Don't crash on "else" instructions without preceding "if"

Change-Id: I85e51f9a98bae8e2617ecc0d64c14040dc4bf1b5
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>

2 files changed, 20 insertions, 4 deletions

diff --git a/src/scxml/qscxmlparser.cpp b/src/scxml/qscxmlparser.cpp
index a7aca80..a0f247b 100644
--- a/src/scxml/qscxmlparser.cpp
+++ b/src/scxml/qscxmlparser.cpp
@@ -2005,15 +2005,15 @@ void QScxmlParserPrivate::parse()
                 m_stack.append(pNew);
             } else if (elName == QLatin1String("elseif")) {
                 if (!checkAttributes(attributes, "cond")) return;
-                DocumentModel::If *ifI = m_stack.last().instruction->asIf();
-                Q_ASSERT(ifI);
+                DocumentModel::If *ifI = lastIf();
+                if (!ifI) return;
                 ifI->conditions.append(attributes.value(QLatin1String("cond")).toString());
                 m_stack.last().instructionContainer = m_doc->newSequence(&ifI->blocks);
                 m_stack.append(ParserState(ParserState::ElseIf));
             } else if (elName == QLatin1String("else")) {
                 if (!checkAttributes(attributes, "")) return;
-                DocumentModel::If *ifI = m_stack.last().instruction->asIf();
-                Q_ASSERT(ifI);
+                DocumentModel::If *ifI = lastIf();
+                if (!ifI) return;
                 m_stack.last().instructionContainer = m_doc->newSequence(&ifI->blocks);
                 m_stack.append(ParserState(ParserState::Else));
             } else if (elName == QLatin1String("foreach")) {
@@ -2458,6 +2458,21 @@ bool QScxmlParserPrivate::maybeId(const QXmlStreamAttributes &attributes, QStrin
     return true;
 }
 
+DocumentModel::If *QScxmlParserPrivate::lastIf()
+{
+    DocumentModel::Instruction *lastI = m_stack.last().instruction;
+    if (!lastI) {
+        addError(QStringLiteral("No previous instruction found for else block"));
+        return Q_NULLPTR;
+    }
+    DocumentModel::If *ifI = lastI->asIf();
+    if (!ifI) {
+        addError(QStringLiteral("Previous instruction for else block is not an 'if'"));
+        return Q_NULLPTR;
+    }
+    return ifI;
+}
+
 bool QScxmlParserPrivate::checkAttributes(const QXmlStreamAttributes &attributes, const char *attribStr)
 {
     QString allAttrib = QString::fromLatin1(attribStr);
diff --git a/src/scxml/qscxmlparser_p.h b/src/scxml/qscxmlparser_p.h
index 53853c6..87f5a29 100644
--- a/src/scxml/qscxmlparser_p.h
+++ b/src/scxml/qscxmlparser_p.h
@@ -583,6 +583,7 @@ private:
     DocumentModel::AbstractState *currentParent() const;
     DocumentModel::XmlLocation xmlLocation() const;
     bool maybeId(const QXmlStreamAttributes &attributes, QString *id);
+    DocumentModel::If *lastIf();
     bool checkAttributes(const QXmlStreamAttributes &attributes, const char *attribStr);
     bool checkAttributes(const QXmlStreamAttributes &attributes, QStringList requiredNames,
                          QStringList optionalNames);