cppcheck/test/testnullpointer.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2010 Daniel Marjamäki and Cppcheck team.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "tokenize.h"
#include "checknullpointer.h"
#include "testsuite.h"
#include <sstream>
extern std::ostringstream errout;
class TestNullPointer : public TestFixture
{
public:
TestNullPointer() : TestFixture("TestNullPointer")
{ }
private:
void run()
{
TEST_CASE(nullpointer1);
TEST_CASE(nullpointer2);
TEST_CASE(nullpointer3); // dereferencing struct and then checking if it's null
TEST_CASE(nullpointer4);
TEST_CASE(nullpointer5); // References should not be checked
TEST_CASE(nullpointer6);
TEST_CASE(nullpointer7);
TEST_CASE(nullpointer8);
TEST_CASE(nullpointer9);
TEST_CASE(nullpointer10); // check if pointer is null and then dereference it
}
void check(const char code[])
{
// Tokenize..
Tokenizer tokenizer;
std::istringstream istr(code);
tokenizer.tokenize(istr, "test.cpp");
// Clear the error buffer..
errout.str("");
// Check for redundant code..
Settings settings;
settings._checkCodingStyle = true;
CheckNullPointer checkNullPointer(&tokenizer, &settings, this);
checkNullPointer.nullPointer();
tokenizer.simplifyTokenList();
checkNullPointer.nullConstantDereference();
checkNullPointer.executionPaths();
}
void nullpointer1()
{
check("int foo(const Token *tok)\n"
"{\n"
" while (tok);\n"
" tok = tok->next();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: tok\n", errout.str());
check("void foo()\n"
"{\n"
" for (const Token *tok = tokens; tok; tok = tok->next())\n"
" {\n"
" while (tok && tok->str() != \";\")\n"
" tok = tok->next();\n"
" }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (error) Possible null pointer dereference: tok - otherwise it is redundant to check if tok is null at line 5\n", errout.str());
check("void foo(Token &tok)\n"
"{\n"
" for (int i = 0; i < tok.size(); i++ )\n"
" {\n"
" while (!tok)\n"
" char c = tok.read();\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo()\n"
"{\n"
" for (const Token *tok = tokens; tok; tok = tok->next())\n"
" {\n"
" while (tok && tok->str() != \";\")\n"
" tok = tok->next();\n"
" if( !tok ) break;\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo()\n"
"{\n"
" for (const Token *tok = tokens; tok; tok = tok ? tok->next() : NULL)\n"
" {\n"
" while (tok && tok->str() != \";\")\n"
" tok = tok->next();\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(A*a)\n"
"{\n"
" switch (a->b()) {\n"
" case 1:\n"
" while( a ){\n"
" a = a->next;\n"
" }\n"
" break;\n"
" case 2:\n"
" a->b();\n"
" break;\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// ticket #1923 - no false positive when using else if
check("void f(A *a)\n"
"{\n"
" if (a->x == 1)\n"
" {\n"
" a = a->next;\n"
" }\n"
" else if (a->x == 2) { }\n"
" if (a) { }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// ticket #2134 - sizeof doesn't dereference
check("void f() {\n"
" int c = 1;\n"
" int *list = NULL;\n"
" sizeof(*list);\n"
" if (!list)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
void nullpointer2()
{
// Null pointer dereference can only happen with pointers
check("void foo()\n"
"{\n"
" Fred fred;\n"
" while (fred);\n"
" fred.hello();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
// Dereferencing a struct and then checking if it is null
// This is checked by this function:
// CheckOther::nullPointerStructByDeRefAndChec
void nullpointer3()
{
// errors..
check("void foo(struct ABC *abc)\n"
"{\n"
" int a = abc->a;\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (error) Possible null pointer dereference: abc - otherwise it is redundant to check if abc is null at line 4\n", errout.str());
check("void foo(struct ABC *abc)\n"
"{\n"
" bar(abc->a);\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (error) Possible null pointer dereference: abc - otherwise it is redundant to check if abc is null at line 4\n", errout.str());
// ok dereferencing in a condition
check("void foo(struct ABC *abc)\n"
"{\n"
" if (abc && abc->a);\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// ok to use a linked list..
check("void foo(struct ABC *abc)\n"
"{\n"
" abc = abc->next;\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// reassign struct..
check("void foo(struct ABC *abc)\n"
"{\n"
" int a = abc->a;\n"
" abc = abc->next;\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(struct ABC *abc)\n"
"{\n"
" int a = abc->a;\n"
" f(&abc);\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// goto..
check("void foo(struct ABC *abc)\n"
"{\n"
" int a;\n"
" if (!abc)\n"
" goto out;"
" a = abc->a;\n"
" return;\n"
"out:\n"
" if (!abc)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// loops..
check("void freeAbc(struct ABC *abc)\n"
"{\n"
" while (abc)\n"
" {\n"
" struct ABC *next = abc->next;\n"
" if (abc) delete abc;\n"
" abc = next;\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(struct ABC *abc)\n"
"{\n"
" int a = abc->a;"
" do\n"
" {\n"
" if (abc)\n"
" abc = abc->next;\n"
" --a;\n"
" }\n"
" while (a > 0);\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f()\n"
"{\n"
" for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next())\n"
" {\n"
" while (tok && tok->str() != \"{\")\n"
" tok = tok->next();\n"
" if (!tok)\n"
" return;\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// dynamic_cast..
check("void foo(ABC *abc)\n"
"{\n"
" int a = abc->a;\n"
" if (!dynamic_cast<DEF *>(abc))\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
// Dereferencing a pointer and then checking if it is null
void nullpointer4()
{
// errors..
check("void foo(int *p)\n"
"{\n"
" *p = 0;\n"
" if (!p)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (error) Possible null pointer dereference: p - otherwise it is redundant to check if p is null at line 4\n", errout.str());
check("void foo(int *p)\n"
"{\n"
" bar(*p);\n"
" if (!p)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (error) Possible null pointer dereference: p - otherwise it is redundant to check if p is null at line 4\n", errout.str());
// no error
check("void foo()\n"
"{\n"
" int *p;\n"
" f(&p);\n"
" if (!p)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo()\n"
"{\n"
" int **p = f();\n"
" if (!p)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(int *p)\n"
"{\n"
" if (x)\n"
" p = 0;\n"
" else\n"
" *p = 0;\n"
" if (!p)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(int x)\n"
"{\n"
" int a = 2 * x;"
" if (x == 0)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(int *p)\n"
"{\n"
" int var1 = p ? *p : 0;\n"
" if (!p)\n"
" ;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(P *p)\n"
"{\n"
" while (p)\n"
" if (p->check())\n"
" break;\n"
" else\n"
" p = p->next();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void f(Document *doc) {\n"
" int x = doc && doc->x;\n"
" if (!doc) {\n"
" return;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
}
void nullpointer5()
{
// errors..
check("void foo(A &a)\n"
"{\n"
" char c = a.c();\n"
" if (!a)\n"
" return;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
// Execution paths..
void nullpointer6()
{
// errors..
check("static void foo()\n"
"{\n"
" Foo *p = 0;\n"
" if (a == 1)\n"
" p = new FooBar;\n"
" else if (a == 2)\n"
" p = new FooCar;\n"
" p->abcd();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:8]: (error) Possible null pointer dereference: p\n", errout.str());
check("static void foo()\n"
"{\n"
" int *p = 0;\n"
" int *q = p;\n"
" q[0] = 0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5]: (error) Possible null pointer dereference: q\n", errout.str());
check("static void foo()\n"
"{\n"
" int *p = 0;\n"
" int &r = *p;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Null pointer dereference\n", errout.str());
check("static void foo(int x)\n"
"{\n"
" int *p = 0;\n"
" int y = 5 + *p;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Null pointer dereference\n", errout.str());
check("static void foo(int x)\n"
"{\n"
" Foo<int> *abc = 0;\n"
" abc->a();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: abc\n", errout.str());
check("static void foo()\n"
"{\n"
" int *p(0);\n"
" std::cout << *p;"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Null pointer dereference\n", errout.str());
check("void f()\n"
"{\n"
" char *c = 0;\n"
" {\n"
" delete c;\n"
" }\n"
" c[0] = 0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:7]: (error) Possible null pointer dereference: c\n", errout.str());
check("static void foo()\n"
"{\n"
" int *p = 0;\n"
" if (3 > *p);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Null pointer dereference\n", errout.str());
check("void f()\n"
"{\n"
" if (x) {\n"
" char *c = 0;\n"
" *c = 0;\n"
" }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5]: (error) Null pointer dereference\n", errout.str());
// no false positive..
check("static void foo()\n"
"{\n"
" Foo *p = 0;\n"
" p = new Foo;\n"
" p->abcd();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("static void foo()\n"
"{\n"
" Foo *p = 0;\n"
" if (!p)\n"
" return;\n"
" p->abcd();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("static void foo()\n"
"{\n"
" int *p = 0;\n"
" exit();\n"
" *p = 0;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("static void foo(int a)\n"
"{\n"
" Foo *p = 0;\n"
" if (a && p)\n"
" p->do_something();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo()\n"
"{\n"
" int sz = sizeof((*(struct dummy *)0).x);\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void get_offset(long &offset)\n"
"{\n"
" mystruct * temp; temp = 0;\n"
" offset = (long)(&(temp->z));\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// Ticket #1893 - try/catch inside else
check("int *test(int *Z)\n"
"{\n"
" int *Q=NULL;\n"
" if (Z) {\n"
" Q = Z;\n"
" }\n"
" else {\n"
" Z = new int;\n"
" try {\n"
" } catch(...) {\n"
" }\n"
" Q = Z;\n"
" }\n"
" *Q=1;\n"
" return Q;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("int *test(int *Z)\n"
"{\n"
" int *Q=NULL;\n"
" if (Z) {\n"
" Q = Z;\n"
" }\n"
" else {\n"
" try {\n"
" } catch(...) {\n"
" }\n"
" }\n"
" *Q=1;\n"
" return Q;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:12]: (error) Possible null pointer dereference: Q\n", errout.str());
// Ticket #2052 (false positive for 'else continue;')
check("void f() {\n"
" for (int x = 0; x < 5; ++x) {"
" int *p = 0;\n"
" if (a(x)) p=b(x);\n"
" else continue;\n"
" *p = 0;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
// function pointer..
check("void foo()\n"
"{\n"
" void (*f)();\n"
" f = 0;\n"
" f();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5]: (error) Possible null pointer dereference: f\n", errout.str());
check("static void foo()\n"
"{\n"
" int *p = 0;\n"
" int *p2 = 0;\n"
" int r = *p;\n"
" int r2 = *p2;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5]: (error) Null pointer dereference\n"
"[test.cpp:6]: (error) Null pointer dereference\n", errout.str());
// loops..
check("void f() {\n"
" int *p = 0;\n"
" for (int i = 0; i < 10; ++i) {\n"
" int x = *p + 1;\n"
" }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: p\n", errout.str());
check("void f(int a) {\n"
" const char *p = 0;\n"
" if (a) {\n"
" p = \"abcd\";\n"
" }\n"
" for (int i = 0; i < 3; i++) {\n"
" if (a && (p[i] == '1'));\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
void nullpointer7()
{
check("void foo()\n"
"{\n"
" wxLongLong x = 0;\n"
" int y = x.GetValue();\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
void nullpointer8()
{
check("void foo()\n"
"{\n"
" const char * x = 0;\n"
" strdup(x);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: x\n", errout.str());
check("void foo()\n"
"{\n"
" char const * x = 0;\n"
" strdup(x);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: x\n", errout.str());
}
void nullpointer9() //#ticket 1778
{
check("void foo()\n"
"{\n"
" std::string * x = 0;\n"
" *x = \"test\";\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: x\n", errout.str());
}
// Check if pointer is null and the dereference it
void nullpointer10()
{
check("void foo(char *p) {\n"
" if (!p) {\n"
" }\n"
" *p = 0;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (error) Possible null pointer dereference: p\n", errout.str());
check("void foo(abc *p) {\n"
" if (!p) {\n"
" }\n"
" else if (!p->x) {\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(char *p) {\n"
" if (!p) {\n"
" abort();\n"
" }\n"
" *p = 0;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo(char *p) {\n"
" if (!p) {\n"
" throw x;\n"
" }\n"
" *p = 0;\n"
"}\n");
ASSERT_EQUALS("", errout.str());
check("void foo() {\n"
" if (!p) {\n"
" switch (x) { }\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// This is why this check can't be used on the simplified token list
check("void f(Foo *foo) {\n"
" if (!dynamic_cast<bar *>(foo)) {\n"
" *foo = 0;\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}
};
REGISTER_TEST(TestNullPointer)