This is the basic interface which describes a field in a C/C++ data structure or a Java object.
The accessors in this class are designed to allow manual coercion of the data within the field, which is often necessary when interfacing with C programs. Therefore, the accessors here do not perform any type checking. Specializations of the Field interface, such as JByteField, provide getValue() methods which both perform type checking and return the appropriate specialized type.
See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".
As an example, coercing a pointer field into an int can be done in the following fashion (assuming the application has registered an integer type in the type database called "intptr_t"):
{
...
Address myObject = ...;
CIntegerType intptr_tType = (CIntegerType) db.lookupType("intptr_t");
long addrVal = field.getCInteger(myObject, intptr_tType);
...
}
FIXME: among other things, this interface is not sufficient to
describe fields which are themselves arrays (like symbolOop's
jbyte _body[1]). */
public interface Field {
/** Get the name of this field */
public String getName();
/** Get the type of this field */
public Type getType();
/** Get the size, in bytes, of this field. Used for manual data
structure traversal where necessary. */
public long getSize();
/** Is this a static field? */
public boolean isStatic();
/** The offset of this field, in bytes, in its containing data
structure, if nonstatic. If this is a static field, throws a
WrongTypeException. */
public long getOffset() throws WrongTypeException;
/** The address of this field, if it is a static field. If this is a
nonstatic field, throws a WrongTypeException. */
public Address getStaticFieldAddress() throws WrongTypeException;
/** These accessors require that the field be nonstatic; otherwise, a WrongTypeException will be thrown. Note that type checking is not performed by these accessors in order to allow manual type coercion of field data. For better protection when accessing primitive fields, use the get(Type)Field accessors in Type.java.
NOTE that the Address passed in to these routines may, in fact, be an OopHandle. Specifically, in a reflective system, dereferencing operations applied to the OopHandle must be performed atomically with respect to GC.
See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".
*/ public boolean getJBoolean (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public byte getJByte (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public char getJChar (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public short getJShort (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public int getJInt (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public long getJLong (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public float getJFloat (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public double getJDouble (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public long getCInteger (Address addr, CIntegerType type) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public Address getAddress (Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public OopHandle getOopHandle(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException, NotInHeapException; public OopHandle getNarrowOopHandle(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException, NotInHeapException; /**These accessors require that the field be static; otherwise, a WrongTypeException will be thrown. Note that type checking is not performed by these accessors in order to allow manual type coercion of field data. For better protection when accessing primitive fields, use the get(Type)Field accessors in Type.java.
NOTE that the Address passed in to these routines may, in fact, be an OopHandle. Specifically, in a reflective system, dereferencing operations applied to the OopHandle must be performed atomically with respect to GC.
See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".
*/ public boolean getJBoolean () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public byte getJByte () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public char getJChar () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public float getJFloat () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public double getJDouble () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public int getJInt () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public long getJLong () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public short getJShort () throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public long getCInteger (CIntegerType type) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException; public Address getAddress () throws UnmappedAddressException, UnalignedAddressException; public OopHandle getOopHandle() throws UnmappedAddressException, UnalignedAddressException, NotInHeapException; public OopHandle getNarrowOopHandle() throws UnmappedAddressException, UnalignedAddressException, NotInHeapException; }