checkexceptionsafety.cpp

/*
 * Cppcheck - A tool for static C/C++ code analysis
 * Copyright (C) 2007-2012 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 "checkexceptionsafety.h"
#include "symboldatabase.h"
#include "token.h"

//---------------------------------------------------------------------------

// Register CheckExceptionSafety..
namespace {
    CheckExceptionSafety instance;
}


//---------------------------------------------------------------------------

void CheckExceptionSafety::destructors()
{
    const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();

    // Perform check..
    for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) {
        for (std::list<Function>::const_iterator j = i->functionList.begin(); j != i->functionList.end(); ++j) {
            // only looking for destructors
            if (j->type == Function::eDestructor && j->functionScope) {
                // Inspect this destructor..
                for (const Token *tok = j->functionScope->classStart->next(); tok != j->functionScope->classEnd; tok = tok->next()) {
                    // Skip try blocks
                    if (Token::simpleMatch(tok, "try {")) {
                        tok = tok->next()->link();
                    }

                    // throw found within a destructor
                    if (tok->str() == "throw") {
                        destructorsError(tok);
                        break;
                    }
                }
            }
        }
    }
}




void CheckExceptionSafety::deallocThrow()
{
    if (!_settings->isEnabled("style"))
        return;

    const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();

    // Deallocate a global/member pointer and then throw exception
    // the pointer will be a dead pointer
    for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
        // only looking for delete now
        if (tok->str() != "delete")
            continue;

        // Check if this is something similar with: "delete p;"
        tok = tok->next();
        if (Token::simpleMatch(tok, "[ ]"))
            tok = tok->tokAt(2);
        if (!tok)
            break;
        if (!Token::Match(tok, "%var% ;"))
            continue;
        const unsigned int varid(tok->varId());
        if (varid == 0)
            continue;

        // we only look for global variables
        const Variable* var = symbolDatabase->getVariableFromVarId(varid);
        if (!var || !(var->isGlobal() || var->isStatic()))
            continue;

        // Token where throw occurs
        const Token *ThrowToken = 0;

        // is there a throw after the deallocation?
        const Token* const end2 = tok->scope()->classEnd;
        for (const Token *tok2 = tok; tok2 != end2; tok2 = tok2->next()) {
            // Throw after delete -> Dead pointer
            if (tok2->str() == "throw") {
                if (_settings->inconclusive) { // For inconclusive checking, throw directly.
                    deallocThrowError(tok2, tok->str());
                    break;
                }
                ThrowToken = tok2;
            }

            // Variable is assigned -> Bail out
            else if (Token::Match(tok2, "%varid% =", varid)) {
                if (ThrowToken) // For non-inconclusive checking, wait until we find an assignement to it. Otherwise we assume it is safe to leave a dead pointer.
                    deallocThrowError(ThrowToken, tok2->str());
                break;
            }
            // Variable passed to function. Assume it becomes assigned -> Bail out
            else if (Token::Match(tok2, "[,(] &| %varid% [,)]", varid)) // TODO: No bailout if passed by value or as const reference
                break;
        }
    }
}

//---------------------------------------------------------------------------
//      catch(const exception & err)
//      {
//         throw err;            // <- should be just "throw;"
//      }
//---------------------------------------------------------------------------
void CheckExceptionSafety::checkRethrowCopy()
{
    if (!_settings->isEnabled("style"))
        return;

    const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();

    for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) {
        if (i->type != Scope::eCatch)
            continue;

        const unsigned int varid = i->classStart->tokAt(-2)->varId();
        if (varid) {
            for (const Token* tok = i->classStart->next(); tok && tok != i->classEnd; tok = tok->next()) {
                if (Token::simpleMatch(tok, "catch (") && tok->next()->link() && tok->next()->link()->next()) // Don't check inner catch - it is handled in another iteration of outer loop.
                    tok = tok->next()->link()->next()->link();
                else if (Token::Match(tok, "throw %varid% ;", varid))
                    rethrowCopyError(tok, tok->strAt(1));
            }
        }
    }
}

//---------------------------------------------------------------------------
//    try {} catch (std::exception err) {} <- Should be "std::exception& err"
//---------------------------------------------------------------------------
void CheckExceptionSafety::checkCatchExceptionByValue()
{
    if (!_settings->isEnabled("style"))
        return;

    const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();

    for (std::list<Scope>::const_iterator i = symbolDatabase->scopeList.begin(); i != symbolDatabase->scopeList.end(); ++i) {
        if (i->type != Scope::eCatch)
            continue;

        // Find a pass-by-value declaration in the catch(), excluding basic types
        // e.g. catch (std::exception err)
        const Variable* var = symbolDatabase->getVariableFromVarId(i->classStart->tokAt(-2)->varId());
        if (var && var->isClass() && !var->isPointer() && !var->isReference())
            catchExceptionByValueError(i->classDef);
    }
}