (8 * count);
// now at attributes
count = ci.getU2();
if (count == 0) return;
int newCount = count;
for (int i = 0; i < count; i++) {
int nameIndex = ci.getU2();
String name = nameIndexToString(nameIndex);
if (name.equals("LineNumberTable") || name.equals("LocalVariableTable")) newCount--;
else System.err.println("ERROR - Unknown code attribute " + name);
len = ci.getU4();
DataInputUtil.skipFully(ci, len);
}
if (newCount != 0) {
System.err.println("ERROR - expecting all code attributes to be removed");
System.exit(1);
}
// this is only coded for all attributes within a Code attribute being removed.
byte[] newInfo = new byte[nonAttrLength + 2];
System.arraycopy(ae.infoIn, 0, newInfo, 0, nonAttrLength);
// last two bytes are left at 0 which means 0 attributes
ae.infoIn = newInfo;
}
public static ClassInvestigator load(InputStream is) throws IOException {
ClassInput classInput = new ClassInput(is);
// Check the header
int magic = classInput.getU4();
int minor_version = classInput.getU2();
int major_version = classInput.getU2();
if (magic != VMDescriptor.JAVA_CLASS_FORMAT_MAGIC) throw new ClassFormatError();
// Read in the Constant Pool
int constantPoolCount = classInput.getU2();
ClassInvestigator ci = new ClassInvestigator(constantPoolCount);
ci.minor_version = minor_version;
ci.major_version = major_version;
// Yes, index starts at 1, The '0'th constant pool entry
// is reserved for the JVM and is not present in the class file.
for (int i = 1; i < constantPoolCount; ) {
ConstantPoolEntry item = ClassInvestigator.getConstant(classInput);
i += ci.addEntry(item.getKey(), item);
}
// Read in access_flags and class indexes
ci.access_flags = classInput.getU2();
ci.this_class = classInput.getU2();
ci.super_class = classInput.getU2();
// interfaces is a simple int array
int interfaceCount = classInput.getU2();
if (interfaceCount != 0) {
ci.interfaces = new int[interfaceCount];
for (int i = 0; i < interfaceCount; i++) ci.interfaces[i] = classInput.getU2();
}
int fieldCount = classInput.getU2();
if (fieldCount != 0) {
ci.field_info = new MemberTable(fieldCount);
for (int i = 0; i < fieldCount; i++) {
ci.field_info.addEntry(readClassMember(ci, classInput));
}
}
int methodCount = classInput.getU2();
if (methodCount != 0) {
ci.method_info = new MemberTable(methodCount);
for (int i = 0; i < methodCount; i++) {
ci.method_info.addEntry(readClassMember(ci, classInput));
}
}
int attributeCount = classInput.getU2();
if (attributeCount != 0) {
ci.attribute_info = new Attributes(attributeCount);
for (int i = 0; i < attributeCount; i++)
ci.attribute_info.addEntry(new AttributeEntry(classInput));
}
return ci;
}
