Fixed #9295 (ValueFlow: Does not handle noreturn function)

cfg/cppcheck-cfg.rng

@@ -101,7 +101,13 @@
 
         <interleave>
           <optional>
-            <element name="noreturn"><ref name="DATA-BOOL"/></element>
+            <element name="noreturn">
+              <choice>
+                <value>true</value>
+                <value>false</value>
+                <value>maybe</value>
+              </choice>
+            </element>
           </optional>
           <optional>
             <element name="pure"><empty/></element>

cfg/std.cfg

@@ -4566,7 +4566,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
   <!-- int raise(int sig); -->
   <function name="raise,std::raise">
     <returnValue type="int"/>
-    <noreturn>false</noreturn>
+    <noreturn>maybe</noreturn>
     <arg nr="1" direction="in">
       <not-uninit/>
     </arg>

lib/cppcheck.cpp

@@ -934,6 +934,7 @@ void CppCheck::checkRawTokens(const Tokenizer &tokenizer)
 
 void CppCheck::checkNormalTokens(const Tokenizer &tokenizer)
 {
+    mSettings.library.bugHunting = mSettings.bugHunting;
     if (mSettings.bugHunting)
         ExprEngine::runChecks(this, &tokenizer, &mSettings);
     else {

lib/library.cpp

@@ -56,7 +56,7 @@ static void gettokenlistfromvalid(const std::string& valid, TokenList& tokenList
     }
 }
 
-Library::Library() : mAllocId(0)
+Library::Library() : bugHunting(false), mAllocId(0)
 {
 }
 
@@ -646,9 +646,14 @@ Library::Error Library::loadFunction(const tinyxml2::XMLElement * const node, co
 
     for (const tinyxml2::XMLElement *functionnode = node->FirstChildElement(); functionnode; functionnode = functionnode->NextSiblingElement()) {
         const std::string functionnodename = functionnode->Name();
-        if (functionnodename == "noreturn")
+        if (functionnodename == "noreturn") {
-            mNoReturn[name] = (strcmp(functionnode->GetText(), "true") == 0);
+            if (strcmp(functionnode->GetText(), "false") == 0)
-        else if (functionnodename == "pure")
+                mNoReturn[name] = FalseTrueMaybe::False;
+            else if (strcmp(functionnode->GetText(), "maybe") == 0)
+                mNoReturn[name] = FalseTrueMaybe::Maybe;
+            else
+                mNoReturn[name] = FalseTrueMaybe::True; // Safe
+        } else if (functionnodename == "pure")
             func.ispure = true;
         else if (functionnodename == "const") {
             func.ispure = true;
@@ -1402,14 +1407,19 @@ bool Library::isFunctionConst(const Token *ftok) const
     const std::map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
     return (it != functions.end() && it->second.isconst);
 }
+
 bool Library::isnoreturn(const Token *ftok) const
 {
     if (ftok->function() && ftok->function()->isAttributeNoreturn())
         return true;
     if (isNotLibraryFunction(ftok))
         return false;
-    const std::map<std::string, bool>::const_iterator it = mNoReturn.find(getFunctionName(ftok));
+    const std::map<std::string, FalseTrueMaybe>::const_iterator it = mNoReturn.find(getFunctionName(ftok));
-    return (it != mNoReturn.end() && it->second);
+    if (it == mNoReturn.end())
+        return false;
+    if (it->second == FalseTrueMaybe::Maybe)
+        return !bugHunting; // in bugHunting "maybe" means function is not noreturn
+    return it->second == FalseTrueMaybe::True;
 }
 
 bool Library::isnotnoreturn(const Token *ftok) const
@@ -1418,8 +1428,12 @@ bool Library::isnotnoreturn(const Token *ftok) const
         return false;
     if (isNotLibraryFunction(ftok))
         return false;
-    const std::map<std::string, bool>::const_iterator it = mNoReturn.find(getFunctionName(ftok));
+    const std::map<std::string, FalseTrueMaybe>::const_iterator it = mNoReturn.find(getFunctionName(ftok));
-    return (it != mNoReturn.end() && !it->second);
+    if (it == mNoReturn.end())
+        return false;
+    if (it->second == FalseTrueMaybe::Maybe)
+        return bugHunting; // in bugHunting "maybe" means function is not noreturn
+    return it->second == FalseTrueMaybe::False;
 }
 
 bool Library::markupFile(const std::string &path) const

lib/library.h

@@ -140,7 +140,7 @@ public:
 
     /** add noreturn function setting */
     void setnoreturn(const std::string& funcname, bool noreturn) {
-        mNoReturn[funcname] = noreturn;
+        mNoReturn[funcname] = noreturn ? FalseTrueMaybe::True : FalseTrueMaybe::False;
     }
 
     static bool isCompliantValidationExpression(const char* p);
@@ -496,6 +496,8 @@ public:
     enum class TypeCheck { def, check, suppress };
     TypeCheck getTypeCheck(const std::string &check, const std::string &typeName) const;
 
+    bool bugHunting;
+
 private:
     // load a <function> xml node
     Error loadFunction(const tinyxml2::XMLElement * const node, const std::string &name, std::set<std::string> &unknown_elements);
@@ -554,12 +556,13 @@ private:
         int mOffset;
         std::set<std::string> mBlocks;
     };
+    enum class FalseTrueMaybe { False, True, Maybe };
     int mAllocId;
     std::set<std::string> mFiles;
     std::map<std::string, AllocFunc> mAlloc; // allocation functions
     std::map<std::string, AllocFunc> mDealloc; // deallocation functions
     std::map<std::string, AllocFunc> mRealloc; // reallocation functions
-    std::map<std::string, bool> mNoReturn; // is function noreturn?
+    std::map<std::string, FalseTrueMaybe> mNoReturn; // is function noreturn?
     std::map<std::string, std::string> mReturnValue;
     std::map<std::string, std::string> mReturnValueType;
     std::map<std::string, int> mReturnValueContainer;

test/testbughuntingchecks.cpp

@@ -46,6 +46,9 @@ private:
         TEST_CASE(bufferOverflowMemCmp2);
         TEST_CASE(bufferOverflowStrcpy1);
         TEST_CASE(bufferOverflowStrcpy2);
+
+        TEST_CASE(divisionByZeroNoReturn);
+
         TEST_CASE(uninit);
         TEST_CASE(uninit_array);
         TEST_CASE(uninit_function_par);
@@ -61,6 +64,7 @@ private:
     }
 
     void check(const char code[]) {
+        settings.bugHunting = settings.library.bugHunting = true;
         Tokenizer tokenizer(&settings, this);
         std::istringstream istr(code);
         tokenizer.tokenize(istr, "test.cpp");
@@ -191,6 +195,18 @@ private:
         ASSERT_EQUALS("[test.cpp:2]: (error) Buffer read/write, when calling 'strcpy' it cannot be determined that 1st argument is not overflowed\n", errout.str());
     }
 
+
+    void divisionByZeroNoReturn() {
+        // Don't know if function is noreturn or not..
+        check("int f(int leftarg, int rightarg) {\n"
+              "  if (rightarg == 0)\n"
+              "    raise (SIGFPE);\n"  // <- maybe noreturn
+              "  return leftarg / rightarg;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:4]: (error) There is division, cannot determine that there can't be a division by zero.\n", errout.str());
+    }
+
+
     void uninit() {
         check("void foo() { int x; x = x + 1; }");
         ASSERT_EQUALS("[test.cpp:1]: (error) Cannot determine that 'x' is initialized\n", errout.str());