org.apache.pdfbox.preflight.utils.FilterHelper Maven / Gradle / Ivy
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package org.apache.pdfbox.preflight.utils;
import java.util.HashSet;
import java.util.Set;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_INVALID_FILTER;
import static org.apache.pdfbox.preflight.PreflightConstants.ERROR_SYNTAX_STREAM_UNDEFINED_FILTER;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_ASCII_85;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_ASCII_HEX;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_CCITTFF;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_DCT;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_FLATE_DECODE;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_LZW;
import static org.apache.pdfbox.preflight.PreflightConstants.INLINE_DICTIONARY_VALUE_FILTER_RUN;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_ASCII_85;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_ASCII_HEX;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_CCITTFF;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_DCT;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_FLATE_DECODE;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_JBIG;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_LZW;
import static org.apache.pdfbox.preflight.PreflightConstants.STREAM_DICTIONARY_VALUE_FILTER_RUN;
import org.apache.pdfbox.preflight.PreflightContext;
import org.apache.pdfbox.preflight.PreflightDocument;
import org.apache.pdfbox.preflight.ValidationResult.ValidationError;
public final class FilterHelper
{
private static final Set ALLOWED_FILTERS = new HashSet<>();
static
{
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_FLATE_DECODE);
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_ASCII_HEX);
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_ASCII_85);
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_CCITTFF);
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_DCT);
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_JBIG);
ALLOWED_FILTERS.add(STREAM_DICTIONARY_VALUE_FILTER_RUN);
ALLOWED_FILTERS.add(INLINE_DICTIONARY_VALUE_FILTER_FLATE_DECODE);
ALLOWED_FILTERS.add(INLINE_DICTIONARY_VALUE_FILTER_ASCII_HEX);
ALLOWED_FILTERS.add(INLINE_DICTIONARY_VALUE_FILTER_ASCII_85);
ALLOWED_FILTERS.add(INLINE_DICTIONARY_VALUE_FILTER_CCITTFF);
ALLOWED_FILTERS.add(INLINE_DICTIONARY_VALUE_FILTER_DCT);
ALLOWED_FILTERS.add(INLINE_DICTIONARY_VALUE_FILTER_RUN);
}
private FilterHelper()
{
}
/**
* This method checks if the filter is authorized for the PDF file according to the preflight document specification
* attribute. For example according to the PDF/A-1 specification, only the LZW filter is forbidden due to Copyright
* compatibility. Because of the PDF/A is based on the PDF1.4 specification, all filters that aren't declared in the
* PDF Reference Third Edition are rejected.
*
* @param context
* the preflight context
* @param filter
* the filter to check
*/
public static void isAuthorizedFilter(PreflightContext context, String filter)
{
PreflightDocument preflightDocument = context.getDocument();
switch (preflightDocument.getSpecification())
{
case PDF_A1A:
isAuthorizedFilterInPDFA(context, filter);
break;
default:
// PDF/A-1b is the default format
isAuthorizedFilterInPDFA(context, filter);
break;
}
}
/**
* This method checks if the filter is authorized for a PDF/A file. According to the PDF/A-1 specification, only the
* LZW filter is forbidden due to Copyright compatibility. Because of the PDF/A is based on the PDF1.4
* specification, all filters that aren't declared in the PDF Reference Third Edition are rejected.
*
* @param context the preflight context
* @param filter the filter to check
*/
public static void isAuthorizedFilterInPDFA(PreflightContext context, String filter)
{
if (filter != null)
{
// --- LZW is forbidden.
if (STREAM_DICTIONARY_VALUE_FILTER_LZW.equals(filter) || INLINE_DICTIONARY_VALUE_FILTER_LZW.equals(filter))
{
context.addValidationError(new ValidationError(ERROR_SYNTAX_STREAM_INVALID_FILTER,
"LZWDecode is forbidden"));
return;
}
// --- Filters declared in the PDF Reference for PDF 1.4
// --- Other Filters are considered as invalid to avoid not consistent behaviour
if (!ALLOWED_FILTERS.contains(filter))
{
context.addValidationError(new ValidationError(ERROR_SYNTAX_STREAM_UNDEFINED_FILTER,
"This filter isn't defined in the PDF Reference Third Edition : " + filter));
}
}
}
}