Class COSParser

java.lang.Object
org.apache.pdfbox.pdfparser.BaseParser
org.apache.pdfbox.pdfparser.COSParser
Direct Known Subclasses:
FDFParser, PDFParser

public class COSParser extends BaseParser
PDF-Parser which first reads startxref and xref tables in order to know valid objects and parse only these objects. First PDFParser.parse() or FDFParser.parse() must be called before page objects can be retrieved, e.g. PDFParser.getPDDocument(). This class is a much enhanced version of QuickParser presented in PDFBOX-1104 by Jeremy Villalobos.
  • Field Details

    • source

      protected final RandomAccessRead source
    • SYSPROP_PARSEMINIMAL

      public static final String SYSPROP_PARSEMINIMAL
      Only parse the PDF file minimally allowing access to basic information.
      See Also:
    • SYSPROP_EOFLOOKUPRANGE

      public static final String SYSPROP_EOFLOOKUPRANGE
      The range within the %%EOF marker will be searched. Useful if there are additional characters after %%EOF within the PDF.
      See Also:
    • EOF_MARKER

      protected static final char[] EOF_MARKER
      EOF-marker.
    • OBJ_MARKER

      protected static final char[] OBJ_MARKER
      obj-marker.
    • fileLen

      protected long fileLen
      file length.
    • initialParseDone

      protected boolean initialParseDone
    • securityHandler

      protected SecurityHandler securityHandler
      The security handler.
    • xrefTrailerResolver

      protected XrefTrailerResolver xrefTrailerResolver
      Collects all Xref/trailer objects and resolves them into single object using startxref reference.
    • TMP_FILE_PREFIX

      public static final String TMP_FILE_PREFIX
      The prefix for the temp file being used.
      See Also:
  • Constructor Details

    • COSParser

      public COSParser(RandomAccessRead source)
      Default constructor.
      Parameters:
      source - input representing the pdf.
    • COSParser

      public COSParser(RandomAccessRead source, String password, InputStream keyStore, String keyAlias)
      Constructor for encrypted pdfs.
      Parameters:
      source - input representing the pdf.
      password - password to be used for decryption.
      keyStore - key store to be used for decryption when using public key security
      keyAlias - alias to be used for decryption when using public key security
  • Method Details

    • setEOFLookupRange

      public void setEOFLookupRange(int byteCount)
      Sets how many trailing bytes of PDF file are searched for EOF marker and 'startxref' marker. If not set we use default value DEFAULT_TRAIL_BYTECOUNT.

      We check that new value is at least 16. However for practical use cases this value should not be lower than 1000; even 2000 was found to not be enough in some cases where some trailing garbage like HTML snippets followed the EOF marker.

      In case system property SYSPROP_EOFLOOKUPRANGE is defined this value will be set on initialization but can be overwritten later.

      Parameters:
      byteCount - number of trailing bytes
    • retrieveTrailer

      protected COSDictionary retrieveTrailer() throws IOException
      Read the trailer information and provide a COSDictionary containing the trailer information.
      Returns:
      a COSDictionary containing the trailer information
      Throws:
      IOException - if something went wrong
    • parseXref

      protected COSDictionary parseXref(long startXRefOffset) throws IOException
      Parses cross reference tables.
      Parameters:
      startXRefOffset - start offset of the first table
      Returns:
      the trailer dictionary
      Throws:
      IOException - if something went wrong
    • getStartxrefOffset

      protected final long getStartxrefOffset() throws IOException
      Looks for and parses startxref. We first look for last '%%EOF' marker (within last DEFAULT_TRAIL_BYTECOUNT bytes (or range set via setEOFLookupRange(int)) and go back to find startxref.
      Returns:
      the offset of StartXref
      Throws:
      IOException - If something went wrong.
    • lastIndexOf

      protected int lastIndexOf(char[] pattern, byte[] buf, int endOff)
      Searches last appearance of pattern within buffer. Lookup before _lastOff and goes back until 0.
      Parameters:
      pattern - pattern to search for
      buf - buffer to search pattern in
      endOff - offset (exclusive) where lookup starts at
      Returns:
      start offset of pattern within buffer or -1 if pattern could not be found
    • isLenient

      public boolean isLenient()
      Return true if parser is lenient. Meaning auto healing capacity of the parser are used.
      Returns:
      true if parser is lenient
    • setLenient

      public void setLenient(boolean lenient)
      Change the parser leniency flag. This method can only be called before the parsing of the file.
      Parameters:
      lenient - try to handle malformed PDFs.
    • parseDictObjects

      protected void parseDictObjects(COSDictionary dict, COSName... excludeObjects) throws IOException
      Will parse every object necessary to load a single page from the pdf document. We try our best to order objects according to offset in file before reading to minimize seek operations.
      Parameters:
      dict - the COSObject from the parent pages.
      excludeObjects - dictionary object reference entries with these names will not be parsed
      Throws:
      IOException - if something went wrong
    • parseObjectDynamically

      protected final COSBase parseObjectDynamically(COSObject obj, boolean requireExistingNotCompressedObj) throws IOException
      This will parse the next object from the stream and add it to the local state.
      Parameters:
      obj - object to be parsed (we only take object number and generation number for lookup start offset)
      requireExistingNotCompressedObj - if true object to be parsed must not be contained within compressed stream
      Returns:
      the parsed object (which is also added to document object)
      Throws:
      IOException - If an IO error occurs.
    • parseObjectDynamically

      protected COSBase parseObjectDynamically(long objNr, int objGenNr, boolean requireExistingNotCompressedObj) throws IOException
      This will parse the next object from the stream and add it to the local state. It's reduced to parsing an indirect object.
      Parameters:
      objNr - object number of object to be parsed
      objGenNr - object generation number of object to be parsed
      requireExistingNotCompressedObj - if true the object to be parsed must be defined in xref (comment: null objects may be missing from xref) and it must not be a compressed object within object stream (this is used to circumvent being stuck in a loop in a malicious PDF)
      Returns:
      the parsed object (which is also added to document object)
      Throws:
      IOException - If an IO error occurs.
    • parseCOSStream

      protected COSStream parseCOSStream(COSDictionary dic) throws IOException
      This will read a COSStream from the input stream using length attribute within dictionary. If length attribute is a indirect reference it is first resolved to get the stream length. This means we copy stream data without testing for 'endstream' or 'endobj' and thus it is no problem if these keywords occur within stream. We require 'endstream' to be found after stream data is read.
      Parameters:
      dic - dictionary that goes with this stream.
      Returns:
      parsed pdf stream.
      Throws:
      IOException - if an error occurred reading the stream, like problems with reading length attribute, stream does not end with 'endstream' after data read, stream too short etc.
    • rebuildTrailer

      protected final COSDictionary rebuildTrailer() throws IOException
      Rebuild the trailer dictionary if startxref can't be found.
      Returns:
      the rebuild trailer dictionary
      Throws:
      IOException - if something went wrong
    • checkPages

      protected void checkPages(COSDictionary root)
      Check if all entries of the pages dictionary are present. Those which can't be dereferenced are removed.
      Parameters:
      root - the root dictionary of the pdf
    • isCatalog

      protected boolean isCatalog(COSDictionary dictionary)
      Tell if the dictionary is a PDF catalog. Override this for an FDF catalog.
      Parameters:
      dictionary -
      Returns:
      true if the given dictionary is a root dictionary
    • parsePDFHeader

      protected boolean parsePDFHeader() throws IOException
      Parse the header of a pdf.
      Returns:
      true if a PDF header was found
      Throws:
      IOException - if something went wrong
    • parseFDFHeader

      protected boolean parseFDFHeader() throws IOException
      Parse the header of a fdf.
      Returns:
      true if a FDF header was found
      Throws:
      IOException - if something went wrong
    • parseXrefTable

      protected boolean parseXrefTable(long startByteOffset) throws IOException
      This will parse the xref table from the stream and add it to the state The XrefTable contents are ignored.
      Parameters:
      startByteOffset - the offset to start at
      Returns:
      false on parsing error
      Throws:
      IOException - If an IO error occurs.
    • getDocument

      public COSDocument getDocument() throws IOException
      This will get the document that was parsed. The document must be parsed before this is called. When you are done with this document you must call close() on it to release resources.
      Returns:
      The document that was parsed.
      Throws:
      IOException - If there is an error getting the document.
    • getEncryption

      public PDEncryption getEncryption() throws IOException
      This will get the encryption dictionary. The document must be parsed before this is called.
      Returns:
      The encryption dictionary of the document that was parsed.
      Throws:
      IOException - If there is an error getting the document.
    • getAccessPermission

      public AccessPermission getAccessPermission() throws IOException
      This will get the AccessPermission. The document must be parsed before this is called.
      Returns:
      The access permission of document that was parsed.
      Throws:
      IOException - If there is an error getting the document.
    • parseTrailerValuesDynamically

      protected COSBase parseTrailerValuesDynamically(COSDictionary trailer) throws IOException
      Parse the values of the trailer dictionary and return the root object.
      Parameters:
      trailer - The trailer dictionary.
      Returns:
      The parsed root object.
      Throws:
      IOException - If an IO error occurs or if the root object is missing in the trailer dictionary.