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Array index checking: Fixed TODO comment (false negatives when using ?:)

This commit is contained in:
Daniel Marjamäki 2012-11-30 09:01:15 +01:00
parent 1c4afbce8c
commit 031adef6ea
2 changed files with 43 additions and 4 deletions
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30
lib/checkbufferoverrun.cpp
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@ -431,10 +431,32 @@ void CheckBufferOverrun::parse_for_body(const Token *tok, const ArrayInfo &array
const std::string pattern = (arrayInfo.varid() ? std::string("%varid%") : arrayInfo.varname()) + " [ " + strindex + " ]";
for (const Token* tok2 = tok; tok2 && tok2 != tok->link(); tok2 = tok2->next()) {
// TODO: try to reduce false negatives. This is just a quick fix
// for TestBufferOverrun::array_index_for_question
if (tok2->str() == "?")
break;
// TestBufferOverrun::array_index_for_question
if (tok2->str() == "?") {
// does condition check counter variable?
bool usesCounter = false;
const Token *tok3 = tok2->previous();
while (Token::Match(tok3, "%var%|%num%|)|>=|>|<=|<|==|!=")) {
if (tok3->str() == strindex) {
usesCounter = true;
break;
}
tok3 = tok3->previous();
}
// If strindex is used in the condition then skip the
// conditional expressions
if (usesCounter) {
while (tok2 && !Token::Match(tok2, "[)],;]")) {
if (tok2->str() == "(" || tok2->str() == "[")
tok2 = tok2->link();
tok2 = tok2->next();
}
if (!tok2)
break;
continue;
}
}
if (Token::simpleMatch(tok2, "for (") && Token::simpleMatch(tok2->next()->link(), ") {")) {
const Token *endpar = tok2->next()->link();

17
test/testbufferoverrun.cpp
View File

@ -1872,6 +1872,23 @@ private:
" }\n"
"}");
ASSERT_EQUALS("", errout.str());
check("void f() {\n"
" int a[10];\n"
" for (int i = 0; i != 10; ++i) {\n"
" some_condition ? 0 : a[i-1];\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:4]: (error) Array 'a[10]' accessed at index -1, which is out of bounds.\n", errout.str());
check("void f() {\n"
" int a[10];\n"
" for (int i = 0; i != 10; ++i) {\n"
" i==0 ? 0 : a[i-1];\n"
" a[i-1] = 0;\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:5]: (error) Array 'a[10]' accessed at index -1, which is out of bounds.\n", errout.str());
}
void array_index_for_varid0() { // #4228: No varid for counter variable