Package com.itextpdf.kernel.pdf

Class MemoryLimitsAwareHandler

java.lang.Object

com.itextpdf.kernel.pdf.MemoryLimitsAwareHandler

public class MemoryLimitsAwareHandler
extends java.lang.Object

A MemoryLimitsAwareHandler handles memory allocation and prevents decompressed pdf streams from occupation of more space than allowed.

A configured MemoryLimitsAwareHandler can be set as a property of ReaderProperties instance which is passed to PdfReader.

See Also:

ReaderProperties.setMemoryLimitsAwareHandler(MemoryLimitsAwareHandler)

Field Summary

Fields

Modifier and Type	Field	Description
private long	allMemoryUsedForDecompression
(package private) boolean	considerCurrentPdfStream
private static org.slf4j.Logger	LOGGER
private static int	MAX_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE
private static long	MAX_X_OBJECTS_SIZE_PER_PAGE
private int	maxNumberOfElementsInXrefStructure
private long	maxSizeOfDecompressedPdfStreamsSum
private int	maxSizeOfSingleDecompressedPdfStream
private long	maxXObjectsSizePerPage
private long	memoryUsedForCurrentPdfStreamDecompression
private static int	MIN_LIMIT_FOR_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE
private static int	SINGLE_DECOMPRESSED_PDF_STREAM_MIN_SIZE
private static int	SINGLE_SCALE_COEFFICIENT
private static long	SUM_OF_DECOMPRESSED_PDF_STREAMS_MIN_SIZE
private static int	SUM_SCALE_COEFFICIENT

Constructor Summary

Constructors

Modifier	Constructor	Description
	MemoryLimitsAwareHandler()	Creates a MemoryLimitsAwareHandler which will be used to handle decompression of pdf streams.
private	MemoryLimitsAwareHandler(int maxSizeOfSingleDecompressedPdfStream, long maxSizeOfDecompressedPdfStreamsSum, int maxNumberOfElementsInXrefStructure, long maxXObjectsSizePerPage)
	MemoryLimitsAwareHandler(long documentSize)	Creates a MemoryLimitsAwareHandler which will be used to handle decompression of pdf streams.

Method Summary

Modifier and Type	Method	Description
(package private) MemoryLimitsAwareHandler	beginDecompressedPdfStreamProcessing()	Begins handling of current pdf stream decompression.
private static long	calculateDefaultParameter(long documentSize, int scale, long min)
protected static int	calculateMaxElementsInXref(long documentSizeInBytes)	Calculate max number of elements allowed in xref table based on the size of the document, achieving max limit at 100MB.
void	checkIfPageSizeExceedsTheLimit(long totalXObjectsSize)
void	checkIfXrefStructureExceedsTheLimit(int requestedCapacity)	Performs a check of possible extension of xref structure.
(package private) MemoryLimitsAwareHandler	considerBytesOccupiedByDecompressedPdfStream(long numOfOccupiedBytes)	Considers the number of bytes which are occupied by the decompressed pdf stream.
MemoryLimitsAwareHandler	createNewInstance()	Creates a new instance of MemoryLimitsAwareHandler by copying settings from this instance of MemoryLimitsAwareHandler.
(package private) MemoryLimitsAwareHandler	endDecompressedPdfStreamProcessing()	Ends handling of current pdf stream decompression.
private void	ensureCurrentStreamIsReset()
(package private) long	getAllMemoryUsedForDecompression()
int	getMaxNumberOfElementsInXrefStructure()	Gets maximum number of elements in xref structure.
long	getMaxSizeOfDecompressedPdfStreamsSum()	Gets the maximum allowed size which can be occupied by all decompressed pdf streams.
int	getMaxSizeOfSingleDecompressedPdfStream()	Gets the maximum allowed size which can be occupied by a single decompressed pdf stream.
long	getMaxXObjectsSizePerPage()	Gets maximum page size.
boolean	isMemoryLimitsAwarenessRequiredOnDecompression(PdfArray filters)	Performs a check if the PdfStream with provided setup of the filters requires memory limits awareness during decompression.
void	setMaxNumberOfElementsInXrefStructure(int maxNumberOfElementsInXrefStructure)	Sets maximum number of elements in xref structure.
MemoryLimitsAwareHandler	setMaxSizeOfDecompressedPdfStreamsSum(long maxSizeOfDecompressedPdfStreamsSum)	Sets the maximum allowed size which can be occupied by all decompressed pdf streams.
MemoryLimitsAwareHandler	setMaxSizeOfSingleDecompressedPdfStream(int maxSizeOfSingleDecompressedPdfStream)	Sets the maximum allowed size which can be occupied by a single decompressed pdf stream.
void	setMaxXObjectsSizePerPage(long maxPageSize)	Sets maximum page size.

Methods inherited from class java.lang.Object

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

Field Detail

LOGGER

private static final org.slf4j.Logger LOGGER

SINGLE_SCALE_COEFFICIENT

private static final int SINGLE_SCALE_COEFFICIENT

See Also:

Constant Field Values

SUM_SCALE_COEFFICIENT

private static final int SUM_SCALE_COEFFICIENT

See Also:

Constant Field Values

MAX_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE

private static final int MAX_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE

See Also:

Constant Field Values

MIN_LIMIT_FOR_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE

private static final int MIN_LIMIT_FOR_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE

See Also:

Constant Field Values

SINGLE_DECOMPRESSED_PDF_STREAM_MIN_SIZE

private static final int SINGLE_DECOMPRESSED_PDF_STREAM_MIN_SIZE

See Also:

Constant Field Values

SUM_OF_DECOMPRESSED_PDF_STREAMS_MIN_SIZE

private static final long SUM_OF_DECOMPRESSED_PDF_STREAMS_MIN_SIZE

See Also:

Constant Field Values

MAX_X_OBJECTS_SIZE_PER_PAGE

private static final long MAX_X_OBJECTS_SIZE_PER_PAGE

See Also:

Constant Field Values

maxSizeOfSingleDecompressedPdfStream

private int maxSizeOfSingleDecompressedPdfStream

maxSizeOfDecompressedPdfStreamsSum

private long maxSizeOfDecompressedPdfStreamsSum

maxNumberOfElementsInXrefStructure

private int maxNumberOfElementsInXrefStructure

maxXObjectsSizePerPage

private long maxXObjectsSizePerPage

allMemoryUsedForDecompression

private long allMemoryUsedForDecompression

memoryUsedForCurrentPdfStreamDecompression

private long memoryUsedForCurrentPdfStreamDecompression

considerCurrentPdfStream

boolean considerCurrentPdfStream

Constructor Detail

MemoryLimitsAwareHandler

public MemoryLimitsAwareHandler()

Creates a MemoryLimitsAwareHandler which will be used to handle decompression of pdf streams. The max allowed memory limits will be generated by default.

MemoryLimitsAwareHandler

public MemoryLimitsAwareHandler(long documentSize)

Creates a MemoryLimitsAwareHandler which will be used to handle decompression of pdf streams. The max allowed memory limits will be generated by default, based on the size of the document.

Parameters:

documentSize - the size of the document, which is going to be handled by iText.

MemoryLimitsAwareHandler

private MemoryLimitsAwareHandler(int maxSizeOfSingleDecompressedPdfStream,
                                 long maxSizeOfDecompressedPdfStreamsSum,
                                 int maxNumberOfElementsInXrefStructure,
                                 long maxXObjectsSizePerPage)

Method Detail

createNewInstance

public MemoryLimitsAwareHandler createNewInstance()

Creates a new instance of MemoryLimitsAwareHandler by copying settings from this instance of MemoryLimitsAwareHandler.

Returns:

a new instance of MemoryLimitsAwareHandler.

getMaxSizeOfSingleDecompressedPdfStream

public int getMaxSizeOfSingleDecompressedPdfStream()

Gets the maximum allowed size which can be occupied by a single decompressed pdf stream.

Returns:

the maximum allowed size which can be occupied by a single decompressed pdf stream.

setMaxSizeOfSingleDecompressedPdfStream

public MemoryLimitsAwareHandler setMaxSizeOfSingleDecompressedPdfStream(int maxSizeOfSingleDecompressedPdfStream)

Sets the maximum allowed size which can be occupied by a single decompressed pdf stream. This value correlates with maximum heap size. This value should not exceed limit of the heap size.

iText will throw an exception if during decompression a pdf stream which was identified as requiring memory limits awareness occupies more memory than allowed.

Parameters:

maxSizeOfSingleDecompressedPdfStream - the maximum allowed size which can be occupied by a single decompressed pdf stream.

Returns:

this MemoryLimitsAwareHandler instance.

See Also:

isMemoryLimitsAwarenessRequiredOnDecompression(PdfArray)

getMaxSizeOfDecompressedPdfStreamsSum

public long getMaxSizeOfDecompressedPdfStreamsSum()

Gets the maximum allowed size which can be occupied by all decompressed pdf streams.

Returns:

the maximum allowed size value which streams may occupy

setMaxSizeOfDecompressedPdfStreamsSum

public MemoryLimitsAwareHandler setMaxSizeOfDecompressedPdfStreamsSum(long maxSizeOfDecompressedPdfStreamsSum)

Sets the maximum allowed size which can be occupied by all decompressed pdf streams. This value can be limited by the maximum expected PDF file size when it's completely decompressed. Setting this value correlates with the maximum processing time spent on document reading

iText will throw an exception if during decompression pdf streams which were identified as requiring memory limits awareness occupy more memory than allowed.

Parameters:

maxSizeOfDecompressedPdfStreamsSum - he maximum allowed size which can be occupied by all decompressed pdf streams.

Returns:

this MemoryLimitsAwareHandler instance.

See Also:

isMemoryLimitsAwarenessRequiredOnDecompression(PdfArray)

isMemoryLimitsAwarenessRequiredOnDecompression

public boolean isMemoryLimitsAwarenessRequiredOnDecompression(PdfArray filters)

Performs a check if the PdfStream with provided setup of the filters requires memory limits awareness during decompression.

Parameters:

filters - is an PdfArray of names of filters

Returns:

true if PDF stream is suspicious and false otherwise

getMaxNumberOfElementsInXrefStructure

public int getMaxNumberOfElementsInXrefStructure()

Gets maximum number of elements in xref structure.

Returns:

maximum number of elements in xref structure.

getMaxXObjectsSizePerPage

public long getMaxXObjectsSizePerPage()

Gets maximum page size.

Returns:

maximum page size.

setMaxXObjectsSizePerPage

public void setMaxXObjectsSizePerPage(long maxPageSize)

Sets maximum page size.

Parameters:

maxPageSize - maximum page size.

setMaxNumberOfElementsInXrefStructure

public void setMaxNumberOfElementsInXrefStructure(int maxNumberOfElementsInXrefStructure)

Sets maximum number of elements in xref structure.

Parameters:

maxNumberOfElementsInXrefStructure - maximum number of elements in xref structure.

checkIfXrefStructureExceedsTheLimit

public void checkIfXrefStructureExceedsTheLimit(int requestedCapacity)

Performs a check of possible extension of xref structure.

Parameters:

requestedCapacity - capacity to which we need to expand xref array.

checkIfPageSizeExceedsTheLimit

public void checkIfPageSizeExceedsTheLimit(long totalXObjectsSize)

calculateMaxElementsInXref

protected static int calculateMaxElementsInXref(long documentSizeInBytes)

Calculate max number of elements allowed in xref table based on the size of the document, achieving max limit at 100MB.

Parameters:

documentSizeInBytes - document size in bytes.

Returns:

calculated limit.

considerBytesOccupiedByDecompressedPdfStream

MemoryLimitsAwareHandler considerBytesOccupiedByDecompressedPdfStream(long numOfOccupiedBytes)

Considers the number of bytes which are occupied by the decompressed pdf stream. If memory limits have not been faced, throws an exception.

Parameters:

numOfOccupiedBytes - the number of bytes which are occupied by the decompressed pdf stream.

Returns:

this MemoryLimitsAwareHandler instance.

See Also:

MemoryLimitsAwareException

beginDecompressedPdfStreamProcessing

MemoryLimitsAwareHandler beginDecompressedPdfStreamProcessing()

Begins handling of current pdf stream decompression.

Returns:

this MemoryLimitsAwareHandler instance.

endDecompressedPdfStreamProcessing

MemoryLimitsAwareHandler endDecompressedPdfStreamProcessing()

Ends handling of current pdf stream decompression. If memory limits have not been faced, throws an exception.

Returns:

this MemoryLimitsAwareHandler instance.

See Also:

MemoryLimitsAwareException

getAllMemoryUsedForDecompression

long getAllMemoryUsedForDecompression()

calculateDefaultParameter

private static long calculateDefaultParameter(long documentSize,
                                              int scale,
                                              long min)

ensureCurrentStreamIsReset

private void ensureCurrentStreamIsReset()