Add check for String lengths in PDFA module

DEVSIX-2978

Autoported commit.
Original commit hash: [21a86068a]

Author: dzmitry.kachkou

itext.tests/itext.pdfa.tests/itext/pdfa/PdfALongStringTest.cs

@@ -45,7 +45,6 @@ source product.
 using System.Text;
 using iText.Kernel.Font;
 using iText.Kernel.Pdf;
-using iText.Kernel.Utils;
 using iText.Layout;
 using iText.Layout.Element;
 using iText.Test;
@@ -69,14 +68,14 @@ public static void BeforeClass() {
 
         [NUnit.Framework.Test]
         public virtual void RunTest() {
-            //TODO(DEVSIX-2978): Produces non-conforming PDF/A document
-            String file = "pdfALongString.pdf";
-            String filename = destinationFolder + file;
-            using (Stream icm = new FileStream(sourceFolder + "sRGB Color Space Profile.icm", FileMode.Open, FileAccess.Read
-                )) {
-                using (PdfADocument pdf = new PdfADocument(new PdfWriter(new FileStream(filename, FileMode.Create)), PdfAConformanceLevel
-                    .PDF_A_3U, new PdfOutputIntent("Custom", "", "http://www.color.org", "sRGB ICC preference", icm))) {
-                    using (Document document = new Document(pdf)) {
+            NUnit.Framework.Assert.That(() =>  {
+                String file = "pdfALongString.pdf";
+                String filename = destinationFolder + file;
+                using (Stream icm = new FileStream(sourceFolder + "sRGB Color Space Profile.icm", FileMode.Open, FileAccess.Read
+                    )) {
+                    using (Document document = new Document(new PdfADocument(new PdfWriter(new FileStream(filename, FileMode.Create
+                        )), PdfAConformanceLevel.PDF_A_3U, new PdfOutputIntent("Custom", "", "http://www.color.org", "sRGB ICC preference"
+                        , icm)))) {
                         StringBuilder stringBuilder = new StringBuilder(LOREM_IPSUM);
                         while (stringBuilder.Length < STRING_LENGTH_LIMIT) {
                             stringBuilder.Append(stringBuilder.ToString());
@@ -90,8 +89,11 @@ public virtual void RunTest() {
                     }
                 }
             }
-            NUnit.Framework.Assert.IsNull(new CompareTool().CompareByContent(filename, sourceFolder + "cmp/PdfALongStringTest/cmp_"
-                 + file, destinationFolder, "diff_"));
+            , NUnit.Framework.Throws.InstanceOf<PdfAConformanceException>().With.Message.EqualTo(PdfAConformanceException.PDF_STRING_IS_TOO_LONG))
+;
         }
+        // when document is auto-closing, ISO conformance check is performed
+        // this document contain a string which is longer than it is allowed
+        // per specification. That is why conformance exception should be thrown
     }
 }

itext.tests/itext.pdfa.tests/itext/pdfa/checker/PdfA1CheckerTest.cs

@@ -40,6 +40,7 @@ source product.
 For more information, please contact iText Software Corp. at this
 address: [email protected]
 */
+using System;
 using iText.Kernel.Pdf;
 using iText.Pdfa;
 using iText.Test;
@@ -277,6 +278,39 @@ public virtual void CheckCatalogDictionaryWithoutRequirements() {
                 pdfA2Checker.CheckCatalogValidEntries(catalog);
             }
             , NUnit.Framework.Throws.InstanceOf<PdfAConformanceException>().With.Message.EqualTo(PdfAConformanceException.A_CATALOG_DICTIONARY_SHALL_NOT_CONTAIN_REQUIREMENTS_ENTRY))
+;
+        }
+
+        [NUnit.Framework.Test]
+        public virtual void IndependentLongStringTest() {
+            NUnit.Framework.Assert.That(() =>  {
+                int maxAllowedLength = pdfA2Checker.GetMaxStringLength();
+                int testLength = maxAllowedLength + 1;
+                NUnit.Framework.Assert.AreEqual(testLength, 32768);
+                PdfString longString = new PdfString(PdfACheckerTestUtils.GetLongString(testLength));
+                // An exception should be thrown as provided String is longer then
+                // it is allowed per specification
+                pdfA2Checker.CheckPdfObject(longString);
+            }
+            , NUnit.Framework.Throws.InstanceOf<PdfAConformanceException>().With.Message.EqualTo(PdfAConformanceException.PDF_STRING_IS_TOO_LONG))
+;
+        }
+
+        [NUnit.Framework.Test]
+        public virtual void LongStringInContentStreamTest() {
+            NUnit.Framework.Assert.That(() =>  {
+                pdfA2Checker.SetFullCheckMode(true);
+                int maxAllowedLength = pdfA2Checker.GetMaxStringLength();
+                int testLength = maxAllowedLength + 1;
+                NUnit.Framework.Assert.AreEqual(testLength, 32768);
+                String newContentString = PdfACheckerTestUtils.GetStreamWithLongString(testLength);
+                byte[] newContent = newContentString.GetBytes(System.Text.Encoding.UTF8);
+                PdfStream stream = new PdfStream(newContent);
+                // An exception should be thrown as content stream has a string which
+                // is longer then it is allowed per specification
+                pdfA2Checker.CheckContentStream(stream);
+            }
+            , NUnit.Framework.Throws.InstanceOf<PdfAConformanceException>().With.Message.EqualTo(PdfAConformanceException.PDF_STRING_IS_TOO_LONG))
 ;
         }
     }

itext.tests/itext.pdfa.tests/itext/pdfa/checker/PdfA2CheckerTest.cs

@@ -0,0 +1,75 @@
+/*
+This file is part of the iText (R) project.
+Copyright (c) 1998-2020 iText Group NV
+Authors: iText Software.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License version 3
+as published by the Free Software Foundation with the addition of the
+following permission added to Section 15 as permitted in Section 7(a):
+FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
+ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
+OF THIRD PARTY RIGHTS
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.
+See the GNU Affero General Public License for more details.
+You should have received a copy of the GNU Affero General Public License
+along with this program; if not, see http://www.gnu.org/licenses or write to
+the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+Boston, MA, 02110-1301 USA, or download the license from the following URL:
+http://itextpdf.com/terms-of-use/
+
+The interactive user interfaces in modified source and object code versions
+of this program must display Appropriate Legal Notices, as required under
+Section 5 of the GNU Affero General Public License.
+
+In accordance with Section 7(b) of the GNU Affero General Public License,
+a covered work must retain the producer line in every PDF that is created
+or manipulated using iText.
+
+You can be released from the requirements of the license by purchasing
+a commercial license. Buying such a license is mandatory as soon as you
+develop commercial activities involving the iText software without
+disclosing the source code of your own applications.
+These activities include: offering paid services to customers as an ASP,
+serving PDFs on the fly in a web application, shipping iText with a closed
+source product.
+
+For more information, please contact iText Software Corp. at this
+address: [email protected]
+*/
+using System;
+
+namespace iText.Pdfa.Checker {
+    public class PdfACheckerTestUtils {
+        private PdfACheckerTestUtils() {
+        }
+
+        internal static String GetLongString(int length) {
+            char charToFill = 'A';
+            char[] array = new char[length];
+            for (int i = 0; i < array.Length; i++) {
+                array[i] = charToFill;
+            }
+            return new String(array);
+        }
+
+        internal static String GetStreamWithLongString(int length) {
+            return GetStreamWithValue("(" + GetLongString(length) + ")");
+        }
+
+        internal static String GetStreamWithLongStringInArray(int length) {
+            return GetStreamWithValue("[(" + GetLongString(length) + "), (a)]");
+        }
+
+        internal static String GetStreamWithLongStringInDictionary(int length) {
+            return GetStreamWithValue("<</Value (" + GetLongString(length) + ")>>");
+        }
+
+        private static String GetStreamWithValue(String value) {
+            return "q\n" + "BT\n" + "/F1 12 Tf\n" + "36 787.96 Td\n" + value + " Tj\n" + "ET\n" + "Q";
+        }
+    }
+}

itext.tests/itext.pdfa.tests/itext/pdfa/checker/PdfACheckerTestUtils.cs

@@ -45,12 +45,15 @@ source product.
 using System.Collections.Generic;
 using Common.Logging;
 using iText.IO.Font;
+using iText.IO.Source;
 using iText.IO.Util;
+using iText.Kernel;
 using iText.Kernel.Colors;
 using iText.Kernel.Font;
 using iText.Kernel.Pdf;
 using iText.Kernel.Pdf.Annot;
 using iText.Kernel.Pdf.Canvas;
+using iText.Kernel.Pdf.Canvas.Parser.Util;
 using iText.Kernel.Pdf.Colorspace;
 using iText.Pdfa;
 
@@ -136,6 +139,12 @@ public override void CheckColor(Color color, PdfDictionary currentColorSpaces, b
         public override void CheckColor(Color color, PdfDictionary currentColorSpaces, bool? fill, PdfStream stream
             ) {
             CheckColorSpace(color.GetColorSpace(), currentColorSpaces, true, fill);
+            if (color is PatternColor) {
+                PdfPattern pattern = ((PatternColor)color).GetPattern();
+                if (pattern is PdfPattern.Tiling) {
+                    CheckContentStream((PdfStream)pattern.GetPdfObject());
+                }
+            }
         }
 
         public override void CheckColorSpace(PdfColorSpace colorSpace, PdfDictionary currentColorSpaces, bool checkAlternate
@@ -259,6 +268,57 @@ public override void CheckFont(PdfFont pdfFont) {
                     CheckNonSymbolicTrueTypeFont(trueTypeFont);
                 }
             }
+            if (pdfFont is PdfType3Font) {
+                PdfDictionary charProcs = pdfFont.GetPdfObject().GetAsDictionary(PdfName.CharProcs);
+                foreach (PdfName charName in charProcs.KeySet()) {
+                    CheckContentStream(charProcs.GetAsStream(charName));
+                }
+            }
+        }
+
+        protected internal override void CheckContentStream(PdfStream contentStream) {
+            if (IsFullCheckMode() || contentStream.IsModified()) {
+                byte[] contentBytes = contentStream.GetBytes();
+                PdfTokenizer tokenizer = new PdfTokenizer(new RandomAccessFileOrArray(new RandomAccessSourceFactory().CreateSource
+                    (contentBytes)));
+                PdfCanvasParser parser = new PdfCanvasParser(tokenizer);
+                IList<PdfObject> operands = new List<PdfObject>();
+                try {
+                    while (parser.Parse(operands).Count > 0) {
+                        foreach (PdfObject operand in operands) {
+                            CheckContentStreamObject(operand);
+                        }
+                    }
+                }
+                catch (System.IO.IOException e) {
+                    throw new PdfException(PdfException.CannotParseContentStream, e);
+                }
+            }
+        }
+
+        protected internal override void CheckContentStreamObject(PdfObject @object) {
+            byte type = @object.GetObjectType();
+            switch (type) {
+                case PdfObject.STRING: {
+                    CheckPdfString((PdfString)@object);
+                    break;
+                }
+
+                case PdfObject.ARRAY: {
+                    foreach (PdfObject obj in (PdfArray)@object) {
+                        CheckContentStreamObject(obj);
+                    }
+                    break;
+                }
+
+                case PdfObject.DICTIONARY: {
+                    PdfDictionary dictionary = (PdfDictionary)@object;
+                    foreach (PdfObject obj in dictionary.Values()) {
+                        CheckContentStreamObject(obj);
+                    }
+                    break;
+                }
+            }
         }
 
         protected internal override void CheckNonSymbolicTrueTypeFont(PdfTrueTypeFont trueTypeFont) {
@@ -333,6 +393,7 @@ protected internal override void CheckFormXObject(PdfStream form) {
                     );
             }
             CheckResources(form.GetAsDictionary(PdfName.Resources));
+            CheckContentStream(form);
         }
 
         protected internal override void CheckLogicalStructure(PdfDictionary catalog) {

itext.tests/itext.pdfa.tests/resources/itext/pdfa/cmp/PdfALongStringTest/cmp_pdfALongString.pdf

@@ -149,8 +149,13 @@ public override void CheckColor(Color color, PdfDictionary currentColorSpaces, b
                     CanvasGraphicsState gState = new _CanvasGraphicsState_164(extGStateDict);
                     CheckExtGState(gState, contentStream);
                 }
+                else {
+                    if (pattern is PdfPattern.Tiling) {
+                        CheckContentStream((PdfStream)pattern.GetPdfObject());
+                    }
+                }
             }
-            CheckColorSpace(color.GetColorSpace(), currentColorSpaces, true, fill);
+            base.CheckColor(color, currentColorSpaces, fill, contentStream);
         }
 
         private sealed class _CanvasGraphicsState_164 : CanvasGraphicsState {
@@ -841,6 +846,7 @@ protected internal virtual void CheckFormXObject(PdfStream form, PdfStream conte
                 }
             }
             CheckResources(form.GetAsDictionary(PdfName.Resources));
+            CheckContentStream(form);
         }
 
         private void CheckContentsForTransparency(PdfDictionary pageDict) {