CPlusPlus: Check maximum include depth in lexer

We use a value of 200, which is also GCC's default.

Fixes: QTCREATORBUG-28770
Change-Id: Id02b324cd2ffa81a709441a5d93856bcd06501c3
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/cplusplus/pp-engine.cpp

@@ -57,6 +57,7 @@ using namespace Utils;
 namespace {
 enum {
     MAX_FUNCTION_LIKE_ARGUMENTS_COUNT = 100,
+    MAX_INCLUDE_DEPTH = 200,
     MAX_TOKEN_EXPANSION_COUNT = 5000,
     MAX_TOKEN_BUFFER_DEPTH = 16000 // for when macros are using some kind of right-folding, this is the list of "delayed" buffers waiting to be expanded after the current one.
 };
@@ -1677,6 +1678,15 @@ void Preprocessor::handleIncludeDirective(PPToken *tk, bool includeNext)
     if (m_cancelChecker && m_cancelChecker())
         return;
 
+    GuardLocker depthLocker(m_includeDepthGuard);
+    if (m_includeDepthGuard.lockCount() > MAX_INCLUDE_DEPTH) {
+        // FIXME: Categorized logging!
+#ifndef NO_DEBUG
+        std::cerr << "Maximum include depth exceeded" << m_state.m_currentFileName << std::endl;
+#endif
+        return;
+    }
+
     m_state.m_lexer->setScanAngleStringLiteralTokens(true);
     lex(tk); // consume "include" token
     m_state.m_lexer->setScanAngleStringLiteralTokens(false);

src/libs/cplusplus/pp-engine.h

@@ -29,6 +29,8 @@
 #include <cplusplus/Lexer.h>
 #include <cplusplus/Token.h>
 
+#include <utils/guard.h>
+
 #include <QVector>
 #include <QBitArray>
 #include <QByteArray>
@@ -241,6 +243,7 @@ private:
     Environment *m_env;
     QByteArray m_scratchBuffer;
     CancelChecker m_cancelChecker;
+    Utils::Guard m_includeDepthGuard;
 
     bool m_expandFunctionlikeMacros;
     bool m_keepComments;

src/libs/utils/guard.h

@@ -16,6 +16,7 @@ public:
     Guard();
     ~Guard();
     bool isLocked() const;
+    int lockCount() const { return m_lockCount; }
 
     // Prefer using GuardLocker when possible. These two methods are provided only for cases
     // when locking and unlocking are done in separate methods, so that GuardLocker can't be

tests/auto/cplusplus/translationunit/CMakeLists.txt

@@ -1,4 +1,4 @@
 add_qtc_test(tst_cplusplus_translationunit
-  DEPENDS CppEditor
+  DEPENDS CppEditor Utils
   SOURCES tst_translationunit.cpp
 )