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Null pointer: improved inconclusive checking in CheckNullPointer::nullPointerAfterLoop

This commit is contained in:
Daniel Marjamäki 2011-10-09 15:09:02 +02:00
parent 1d9a99012b
commit 175503ef94
3 changed files with 57 additions and 9 deletions
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39
lib/checknullpointer.cpp
View File

@ -228,15 +228,38 @@ void CheckNullPointer::nullPointerAfterLoop()
// Locate the end of the while loop body..
const Token *tok2 = tok->next()->link()->next()->link();
// Is this checking inconclusive?
bool inconclusive = false;
// Check if the variable is dereferenced after the while loop
while (0 != (tok2 = tok2 ? tok2->next() : 0))
{
// Don't check into inner scopes or outer scopes. Stop checking if "break" is found
if (tok2->str() == "{" || tok2->str() == "}" || tok2->str() == "break")
// inner and outer scopes
if (tok2->str() == "{" || tok2->str() == "}")
{
// Not inconclusive: bail out
if (!_settings->inconclusive)
break;
inconclusive = true;
if (tok2->str() == "}")
{
// "}" => leaving function? then break.
const Token *tok3 = tok2->link()->previous();
if (!tok3 || !Token::Match(tok3, "[);]"))
break;
if (tok3->str() == ")" && !Token::Match(tok3->link()->previous(), "if|for|while"))
break;
}
}
// Stop checking if "break" is found
else if (tok2->str() == "break")
break;
// loop variable is found..
if (tok2->varId() == varid)
else if (tok2->varId() == varid)
{
// dummy variable.. is it unknown if pointer is dereferenced or not?
bool unknown = false;
@ -244,7 +267,7 @@ void CheckNullPointer::nullPointerAfterLoop()
// Is the loop variable dereferenced?
if (CheckNullPointer::isPointerDeRef(tok2, unknown))
{
nullPointerError(tok2, varname, tok->linenr());
nullPointerError(tok2, varname, tok->linenr(), inconclusive);
}
break;
}
@ -1178,8 +1201,12 @@ void CheckNullPointer::nullPointerError(const Token *tok, const std::string &var
reportError(tok, Severity::error, "nullPointer", "Possible null pointer dereference: " + varname);
}
void CheckNullPointer::nullPointerError(const Token *tok, const std::string &varname, const unsigned int line)
void CheckNullPointer::nullPointerError(const Token *tok, const std::string &varname, const unsigned int line, bool inconclusive)
{
reportError(tok, Severity::error, "nullPointer", "Possible null pointer dereference: " + varname + " - otherwise it is redundant to check if " + varname + " is null at line " + MathLib::toString<unsigned int>(line));
const std::string errmsg("Possible null pointer dereference: " + varname + " - otherwise it is redundant to check if " + varname + " is null at line " + MathLib::toString<unsigned int>(line));
if (inconclusive)
reportInconclusiveError(tok, Severity::error, "nullPointer", errmsg);
else
reportError(tok, Severity::error, "nullPointer", errmsg);
}

2
lib/checknullpointer.h
View File

@ -102,7 +102,7 @@ public:
void nullPointerError(const Token *tok); // variable name unknown / doesn't exist
void nullPointerError(const Token *tok, const std::string &varname);
void nullPointerError(const Token *tok, const std::string &varname, const unsigned int line);
void nullPointerError(const Token *tok, const std::string &varname, const unsigned int line, bool inconclusive = false);
/** Get error messages. Used by --errorlist */
void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings)

25
test/testnullpointer.cpp
View File

@ -34,6 +34,7 @@ private:
void run()
{
TEST_CASE(nullpointerAfterLoop);
TEST_CASE(nullpointer1);
TEST_CASE(nullpointer2);
TEST_CASE(structDerefAndCheck); // dereferencing struct and then checking if it's null
@ -53,13 +54,14 @@ private:
TEST_CASE(snprintf_with_non_zero_size);
}
void check(const char code[])
void check(const char code[], bool inconclusive = false)
{
// Clear the error buffer..
errout.str("");
Settings settings;
settings.addEnabled("style");
settings.inconclusive = inconclusive;
// Tokenize..
Tokenizer tokenizer(&settings, this);
@ -75,7 +77,7 @@ private:
}
void nullpointer1()
void nullpointerAfterLoop()
{
check("int foo(const Token *tok)\n"
"{\n"
@ -151,6 +153,25 @@ private:
"}\n");
ASSERT_EQUALS("", errout.str());
// dereference in outer scope..
{
const char code[] = "void foo(int x, const Token *tok) {\n"
" if (x == 123) {\n"
" while (tok) tok = tok->next();\n"
" }\n"
" tok->str();\n"
"}\n";
check(code, false);
ASSERT_EQUALS("", errout.str());
check(code, true);
ASSERT_EQUALS("[test.cpp:5]: (error) Possible null pointer dereference: tok - otherwise it is redundant to check if tok is null at line 3\n", errout.str());
}
}
void nullpointer1()
{
// ticket #1923 - no false positive when using else if
check("void f(A *a)\n"
"{\n"