Module openj9.dtfj

Package com.ibm.dtfj.image.j9

Class ImagePointer

java.lang.Object

com.ibm.dtfj.image.j9.ImagePointer

All Implemented Interfaces:

ImagePointer

public class ImagePointer
extends Object
implements ImagePointer

Constructor Summary

Constructors

Constructor	Description
ImagePointer(ImageAddressSpace resident, long localAddress)

Method Summary

Modifier and Type	Method	Description
ImagePointer	add(long offset)	Build a new image pointer offset from this one by the given amount.
boolean	equals(Object obj)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
long	getAddress()	Get the unwrapped address, represented as a Java long.
ImageAddressSpace	getAddressSpace()	Get the address space to which this pointer belongs.
byte	getByteAt(long index)	Get the value at the given offset from this pointer.
double	getDoubleAt(long index)	Get the value at the given offset from this pointer.
float	getFloatAt(long index)	Get the value at the given offset from this pointer.
int	getIntAt(long index)	Get the value at the given offset from this pointer.
long	getLongAt(long index)	Get the value at the given offset from this pointer.
ImagePointer	getPointerAt(long index)	Get the value at the given offset from this pointer.
Properties	getProperties()	Get the OS-specific properties for this address
short	getShortAt(long index)	Get the value at the given offset from this pointer.
int	hashCode()	Answers an integer hash code for the receiver.
boolean	isExecutable()	Tests memory execute permission.
boolean	isReadOnly()	Tests memory read/write permission.
boolean	isShared()	Tests memory shared permission.

Methods declared in class java.lang.Object

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

Constructor Details

ImagePointer

public ImagePointer(ImageAddressSpace resident,
 long localAddress)

Method Details

getAddress

public long getAddress()

Description copied from interface: ImagePointer

Get the unwrapped address, represented as a Java long.

Use caution when comparing addresses, as some addresses may be negative.

Note that, on segmented memory architectures, it may not be possible to represent all addresses accurately as integers.

Specified by:

getAddress in interface ImagePointer

Returns:

the unwrapped address, represented as a 64-bit integer.

getAddressSpace

public ImageAddressSpace getAddressSpace()

Description copied from interface: ImagePointer

Get the address space to which this pointer belongs.

Specified by:

getAddressSpace in interface ImagePointer

Returns:

the address space to which this pointer belongs.

add

public ImagePointer add(long offset)

Description copied from interface: ImagePointer

Build a new image pointer offset from this one by the given amount.

Specified by:

add in interface ImagePointer

Parameters:

offset - Offset in bytes.

Returns:

a new ImagePointer based at getAddress() + offset

isExecutable

public boolean isExecutable()
                     throws DataUnavailable

Description copied from interface: ImagePointer

Tests memory execute permission.

Specified by:

isExecutable in interface ImagePointer

Returns:

true if this memory address is within an executable page.

Throws:

DataUnavailable

isReadOnly

public boolean isReadOnly()
                   throws DataUnavailable

Description copied from interface: ImagePointer

Tests memory read/write permission.

Specified by:

isReadOnly in interface ImagePointer

Returns:

true if this memory address is read-only. False otherwise.

Throws:

DataUnavailable

isShared

public boolean isShared()
                 throws DataUnavailable

Description copied from interface: ImagePointer

Tests memory shared permission.

Specified by:

isShared in interface ImagePointer

Returns:

true if this memory address is shared between processes.

Throws:

DataUnavailable

getProperties

public Properties getProperties()

Description copied from interface: ImagePointer

Get the OS-specific properties for this address

Specified by:

getProperties in interface ImagePointer

Returns:

a table of OS-specific properties for this address. Values which are commonly available include

• "readable" -- whether the memory address can be read from
• "writable" -- whether the memory address can be written to
• "executable" -- whether data in the memory address can be executed

getPointerAt

public ImagePointer getPointerAt(long index)
                          throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer. To determine the number of bytes to skip after this call to read the next value, use ImageProcess.getPointerSize(). Note: to create an ImagePointer using an absolute address use com.ibm.dtfj.image.ImageAddressSpace.getPointer()

Specified by:

getPointerAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 32 or 64-bit pointer stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

See Also:

• ImageProcess.getPointerSize()
• ImageAddressSpace.getPointer(long)

getLongAt

public long getLongAt(long index)
               throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer.

Specified by:

getLongAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 64-bit long stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

getIntAt

public int getIntAt(long index)
             throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer.

Specified by:

getIntAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 32-bit int stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

getShortAt

public short getShortAt(long index)
                 throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer.

Specified by:

getShortAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 16-bit short stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

getByteAt

public byte getByteAt(long index)
               throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer.

Specified by:

getByteAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 8-bit byte stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

getFloatAt

public float getFloatAt(long index)
                 throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer.

Specified by:

getFloatAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 32-bit float stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

getDoubleAt

public double getDoubleAt(long index)
                   throws MemoryAccessException,
CorruptDataException

Description copied from interface: ImagePointer

Get the value at the given offset from this pointer.

Specified by:

getDoubleAt in interface ImagePointer

Parameters:

index - an offset (in bytes) from the current position

Returns:

the 64-bit double stored at getAddress() + index

Throws:

MemoryAccessException - if the memory cannot be read

CorruptDataException - if the memory should be in the image, but is missing or corrupted

equals

public boolean equals(Object obj)

Description copied from class: java.lang.Object

Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison. The implementation in Object answers true only if the argument is the exact same object as the receiver (==).

Specified by:

equals in interface ImagePointer

Overrides:

equals in class Object

Parameters:

obj -

Returns:

True obj refers to the same Image Pointer in the image

See Also:

• Object.hashCode()

hashCode

public int hashCode()

Description copied from class: java.lang.Object

Answers an integer hash code for the receiver. Any two objects which answer true when passed to .equals must answer the same value for this method.

Specified by:

hashCode in interface ImagePointer

Overrides:

hashCode in class Object

Returns:

the receiver's hash.

See Also:

• Object.equals(java.lang.Object)