Fixed #264 (Memory Leak: alloc by assigning to a return value)

The fix was inspired by the previous patch submitted by hoangtuansu

src/checkmemoryleak.cpp

@@ -252,7 +252,37 @@ void CheckMemoryLeak::mismatchAllocDealloc(const std::list<const Token *> &calls
     error(callstack, "error", "mismatchAllocDealloc", "Mismatching allocation and deallocation: " + varname);
 }
 
+CheckMemoryLeak::AllocType CheckMemoryLeak::functionReturnType(const Token *tok) const
+{
+    // Locate the start of the function..
+    unsigned int parlevel = 0;
+    while (tok)
+    {
+        if (tok->str() == "{" || tok->str() == "}")
+            return No;
 
+        if (tok->str() == "(")
+        {
+            if (parlevel != 0)
+                return No;
+            ++parlevel;
+        }
+
+        else if (tok->str() == ")")
+        {
+            if (parlevel != 1)
+                return No;
+            if (Token::Match(tok, ") const| { return new %type% ; }"))
+                return New;
+            if (Token::Match(tok, ") const| { return new %type% [ %any% ] ; }"))
+                return NewArray;
+            break;
+        }
+
+        tok = tok->next();
+    }
+    return No;
+}
 
 
 
@@ -355,6 +385,14 @@ const char * CheckMemoryLeakInFunction::call_func(const Token *tok, std::list<co
     }
     callstack.push_back(tok);
 
+    // Check if this is a function that allocates memory..
+    {
+        const Token *ftok = _tokenizer->GetFunctionTokenByName(funcname.c_str());
+        AllocType a = functionReturnType(ftok);
+        if (a != No)
+            return "alloc";
+    }
+
     // how many parameters is there in the function call?
     int numpar = countParameters(tok);
     if (numpar <= 0)

src/checkmemoryleak.h

@@ -43,7 +43,7 @@ class Token;
 
 class CheckMemoryLeak
 {
-protected:
+public:
     CheckMemoryLeak() { }
 
     /** What type of allocation are used.. the "Many" means that several types of allocation and deallocation are used */
@@ -68,6 +68,9 @@ protected:
     // error message
     virtual void error(const Token *tok, const std::string &severity, const std::string &id, const std::string &msg) = 0;
     virtual void error(const std::list<const Token *> &callstack, const std::string &severity, const std::string &id, const std::string &msg) = 0;
+
+    /** What type of allocated memory does the given function return? */
+    AllocType functionReturnType(const Token *tok) const;
 };
 
 

test/testmemleak.cpp

@@ -24,11 +24,61 @@
 #include "../src/checkmemoryleak.h"
 #include "testsuite.h"
 
-#include <iostream>
 #include <sstream>
 
 extern std::ostringstream errout;
 
+
+class TestMemleak : private TestFixture
+{
+public:
+    TestMemleak() : TestFixture("TestMemleak")
+    { }
+
+private:
+    void run()
+    {
+        TEST_CASE(testFunctionReturnType);
+    }
+
+    CheckMemoryLeak::AllocType functionReturnType(const char code[])
+    {
+        // Tokenize..
+        Tokenizer tokenizer;
+        std::istringstream istr(code);
+        tokenizer.tokenize(istr, "test.cpp");
+
+        return ((const CheckMemoryLeak *)0)->functionReturnType(tokenizer.tokens());
+    }
+
+    void testFunctionReturnType()
+    {
+        {
+            const char code[] = "const char *foo()\n"
+                                "{ return 0; }";
+            ASSERT_EQUALS(CheckMemoryLeak::No, functionReturnType(code));
+        }
+
+        {
+            const char code[] = "Fred *newFred()\n"
+                                "{ return new Fred; }";
+            ASSERT_EQUALS(CheckMemoryLeak::New, functionReturnType(code));
+        }
+
+        {
+            const char code[] = "char *foo()\n"
+                                "{ return new char[100]; }";
+            ASSERT_EQUALS(CheckMemoryLeak::NewArray, functionReturnType(code));
+        }
+    }
+};
+
+static TestMemleak testMemleak;
+
+
+
+
+
 class TestMemleakInFunction : public TestFixture
 {
 public:
@@ -145,6 +195,8 @@ private:
         TEST_CASE(func13);
         TEST_CASE(func14);
 
+        TEST_CASE(allocfunc1);
+
         TEST_CASE(throw1);
         TEST_CASE(throw2);
 
@@ -1366,38 +1418,20 @@ private:
     }
 
 
-    /*
-        void func3()
-        {
-            check( "static char *dmalloc()\n"
-                   "{\n"
-                   "    char *p = new char[100];\n"
-                   "    return p;\n"
-                   "}\n"
-                   "static void f()\n"
-                   "{\n"
-                   "    char *p = dmalloc();\n"
-                   "}\n" );
-            ASSERT_EQUALS( std::string("[test.cpp:9]: Memory leak: p\n"), errout.str() );
-        }
+    void allocfunc1()
+    {
+        check("static char *a()\n"
+              "{\n"
+              "    return new char[100];\n"
+              "}\n"
+              "static void b()\n"
+              "{\n"
+              "    char *p = a();\n"
+              "}\n");
+        ASSERT_EQUALS(std::string("[test.cpp:8]: (error) Memory leak: p\n"), errout.str());
+    }
 
 
-        void func4()
-        {
-            check( "static char *dmalloc()\n"
-                   "{\n"
-                   "    char *p = new char[100];\n"
-                   "    return p;\n"
-                   "}\n"
-                   "static void f()\n"
-                   "{\n"
-                   "    char *p = dmalloc();\n"
-                   "    delete p;\n"
-                   "}\n" );
-            ASSERT_EQUALS( std::string("[test.cpp:9]: Mismatching allocation and deallocation: p\n"), errout.str() );
-        }
-    */
-