Merge pull request #1317 from ispyisail/fix/pdf-trailer-startxref

Fix repeatable PDF changing with the output folder (#1178)

sources/pdf_links.cpp

@@ -194,6 +194,22 @@ void injectCrossRefLinks(QPdfEngine *engine, Diagram *diagram,
 		engine->drawHyperlink(link.rect, link.url);
 }
 
+/// The trailer dictionary of the xref table at \a xrefStart, from
+/// "trailer" up to its startxref, which the caller writes again with the
+/// new offset. Copying the old startxref too left a second one in the
+/// file, with the size the file had before its links were rewritten, so
+/// the bytes depended on the output path the links carry (#1178).
+static QByteArray trailerDictionary(const QByteArray &data, int xrefStart)
+{
+	const int start = data.indexOf("trailer", xrefStart);
+	if (start == -1)
+		return "trailer\n<<>>";
+	const int end = data.indexOf("startxref", start);
+	if (end == -1)
+		return "trailer\n<<>>";
+	return data.mid(start, end - start).trimmed();
+}
+
 void convertUriToGoTo(const QString &pdfPath)
 {
 	// --- 1. Read raw bytes ---
@@ -383,19 +399,7 @@ void convertUriToGoTo(const QString &pdfPath)
 		}
 	}
 
-	// Find trailer dict from the original xref section
-	int trailerPos = data.indexOf("trailer", xrefStart);
-	int trailerEnd = -1;
-	if (trailerPos != -1) {
-		trailerEnd = data.indexOf("%%EOF", trailerPos);
-		if (trailerEnd != -1) trailerEnd += 5;
-	}
-
-	QByteArray trailer;
-	if (trailerPos != -1 && trailerEnd != -1)
-		trailer = data.mid(trailerPos, trailerEnd - trailerPos);
-	else
-		trailer = "trailer\n<<>>\n%%EOF";
+	const QByteArray trailer = trailerDictionary(data, xrefStart);
 
 	int newXrefOffset = body.size();
 
@@ -814,18 +818,7 @@ void convertComponentInfoAnnotations(const QString &pdfPath,
 	}
 
 	// Copy trailer and bump /Size to account for the new XObject
-	QByteArray trailer;
-	{
-		int tPos = data.indexOf("trailer", xrefStart);
-		if (tPos != -1) {
-			int tEnd = data.indexOf("%%EOF", tPos);
-			if (tEnd != -1) tEnd += 5;
-			if (tEnd != -1)
-				trailer = data.mid(tPos, tEnd - tPos);
-		}
-	}
-	if (trailer.isEmpty())
-		trailer = "trailer\n<<>>\n%%EOF";
+	QByteArray trailer = trailerDictionary(data, xrefStart);
 
 	// Bump /Size: original was maxObjNum+1, now it's emptyXObjNum+1
 	{
@@ -842,16 +835,6 @@ void convertComponentInfoAnnotations(const QString &pdfPath,
 		}
 	}
 
-	// Remove duplicate startxref if present in copied trailer
-	{
-		int stPos = trailer.indexOf("\nstartxref\n");
-		if (stPos != -1)
-			trailer = trailer.left(stPos);
-		// Ensure trailer ends with %%EOF
-		if (!trailer.endsWith("%%EOF\n"))
-			trailer += "\n%%EOF\n";
-	}
-
 	QByteArray result;
 	result.reserve(out.size() + xref.size() + trailer.size() + 64);
 	result += out;

tests/qttest/tst_pdfreproducible.cpp

@@ -22,12 +22,17 @@ class tst_pdfreproducible : public QObject
 	QTemporaryDir m_dir;
 	int m_run = 0;
 
-	QByteArray exportPdf(const QString &project, const QByteArray &epoch)
+	QByteArray exportPdf(const QString &project, const QByteArray &epoch,
+						 const QString &folder = QString())
 	{
 		const int run = m_run++;
 		const QString home = m_dir.filePath(QStringLiteral("home%1").arg(run));
 		const QString tmp = m_dir.filePath(QStringLiteral("tmp%1").arg(run));
-		const QString out = m_dir.filePath(QStringLiteral("out%1.pdf").arg(run));
+		const QString out = folder.isEmpty()
+			? m_dir.filePath(QStringLiteral("out%1.pdf").arg(run))
+			: m_dir.filePath(folder + QStringLiteral("/same.pdf"));
+		if (!folder.isEmpty())
+			QDir().mkpath(m_dir.filePath(folder));
 		QDir().mkpath(home);
 		QDir().mkpath(tmp);
 		QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
@@ -145,6 +150,23 @@ private slots:
 				 "the same drawing with new uuids gives a different PDF");
 	}
 
+	void sameBytesInAnyFolder()
+	{
+		// #1178: the links carry the output path, and rewriting them left
+		// the old startxref in the file, with the size the file had before.
+		const QString project =
+			QStringLiteral(QET_EXAMPLES_DIR) + QStringLiteral("/iso_sfc_example.qet");
+		QVERIFY2(QFile::exists(project), "examples/iso_sfc_example.qet not found");
+
+		const QByteArray first = exportPdf(project, "1700000000", QStringLiteral("p"));
+		QVERIFY(!first.isEmpty());
+		QVERIFY(first.contains("/GoTo"));
+		QCOMPARE(first.count("startxref"), 1);
+		QVERIFY2(xrefMatches(first), "the xref table does not match the file");
+		QVERIFY2(exportPdf(project, "1700000000", QStringLiteral("longer-folder-name")) == first,
+				 "the same project gives a different PDF in another folder");
+	}
+
 	void nowWithoutTheVariable()
 	{
 		const QString project =