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CheckNullPointer: Refactoring. Created the function CheckNullPointer::isPointerDeRef that can be used to detect if a pointer is dereferenced

This commit is contained in:
Daniel Marjamäki 2010-10-31 15:32:19 +01:00
parent c80c709d7e
commit 6faa4b79d3
2 changed files with 59 additions and 24 deletions
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72
lib/checknullpointer.cpp
View File

@ -98,6 +98,47 @@ void CheckNullPointer::parseFunctionCall(const Token &tok, std::list<const Token
} }
/**
* Is there a pointer dereference? Everything that should result in
* a nullpointer dereference error message will result in a true
* return value. If it's unknown if the pointer is dereferenced false
* is returned.
* @param tok token for the pointer
* @param unknown it is not known if there is a pointer dereference (could be reported as a debug message)
* @return true => there is a dereference
*/
bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown)
{
unknown = false;
// Dereferencing pointer..
if (Token::Match(tok->tokAt(-2), "[;{}=+-/(,] * %var%"))
return true;
if (!Token::simpleMatch(tok->tokAt(-2), "& (") && Token::Match(tok->next(), ". %var%"))
return true;
if (Token::Match(tok->previous(), "[;{}=+-/(,] %var% [ %any% ]"))
return true;
if (Token::Match(tok->previous(), "return %var% [ %any% ]"))
return true;
if (Token::Match(tok, "%var% ("))
return true;
// Not a dereference..
if (Token::Match(tok->previous(), "[;{}] %var% ="))
return false;
// unknown if it's a dereference
unknown = true;
// assume that it's not a dereference (no false positives)
return false;
}
void CheckNullPointer::nullPointerAfterLoop() void CheckNullPointer::nullPointerAfterLoop()
{ {
@ -432,22 +473,12 @@ void CheckNullPointer::nullPointerByCheckAndDeRef()
if (tok2->varId() == varid) if (tok2->varId() == varid)
{ {
bool unknown = false;
if (Token::Match(tok2->previous(), "[;{}=] %var% = 0 ;")) if (Token::Match(tok2->previous(), "[;{}=] %var% = 0 ;"))
; ;
else if (Token::Match(tok2->tokAt(-2), "[;{}=+-/(,] * %var%")) else if (CheckNullPointer::isPointerDeRef(tok2, unknown))
nullPointerError(tok2, tok->strAt(3));
else if (!Token::simpleMatch(tok2->tokAt(-2), "& (") && Token::Match(tok2->next(), ". %var%"))
nullPointerError(tok2, tok->strAt(3));
else if (Token::Match(tok2->previous(), "[;{}=+-/(,] %var% [ %any% ]"))
nullPointerError(tok2, tok->strAt(3));
else if (Token::Match(tok2->previous(), "return %var% [ %any% ]"))
nullPointerError(tok2, tok->strAt(3));
else if (Token::Match(tok2, "%var% ("))
nullPointerError(tok2, tok->strAt(3)); nullPointerError(tok2, tok->strAt(3));
else else
@ -680,21 +711,14 @@ private:
if (tok.varId() != 0) if (tok.varId() != 0)
{ {
bool unknown = false;
if (Token::Match(tok.previous(), "[;{}=] %var% = 0 ;")) if (Token::Match(tok.previous(), "[;{}=] %var% = 0 ;"))
setnull(checks, tok.varId()); setnull(checks, tok.varId());
else if (Token::Match(tok.tokAt(-2), "[;{}=+-/(,] * %var%")) else if (CheckNullPointer::isPointerDeRef(&tok, unknown))
dereference(checks, &tok);
else if (Token::Match(tok.tokAt(-2), "return * %var%"))
dereference(checks, &tok);
else if (!Token::simpleMatch(tok.tokAt(-2), "& (") && Token::Match(tok.next(), ". %var%"))
dereference(checks, &tok);
else if (Token::Match(tok.previous(), "[;{}=+-/(,] %var% [ %any% ]"))
dereference(checks, &tok);
else if (Token::Match(tok.previous(), "return %var% [ %any% ]"))
dereference(checks, &tok);
else if (Token::Match(&tok, "%var% ("))
dereference(checks, &tok); dereference(checks, &tok);
else else
// TODO: Report debug warning that it's unknown if a
// pointer is dereferenced
bailOutVar(checks, tok.varId()); bailOutVar(checks, tok.varId());
} }

11
lib/checknullpointer.h
View File

@ -71,6 +71,17 @@ public:
std::list<const Token *> &var, std::list<const Token *> &var,
unsigned char value); unsigned char value);
/**
* Is there a pointer dereference? Everything that should result in
* a nullpointer dereference error message will result in a true
* return value. If it's unknown if the pointer is dereferenced false
* is returned.
* @param tok token for the pointer
* @param unknown it is not known if there is a pointer dereference (could be reported as a debug message)
* @return true => there is a dereference
*/
static bool isPointerDeRef(const Token *tok, bool &unknown);
/** @brief possible null pointer dereference */ /** @brief possible null pointer dereference */
void nullPointer(); void nullPointer();