Fixed cppcheck-opensource#5082 (False positive: (error) Possible null pointer dereference: p2)

danmar · danmar · commit fc26de89a93b · 2013-10-20T13:37:36.000+02:00
diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
@@ -1401,12 +1401,12 @@ class Nullpointer : public ExecutionPath {
     bool null;
 
     /** variable is set to null */
-    static void setnull(std::list<ExecutionPath *> &checks, const unsigned int varid) {
+    static void setnull(std::list<ExecutionPath *> &checks, const unsigned int varid, bool null) {
         std::list<ExecutionPath *>::iterator it;
         for (it = checks.begin(); it != checks.end(); ++it) {
             Nullpointer *c = dynamic_cast<Nullpointer *>(*it);
             if (c && c->varId == varid)
-                c->null = true;
+                c->null = null;
         }
     }
 
@@ -1483,8 +1483,8 @@ class Nullpointer : public ExecutionPath {
                 dereference(checks, &tok);
             else if (unknown && owner->inconclusiveFlag())
                 dereference(checks, &tok);
-            if (Token::Match(tok.previous(), "[;{}=] %var% = 0 ;"))
-                setnull(checks, tok.varId());
+            if (Token::Match(tok.previous(), "[;{}=] %var% ="))
+                setnull(checks, tok.varId(), Token::simpleMatch(tok.tokAt(2), "0 ;"));
             else if (!deref &&
                      (!tok.previous()->isOp() || tok.previous()->str() == "&") &&
                      (!tok.next()->isConstOp() || tok.next()->str() == ">>"))
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
@@ -55,6 +55,7 @@ class TestNullPointer : public TestFixture {
         TEST_CASE(nullpointer20); // #3807 (fp: return p ? (p->x() || p->y()) : z)
         TEST_CASE(nullpointer21); // #4038 (fp: if (x) p=q; else return;)
         TEST_CASE(nullpointer23); // #4665 (false positive)
+        TEST_CASE(nullpointer24); // #5082 fp: chained assignment
         TEST_CASE(nullpointer_cast); // #4692
         TEST_CASE(nullpointer_castToVoid); // #3771
         TEST_CASE(pointerCheckAndDeRef);     // check if pointer is null and then dereference it
@@ -1241,6 +1242,15 @@ class TestNullPointer : public TestFixture {
         TODO_ASSERT_EQUALS("","[test.cpp:4]: (error) Possible null pointer dereference: c\n", errout.str());
     }
 
+    void nullpointer24() {  // #5083 - fp: chained assignment
+        check("void f(){\n"
+              "    char *c = NULL;\n"
+              "    x = c = new char[10];\n"
+              "    *c = 0;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void nullpointer_cast() { // #4692
         check("char *nasm_skip_spaces(const char *p) {\n"
               "    if (p)\n"
