Package com.tom_roush.pdfbox.pdfparser

Class COSParser

java.lang.Object

com.tom_roush.pdfbox.pdfparser.BaseParser

com.tom_roush.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. This class can be used as a PDFParser replacement. 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 Summary

Fields

Modifier and Type	Field	Description
static byte[]	ENDOBJ
static byte[]	ENDSTREAM
protected static char[]	EOF_MARKER	EOF-marker.
protected long	fileLen	file length.
protected boolean	initialParseDone
protected static char[]	OBJ_MARKER	obj-marker.
protected SecurityHandler	securityHandler	The security handler.
protected RandomAccessRead	source
static String	SYSPROP_EOFLOOKUPRANGE	The range within the %%EOF marker will be searched.
static String	SYSPROP_PARSEMINIMAL	Only parse the PDF file minimally allowing access to basic information.
static String	TMP_FILE_PREFIX	The prefix for the temp file being used.
protected XrefTrailerResolver	xrefTrailerResolver	Collects all Xref/trailer objects and resolves them into single object using startxref reference.

Fields inherited from class com.tom_roush.pdfbox.pdfparser.BaseParser

A, ASCII_CR, ASCII_LF, B, D, DEF, document, E, ENDOBJ_STRING, ENDSTREAM_STRING, J, M, N, O, R, S, seqSource, STREAM_STRING, T

Constructor Summary

Constructors

Constructor	Description
COSParser(RandomAccessRead source)	Default constructor.

Method Summary

Modifier and Type	Method	Description
COSDocument	getDocument()	This will get the document that was parsed.
protected long	getStartxrefOffset()	Looks for and parses startxref.
boolean	isLenient()	Return true if parser is lenient.
protected int	lastIndexOf(char[] pattern, byte[] buf, int endOff)	Searches last appearance of pattern within buffer.
protected COSStream	parseCOSStream(COSDictionary dic)	This will read a COSStream from the input stream using length attribute within dictionary.
protected void	parseDictObjects(COSDictionary dict, COSName... excludeObjects)	Will parse every object necessary to load a single page from the pdf document.
protected boolean	parseFDFHeader()	Parse the header of a fdf.
protected COSBase	parseObjectDynamically(long objNr, int objGenNr, boolean requireExistingNotCompressedObj)	This will parse the next object from the stream and add it to the local state.
protected COSBase	parseObjectDynamically(COSObject obj, boolean requireExistingNotCompressedObj)	This will parse the next object from the stream and add it to the local state.
protected boolean	parsePDFHeader()	Parse the header of a pdf.
protected long	parseStartXref()	This will parse the startxref section from the stream.
protected boolean	parseTrailer()	This will parse the trailer from the stream and add it to the state.
protected COSBase	parseTrailerValuesDynamically(COSDictionary trailer)	Parse the values of the trailer dictionary and return the root object
protected COSDictionary	parseXref(long startXRefOffset)	Parses cross reference tables.
void	parseXrefStream(COSStream stream, long objByteOffset, boolean isStandalone)	Fills XRefTrailerResolver with data of given stream.
protected boolean	parseXrefTable(long startByteOffset)	This will parse the xref table from the stream and add it to the state The XrefTable contents are ignored.
protected COSDictionary	rebuildTrailer()	Rebuild the trailer dictionary if startxref can't be found.
void	setEOFLookupRange(int byteCount)	Sets how many trailing bytes of PDF file are searched for EOF marker and 'startxref' marker.
void	setLenient(boolean lenient)	Change the parser leniency flag.

Methods inherited from class com.tom_roush.pdfbox.pdfparser.BaseParser

isClosing, isClosing, isDigit, isDigit, isEndOfName, isEOL, isEOL, isSpace, isSpace, isWhitespace, isWhitespace, parseBoolean, parseCOSArray, parseCOSDictionary, parseCOSName, parseCOSString, parseDirObject, readExpectedChar, readExpectedString, readExpectedString, readGenerationNumber, readInt, readLine, readLong, readObjectNumber, readString, readString, readStringNumber, skipSpaces, skipWhiteSpace

Methods inherited from class java.lang.Object

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

Field Detail

ENDSTREAM

public static final byte[] ENDSTREAM

ENDOBJ

public static final byte[] ENDOBJ

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:

Constant Field Values

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:

Constant Field Values

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:

Constant Field Values

Constructor Detail

COSParser

public COSParser(RandomAccessRead source)

Default constructor.

Method Detail

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

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

parseStartXref

protected long parseStartXref()
                       throws IOException

This will parse the startxref section from the stream. The startxref value is ignored.

Returns:

the startxref value or -1 on parsing error on parsing error

Throws:

IOException - If an IO error occurs.

parseTrailer

protected boolean parseTrailer()
                        throws IOException

This will parse the trailer from the stream and add it to the state.

Returns:

false on parsing error

Throws:

IOException - If an IO error occurs.

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.

parseXrefStream

public void parseXrefStream(COSStream stream,
                            long objByteOffset,
                            boolean isStandalone)
                     throws IOException

Fills XRefTrailerResolver with data of given stream. Stream must be of type XRef.

Parameters:

stream - the stream to be read

objByteOffset - the offset to start at

isStandalone - should be set to true if the stream is not part of a hybrid xref table

Throws:

IOException - if there is an error parsing the stream

getDocument

public COSDocument getDocument()
                        throws IOException

This will get the document that was parsed. parse() must be called 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.

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