Class MemoryLimitsAwareHandler

java.lang.Object
com.itextpdf.kernel.pdf.MemoryLimitsAwareHandler

public class MemoryLimitsAwareHandler extends 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:
  • Field Details

    • SINGLE_SCALE_COEFFICIENT

      private static final int SINGLE_SCALE_COEFFICIENT
      See Also:
    • SUM_SCALE_COEFFICIENT

      private static final int SUM_SCALE_COEFFICIENT
      See Also:
    • MAX_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE

      private static final int MAX_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE
      See Also:
    • MIN_LIMIT_FOR_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE

      private static final int MIN_LIMIT_FOR_NUMBER_OF_ELEMENTS_IN_XREF_STRUCTURE
      See Also:
    • SINGLE_DECOMPRESSED_PDF_STREAM_MIN_SIZE

      private static final int SINGLE_DECOMPRESSED_PDF_STREAM_MIN_SIZE
      See Also:
    • SUM_OF_DECOMPRESSED_PDF_STREAMS_MIN_SIZE

      private static final long SUM_OF_DECOMPRESSED_PDF_STREAMS_MIN_SIZE
      See Also:
    • MAX_X_OBJECTS_SIZE_PER_PAGE

      private static final long MAX_X_OBJECTS_SIZE_PER_PAGE
      See Also:
    • 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 Details

    • 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 Details

    • 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:
    • 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

      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:
    • 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:
    • getAllMemoryUsedForDecompression

      long getAllMemoryUsedForDecompression()
    • calculateDefaultParameter

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

      private void ensureCurrentStreamIsReset()