Fixed #629 (Tokenizer: expand nested strcat() calls)

http://sourceforge.net/apps/trac/cppcheck/ticket/629

src/tokenize.cpp

@@ -1629,6 +1629,8 @@ void Tokenizer::simplifyTokenList()
     simplifyIfNotNull();
     simplifyIfAssign();
 
+    simplifyNestedStrcat();
+
     for (Token *tok = _tokens; tok; tok = tok->next())
     {
         if (Token::Match(tok, "case %any% : %var%"))
@@ -3313,8 +3315,69 @@ void Tokenizer::simplifyGoto()
     }
 }
 
+void Tokenizer::simplifyNestedStrcat()
+{
+    for (Token *tok = _tokens; tok; tok = tok->next())
+    {
+        if (! Token::Match(tok, "[;{}] strcat ( strcat ("))
+        {
+            continue;
+        }
 
+        // insert extracted function calls before first strcat call
+        Token *insertPos = tok;
 
+        // find inner strcat call
+        Token *tok2 = tok->tokAt(3);
+        while (Token::simpleMatch(tok2, "strcat ( strcat"))
+        {
+            tok2 = tok2->tokAt(2);
+        }
+
+        Token *end   = tok2->next()->link()->next();
+        Token *endOfFirstArg = NULL;
+        std::stack<Token *> brackets;
+
+        // copy tokens to new place
+        for (Token *cur = tok2; cur != end; cur = cur->next())
+        {
+            insertPos->insertToken(cur->strAt(0));
+            insertPos = insertPos->next();
+
+            if (cur->str() == "," && endOfFirstArg == NULL)
+            {
+                endOfFirstArg = cur;
+            }
+
+            // preserve varId
+            if (cur->varId())
+            {
+                insertPos->varId(cur->varId());
+            }
+
+            // linkify braces
+            if (insertPos->str() == "(")
+            {
+                brackets.push(insertPos);
+            }
+            else if (insertPos->str() == ")")
+            {
+                Token::createMutualLinks(brackets.top(), insertPos);
+                brackets.pop();
+            }
+        }
+        insertPos->insertToken(";");
+
+        // remove tokens at old place, but don't remove token with
+        // variable name (1st argument)
+        Token::eraseTokens(tok2->previous(), tok2->tokAt(2));
+        Token::eraseTokens(endOfFirstArg->previous(), end);
+
+        // skip just inserted tokens
+        tok = insertPos;
+    }
+
+}
 
 
 //---------------------------------------------------------------------------

src/tokenize.h

@@ -196,6 +196,9 @@ private:
     /** Replace a "goto" with the statements */
     void simplifyGoto();
 
+    /** Expand nested strcat() calls. */
+    void simplifyNestedStrcat();
+
     /** Simplify "if else" */
     void elseif();
 

test/testbufferoverrun.cpp

@@ -568,6 +568,13 @@ private:
               "   strcat(n, \"def\");\n"
               "}\n");
         ASSERT_EQUALS("[test.cpp:5]: (possible error) Buffer overrun\n", errout.str());
+
+        check("void f()\n"
+              "{\n"
+              "   char n[5];\n"
+              "   strcat(strcat(n, \"abc\"), \"def\");\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:4]: (possible error) Buffer overrun\n", errout.str());
     }
 
     void sprintf1()

test/testsimplifytokens.cpp

@@ -108,6 +108,9 @@ private:
 
         // Simplify goto..
         TEST_CASE(goto1);
+
+        // Simplify nested strcat() calls
+        TEST_CASE(strcat1);
     }
 
     std::string tok(const char code[])
@@ -1345,6 +1348,21 @@ private:
             ASSERT_EQUALS(code, tok(code));
         }
     }
+
+
+    void strcat1()
+    {
+        const char code[] = "; strcat(strcat(strcat(strcat(strcat(strcat(dst, \"this \"), \"\"), \"is \"), \"a \"), \"test\"), \".\");";
+        const char expect[] = "; "
+                              "strcat ( dst , \"this \" ) ; "
+                              "strcat ( dst , \"\" ) ; "
+                              "strcat ( dst , \"is \" ) ; "
+                              "strcat ( dst , \"a \" ) ; "
+                              "strcat ( dst , \"test\" ) ; "
+                              "strcat ( dst , \".\" ) ;";
+
+        ASSERT_EQUALS(expect, tok(code));
+    }
 };
 
 REGISTER_TEST(TestSimplifyTokens)