/* * Cppcheck - A tool for static C/C++ code analysis * Copyright (C) 2007-2019 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 . */ //--------------------------------------------------------------------------- #include "checkother.h" #include "checkuninitvar.h" // CheckUninitVar::isVariableUsage #include "astutils.h" #include "errorlogger.h" #include "library.h" #include "mathlib.h" #include "settings.h" #include "standards.h" #include "symboldatabase.h" #include "token.h" #include "tokenize.h" #include "utils.h" #include // find_if() #include #include #include #include #include //--------------------------------------------------------------------------- // Register this check class (by creating a static instance of it) namespace { CheckOther instance; } static const struct CWE CWE128(128U); // Wrap-around Error static const struct CWE CWE131(131U); // Incorrect Calculation of Buffer Size static const struct CWE CWE197(197U); // Numeric Truncation Error static const struct CWE CWE362(362U); // Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') static const struct CWE CWE369(369U); // Divide By Zero static const struct CWE CWE398(398U); // Indicator of Poor Code Quality static const struct CWE CWE475(475U); // Undefined Behavior for Input to API static const struct CWE CWE482(482U); // Comparing instead of Assigning static const struct CWE CWE561(561U); // Dead Code static const struct CWE CWE563(563U); // Assignment to Variable without Use ('Unused Variable') static const struct CWE CWE570(570U); // Expression is Always False static const struct CWE CWE571(571U); // Expression is Always True static const struct CWE CWE672(672U); // Operation on a Resource after Expiration or Release static const struct CWE CWE628(628U); // Function Call with Incorrectly Specified Arguments static const struct CWE CWE683(683U); // Function Call With Incorrect Order of Arguments static const struct CWE CWE686(686U); // Function Call With Incorrect Argument Type static const struct CWE CWE704(704U); // Incorrect Type Conversion or Cast static const struct CWE CWE758(758U); // Reliance on Undefined, Unspecified, or Implementation-Defined Behavior static const struct CWE CWE768(768U); // Incorrect Short Circuit Evaluation static const struct CWE CWE783(783U); // Operator Precedence Logic Error //---------------------------------------------------------------------------------- // The return value of fgetc(), getc(), ungetc(), getchar() etc. is an integer value. // If this return value is stored in a character variable and then compared // to EOF, which is an integer, the comparison maybe be false. // // Reference: // - Ticket #160 // - http://www.cplusplus.com/reference/cstdio/fgetc/ // - http://www.cplusplus.com/reference/cstdio/getc/ // - http://www.cplusplus.com/reference/cstdio/getchar/ // - http://www.cplusplus.com/reference/cstdio/ungetc/ ... //---------------------------------------------------------------------------------- void CheckOther::checkCastIntToCharAndBack() { if (!mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { std::map vars; for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { // Quick check to see if any of the matches below have any chances if (!Token::Match(tok, "%var%|EOF %comp%|=")) continue; if (Token::Match(tok, "%var% = fclose|fflush|fputc|fputs|fscanf|getchar|getc|fgetc|putchar|putc|puts|scanf|sscanf|ungetc (")) { const Variable *var = tok->variable(); if (var && var->typeEndToken()->str() == "char" && !var->typeEndToken()->isSigned()) { vars[tok->varId()] = tok->strAt(2); } } else if (Token::Match(tok, "EOF %comp% ( %var% = fclose|fflush|fputc|fputs|fscanf|getchar|getc|fgetc|putchar|putc|puts|scanf|sscanf|ungetc (")) { tok = tok->tokAt(3); const Variable *var = tok->variable(); if (var && var->typeEndToken()->str() == "char" && !var->typeEndToken()->isSigned()) { checkCastIntToCharAndBackError(tok, tok->strAt(2)); } } else if (mTokenizer->isCPP() && (Token::Match(tok, "EOF %comp% ( %var% = std :: cin . get (") || Token::Match(tok, "EOF %comp% ( %var% = cin . get ("))) { tok = tok->tokAt(3); const Variable *var = tok->variable(); if (var && var->typeEndToken()->str() == "char" && !var->typeEndToken()->isSigned()) { checkCastIntToCharAndBackError(tok, "cin.get"); } } else if (mTokenizer->isCPP() && (Token::Match(tok, "%var% = std :: cin . get (") || Token::Match(tok, "%var% = cin . get ("))) { const Variable *var = tok->variable(); if (var && var->typeEndToken()->str() == "char" && !var->typeEndToken()->isSigned()) { vars[tok->varId()] = "cin.get"; } } else if (Token::Match(tok, "%var% %comp% EOF")) { if (vars.find(tok->varId()) != vars.end()) { checkCastIntToCharAndBackError(tok, vars[tok->varId()]); } } else if (Token::Match(tok, "EOF %comp% %var%")) { tok = tok->tokAt(2); if (vars.find(tok->varId()) != vars.end()) { checkCastIntToCharAndBackError(tok, vars[tok->varId()]); } } } } } void CheckOther::checkCastIntToCharAndBackError(const Token *tok, const std::string &strFunctionName) { reportError( tok, Severity::warning, "checkCastIntToCharAndBack", "$symbol:" + strFunctionName + "\n" "Storing $symbol() return value in char variable and then comparing with EOF.\n" "When saving $symbol() return value in char variable there is loss of precision. " " When $symbol() returns EOF this value is truncated. Comparing the char " "variable with EOF can have unexpected results. For instance a loop \"while (EOF != (c = $symbol());\" " "loops forever on some compilers/platforms and on other compilers/platforms it will stop " "when the file contains a matching character.", CWE197, false ); } //--------------------------------------------------------------------------- // Clarify calculation precedence for ternary operators. //--------------------------------------------------------------------------- void CheckOther::clarifyCalculation() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { // ? operator where lhs is arithmetical expression if (tok->str() != "?" || !tok->astOperand1() || !tok->astOperand1()->isCalculation()) continue; if (!tok->astOperand1()->isArithmeticalOp() && tok->astOperand1()->tokType() != Token::eBitOp) continue; // Is code clarified by parentheses already? const Token *tok2 = tok->astOperand1(); for (; tok2; tok2 = tok2->next()) { if (tok2->str() == "(") tok2 = tok2->link(); else if (tok2->str() == ")") break; else if (tok2->str() == "?") { clarifyCalculationError(tok, tok->astOperand1()->str()); break; } } } } } void CheckOther::clarifyCalculationError(const Token *tok, const std::string &op) { // suspicious calculation const std::string calc("'a" + op + "b?c:d'"); // recommended calculation #1 const std::string s1("'(a" + op + "b)?c:d'"); // recommended calculation #2 const std::string s2("'a" + op + "(b?c:d)'"); reportError(tok, Severity::style, "clarifyCalculation", "Clarify calculation precedence for '" + op + "' and '?'.\n" "Suspicious calculation. Please use parentheses to clarify the code. " "The code '" + calc + "' should be written as either '" + s1 + "' or '" + s2 + "'.", CWE783, false); } //--------------------------------------------------------------------------- // Clarify (meaningless) statements like *foo++; with parentheses. //--------------------------------------------------------------------------- void CheckOther::clarifyStatement() { if (!mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "* %name%") && tok->astOperand1()) { const Token *tok2 = tok->previous(); while (tok2 && tok2->str() == "*") tok2 = tok2->previous(); if (tok2 && !tok2->astParent() && Token::Match(tok2, "[{};]")) { tok2 = tok->astOperand1(); if (Token::Match(tok2, "++|-- [;,]")) clarifyStatementError(tok2); } } } } } void CheckOther::clarifyStatementError(const Token *tok) { reportError(tok, Severity::warning, "clarifyStatement", "In expression like '*A++' the result of '*' is unused. Did you intend to write '(*A)++;'?\n" "A statement like '*A++;' might not do what you intended. Postfix 'operator++' is executed before 'operator*'. " "Thus, the dereference is meaningless. Did you intend to write '(*A)++;'?", CWE783, false); } //--------------------------------------------------------------------------- // Check for suspicious occurrences of 'if(); {}'. //--------------------------------------------------------------------------- void CheckOther::checkSuspiciousSemicolon() { if (!mSettings->inconclusive || !mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); // Look for "if(); {}", "for(); {}" or "while(); {}" for (const Scope &scope : symbolDatabase->scopeList) { if (scope.type == Scope::eIf || scope.type == Scope::eElse || scope.type == Scope::eWhile || scope.type == Scope::eFor) { // Ensure the semicolon is at the same line number as the if/for/while statement // and the {..} block follows it without an extra empty line. if (Token::simpleMatch(scope.bodyStart, "{ ; } {") && scope.bodyStart->previous()->linenr() == scope.bodyStart->tokAt(2)->linenr() && scope.bodyStart->linenr()+1 >= scope.bodyStart->tokAt(3)->linenr()) { SuspiciousSemicolonError(scope.classDef); } } } } void CheckOther::SuspiciousSemicolonError(const Token* tok) { reportError(tok, Severity::warning, "suspiciousSemicolon", "Suspicious use of ; at the end of '" + (tok ? tok->str() : std::string()) + "' statement.", CWE398, true); } //--------------------------------------------------------------------------- // For C++ code, warn if C-style casts are used on pointer types //--------------------------------------------------------------------------- void CheckOther::warningOldStylePointerCast() { // Only valid on C++ code if (!mSettings->isEnabled(Settings::STYLE) || !mTokenizer->isCPP()) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { const Token* tok; if (scope->function && scope->function->isConstructor()) tok = scope->classDef; else tok = scope->bodyStart; for (; tok && tok != scope->bodyEnd; tok = tok->next()) { // Old style pointer casting.. if (!Token::Match(tok, "( const|volatile| const|volatile| %type% * const| ) (| %name%|%num%|%bool%|%char%|%str%")) continue; // skip first "const" in "const Type* const" while (Token::Match(tok->next(), "const|volatile")) tok = tok->next(); const Token* typeTok = tok->next(); // skip second "const" in "const Type* const" if (tok->strAt(3) == "const") tok = tok->next(); const Token *p = tok->tokAt(4); if (p->hasKnownIntValue() && p->values().front().intvalue==0) // Casting nullpointers is safe continue; // Is "type" a class? if (typeTok->type()) cstyleCastError(tok); } } } void CheckOther::cstyleCastError(const Token *tok) { reportError(tok, Severity::style, "cstyleCast", "C-style pointer casting\n" "C-style pointer casting detected. C++ offers four different kinds of casts as replacements: " "static_cast, const_cast, dynamic_cast and reinterpret_cast. A C-style cast could evaluate to " "any of those automatically, thus it is considered safer if the programmer explicitly states " "which kind of cast is expected. See also: https://www.securecoding.cert.org/confluence/display/cplusplus/EXP05-CPP.+Do+not+use+C-style+casts.", CWE398, false); } //--------------------------------------------------------------------------- // float* f; double* d = (double*)f; <-- Pointer cast to a type with an incompatible binary data representation //--------------------------------------------------------------------------- void CheckOther::invalidPointerCast() { if (!mSettings->isEnabled(Settings::PORTABILITY)) return; const bool printInconclusive = mSettings->inconclusive; const SymbolDatabase* const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { const Token* toTok = nullptr; const Token* fromTok = nullptr; // Find cast if (Token::Match(tok, "( const|volatile| const|volatile| %type% %type%| const| * )")) { toTok = tok; fromTok = tok->astOperand1(); } else if (Token::simpleMatch(tok, "reinterpret_cast <") && tok->linkAt(1)) { toTok = tok->linkAt(1)->next(); fromTok = toTok->astOperand2(); } if (!fromTok) continue; const ValueType* fromType = fromTok->valueType(); const ValueType* toType = toTok->valueType(); if (!fromType || !toType || !fromType->pointer || !toType->pointer) continue; if (fromType->type != toType->type && fromType->type >= ValueType::Type::BOOL && toType->type >= ValueType::Type::BOOL && (toType->type != ValueType::Type::CHAR || printInconclusive)) { if (toType->isIntegral() && fromType->isIntegral()) continue; invalidPointerCastError(tok, fromType->str(), toType->str(), toType->type == ValueType::Type::CHAR, toType->isIntegral()); } } } } void CheckOther::invalidPointerCastError(const Token* tok, const std::string& from, const std::string& to, bool inconclusive, bool toIsInt) { if (toIsInt) { // If we cast something to int*, this can be useful to play with its binary data representation reportError(tok, Severity::portability, "invalidPointerCast", "Casting from " + from + " to " + to + " is not portable due to different binary data representations on different platforms.", CWE704, inconclusive); } else reportError(tok, Severity::portability, "invalidPointerCast", "Casting between " + from + " and " + to + " which have an incompatible binary data representation.", CWE704, false); } //--------------------------------------------------------------------------- // This check detects errors on POSIX systems, when a pipe command called // with a wrong dimensioned file descriptor array. The pipe command requires // exactly an integer array of dimension two as parameter. // // References: // - http://linux.die.net/man/2/pipe // - ticket #3521 //--------------------------------------------------------------------------- void CheckOther::checkPipeParameterSize() { if (!mSettings->posix()) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "pipe ( %var% )") || Token::Match(tok, "pipe2 ( %var% ,")) { const Token * const varTok = tok->tokAt(2); const Variable *var = varTok->variable(); MathLib::bigint dim; if (var && var->isArray() && !var->isArgument() && ((dim=var->dimension(0U)) < 2)) { const std::string strDim = MathLib::toString(dim); checkPipeParameterSizeError(varTok,varTok->str(), strDim); } } } } } void CheckOther::checkPipeParameterSizeError(const Token *tok, const std::string &strVarName, const std::string &strDim) { reportError(tok, Severity::error, "wrongPipeParameterSize", "$symbol:" + strVarName + "\n" "Buffer '$symbol' must have size of 2 integers if used as parameter of pipe().\n" "The pipe()/pipe2() system command takes an argument, which is an array of exactly two integers.\n" "The variable '$symbol' is an array of size " + strDim + ", which does not match.", CWE686, false); } //--------------------------------------------------------------------------- // Detect redundant assignments: x = 0; x = 4; //--------------------------------------------------------------------------- void CheckOther::checkRedundantAssignment() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope *scope : symbolDatabase->functionScopes) { if (!scope->bodyStart) continue; for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (Token::simpleMatch(tok, "] (")) // todo: handle lambdas break; if (Token::simpleMatch(tok, "try {")) // todo: check try blocks tok = tok->linkAt(1); if ((tok->isAssignmentOp() || Token::Match(tok, "++|--")) && tok->astOperand1()) { if (tok->astParent()) continue; // Do not warn about redundant initialization when rhs is trivial // TODO : do not simplify the variable declarations bool isInitialization = false; if (Token::Match(tok->tokAt(-3), "%var% ; %var% =") && tok->previous()->variable() && tok->previous()->variable()->nameToken() == tok->tokAt(-3) && tok->tokAt(-3)->linenr() == tok->previous()->linenr()) { isInitialization = true; bool trivial = true; visitAstNodes(tok->astOperand2(), [&](const Token *rhs) { if (Token::simpleMatch(rhs, "{ 0 }")) return ChildrenToVisit::none; if (Token::Match(rhs, "%str%|%num%|%name%") && !rhs->varId()) return ChildrenToVisit::none; if (Token::Match(rhs, ":: %name%") && rhs->hasKnownIntValue()) return ChildrenToVisit::none; if (rhs->isCast()) return ChildrenToVisit::op2; trivial = false; return ChildrenToVisit::done; }); if (trivial) continue; } // Do not warn about assignment with 0 / NULL if (Token::simpleMatch(tok->astOperand2(), "0") || FwdAnalysis::isNullOperand(tok->astOperand2())) continue; if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isReference()) // todo: check references continue; if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isStatic()) // todo: check static variables continue; // If there is a custom assignment operator => this is inconclusive bool inconclusive = false; if (mTokenizer->isCPP() && tok->astOperand1()->valueType() && tok->astOperand1()->valueType()->typeScope) { const std::string op = "operator" + tok->str(); for (const Function &f : tok->astOperand1()->valueType()->typeScope->functionList) { if (f.name() == op) { inconclusive = true; break; } } } if (inconclusive && !mSettings->inconclusive) continue; FwdAnalysis fwdAnalysis(mTokenizer->isCPP(), mSettings->library); if (fwdAnalysis.hasOperand(tok->astOperand2(), tok->astOperand1())) continue; // Is there a redundant assignment? const Token *start; if (tok->isAssignmentOp()) start = tok->next(); else start = tok->findExpressionStartEndTokens().second->next(); // Get next assignment.. const Token *nextAssign = fwdAnalysis.reassign(tok->astOperand1(), start, scope->bodyEnd); if (!nextAssign) continue; // there is redundant assignment. Is there a case between the assignments? bool hasCase = false; for (const Token *tok2 = tok; tok2 != nextAssign; tok2 = tok2->next()) { if (tok2->str() == "break" || tok2->str() == "return") break; if (tok2->str() == "case") { hasCase = true; break; } } // warn if (hasCase) redundantAssignmentInSwitchError(tok, nextAssign, tok->astOperand1()->expressionString()); else if (isInitialization) redundantInitializationError(tok, nextAssign, tok->astOperand1()->expressionString(), inconclusive); else redundantAssignmentError(tok, nextAssign, tok->astOperand1()->expressionString(), inconclusive); } } } } void CheckOther::redundantCopyError(const Token *tok1, const Token* tok2, const std::string& var) { const std::list callstack = { tok1, tok2 }; reportError(callstack, Severity::performance, "redundantCopy", "$symbol:" + var + "\n" "Buffer '$symbol' is being written before its old content has been used.", CWE563, false); } void CheckOther::redundantCopyInSwitchError(const Token *tok1, const Token* tok2, const std::string &var) { const std::list callstack = { tok1, tok2 }; reportError(callstack, Severity::warning, "redundantCopyInSwitch", "$symbol:" + var + "\n" "Buffer '$symbol' is being written before its old content has been used. 'break;' missing?", CWE563, false); } void CheckOther::redundantAssignmentError(const Token *tok1, const Token* tok2, const std::string& var, bool inconclusive) { const ErrorPath errorPath = { ErrorPathItem(tok1, var + " is assigned"), ErrorPathItem(tok2, var + " is overwritten") }; if (inconclusive) reportError(errorPath, Severity::style, "redundantAssignment", "$symbol:" + var + "\n" "Variable '$symbol' is reassigned a value before the old one has been used if variable is no semaphore variable.\n" "Variable '$symbol' is reassigned a value before the old one has been used. Make sure that this variable is not used like a semaphore in a threading environment before simplifying this code.", CWE563, true); else reportError(errorPath, Severity::style, "redundantAssignment", "$symbol:" + var + "\n" "Variable '$symbol' is reassigned a value before the old one has been used.", CWE563, false); } void CheckOther::redundantInitializationError(const Token *tok1, const Token* tok2, const std::string& var, bool inconclusive) { const ErrorPath errorPath = { ErrorPathItem(tok1, var + " is initialized"), ErrorPathItem(tok2, var + " is overwritten") }; reportError(errorPath, Severity::style, "redundantInitialization", "$symbol:" + var + "\nRedundant initialization for '$symbol'. The initialized value is overwritten before it is read.", CWE563, inconclusive); } void CheckOther::redundantAssignmentInSwitchError(const Token *tok1, const Token* tok2, const std::string &var) { const ErrorPath errorPath = { ErrorPathItem(tok1, "$symbol is assigned"), ErrorPathItem(tok2, "$symbol is overwritten") }; reportError(errorPath, Severity::warning, "redundantAssignInSwitch", "$symbol:" + var + "\n" "Variable '$symbol' is reassigned a value before the old one has been used. 'break;' missing?", CWE563, false); } //--------------------------------------------------------------------------- // switch (x) // { // case 2: // y = a; // <- this assignment is redundant // case 3: // y = b; // <- case 2 falls through and sets y twice // } //--------------------------------------------------------------------------- static inline bool isFunctionOrBreakPattern(const Token *tok) { if (Token::Match(tok, "%name% (") || Token::Match(tok, "break|continue|return|exit|goto|throw")) return true; return false; } void CheckOther::checkRedundantAssignmentInSwitch() { if (!mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); // Find the beginning of a switch. E.g.: // switch (var) { ... for (const Scope &switchScope : symbolDatabase->scopeList) { if (switchScope.type != Scope::eSwitch || !switchScope.bodyStart) continue; // Check the contents of the switch statement std::map varsWithBitsSet; std::map bitOperations; for (const Token *tok2 = switchScope.bodyStart->next(); tok2 != switchScope.bodyEnd; tok2 = tok2->next()) { if (tok2->str() == "{") { // Inside a conditional or loop. Don't mark variable accesses as being redundant. E.g.: // case 3: b = 1; // case 4: if (a) { b = 2; } // Doesn't make the b=1 redundant because it's conditional if (Token::Match(tok2->previous(), ")|else {") && tok2->link()) { const Token* endOfConditional = tok2->link(); for (const Token* tok3 = tok2; tok3 != endOfConditional; tok3 = tok3->next()) { if (tok3->varId() != 0) { varsWithBitsSet.erase(tok3->varId()); bitOperations.erase(tok3->varId()); } else if (isFunctionOrBreakPattern(tok3)) { varsWithBitsSet.clear(); bitOperations.clear(); } } tok2 = endOfConditional; } } // Variable assignment. Report an error if it's assigned to twice before a break. E.g.: // case 3: b = 1; // <== redundant // case 4: b = 2; if (Token::Match(tok2->previous(), ";|{|}|: %var% = %any% ;")) { varsWithBitsSet.erase(tok2->varId()); bitOperations.erase(tok2->varId()); } // Bitwise operation. Report an error if it's performed twice before a break. E.g.: // case 3: b |= 1; // <== redundant // case 4: b |= 1; else if (Token::Match(tok2->previous(), ";|{|}|: %var% %assign% %num% ;") && (tok2->strAt(1) == "|=" || tok2->strAt(1) == "&=") && Token::Match(tok2->next()->astOperand2(), "%num%")) { const std::string bitOp = tok2->strAt(1)[0] + tok2->strAt(2); const std::map::const_iterator i2 = varsWithBitsSet.find(tok2->varId()); // This variable has not had a bit operation performed on it yet, so just make a note of it if (i2 == varsWithBitsSet.end()) { varsWithBitsSet[tok2->varId()] = tok2; bitOperations[tok2->varId()] = bitOp; } // The same bit operation has been performed on the same variable twice, so report an error else if (bitOperations[tok2->varId()] == bitOp) redundantBitwiseOperationInSwitchError(i2->second, i2->second->str()); // A different bit operation was performed on the variable, so clear it else { varsWithBitsSet.erase(tok2->varId()); bitOperations.erase(tok2->varId()); } } // Bitwise operation. Report an error if it's performed twice before a break. E.g.: // case 3: b = b | 1; // <== redundant // case 4: b = b | 1; else if (Token::Match(tok2->previous(), ";|{|}|: %var% = %name% %or%|& %num% ;") && tok2->varId() == tok2->tokAt(2)->varId()) { const std::string bitOp = tok2->strAt(3) + tok2->strAt(4); const std::map::const_iterator i2 = varsWithBitsSet.find(tok2->varId()); // This variable has not had a bit operation performed on it yet, so just make a note of it if (i2 == varsWithBitsSet.end()) { varsWithBitsSet[tok2->varId()] = tok2; bitOperations[tok2->varId()] = bitOp; } // The same bit operation has been performed on the same variable twice, so report an error else if (bitOperations[tok2->varId()] == bitOp) redundantBitwiseOperationInSwitchError(i2->second, i2->second->str()); // A different bit operation was performed on the variable, so clear it else { varsWithBitsSet.erase(tok2->varId()); bitOperations.erase(tok2->varId()); } } // Not a simple assignment so there may be good reason if this variable is assigned to twice. E.g.: // case 3: b = 1; // case 4: b++; else if (tok2->varId() != 0 && tok2->strAt(1) != "|" && tok2->strAt(1) != "&") { varsWithBitsSet.erase(tok2->varId()); bitOperations.erase(tok2->varId()); } // Reset our record of assignments if there is a break or function call. E.g.: // case 3: b = 1; break; if (isFunctionOrBreakPattern(tok2)) { varsWithBitsSet.clear(); bitOperations.clear(); } } } } void CheckOther::redundantBitwiseOperationInSwitchError(const Token *tok, const std::string &varname) { reportError(tok, Severity::warning, "redundantBitwiseOperationInSwitch", "$symbol:" + varname + "\n" "Redundant bitwise operation on '$symbol' in 'switch' statement. 'break;' missing?"); } //--------------------------------------------------------------------------- // Check for statements like case A||B: in switch() //--------------------------------------------------------------------------- void CheckOther::checkSuspiciousCaseInSwitch() { if (!mSettings->inconclusive || !mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope & scope : symbolDatabase->scopeList) { if (scope.type != Scope::eSwitch) continue; for (const Token* tok = scope.bodyStart->next(); tok != scope.bodyEnd; tok = tok->next()) { if (tok->str() == "case") { const Token* finding = nullptr; for (const Token* tok2 = tok->next(); tok2; tok2 = tok2->next()) { if (tok2->str() == ":") break; if (Token::Match(tok2, "[;}{]")) break; if (tok2->str() == "?") finding = nullptr; else if (Token::Match(tok2, "&&|%oror%")) finding = tok2; } if (finding) suspiciousCaseInSwitchError(finding, finding->str()); } } } } void CheckOther::suspiciousCaseInSwitchError(const Token* tok, const std::string& operatorString) { reportError(tok, Severity::warning, "suspiciousCase", "Found suspicious case label in switch(). Operator '" + operatorString + "' probably doesn't work as intended.\n" "Using an operator like '" + operatorString + "' in a case label is suspicious. Did you intend to use a bitwise operator, multiple case labels or if/else instead?", CWE398, true); } //--------------------------------------------------------------------------- // Find consecutive return, break, continue, goto or throw statements. e.g.: // break; break; // Detect dead code, that follows such a statement. e.g.: // return(0); foo(); //--------------------------------------------------------------------------- void CheckOther::checkUnreachableCode() { if (!mSettings->isEnabled(Settings::STYLE)) return; const bool printInconclusive = mSettings->inconclusive; const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) { const Token* secondBreak = nullptr; const Token* labelName = nullptr; if (tok->link() && Token::Match(tok, "(|[|<")) tok = tok->link(); else if (Token::Match(tok, "break|continue ;")) secondBreak = tok->tokAt(2); else if (Token::Match(tok, "[;{}:] return|throw")) { if (Token::simpleMatch(tok->astParent(), "?")) continue; tok = tok->next(); // tok should point to return or throw for (const Token *tok2 = tok->next(); tok2; tok2 = tok2->next()) { if (tok2->str() == "(" || tok2->str() == "{") tok2 = tok2->link(); if (tok2->str() == ";") { secondBreak = tok2->next(); break; } } } else if (Token::Match(tok, "goto %any% ;")) { secondBreak = tok->tokAt(3); labelName = tok->next(); } else if (Token::Match(tok, "%name% (") && mSettings->library.isnoreturn(tok) && !Token::Match(tok->next()->astParent(), "?|:")) { if ((!tok->function() || (tok->function()->token != tok && tok->function()->tokenDef != tok)) && tok->linkAt(1)->strAt(1) != "{") secondBreak = tok->linkAt(1)->tokAt(2); } // Statements follow directly, no line between them. (#3383) // TODO: Try to find a better way to avoid false positives due to preprocessor configurations. const bool inconclusive = secondBreak && (secondBreak->linenr() - 1 > secondBreak->previous()->linenr()); if (secondBreak && (printInconclusive || !inconclusive)) { if (Token::Match(secondBreak, "continue|goto|throw") || (secondBreak->str() == "return" && (tok->str() == "return" || secondBreak->strAt(1) == ";"))) { // return with value after statements like throw can be necessary to make a function compile duplicateBreakError(secondBreak, inconclusive); tok = Token::findmatch(secondBreak, "[}:]"); } else if (secondBreak->str() == "break") { // break inside switch as second break statement should not issue a warning if (tok->str() == "break") // If the previous was a break, too: Issue warning duplicateBreakError(secondBreak, inconclusive); else { if (tok->scope()->type != Scope::eSwitch) // Check, if the enclosing scope is a switch duplicateBreakError(secondBreak, inconclusive); } tok = Token::findmatch(secondBreak, "[}:]"); } else if (!Token::Match(secondBreak, "return|}|case|default") && secondBreak->strAt(1) != ":") { // TODO: No bailout for unconditional scopes // If the goto label is followed by a loop construct in which the label is defined it's quite likely // that the goto jump was intended to skip some code on the first loop iteration. bool labelInFollowingLoop = false; if (labelName && Token::Match(secondBreak, "while|do|for")) { const Token *scope2 = Token::findsimplematch(secondBreak, "{"); if (scope2) { for (const Token *tokIter = scope2; tokIter != scope2->link() && tokIter; tokIter = tokIter->next()) { if (Token::Match(tokIter, "[;{}] %any% :") && labelName->str() == tokIter->strAt(1)) { labelInFollowingLoop = true; break; } } } } // hide FP for statements that just hide compiler warnings about unused function arguments bool silencedCompilerWarningOnly = false; const Token *silencedWarning = secondBreak; for (;;) { if (Token::Match(silencedWarning, "( void ) %name% ;")) { silencedWarning = silencedWarning->tokAt(5); continue; } else if (silencedWarning && silencedWarning == scope->bodyEnd) silencedCompilerWarningOnly = true; break; } if (silencedWarning) secondBreak = silencedWarning; if (!labelInFollowingLoop && !silencedCompilerWarningOnly) unreachableCodeError(secondBreak, inconclusive); tok = Token::findmatch(secondBreak, "[}:]"); } else tok = secondBreak; if (!tok) break; tok = tok->previous(); // Will be advanced again by for loop } } } } void CheckOther::duplicateBreakError(const Token *tok, bool inconclusive) { reportError(tok, Severity::style, "duplicateBreak", "Consecutive return, break, continue, goto or throw statements are unnecessary.\n" "Consecutive return, break, continue, goto or throw statements are unnecessary. " "The second statement can never be executed, and so should be removed.", CWE561, inconclusive); } void CheckOther::unreachableCodeError(const Token *tok, bool inconclusive) { reportError(tok, Severity::style, "unreachableCode", "Statements following return, break, continue, goto or throw will never be executed.", CWE561, inconclusive); } //--------------------------------------------------------------------------- // Check scope of variables.. //--------------------------------------------------------------------------- void CheckOther::checkVariableScope() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Variable* var : symbolDatabase->variableList()) { if (!var || !var->isLocal() || (!var->isPointer() && !var->isReference() && !var->typeStartToken()->isStandardType())) continue; if (var->isConst()) continue; // reference of range for loop variable.. if (Token::Match(var->nameToken()->previous(), "& %var% = %var% .")) { const Token *otherVarToken = var->nameToken()->tokAt(2); const Variable *otherVar = otherVarToken->variable(); if (otherVar && Token::Match(otherVar->nameToken(), "%var% :") && otherVar->nameToken()->next()->astParent() && Token::simpleMatch(otherVar->nameToken()->next()->astParent()->previous(), "for (")) continue; } bool forHead = false; // Don't check variables declared in header of a for loop for (const Token* tok = var->typeStartToken(); tok; tok = tok->previous()) { if (tok->str() == "(") { forHead = true; break; } else if (Token::Match(tok, "[;{}]")) break; } if (forHead) continue; const Token* tok = var->nameToken()->next(); if (Token::Match(tok, "; %varid% = %any% ;", var->declarationId())) { tok = tok->tokAt(3); if (!tok->isNumber() && tok->tokType() != Token::eString && tok->tokType() != Token::eChar && !tok->isBoolean()) continue; } // bailout if initialized with function call that has possible side effects if (Token::Match(tok, "[(=]") && Token::simpleMatch(tok->astOperand2(), "(")) continue; bool reduce = true; bool used = false; // Don't warn about unused variables for (; tok && tok != var->scope()->bodyEnd; tok = tok->next()) { if (tok->str() == "{" && tok->scope() != tok->previous()->scope() && !tok->isExpandedMacro() && tok->scope()->type != Scope::eLambda) { if (used) { bool used2 = false; if (!checkInnerScope(tok, var, used2) || used2) { reduce = false; break; } } else if (!checkInnerScope(tok, var, used)) { reduce = false; break; } tok = tok->link(); // parse else if blocks.. } else if (Token::simpleMatch(tok, "else { if (") && Token::simpleMatch(tok->linkAt(3), ") {")) { const Token *endif = tok->linkAt(3)->linkAt(1); bool elseif = false; if (Token::simpleMatch(endif, "} }")) elseif = true; else if (Token::simpleMatch(endif, "} else {") && Token::simpleMatch(endif->linkAt(2),"} }")) elseif = true; if (elseif && Token::findmatch(tok->next(), "%varid%", tok->linkAt(1), var->declarationId())) { reduce = false; break; } } else if (tok->varId() == var->declarationId() || tok->str() == "goto") { reduce = false; break; } } if (reduce && used) variableScopeError(var->nameToken(), var->name()); } } bool CheckOther::checkInnerScope(const Token *tok, const Variable* var, bool& used) { const Scope* scope = tok->next()->scope(); bool loopVariable = scope->type == Scope::eFor || scope->type == Scope::eWhile || scope->type == Scope::eDo; bool noContinue = true; const Token* forHeadEnd = nullptr; const Token* end = tok->link(); if (scope->type == Scope::eUnconditional && (tok->strAt(-1) == ")" || tok->previous()->isName())) // Might be an unknown macro like BOOST_FOREACH loopVariable = true; if (scope->type == Scope::eDo) { end = end->linkAt(2); } else if (loopVariable && tok->strAt(-1) == ")") { tok = tok->linkAt(-1); // Jump to opening ( of for/while statement } else if (scope->type == Scope::eSwitch) { for (const Scope* innerScope : scope->nestedList) { if (used) { bool used2 = false; if (!checkInnerScope(innerScope->bodyStart, var, used2) || used2) { return false; } } else if (!checkInnerScope(innerScope->bodyStart, var, used)) { return false; } } } bool bFirstAssignment=false; for (; tok && tok != end; tok = tok->next()) { if (tok->str() == "goto") return false; if (tok->str() == "continue") noContinue = false; if (Token::simpleMatch(tok, "for (")) forHeadEnd = tok->linkAt(1); if (tok == forHeadEnd) forHeadEnd = nullptr; if (loopVariable && noContinue && tok->scope() == scope && !forHeadEnd && scope->type != Scope::eSwitch && Token::Match(tok, "%varid% =", var->declarationId())) { // Assigned in outer scope. loopVariable = false; int indent = 0; for (const Token* tok2 = tok->tokAt(2); tok2; tok2 = tok2->next()) { // Ensure that variable isn't used on right side of =, too if (tok2->str() == "(") indent++; else if (tok2->str() == ")") { if (indent == 0) break; indent--; } else if (tok2->str() == ";") break; else if (tok2->varId() == var->declarationId()) { loopVariable = true; break; } } } if (loopVariable && Token::Match(tok, "%varid% !!=", var->declarationId())) // Variable used in loop return false; if (Token::Match(tok, "& %varid%", var->declarationId())) // Taking address of variable return false; if (Token::Match(tok, "%varid% =", var->declarationId())) bFirstAssignment = true; if (!bFirstAssignment && Token::Match(tok, "* %varid%", var->declarationId())) // dereferencing means access to previous content return false; if (Token::Match(tok, "= %varid%", var->declarationId()) && (var->isArray() || var->isPointer())) // Create a copy of array/pointer. Bailout, because the memory it points to might be necessary in outer scope return false; if (tok->varId() == var->declarationId()) { used = true; if (scope->type == Scope::eSwitch && scope == tok->scope()) return false; // Used in outer switch scope - unsafe or impossible to reduce scope } } return true; } void CheckOther::variableScopeError(const Token *tok, const std::string &varname) { reportError(tok, Severity::style, "variableScope", "$symbol:" + varname + "\n" "The scope of the variable '$symbol' can be reduced.\n" "The scope of the variable '$symbol' can be reduced. Warning: Be careful " "when fixing this message, especially when there are inner loops. Here is an " "example where cppcheck will write that the scope for 'i' can be reduced:\n" "void f(int x)\n" "{\n" " int i = 0;\n" " if (x) {\n" " // it's safe to move 'int i = 0;' here\n" " for (int n = 0; n < 10; ++n) {\n" " // it is possible but not safe to move 'int i = 0;' here\n" " do_something(&i);\n" " }\n" " }\n" "}\n" "When you see this message it is always safe to reduce the variable scope 1 level.", CWE398, false); } //--------------------------------------------------------------------------- // Comma in return statement: return a+1, b++;. (experimental) //--------------------------------------------------------------------------- void CheckOther::checkCommaSeparatedReturn() { // This is experimental for now. See #5076 if (!mSettings->experimental) return; if (!mSettings->isEnabled(Settings::STYLE)) return; for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (tok->str() == "return") { tok = tok->next(); while (tok && tok->str() != ";") { if (tok->link() && Token::Match(tok, "[([{<]")) tok = tok->link(); if (!tok->isExpandedMacro() && tok->str() == "," && tok->linenr() != tok->next()->linenr()) commaSeparatedReturnError(tok); tok = tok->next(); } // bailout: missing semicolon (invalid code / bad tokenizer) if (!tok) break; } } } void CheckOther::commaSeparatedReturnError(const Token *tok) { reportError(tok, Severity::style, "commaSeparatedReturn", "Comma is used in return statement. The comma can easily be misread as a ';'.\n" "Comma is used in return statement. When comma is used in a return statement it can " "easily be misread as a semicolon. For example in the code below the value " "of 'b' is returned if the condition is true, but it is easy to think that 'a+1' is " "returned:\n" " if (x)\n" " return a + 1,\n" " b++;\n" "However it can be useful to use comma in macros. Cppcheck does not warn when such a " "macro is then used in a return statement, it is less likely such code is misunderstood.", CWE398, false); } //--------------------------------------------------------------------------- // Check for function parameters that should be passed by const reference //--------------------------------------------------------------------------- static int estimateSize(const Type* type, const Settings* settings, const SymbolDatabase* symbolDatabase, int recursionDepth = 0) { if (recursionDepth > 20) return 0; int cumulatedSize = 0; for (const Variable&var : type->classScope->varlist) { int size = 0; if (var.isStatic()) continue; if (var.isPointer() || var.isReference()) size = settings->sizeof_pointer; else if (var.type() && var.type()->classScope) size = estimateSize(var.type(), settings, symbolDatabase, recursionDepth+1); else if (var.valueType()->type == ValueType::Type::CONTAINER) size = 3 * settings->sizeof_pointer; // Just guess else size = symbolDatabase->sizeOfType(var.typeStartToken()); if (var.isArray()) cumulatedSize += size * var.dimension(0); else cumulatedSize += size; } for (const Type::BaseInfo &baseInfo : type->derivedFrom) { if (baseInfo.type && baseInfo.type->classScope) cumulatedSize += estimateSize(baseInfo.type, settings, symbolDatabase, recursionDepth+1); } return cumulatedSize; } static bool canBeConst(const Variable *var) { { // check initializer list. If variable is moved from it can't be const. const Function* func_scope = var->scope()->function; if (func_scope->type == Function::Type::eConstructor) { //could be initialized in initializer list if (func_scope->arg->link()->next()->str() == ":") { for (const Token* tok2 = func_scope->arg->link()->next()->next(); tok2 != var->scope()->bodyStart; tok2 = tok2->next()) { if (tok2->varId() != var->declarationId()) continue; const Token* parent = tok2->astParent(); if (parent && Token::simpleMatch(parent->previous(), "move (")) return false; } } } } for (const Token* tok2 = var->scope()->bodyStart; tok2 != var->scope()->bodyEnd; tok2 = tok2->next()) { if (tok2->varId() != var->declarationId()) continue; const Token* parent = tok2->astParent(); if (!parent) continue; if (parent->str() == "<<" || isLikelyStreamRead(true, parent)) { if (parent->str() == "<<" && parent->astOperand1() == tok2) return false; if (parent->str() == ">>" && parent->astOperand2() == tok2) return false; } else if (parent->str() == "," || parent->str() == "(") { // function argument const Token* tok3 = tok2->previous(); int argNr = 0; while (tok3 && tok3->str() != "(") { if (tok3->link() && Token::Match(tok3, ")|]|}|>")) tok3 = tok3->link(); else if (tok3->link()) break; else if (tok3->str() == ";") break; else if (tok3->str() == ",") argNr++; tok3 = tok3->previous(); } if (!tok3 || tok3->str() != "(" || !tok3->astOperand1() || !tok3->astOperand1()->function()) return false; else { const Variable* argVar = tok3->astOperand1()->function()->getArgumentVar(argNr); if (!argVar|| (!argVar->isConst() && argVar->isReference())) return false; } } else if (parent->isUnaryOp("&")) { // TODO: check how pointer is used return false; } else if (parent->isConstOp()) continue; else if (parent->isAssignmentOp()) { if (parent->astOperand1() == tok2) return false; else if (parent->astOperand1()->str() == "&") { const Variable* assignedVar = parent->previous()->variable(); if (!assignedVar || !assignedVar->isConst()) return false; } } else if (Token::Match(tok2, "%var% . %name% (")) { const Function* func = tok2->tokAt(2)->function(); if (func && (func->isConst() || func->isStatic())) continue; else return false; } else return false; } return true; } void CheckOther::checkPassByReference() { if (!mSettings->isEnabled(Settings::PERFORMANCE) || mTokenizer->isC()) return; const SymbolDatabase * const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Variable* var : symbolDatabase->variableList()) { if (!var || !var->isArgument() || !var->isClass() || var->isPointer() || var->isArray() || var->isReference() || var->isEnumType()) continue; if (var->scope() && var->scope()->function->arg->link()->strAt(-1) == "...") continue; // references could not be used as va_start parameters (#5824) if ((var->declEndToken() && var->declEndToken()->isExternC()) || (var->scope() && var->scope()->function && var->scope()->function->tokenDef && var->scope()->function->tokenDef->isExternC())) continue; // references cannot be used in functions in extern "C" blocks bool inconclusive = false; if (var->valueType()->type == ValueType::Type::CONTAINER) { } else if (var->type() && !var->type()->isEnumType()) { // Check if type is a struct or class. // Ensure that it is a large object. if (!var->type()->classScope) inconclusive = true; else if (estimateSize(var->type(), mSettings, symbolDatabase) <= 2 * mSettings->sizeof_pointer) continue; } else continue; if (inconclusive && !mSettings->inconclusive) continue; const bool isConst = var->isConst(); if (isConst) { passedByValueError(var->nameToken(), var->name(), inconclusive); continue; } // Check if variable could be const if (!var->scope() || var->scope()->function->hasVirtualSpecifier()) continue; if (canBeConst(var)) { passedByValueError(var->nameToken(), var->name(), inconclusive); } } } void CheckOther::passedByValueError(const Token *tok, const std::string &parname, bool inconclusive) { reportError(tok, Severity::performance, "passedByValue", "$symbol:" + parname + "\n" "Function parameter '$symbol' should be passed by const reference.\n" "Parameter '$symbol' is passed by value. It could be passed " "as a const reference which is usually faster and recommended in C++.", CWE398, inconclusive); } static bool isUnusedVariable(const Variable *var) { if (!var) return false; if (!var->scope()) return false; const Token *start = var->declEndToken(); if (!start) return false; if (Token::Match(start, "; %varid% =", var->declarationId())) start = start->tokAt(2); return !Token::findmatch(start->next(), "%varid%", var->scope()->bodyEnd, var->declarationId()); } static bool isVariableMutableInInitializer(const Token* start, const Token * end, nonneg int varid) { if (!start) return false; if (!end) return false; for (const Token *tok = start; tok != end; tok = tok->next()) { if (tok->varId() != varid) continue; if (tok->astParent()) { const Token * memberTok = tok->astParent()->previous(); if (Token::Match(memberTok, "%var% (") && memberTok->variable()) { const Variable * memberVar = memberTok->variable(); if (!memberVar->isReference()) continue; if (memberVar->isConst()) continue; } return true; } else { return true; } } return false; } void CheckOther::checkConstVariable() { if (!mSettings->isEnabled(Settings::STYLE) || mTokenizer->isC()) return; const SymbolDatabase *const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Variable *var : symbolDatabase->variableList()) { if (!var) continue; if (!var->isReference()) continue; if (var->isRValueReference()) continue; if (var->isConst()) continue; if (!var->scope()) continue; const Scope *scope = var->scope(); if (!scope->function) continue; Function *function = scope->function; if (var->isArgument()) { if (function->isImplicitlyVirtual() || function->templateDef) continue; if (isUnusedVariable(var)) continue; if (function->isConstructor() && isVariableMutableInInitializer(function->constructorMemberInitialization(), scope->bodyStart, var->declarationId())) continue; } if (var->isGlobal()) continue; if (var->isStatic()) continue; if (var->isArray()) continue; if (var->isEnumType()) continue; if (var->isVolatile()) continue; if (isAliased(var)) continue; if (isVariableChanged(var, mSettings, mTokenizer->isCPP())) continue; if (Function::returnsReference(function) && Token::findmatch(var->nameToken(), "return %varid% ;|[", scope->bodyEnd, var->declarationId())) continue; // Skip if address is taken if (Token::findmatch(var->nameToken(), "& %varid%", scope->bodyEnd, var->declarationId())) continue; constVariableError(var); } } void CheckOther::constVariableError(const Variable *var) { const Token *tok = nullptr; std::string name = "x"; std::string id = "Variable"; if (var) { tok = var->nameToken(); name = var->name(); if (var->isArgument()) id = "Parameter"; } reportError(tok, Severity::style, "const" + id, id + " '" + name + "' can be declared with const", CWE398, false); } //--------------------------------------------------------------------------- // Check usage of char variables.. //--------------------------------------------------------------------------- void CheckOther::checkCharVariable() { const bool warning = mSettings->isEnabled(Settings::WARNING); const bool portability = mSettings->isEnabled(Settings::PORTABILITY); if (!warning && !portability) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "%var% [")) { if (!tok->variable()) continue; if (!tok->variable()->isArray() && !tok->variable()->isPointer()) continue; const Token *index = tok->next()->astOperand2(); if (warning && tok->variable()->isArray() && astIsSignedChar(index) && index->getValueGE(0x80, mSettings)) signedCharArrayIndexError(tok); if (portability && astIsUnknownSignChar(index) && index->getValueGE(0x80, mSettings)) unknownSignCharArrayIndexError(tok); } else if (warning && Token::Match(tok, "[&|^]") && tok->isBinaryOp()) { bool warn = false; if (astIsSignedChar(tok->astOperand1())) { const ValueFlow::Value *v1 = tok->astOperand1()->getValueLE(-1, mSettings); const ValueFlow::Value *v2 = tok->astOperand2()->getMaxValue(false); if (!v1) v1 = tok->astOperand1()->getValueGE(0x80, mSettings); if (v1 && !(tok->str() == "&" && v2 && v2->isKnown() && v2->intvalue >= 0 && v2->intvalue < 0x100)) warn = true; } else if (astIsSignedChar(tok->astOperand2())) { const ValueFlow::Value *v1 = tok->astOperand2()->getValueLE(-1, mSettings); const ValueFlow::Value *v2 = tok->astOperand1()->getMaxValue(false); if (!v1) v1 = tok->astOperand2()->getValueGE(0x80, mSettings); if (v1 && !(tok->str() == "&" && v2 && v2->isKnown() && v2->intvalue >= 0 && v2->intvalue < 0x100)) warn = true; } // is the result stored in a short|int|long? if (warn && Token::simpleMatch(tok->astParent(), "=")) { const Token *lhs = tok->astParent()->astOperand1(); if (lhs && lhs->valueType() && lhs->valueType()->type >= ValueType::Type::SHORT) charBitOpError(tok); // This is an error.. } } } } } void CheckOther::signedCharArrayIndexError(const Token *tok) { reportError(tok, Severity::warning, "signedCharArrayIndex", "Signed 'char' type used as array index.\n" "Signed 'char' type used as array index. If the value " "can be greater than 127 there will be a buffer underflow " "because of sign extension.", CWE128, false); } void CheckOther::unknownSignCharArrayIndexError(const Token *tok) { reportError(tok, Severity::portability, "unknownSignCharArrayIndex", "'char' type used as array index.\n" "'char' type used as array index. Values greater than 127 will be " "treated depending on whether 'char' is signed or unsigned on target platform.", CWE758, false); } void CheckOther::charBitOpError(const Token *tok) { reportError(tok, Severity::warning, "charBitOp", "When using 'char' variables in bit operations, sign extension can generate unexpected results.\n" "When using 'char' variables in bit operations, sign extension can generate unexpected results. For example:\n" " char c = 0x80;\n" " int i = 0 | c;\n" " if (i & 0x8000)\n" " printf(\"not expected\");\n" "The \"not expected\" will be printed on the screen.", CWE398, false); } //--------------------------------------------------------------------------- // Incomplete statement.. //--------------------------------------------------------------------------- static bool isType(const Token * tok, bool unknown) { if (Token::Match(tok, "%type%")) return true; if (Token::simpleMatch(tok, "::")) return isType(tok->astOperand2(), unknown); if (Token::simpleMatch(tok, "<") && tok->link()) return true; if (unknown && Token::Match(tok, "%name% !!(")) return true; return false; } static bool isVarDeclOp(const Token* tok) { if (!tok) return false; const Token * vartok = tok->astOperand2(); if (vartok && vartok->variable() && vartok->variable()->nameToken() == vartok) return true; const Token * typetok = tok->astOperand1(); return isType(typetok, Token::Match(vartok, "%var%")); } static bool isConstStatement(const Token *tok) { if (!tok) return false; if (tok->isExpandedMacro()) return false; if (Token::Match(tok, "%bool%|%num%|%str%|%char%|nullptr|NULL")) return true; if (Token::Match(tok, "%var%")) return true; if (Token::Match(tok, "*|&|&&") && (Token::Match(tok->previous(), "::|.|const|volatile|restrict") || isVarDeclOp(tok))) return false; if (Token::Match(tok, "<<|>>") && !astIsIntegral(tok, false)) return false; if (Token::Match(tok, "!|~|%cop%") && (tok->astOperand1() || tok->astOperand2())) return true; if (Token::simpleMatch(tok->previous(), "sizeof (")) return true; if (isCPPCast(tok)) return isConstStatement(tok->astOperand2()); if (Token::Match(tok, "( %type%")) return isConstStatement(tok->astOperand1()); if (Token::simpleMatch(tok, ",")) return isConstStatement(tok->astOperand2()); return false; } static bool isVoidStmt(const Token *tok) { if (Token::simpleMatch(tok, "( void")) return true; const Token *tok2 = tok; while (tok2->astOperand1()) tok2 = tok2->astOperand1(); if (Token::simpleMatch(tok2->previous(), ")") && Token::simpleMatch(tok2->previous()->link(), "( void")) return true; if (Token::simpleMatch(tok2, "( void")) return true; return Token::Match(tok2->previous(), "delete|throw|return"); } static bool isConstTop(const Token *tok) { if (!tok) return false; if (tok == tok->astTop()) return true; if (Token::simpleMatch(tok->astParent(), ";") && tok->astTop() && Token::Match(tok->astTop()->previous(), "for|if (") && Token::simpleMatch(tok->astTop()->astOperand2(), ";")) { if (Token::simpleMatch(tok->astParent()->astParent(), ";")) return tok->astParent()->astOperand2() == tok; else return tok->astParent()->astOperand1() == tok; } return false; } void CheckOther::checkIncompleteStatement() { if (!mSettings->isEnabled(Settings::WARNING)) return; for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { const Scope *scope = tok->scope(); if (scope && !scope->isExecutable()) continue; if (!isConstTop(tok)) continue; const Token *rtok = nextAfterAstRightmostLeaf(tok); if (!Token::simpleMatch(tok->astParent(), ";") && !Token::simpleMatch(rtok, ";") && !Token::Match(tok->previous(), ";|}|{ %any% ;")) continue; // Skipe statement expressions if (Token::simpleMatch(rtok, "; } )")) continue; if (!isConstStatement(tok)) continue; if (isVoidStmt(tok)) continue; if (mTokenizer->isCPP() && tok->str() == "&" && !(tok->astOperand1()->valueType() && tok->astOperand1()->valueType()->isIntegral())) // Possible archive continue; bool inconclusive = Token::Match(tok, "%cop%"); if (mSettings->inconclusive || !inconclusive) constStatementError(tok, tok->isNumber() ? "numeric" : "string", inconclusive); } } void CheckOther::constStatementError(const Token *tok, const std::string &type, bool inconclusive) { std::string msg; if (Token::simpleMatch(tok, "==")) msg = "Found suspicious equality comparison. Did you intend to assign a value instead?"; else if (Token::Match(tok, ",|!|~|%cop%")) msg = "Found suspicious operator '" + tok->str() + "'"; else if (Token::Match(tok, "%var%")) msg = "Unused variable value '" + tok->str() + "'"; else msg = "Redundant code: Found a statement that begins with " + type + " constant."; reportError(tok, Severity::warning, "constStatement", msg, CWE398, inconclusive); } //--------------------------------------------------------------------------- // Detect division by zero. //--------------------------------------------------------------------------- void CheckOther::checkZeroDivision() { for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (!tok->astOperand2() || !tok->astOperand1()) continue; if (tok->str() != "%" && tok->str() != "/" && tok->str() != "%=" && tok->str() != "/=") continue; if (!tok->valueType() || !tok->valueType()->isIntegral()) continue; // Value flow.. const ValueFlow::Value *value = tok->astOperand2()->getValue(0LL); if (value && mSettings->isEnabled(value, false)) zerodivError(tok, value); } } void CheckOther::zerodivError(const Token *tok, const ValueFlow::Value *value) { if (!tok && !value) { reportError(tok, Severity::error, "zerodiv", "Division by zero.", CWE369, false); reportError(tok, Severity::error, "zerodivcond", ValueFlow::eitherTheConditionIsRedundant(nullptr) + " or there is division by zero.", CWE369, false); return; } const ErrorPath errorPath = getErrorPath(tok, value, "Division by zero"); std::ostringstream errmsg; if (value->condition) { const int line = tok ? tok->linenr() : 0; errmsg << ValueFlow::eitherTheConditionIsRedundant(value->condition) << " or there is division by zero at line " << line << "."; } else errmsg << "Division by zero."; reportError(errorPath, value->errorSeverity() ? Severity::error : Severity::warning, value->condition ? "zerodivcond" : "zerodiv", errmsg.str(), CWE369, value->isInconclusive()); } //--------------------------------------------------------------------------- // Check for NaN (not-a-number) in an arithmetic expression, e.g. // double d = 1.0 / 0.0 + 100.0; //--------------------------------------------------------------------------- void CheckOther::checkNanInArithmeticExpression() { if (!mSettings->isEnabled(Settings::STYLE)) return; for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (tok->str() != "/") continue; if (!Token::Match(tok->astParent(), "[+-]")) continue; if (Token::simpleMatch(tok->astOperand2(), "0.0")) nanInArithmeticExpressionError(tok); } } void CheckOther::nanInArithmeticExpressionError(const Token *tok) { reportError(tok, Severity::style, "nanInArithmeticExpression", "Using NaN/Inf in a computation.\n" "Using NaN/Inf in a computation. " "Although nothing bad really happens, it is suspicious.", CWE369, false); } //--------------------------------------------------------------------------- // Creating instance of classes which are destroyed immediately //--------------------------------------------------------------------------- void CheckOther::checkMisusedScopedObject() { // Skip this check for .c files if (mTokenizer->isC()) return; if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase * const symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token *tok = scope->bodyStart; tok && tok != scope->bodyEnd; tok = tok->next()) { if ((tok->next()->type() || (tok->next()->function() && tok->next()->function()->isConstructor())) // TODO: The rhs of || should be removed; It is a workaround for a symboldatabase bug && Token::Match(tok, "[;{}] %name% (") && Token::Match(tok->linkAt(2), ") ; !!}") && (!tok->next()->function() || // is not a function on this scope tok->next()->function()->isConstructor())) { // or is function in this scope and it's a ctor tok = tok->next(); misusedScopeObjectError(tok, tok->str()); tok = tok->next(); } } } } void CheckOther::misusedScopeObjectError(const Token *tok, const std::string& varname) { reportError(tok, Severity::style, "unusedScopedObject", "$symbol:" + varname + "\n" "Instance of '$symbol' object is destroyed immediately.", CWE563, false); } static const Token * getSingleExpressionInBlock(const Token * tok) { if (!tok) return nullptr; const Token * top = tok->astTop(); if (!top) return nullptr; const Token * nextExpression = nextAfterAstRightmostLeaf(top); if (!Token::simpleMatch(nextExpression, "; }")) return nullptr; return top; } //----------------------------------------------------------------------------- // check for duplicate code in if and else branches // if (a) { b = true; } else { b = true; } //----------------------------------------------------------------------------- void CheckOther::checkDuplicateBranch() { // This is inconclusive since in practice most warnings are noise: // * There can be unfixed low-priority todos. The code is fine as it // is but it could be possible to enhance it. Writing a warning // here is noise since the code is fine (see cppcheck, abiword, ..) // * There can be overspecified code so some conditions can't be true // and their conditional code is a duplicate of the condition that // is always true just in case it would be false. See for instance // abiword. if (!mSettings->isEnabled(Settings::STYLE) || !mSettings->inconclusive) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope & scope : symbolDatabase->scopeList) { if (scope.type != Scope::eIf) continue; // check all the code in the function for if (..) else if (Token::simpleMatch(scope.bodyEnd, "} else {")) { // Make sure there are no macros (different macros might be expanded // to the same code) bool macro = false; for (const Token *tok = scope.bodyStart; tok != scope.bodyEnd->linkAt(2); tok = tok->next()) { if (tok->isExpandedMacro()) { macro = true; break; } } if (macro) continue; // save if branch code const std::string branch1 = scope.bodyStart->next()->stringifyList(scope.bodyEnd); if (branch1.empty()) continue; // save else branch code const std::string branch2 = scope.bodyEnd->tokAt(3)->stringifyList(scope.bodyEnd->linkAt(2)); ErrorPath errorPath; // check for duplicates if (branch1 == branch2) { duplicateBranchError(scope.classDef, scope.bodyEnd->next(), errorPath); continue; } // check for duplicates using isSameExpression const Token * branchTop1 = getSingleExpressionInBlock(scope.bodyStart->next()); const Token * branchTop2 = getSingleExpressionInBlock(scope.bodyEnd->tokAt(3)); if (!branchTop1 || !branchTop2) continue; if (branchTop1->str() != branchTop2->str()) continue; if (isSameExpression(mTokenizer->isCPP(), false, branchTop1->astOperand1(), branchTop2->astOperand1(), mSettings->library, true, true, &errorPath) && isSameExpression(mTokenizer->isCPP(), false, branchTop1->astOperand2(), branchTop2->astOperand2(), mSettings->library, true, true, &errorPath)) duplicateBranchError(scope.classDef, scope.bodyEnd->next(), errorPath); } } } void CheckOther::duplicateBranchError(const Token *tok1, const Token *tok2, ErrorPath errors) { errors.emplace_back(tok2, ""); errors.emplace_back(tok1, ""); reportError(errors, Severity::style, "duplicateBranch", "Found duplicate branches for 'if' and 'else'.\n" "Finding the same code in an 'if' and related 'else' branch is suspicious and " "might indicate a cut and paste or logic error. Please examine this code " "carefully to determine if it is correct.", CWE398, true); } //----------------------------------------------------------------------------- // Check for a free() of an invalid address // char* p = malloc(100); // free(p + 10); //----------------------------------------------------------------------------- void CheckOther::checkInvalidFree() { std::map inconclusive; std::map allocation; const bool printInconclusive = mSettings->inconclusive; const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { // Keep track of which variables were assigned addresses to newly-allocated memory if (Token::Match(tok, "%var% = malloc|g_malloc|new")) { allocation.insert(std::make_pair(tok->varId(), tok->strAt(2))); inconclusive.insert(std::make_pair(tok->varId(), false)); } // If a previously-allocated pointer is incremented or decremented, any subsequent // free involving pointer arithmetic may or may not be invalid, so we should only // report an inconclusive result. else if (Token::Match(tok, "%var% = %name% +|-") && tok->varId() == tok->tokAt(2)->varId() && allocation.find(tok->varId()) != allocation.end()) { if (printInconclusive) inconclusive[tok->varId()] = true; else { allocation.erase(tok->varId()); inconclusive.erase(tok->varId()); } } // If a previously-allocated pointer is assigned a completely new value, // we can't know if any subsequent free() on that pointer is valid or not. else if (Token::Match(tok, "%var% =")) { allocation.erase(tok->varId()); inconclusive.erase(tok->varId()); } // If a variable that was previously assigned a newly-allocated memory location is // added or subtracted from when used to free the memory, report an error. else if (Token::Match(tok, "free|g_free|delete ( %any% +|-") || Token::Match(tok, "delete [ ] ( %any% +|-") || Token::Match(tok, "delete %any% +|- %any%")) { const int varIndex = tok->strAt(1) == "(" ? 2 : tok->strAt(3) == "(" ? 4 : 1; const int var1 = tok->tokAt(varIndex)->varId(); const int var2 = tok->tokAt(varIndex + 2)->varId(); const std::map::const_iterator alloc1 = inconclusive.find(var1); const std::map::const_iterator alloc2 = inconclusive.find(var2); if (alloc1 != inconclusive.end()) { invalidFreeError(tok, allocation[var1], alloc1->second); } else if (alloc2 != inconclusive.end()) { invalidFreeError(tok, allocation[var2], alloc2->second); } } // If the previously-allocated variable is passed in to another function // as a parameter, it might be modified, so we shouldn't report an error // if it is later used to free memory else if (Token::Match(tok, "%name% (") && !mSettings->library.isFunctionConst(tok->str(), true)) { const Token* tok2 = Token::findmatch(tok->next(), "%var%", tok->linkAt(1)); while (tok2 != nullptr) { allocation.erase(tok->varId()); inconclusive.erase(tok2->varId()); tok2 = Token::findmatch(tok2->next(), "%var%", tok->linkAt(1)); } } } } } void CheckOther::invalidFreeError(const Token *tok, const std::string &allocation, bool inconclusive) { std::string alloc = allocation; if (alloc != "new") alloc += "()"; std::string deallocated = (alloc == "new") ? "deleted" : "freed"; reportError(tok, Severity::error, "invalidFree", "Mismatching address is " + deallocated + ". The address you get from " + alloc + " must be " + deallocated + " without offset.", CWE(0U), inconclusive); } //--------------------------------------------------------------------------- // check for the same expression on both sides of an operator // (x == x), (x && x), (x || x) // (x.y == x.y), (x.y && x.y), (x.y || x.y) //--------------------------------------------------------------------------- namespace { bool notconst(const Function* func) { return !func->isConst(); } void getConstFunctions(const SymbolDatabase *symbolDatabase, std::list &constFunctions) { for (const Scope &scope : symbolDatabase->scopeList) { // only add const functions that do not have a non-const overloaded version // since it is pretty much impossible to tell which is being called. typedef std::map > StringFunctionMap; StringFunctionMap functionsByName; for (const Function &func : scope.functionList) { functionsByName[func.tokenDef->str()].push_back(&func); } for (StringFunctionMap::iterator it = functionsByName.begin(); it != functionsByName.end(); ++it) { const std::list::const_iterator nc = std::find_if(it->second.begin(), it->second.end(), notconst); if (nc == it->second.end()) { // ok to add all of them constFunctions.splice(constFunctions.end(), it->second); } } } } } void CheckOther::checkDuplicateExpression() { const bool styleEnabled = mSettings->isEnabled(Settings::STYLE); const bool warningEnabled = mSettings->isEnabled(Settings::WARNING); if (!styleEnabled && !warningEnabled) return; // Parse all executing scopes.. const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); std::list constFunctions; getConstFunctions(symbolDatabase, constFunctions); for (const Scope *scope : symbolDatabase->functionScopes) { for (const Token *tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) { if (tok->str() == "=" && Token::Match(tok->astOperand1(), "%var%")) { const Token * endStatement = Token::findsimplematch(tok, ";"); if (Token::Match(endStatement, "; %type% %var% ;")) { endStatement = endStatement->tokAt(4); } if (Token::Match(endStatement, "%var% %assign%")) { const Token * nextAssign = endStatement->tokAt(1); const Token * var1 = tok->astOperand1(); const Token * var2 = nextAssign->astOperand1(); if (var1 && var2 && Token::Match(var1->previous(), ";|{|} %var%") && Token::Match(var2->previous(), ";|{|} %var%") && var2->valueType() && var1->valueType() && var2->valueType()->originalTypeName == var1->valueType()->originalTypeName && var2->valueType()->pointer == var1->valueType()->pointer && var2->valueType()->constness == var1->valueType()->constness && var2->varId() != var1->varId() && ( tok->astOperand2()->isArithmeticalOp() || tok->astOperand2()->str() == "." || Token::Match(tok->astOperand2()->previous(), "%name% (") ) && tok->next()->tokType() != Token::eType && isSameExpression(mTokenizer->isCPP(), true, tok->next(), nextAssign->next(), mSettings->library, true, false) && isSameExpression(mTokenizer->isCPP(), true, tok->astOperand2(), nextAssign->astOperand2(), mSettings->library, true, false) && tok->astOperand2()->expressionString() == nextAssign->astOperand2()->expressionString()) { bool assigned = false; const Scope * varScope = var1->scope() ? var1->scope() : scope; for (const Token *assignTok = Token::findsimplematch(var2, ";"); assignTok && assignTok != varScope->bodyEnd; assignTok = assignTok->next()) { if (Token::Match(assignTok, "%varid% = %var%", var1->varId()) && Token::Match(assignTok, "%var% = %varid%", var2->varId())) { assigned = true; } if (Token::Match(assignTok, "%varid% = %var%", var2->varId()) && Token::Match(assignTok, "%var% = %varid%", var1->varId())) { assigned = true; } } if (!assigned && !isUniqueExpression(tok->astOperand2())) duplicateAssignExpressionError(var1, var2, false); else if (mSettings->inconclusive) duplicateAssignExpressionError(var1, var2, true); } } } ErrorPath errorPath; if (tok->isOp() && tok->astOperand1() && !Token::Match(tok, "+|*|<<|>>|+=|*=|<<=|>>=")) { if (Token::Match(tok, "==|!=|-") && astIsFloat(tok->astOperand1(), true)) continue; if (isSameExpression(mTokenizer->isCPP(), true, tok->astOperand1(), tok->astOperand2(), mSettings->library, true, true, &errorPath)) { if (isWithoutSideEffects(mTokenizer->isCPP(), tok->astOperand1())) { const bool assignment = tok->str() == "="; if (assignment && warningEnabled) selfAssignmentError(tok, tok->astOperand1()->expressionString()); else if (styleEnabled) { if (mTokenizer->isCPP() && mSettings->standards.cpp==Standards::CPP11 && tok->str() == "==") { const Token* parent = tok->astParent(); while (parent && parent->astParent()) { parent = parent->astParent(); } if (parent && parent->previous() && parent->previous()->str() == "static_assert") { continue; } } duplicateExpressionError(tok->astOperand1(), tok->astOperand2(), tok, errorPath); } } } else if (tok->str() == "=" && Token::simpleMatch(tok->astOperand2(), "=") && isSameExpression(mTokenizer->isCPP(), false, tok->astOperand1(), tok->astOperand2()->astOperand1(), mSettings->library, true, false)) { if (warningEnabled && isWithoutSideEffects(mTokenizer->isCPP(), tok->astOperand1())) { selfAssignmentError(tok, tok->astOperand1()->expressionString()); } } else if (styleEnabled && isOppositeExpression(mTokenizer->isCPP(), tok->astOperand1(), tok->astOperand2(), mSettings->library, false, true, &errorPath) && !Token::Match(tok, "=|-|-=|/|/=") && isWithoutSideEffects(mTokenizer->isCPP(), tok->astOperand1())) { oppositeExpressionError(tok, errorPath); } else if (!Token::Match(tok, "[-/%]")) { // These operators are not associative if (styleEnabled && tok->astOperand2() && tok->str() == tok->astOperand1()->str() && isSameExpression(mTokenizer->isCPP(), true, tok->astOperand2(), tok->astOperand1()->astOperand2(), mSettings->library, true, true, &errorPath) && isWithoutSideEffects(mTokenizer->isCPP(), tok->astOperand2())) duplicateExpressionError(tok->astOperand2(), tok->astOperand1()->astOperand2(), tok, errorPath); else if (tok->astOperand2() && isConstExpression(tok->astOperand1(), mSettings->library, true, mTokenizer->isCPP())) { const Token *ast1 = tok->astOperand1(); while (ast1 && tok->str() == ast1->str()) { if (isSameExpression(mTokenizer->isCPP(), true, ast1->astOperand1(), tok->astOperand2(), mSettings->library, true, true, &errorPath) && isWithoutSideEffects(mTokenizer->isCPP(), ast1->astOperand1()) && isWithoutSideEffects(mTokenizer->isCPP(), ast1->astOperand2())) // Probably the message should be changed to 'duplicate expressions X in condition or something like that'. duplicateExpressionError(ast1->astOperand1(), tok->astOperand2(), tok, errorPath); ast1 = ast1->astOperand1(); } } } } else if (styleEnabled && tok->astOperand1() && tok->astOperand2() && tok->str() == ":" && tok->astParent() && tok->astParent()->str() == "?") { if (!tok->astOperand1()->values().empty() && !tok->astOperand2()->values().empty() && isEqualKnownValue(tok->astOperand1(), tok->astOperand2())) duplicateValueTernaryError(tok); else if (isSameExpression(mTokenizer->isCPP(), true, tok->astOperand1(), tok->astOperand2(), mSettings->library, false, true, &errorPath)) duplicateExpressionTernaryError(tok, errorPath); } } } } void CheckOther::oppositeExpressionError(const Token *opTok, ErrorPath errors) { errors.emplace_back(opTok, ""); const std::string& op = opTok ? opTok->str() : "&&"; reportError(errors, Severity::style, "oppositeExpression", "Opposite expression on both sides of \'" + op + "\'.\n" "Finding the opposite expression on both sides of an operator is suspicious and might " "indicate a cut and paste or logic error. Please examine this code carefully to " "determine if it is correct.", CWE398, false); } void CheckOther::duplicateExpressionError(const Token *tok1, const Token *tok2, const Token *opTok, ErrorPath errors) { errors.emplace_back(opTok, ""); const std::string& expr1 = tok1 ? tok1->expressionString() : "x"; const std::string& expr2 = tok2 ? tok2->expressionString() : "x"; const std::string& op = opTok ? opTok->str() : "&&"; std::string msg = "Same expression on both sides of \'" + op + "\'"; std::string id = "duplicateExpression"; if (expr1 != expr2) { id = "knownConditionTrueFalse"; std::string exprMsg = "The expression \'" + expr1 + " " + op + " " + expr2 + "\' is always "; if (Token::Match(opTok, "==|>=|<=")) msg = exprMsg + "true"; else if (Token::Match(opTok, "!=|>|<")) msg = exprMsg + "false"; if (!Token::Match(tok1, "%num%|NULL|nullptr") && !Token::Match(tok2, "%num%|NULL|nullptr")) msg += " because '" + expr1 + "' and '" + expr2 + "' represent the same value"; } reportError(errors, Severity::style, id.c_str(), msg + ".\n" "Finding the same expression on both sides of an operator is suspicious and might " "indicate a cut and paste or logic error. Please examine this code carefully to " "determine if it is correct.", CWE398, false); } void CheckOther::duplicateAssignExpressionError(const Token *tok1, const Token *tok2, bool inconclusive) { const std::list toks = { tok2, tok1 }; const std::string& var1 = tok1 ? tok1->str() : "x"; const std::string& var2 = tok2 ? tok2->str() : "x"; reportError(toks, Severity::style, "duplicateAssignExpression", "Same expression used in consecutive assignments of '" + var1 + "' and '" + var2 + "'.\n" "Finding variables '" + var1 + "' and '" + var2 + "' that are assigned the same expression " "is suspicious and might indicate a cut and paste or logic error. Please examine this code carefully to " "determine if it is correct.", CWE398, inconclusive); } void CheckOther::duplicateExpressionTernaryError(const Token *tok, ErrorPath errors) { errors.emplace_back(tok, ""); reportError(errors, Severity::style, "duplicateExpressionTernary", "Same expression in both branches of ternary operator.\n" "Finding the same expression in both branches of ternary operator is suspicious as " "the same code is executed regardless of the condition.", CWE398, false); } void CheckOther::duplicateValueTernaryError(const Token *tok) { reportError(tok, Severity::style, "duplicateValueTernary", "Same value in both branches of ternary operator.\n" "Finding the same value in both branches of ternary operator is suspicious as " "the same code is executed regardless of the condition.", CWE398, false); } void CheckOther::selfAssignmentError(const Token *tok, const std::string &varname) { reportError(tok, Severity::warning, "selfAssignment", "$symbol:" + varname + "\n" "Redundant assignment of '$symbol' to itself.", CWE398, false); } //----------------------------------------------------------------------------- // Check is a comparison of two variables leads to condition, which is // always true or false. // For instance: int a = 1; if(isless(a,a)){...} // In this case isless(a,a) always evaluates to false. // // Reference: // - http://www.cplusplus.com/reference/cmath/ //----------------------------------------------------------------------------- void CheckOther::checkComparisonFunctionIsAlwaysTrueOrFalse() { if (!mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (tok->isName() && Token::Match(tok, "isgreater|isless|islessgreater|isgreaterequal|islessequal ( %var% , %var% )")) { const int varidLeft = tok->tokAt(2)->varId();// get the left varid const int varidRight = tok->tokAt(4)->varId();// get the right varid // compare varids: if they are not zero but equal // --> the comparison function is called with the same variables if (varidLeft == varidRight) { const std::string& functionName = tok->str(); // store function name const std::string& varNameLeft = tok->strAt(2); // get the left variable name if (functionName == "isgreater" || functionName == "isless" || functionName == "islessgreater") { // e.g.: isgreater(x,x) --> (x)>(x) --> false checkComparisonFunctionIsAlwaysTrueOrFalseError(tok, functionName, varNameLeft, false); } else { // functionName == "isgreaterequal" || functionName == "islessequal" // e.g.: isgreaterequal(x,x) --> (x)>=(x) --> true checkComparisonFunctionIsAlwaysTrueOrFalseError(tok, functionName, varNameLeft, true); } } } } } } void CheckOther::checkComparisonFunctionIsAlwaysTrueOrFalseError(const Token* tok, const std::string &functionName, const std::string &varName, const bool result) { const std::string strResult = result ? "true" : "false"; const struct CWE cweResult = result ? CWE571 : CWE570; reportError(tok, Severity::warning, "comparisonFunctionIsAlwaysTrueOrFalse", "$symbol:" + functionName + "\n" "Comparison of two identical variables with $symbol(" + varName + "," + varName + ") always evaluates to " + strResult + ".\n" "The function $symbol is designed to compare two variables. Calling this function with one variable (" + varName + ") " "for both parameters leads to a statement which is always " + strResult + ".", cweResult, false); } //--------------------------------------------------------------------------- // Check testing sign of unsigned variables and pointers. //--------------------------------------------------------------------------- void CheckOther::checkSignOfUnsignedVariable() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { // check all the code in the function for (const Token *tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (!tok->isComparisonOp() || !tok->astOperand1() || !tok->astOperand2()) continue; const ValueFlow::Value *v1 = tok->astOperand1()->getValue(0); const ValueFlow::Value *v2 = tok->astOperand2()->getValue(0); if (Token::Match(tok, "<|<=") && v2 && v2->isKnown()) { const ValueType* vt = tok->astOperand1()->valueType(); if (vt && vt->pointer) pointerLessThanZeroError(tok, v2); if (vt && vt->sign == ValueType::UNSIGNED) unsignedLessThanZeroError(tok, v2, tok->astOperand1()->expressionString()); } else if (Token::Match(tok, ">|>=") && v1 && v1->isKnown()) { const ValueType* vt = tok->astOperand2()->valueType(); if (vt && vt->pointer) pointerLessThanZeroError(tok, v1); if (vt && vt->sign == ValueType::UNSIGNED) unsignedLessThanZeroError(tok, v1, tok->astOperand2()->expressionString()); } else if (Token::simpleMatch(tok, ">=") && v2 && v2->isKnown()) { const ValueType* vt = tok->astOperand1()->valueType(); if (vt && vt->pointer) pointerPositiveError(tok, v2); if (vt && vt->sign == ValueType::UNSIGNED) unsignedPositiveError(tok, v2, tok->astOperand1()->expressionString()); } else if (Token::simpleMatch(tok, "<=") && v1 && v1->isKnown()) { const ValueType* vt = tok->astOperand2()->valueType(); if (vt && vt->pointer) pointerPositiveError(tok, v1); if (vt && vt->sign == ValueType::UNSIGNED) unsignedPositiveError(tok, v1, tok->astOperand2()->expressionString()); } } } } void CheckOther::unsignedLessThanZeroError(const Token *tok, const ValueFlow::Value * v, const std::string &varname) { reportError(getErrorPath(tok, v, "Unsigned less than zero"), Severity::style, "unsignedLessThanZero", "$symbol:" + varname + "\n" "Checking if unsigned expression '$symbol' is less than zero.\n" "The unsigned expression '$symbol' will never be negative so it " "is either pointless or an error to check if it is.", CWE570, false); } void CheckOther::pointerLessThanZeroError(const Token *tok, const ValueFlow::Value *v) { reportError(getErrorPath(tok, v, "Pointer less than zero"), Severity::style, "pointerLessThanZero", "A pointer can not be negative so it is either pointless or an error to check if it is.", CWE570, false); } void CheckOther::unsignedPositiveError(const Token *tok, const ValueFlow::Value * v, const std::string &varname) { reportError(getErrorPath(tok, v, "Unsigned positive"), Severity::style, "unsignedPositive", "$symbol:" + varname + "\n" "Unsigned expression '$symbol' can't be negative so it is unnecessary to test it.", CWE570, false); } void CheckOther::pointerPositiveError(const Token *tok, const ValueFlow::Value * v) { reportError(getErrorPath(tok, v, "Pointer positive"), Severity::style, "pointerPositive", "A pointer can not be negative so it is either pointless or an error to check if it is not.", CWE570, false); } /* check if a constructor in given class scope takes a reference */ static bool constructorTakesReference(const Scope * const classScope) { for (const Function &constructor : classScope->functionList) { if (constructor.isConstructor()) { for (int argnr = 0U; argnr < constructor.argCount(); argnr++) { const Variable * const argVar = constructor.getArgumentVar(argnr); if (argVar && argVar->isReference()) { return true; } } } } return false; } //--------------------------------------------------------------------------- // This check rule works for checking the "const A a = getA()" usage when getA() returns "const A &" or "A &". // In most scenarios, "const A & a = getA()" will be more efficient. //--------------------------------------------------------------------------- void CheckOther::checkRedundantCopy() { if (!mSettings->isEnabled(Settings::PERFORMANCE) || mTokenizer->isC() || !mSettings->inconclusive) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Variable* var : symbolDatabase->variableList()) { if (!var || var->isReference() || !var->isConst() || var->isPointer() || (!var->type() && !var->isStlType())) // bailout if var is of standard type, if it is a pointer or non-const continue; const Token* startTok = var->nameToken(); if (startTok->strAt(1) == "=") // %type% %name% = ... ; ; else if (startTok->strAt(1) == "(" && var->isClass() && var->typeScope()) { // Object is instantiated. Warn if constructor takes arguments by value. if (constructorTakesReference(var->typeScope())) continue; } else continue; const Token* tok = startTok->next()->astOperand2(); if (!tok) continue; if (!Token::Match(tok->previous(), "%name% (")) continue; if (!Token::Match(tok->link(), ") )| ;")) // bailout for usage like "const A a = getA()+3" continue; const Function* func = tok->previous()->function(); if (func && func->tokenDef->strAt(-1) == "&") { redundantCopyError(startTok, startTok->str()); } } } void CheckOther::redundantCopyError(const Token *tok,const std::string& varname) { reportError(tok, Severity::performance, "redundantCopyLocalConst", "$symbol:" + varname + "\n" "Use const reference for '$symbol' to avoid unnecessary data copying.\n" "The const variable '$symbol' is assigned a copy of the data. You can avoid " "the unnecessary data copying by converting '$symbol' to const reference.", CWE398, true); // since #5618 that check became inconclusive } //--------------------------------------------------------------------------- // Checking for shift by negative values //--------------------------------------------------------------------------- static bool isNegative(const Token *tok, const Settings *settings) { return tok->valueType() && tok->valueType()->sign == ValueType::SIGNED && tok->getValueLE(-1LL, settings); } void CheckOther::checkNegativeBitwiseShift() { const bool portability = mSettings->isEnabled(Settings::PORTABILITY); for (const Token* tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (!tok->astOperand1() || !tok->astOperand2()) continue; if (!Token::Match(tok, "<<|>>|<<=|>>=")) continue; // don't warn if lhs is a class. this is an overloaded operator then if (mTokenizer->isCPP()) { const ValueType * lhsType = tok->astOperand1()->valueType(); if (!lhsType || !lhsType->isIntegral()) continue; } // bailout if operation is protected by ?: bool ternary = false; for (const Token *parent = tok; parent; parent = parent->astParent()) { if (Token::Match(parent, "?|:")) { ternary = true; break; } } if (ternary) continue; // Get negative rhs value. preferably a value which doesn't have 'condition'. if (portability && isNegative(tok->astOperand1(), mSettings)) negativeBitwiseShiftError(tok, 1); else if (isNegative(tok->astOperand2(), mSettings)) negativeBitwiseShiftError(tok, 2); } } void CheckOther::negativeBitwiseShiftError(const Token *tok, int op) { if (op == 1) // LHS - this is used by intention in various software, if it // is used often in a project and works as expected then this is // a portability issue reportError(tok, Severity::portability, "shiftNegativeLHS", "Shifting a negative value is technically undefined behaviour", CWE758, false); else // RHS reportError(tok, Severity::error, "shiftNegative", "Shifting by a negative value is undefined behaviour", CWE758, false); } //--------------------------------------------------------------------------- // Check for incompletely filled buffers. //--------------------------------------------------------------------------- void CheckOther::checkIncompleteArrayFill() { if (!mSettings->inconclusive) return; const bool printWarning = mSettings->isEnabled(Settings::WARNING); const bool printPortability = mSettings->isEnabled(Settings::PORTABILITY); if (!printPortability && !printWarning) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) { if (Token::Match(tok, "memset|memcpy|memmove ( %var% ,") && Token::Match(tok->linkAt(1)->tokAt(-2), ", %num% )")) { const Variable *var = tok->tokAt(2)->variable(); if (!var || !var->isArray() || var->dimensions().empty() || !var->dimension(0)) continue; if (MathLib::toLongNumber(tok->linkAt(1)->strAt(-1)) == var->dimension(0)) { int size = mTokenizer->sizeOfType(var->typeStartToken()); if (size == 0 && var->valueType()->pointer) size = mSettings->sizeof_pointer; if ((size != 1 && size != 100 && size != 0) || var->isPointer()) { if (printWarning) incompleteArrayFillError(tok, var->name(), tok->str(), false); } else if (var->valueType()->type == ValueType::Type::BOOL && printPortability) // sizeof(bool) is not 1 on all platforms incompleteArrayFillError(tok, var->name(), tok->str(), true); } } } } } void CheckOther::incompleteArrayFillError(const Token* tok, const std::string& buffer, const std::string& function, bool boolean) { if (boolean) reportError(tok, Severity::portability, "incompleteArrayFill", "$symbol:" + buffer + "\n" "$symbol:" + function + "\n" "Array '" + buffer + "' might be filled incompletely. Did you forget to multiply the size given to '" + function + "()' with 'sizeof(*" + buffer + ")'?\n" "The array '" + buffer + "' is filled incompletely. The function '" + function + "()' needs the size given in bytes, but the type 'bool' is larger than 1 on some platforms. Did you forget to multiply the size with 'sizeof(*" + buffer + ")'?", CWE131, true); else reportError(tok, Severity::warning, "incompleteArrayFill", "$symbol:" + buffer + "\n" "$symbol:" + function + "\n" "Array '" + buffer + "' is filled incompletely. Did you forget to multiply the size given to '" + function + "()' with 'sizeof(*" + buffer + ")'?\n" "The array '" + buffer + "' is filled incompletely. The function '" + function + "()' needs the size given in bytes, but an element of the given array is larger than one byte. Did you forget to multiply the size with 'sizeof(*" + buffer + ")'?", CWE131, true); } //--------------------------------------------------------------------------- // Detect NULL being passed to variadic function. //--------------------------------------------------------------------------- void CheckOther::checkVarFuncNullUB() { if (!mSettings->isEnabled(Settings::PORTABILITY)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) { // Is NULL passed to a function? if (Token::Match(tok,"[(,] NULL [,)]")) { // Locate function name in this function call. const Token *ftok = tok; int argnr = 1; while (ftok && ftok->str() != "(") { if (ftok->str() == ")") ftok = ftok->link(); else if (ftok->str() == ",") ++argnr; ftok = ftok->previous(); } ftok = ftok ? ftok->previous() : nullptr; if (ftok && ftok->isName()) { // If this is a variadic function then report error const Function *f = ftok->function(); if (f && f->argCount() <= argnr) { const Token *tok2 = f->argDef; tok2 = tok2 ? tok2->link() : nullptr; // goto ')' if (tok2 && Token::simpleMatch(tok2->tokAt(-1), "...")) varFuncNullUBError(tok); } } } } } } void CheckOther::varFuncNullUBError(const Token *tok) { reportError(tok, Severity::portability, "varFuncNullUB", "Passing NULL after the last typed argument to a variadic function leads to undefined behaviour.\n" "Passing NULL after the last typed argument to a variadic function leads to undefined behaviour.\n" "The C99 standard, in section 7.15.1.1, states that if the type used by va_arg() is not compatible with the type of the actual next argument (as promoted according to the default argument promotions), the behavior is undefined.\n" "The value of the NULL macro is an implementation-defined null pointer constant (7.17), which can be any integer constant expression with the value 0, or such an expression casted to (void*) (6.3.2.3). This includes values like 0, 0L, or even 0LL.\n" "In practice on common architectures, this will cause real crashes if sizeof(int) != sizeof(void*), and NULL is defined to 0 or any other null pointer constant that promotes to int.\n" "To reproduce you might be able to use this little code example on 64bit platforms. If the output includes \"ERROR\", the sentinel had only 4 out of 8 bytes initialized to zero and was not detected as the final argument to stop argument processing via va_arg(). Changing the 0 to (void*)0 or 0L will make the \"ERROR\" output go away.\n" "#include \n" "#include \n" "\n" "void f(char *s, ...) {\n" " va_list ap;\n" " va_start(ap,s);\n" " for (;;) {\n" " char *p = va_arg(ap,char*);\n" " printf(\"%018p, %s\\n\", p, (long)p & 255 ? p : \"\");\n" " if(!p) break;\n" " }\n" " va_end(ap);\n" "}\n" "\n" "void g() {\n" " char *s2 = \"x\";\n" " char *s3 = \"ERROR\";\n" "\n" " // changing 0 to 0L for the 7th argument (which is intended to act as sentinel) makes the error go away on x86_64\n" " f(\"first\", s2, s2, s2, s2, s2, 0, s3, (char*)0);\n" "}\n" "\n" "void h() {\n" " int i;\n" " volatile unsigned char a[1000];\n" " for (i = 0; iisEnabled(Settings::STYLE)) return; for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (!tok->isUnaryOp("&") || !tok->astOperand1()->isUnaryOp("*")) continue; // variable const Token *varTok = tok->astOperand1()->astOperand1(); if (!varTok || varTok->isExpandedMacro()) continue; const Variable *var = varTok->variable(); if (!var || !var->isPointer()) continue; redundantPointerOpError(tok, var->name(), false); } } void CheckOther::redundantPointerOpError(const Token* tok, const std::string &varname, bool inconclusive) { reportError(tok, Severity::style, "redundantPointerOp", "$symbol:" + varname + "\n" "Redundant pointer operation on '$symbol' - it's already a pointer.", CWE398, inconclusive); } void CheckOther::checkInterlockedDecrement() { if (!mSettings->isWindowsPlatform()) { return; } for (const Token *tok = mTokenizer->tokens(); tok; tok = tok->next()) { if (tok->isName() && Token::Match(tok, "InterlockedDecrement ( & %name% ) ; if ( %name%|!|0")) { const Token* interlockedVarTok = tok->tokAt(3); const Token* checkStartTok = interlockedVarTok->tokAt(5); if ((Token::Match(checkStartTok, "0 %comp% %name% )") && checkStartTok->strAt(2) == interlockedVarTok->str()) || (Token::Match(checkStartTok, "! %name% )") && checkStartTok->strAt(1) == interlockedVarTok->str()) || (Token::Match(checkStartTok, "%name% )") && checkStartTok->str() == interlockedVarTok->str()) || (Token::Match(checkStartTok, "%name% %comp% 0 )") && checkStartTok->str() == interlockedVarTok->str())) { raceAfterInterlockedDecrementError(checkStartTok); } } else if (Token::Match(tok, "if ( ::| InterlockedDecrement ( & %name%")) { const Token* condEnd = tok->next()->link(); const Token* funcTok = tok->tokAt(2); const Token* firstAccessTok = funcTok->str() == "::" ? funcTok->tokAt(4) : funcTok->tokAt(3); if (condEnd && condEnd->next() && condEnd->next()->link()) { const Token* ifEndTok = condEnd->next()->link(); if (Token::Match(ifEndTok, "} return %name%")) { const Token* secondAccessTok = ifEndTok->tokAt(2); if (secondAccessTok->str() == firstAccessTok->str()) { raceAfterInterlockedDecrementError(secondAccessTok); } } else if (Token::Match(ifEndTok, "} else { return %name%")) { const Token* secondAccessTok = ifEndTok->tokAt(4); if (secondAccessTok->str() == firstAccessTok->str()) { raceAfterInterlockedDecrementError(secondAccessTok); } } } } } } void CheckOther::raceAfterInterlockedDecrementError(const Token* tok) { reportError(tok, Severity::error, "raceAfterInterlockedDecrement", "Race condition: non-interlocked access after InterlockedDecrement(). Use InterlockedDecrement() return value instead.", CWE362, false); } void CheckOther::checkUnusedLabel() { if (!mSettings->isEnabled(Settings::STYLE) && !mSettings->isEnabled(Settings::WARNING)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { for (const Token* tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) { if (!tok->scope()->isExecutable()) tok = tok->scope()->bodyEnd; if (Token::Match(tok, "{|}|; %name% :") && tok->strAt(1) != "default") { if (!Token::findsimplematch(scope->bodyStart->next(), ("goto " + tok->strAt(1)).c_str(), scope->bodyEnd->previous())) unusedLabelError(tok->next(), tok->next()->scope()->type == Scope::eSwitch); } } } } void CheckOther::unusedLabelError(const Token* tok, bool inSwitch) { if (inSwitch) { if (!tok || mSettings->isEnabled(Settings::WARNING)) reportError(tok, Severity::warning, "unusedLabelSwitch", "$symbol:" + (tok ? tok->str() : emptyString) + "\n" "Label '$symbol' is not used. Should this be a 'case' of the enclosing switch()?", CWE398, false); } else { if (!tok || mSettings->isEnabled(Settings::STYLE)) reportError(tok, Severity::style, "unusedLabel", "$symbol:" + (tok ? tok->str() : emptyString) + "\n" "Label '$symbol' is not used.", CWE398, false); } } void CheckOther::checkEvaluationOrder() { // This checker is not written according to C++11 sequencing rules if (mTokenizer->isCPP() && mSettings->standards.cpp >= Standards::CPP11) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * functionScope : symbolDatabase->functionScopes) { for (const Token* tok = functionScope->bodyStart; tok != functionScope->bodyEnd; tok = tok->next()) { if (!Token::Match(tok, "++|--") && !tok->isAssignmentOp()) continue; if (!tok->astOperand1()) continue; for (const Token *tok2 = tok;; tok2 = tok2->astParent()) { // If ast parent is a sequence point then break const Token * const parent = tok2->astParent(); if (!parent) break; if (Token::Match(parent, "%oror%|&&|?|:|;")) break; if (parent->str() == ",") { const Token *par = parent; while (Token::simpleMatch(par,",")) par = par->astParent(); // not function or in a while clause => break if (!(par && par->str() == "(" && par->astOperand2() && par->strAt(-1) != "while")) break; // control flow (if|while|etc) => break if (Token::simpleMatch(par->link(),") {")) break; // sequence point in function argument: dostuff((1,2),3) => break par = par->next(); while (par && (par->previous() != parent)) par = par->nextArgument(); if (!par) break; } if (parent->str() == "(" && parent->astOperand2()) break; // self assignment.. if (tok2 == tok && tok->str() == "=" && parent->str() == "=" && isSameExpression(mTokenizer->isCPP(), false, tok->astOperand1(), parent->astOperand1(), mSettings->library, true, false)) { if (mSettings->isEnabled(Settings::WARNING) && isSameExpression(mTokenizer->isCPP(), true, tok->astOperand1(), parent->astOperand1(), mSettings->library, true, false)) selfAssignmentError(parent, tok->astOperand1()->expressionString()); break; } // Is expression used? bool foundError = false; visitAstNodes((parent->astOperand1() != tok2) ? parent->astOperand1() : parent->astOperand2(), [&](const Token *tok3) { if (tok3->str() == "&" && !tok3->astOperand2()) return ChildrenToVisit::none; // don't handle address-of for now if (tok3->str() == "(" && Token::simpleMatch(tok3->previous(), "sizeof")) return ChildrenToVisit::none; // don't care about sizeof usage if (isSameExpression(mTokenizer->isCPP(), false, tok->astOperand1(), tok3, mSettings->library, true, false)) foundError = true; return foundError ? ChildrenToVisit::done : ChildrenToVisit::op1_and_op2; }); if (foundError) { unknownEvaluationOrder(parent); break; } } } } } void CheckOther::unknownEvaluationOrder(const Token* tok) { reportError(tok, Severity::error, "unknownEvaluationOrder", "Expression '" + (tok ? tok->expressionString() : std::string("x = x++;")) + "' depends on order of evaluation of side effects", CWE768, false); } void CheckOther::checkAccessOfMovedVariable() { if (!mTokenizer->isCPP() || mSettings->standards.cpp < Standards::CPP11 || !mSettings->isEnabled(Settings::WARNING)) return; CheckUninitVar checkUninitVar(mTokenizer, mSettings, mErrorLogger); const bool reportInconclusive = mSettings->inconclusive; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope * scope : symbolDatabase->functionScopes) { const Token * scopeStart = scope->bodyStart; if (scope->function) { const Token * memberInitializationStart = scope->function->constructorMemberInitialization(); if (memberInitializationStart) scopeStart = memberInitializationStart; } for (const Token* tok = scopeStart->next(); tok != scope->bodyEnd; tok = tok->next()) { const ValueFlow::Value * movedValue = tok->getMovedValue(); if (!movedValue || movedValue->moveKind == ValueFlow::Value::MoveKind::NonMovedVariable) continue; if (movedValue->isInconclusive() && !reportInconclusive) continue; bool inconclusive = false; bool accessOfMoved = false; if (tok->strAt(1) == ".") { if (tok->next()->originalName() == "->") accessOfMoved = true; else inconclusive = true; } else { const bool isVariableChanged = isVariableChangedByFunctionCall(tok, 0, mSettings, &inconclusive); accessOfMoved = !isVariableChanged && checkUninitVar.isVariableUsage(tok, false, CheckUninitVar::NO_ALLOC); if (inconclusive) { accessOfMoved = !isMovedParameterAllowedForInconclusiveFunction(tok); if (accessOfMoved) inconclusive = false; } } if (accessOfMoved || (inconclusive && reportInconclusive)) accessMovedError(tok, tok->str(), movedValue, inconclusive || movedValue->isInconclusive()); } } } bool CheckOther::isMovedParameterAllowedForInconclusiveFunction(const Token * tok) { if (Token::simpleMatch(tok->tokAt(-4), "std :: move (")) return false; const Token * tokAtM2 = tok->tokAt(-2); if (Token::simpleMatch(tokAtM2, "> (") && tokAtM2->link()) { const Token * leftAngle = tokAtM2->link(); if (Token::simpleMatch(leftAngle->tokAt(-3), "std :: forward <")) return false; } return true; } void CheckOther::accessMovedError(const Token *tok, const std::string &varname, const ValueFlow::Value *value, bool inconclusive) { if (!tok) { reportError(tok, Severity::warning, "accessMoved", "Access of moved variable 'v'.", CWE672, false); reportError(tok, Severity::warning, "accessForwarded", "Access of forwarded variable 'v'.", CWE672, false); return; } const char * errorId = nullptr; std::string kindString; switch (value->moveKind) { case ValueFlow::Value::MoveKind::MovedVariable: errorId = "accessMoved"; kindString = "moved"; break; case ValueFlow::Value::MoveKind::ForwardedVariable: errorId = "accessForwarded"; kindString = "forwarded"; break; default: return; } const std::string errmsg("$symbol:" + varname + "\nAccess of " + kindString + " variable '$symbol'."); const ErrorPath errorPath = getErrorPath(tok, value, errmsg); reportError(errorPath, Severity::warning, errorId, errmsg, CWE672, inconclusive); } void CheckOther::checkFuncArgNamesDifferent() { const bool style = mSettings->isEnabled(Settings::STYLE); const bool inconclusive = mSettings->inconclusive; const bool warning = mSettings->isEnabled(Settings::WARNING); if (!(warning || (style && inconclusive))) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); // check every function for (const Scope *scope : symbolDatabase->functionScopes) { const Function * function = scope->function; // only check functions with arguments if (!function || function->argCount() == 0) continue; // only check functions with separate declarations and definitions if (function->argDef == function->arg) continue; // get the function argument name tokens std::vector declarations(function->argCount()); std::vector definitions(function->argCount()); const Token * decl = function->argDef->next(); for (int j = 0; j < function->argCount(); ++j) { declarations[j] = nullptr; definitions[j] = nullptr; // get the definition const Variable * variable = function->getArgumentVar(j); if (variable) { definitions[j] = variable->nameToken(); } // get the declaration (search for first token with varId) while (decl && !Token::Match(decl, ",|)|;")) { // skip everything after the assignment because // it could also have a varId or be the first // token with a varId if there is no name token if (decl->str() == "=") { decl = decl->nextArgument(); break; } // skip over template if (decl->link()) decl = decl->link(); else if (decl->varId()) declarations[j] = decl; decl = decl->next(); } if (Token::simpleMatch(decl, ",")) decl = decl->next(); } // check for different argument order if (warning) { bool order_different = false; for (int j = 0; j < function->argCount(); ++j) { if (!declarations[j] || !definitions[j] || declarations[j]->str() == definitions[j]->str()) continue; for (int k = 0; k < function->argCount(); ++k) { if (j != k && definitions[k] && declarations[j]->str() == definitions[k]->str()) { order_different = true; break; } } } if (order_different) { funcArgOrderDifferent(function->name(), function->argDef->next(), function->arg->next(), declarations, definitions); continue; } } // check for different argument names if (style && inconclusive) { for (int j = 0; j < function->argCount(); ++j) { if (declarations[j] && definitions[j] && declarations[j]->str() != definitions[j]->str()) funcArgNamesDifferent(function->name(), j, declarations[j], definitions[j]); } } } } void CheckOther::funcArgNamesDifferent(const std::string & functionName, nonneg int index, const Token* declaration, const Token* definition) { std::list tokens = { declaration,definition }; reportError(tokens, Severity::style, "funcArgNamesDifferent", "$symbol:" + functionName + "\n" "Function '$symbol' argument " + MathLib::toString(index + 1) + " names different: declaration '" + (declaration ? declaration->str() : std::string("A")) + "' definition '" + (definition ? definition->str() : std::string("B")) + "'.", CWE628, true); } void CheckOther::funcArgOrderDifferent(const std::string & functionName, const Token* declaration, const Token* definition, const std::vector & declarations, const std::vector & definitions) { std::list tokens = { declarations.size() ? declarations[0] ? declarations[0] : declaration : nullptr, definitions.size() ? definitions[0] ? definitions[0] : definition : nullptr }; std::string msg = "$symbol:" + functionName + "\nFunction '$symbol' argument order different: declaration '"; for (int i = 0; i < declarations.size(); ++i) { if (i != 0) msg += ", "; if (declarations[i]) msg += declarations[i]->str(); } msg += "' definition '"; for (int i = 0; i < definitions.size(); ++i) { if (i != 0) msg += ", "; if (definitions[i]) msg += definitions[i]->str(); } msg += "'"; reportError(tokens, Severity::warning, "funcArgOrderDifferent", msg, CWE683, false); } static const Token *findShadowed(const Scope *scope, const std::string &varname, int linenr) { if (!scope) return nullptr; for (const Variable &var : scope->varlist) { if (scope->isExecutable() && var.nameToken()->linenr() > linenr) continue; if (var.name() == varname) return var.nameToken(); } for (const Function &f : scope->functionList) { if (f.name() == varname) return f.tokenDef; } if (scope->type == Scope::eLambda) return nullptr; return findShadowed(scope->nestedIn, varname, linenr); } void CheckOther::checkShadowVariables() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope & scope : symbolDatabase->scopeList) { if (!scope.isExecutable() || scope.type == Scope::eLambda) continue; const Scope *functionScope = &scope; while (functionScope && functionScope->type != Scope::ScopeType::eFunction && functionScope->type != Scope::ScopeType::eLambda) functionScope = functionScope->nestedIn; for (const Variable &var : scope.varlist) { if (var.nameToken() && var.nameToken()->isExpandedMacro()) // #8903 continue; if (functionScope && functionScope->type == Scope::ScopeType::eFunction && functionScope->function) { bool shadowArg = false; for (const Variable &arg : functionScope->function->argumentList) { if (arg.nameToken() && var.name() == arg.name()) { shadowError(var.nameToken(), arg.nameToken(), "argument"); shadowArg = true; break; } } if (shadowArg) continue; } const Token *shadowed = findShadowed(scope.nestedIn, var.name(), var.nameToken()->linenr()); if (!shadowed) continue; if (scope.type == Scope::eFunction && scope.className == var.name()) continue; shadowError(var.nameToken(), shadowed, (shadowed->varId() != 0) ? "variable" : "function"); } } } void CheckOther::shadowError(const Token *var, const Token *shadowed, std::string type) { ErrorPath errorPath; errorPath.push_back(ErrorPathItem(shadowed, "Shadowed declaration")); errorPath.push_back(ErrorPathItem(var, "Shadow variable")); const std::string &varname = var ? var->str() : type; const std::string Type = char(std::toupper(type[0])) + type.substr(1); const std::string id = "shadow" + Type; const std::string message = "$symbol:" + varname + "\nLocal variable \'$symbol\' shadows outer " + type; reportError(errorPath, Severity::style, id.c_str(), message, CWE398, false); } static bool isVariableExpression(const Token* tok) { if (Token::Match(tok, "%var%")) return true; if (Token::simpleMatch(tok, ".")) return isVariableExpression(tok->astOperand1()) && isVariableExpression(tok->astOperand2()); return false; } void CheckOther::checkConstArgument() { if (!mSettings->isEnabled(Settings::STYLE)) return; const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope *functionScope : symbolDatabase->functionScopes) { for (const Token *tok = functionScope->bodyStart; tok != functionScope->bodyEnd; tok = tok->next()) { if (!Token::simpleMatch(tok->astParent(), "(")) continue; if (!Token::Match(tok->astParent()->previous(), "%name%")) continue; if (Token::Match(tok->astParent()->previous(), "if|while|switch|sizeof")) continue; if (tok == tok->astParent()->previous()) continue; if (!tok->hasKnownIntValue()) continue; if (Token::Match(tok, "++|--")) continue; if (isConstVarExpression(tok)) continue; const Token * tok2 = tok; if (isCPPCast(tok2)) tok2 = tok2->astOperand2(); if (isVariableExpression(tok2)) continue; constArgumentError(tok, tok->astParent()->previous(), &tok->values().front()); } } } void CheckOther::constArgumentError(const Token *tok, const Token *ftok, const ValueFlow::Value *value) { MathLib::bigint intvalue = value ? value->intvalue : 0; const std::string expr = tok ? tok->expressionString() : std::string("x"); const std::string fun = ftok ? ftok->str() : std::string("f"); const std::string errmsg = "Argument '" + expr + "' to function " + fun + " is always " + std::to_string(intvalue); const ErrorPath errorPath = getErrorPath(tok, value, errmsg); reportError(errorPath, Severity::style, "constArgument", errmsg, CWE570, false); } void CheckOther::checkComparePointers() { const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase(); for (const Scope *functionScope : symbolDatabase->functionScopes) { for (const Token *tok = functionScope->bodyStart; tok != functionScope->bodyEnd; tok = tok->next()) { if (!Token::Match(tok, "<|>|<=|>=|-")) continue; const Token *tok1 = tok->astOperand1(); const Token *tok2 = tok->astOperand2(); if (!astIsPointer(tok1) || !astIsPointer(tok2)) continue; ValueFlow::Value v1 = getLifetimeObjValue(tok1); ValueFlow::Value v2 = getLifetimeObjValue(tok2); if (!v1.isLocalLifetimeValue() || !v2.isLocalLifetimeValue()) continue; const Variable *var1 = v1.tokvalue->variable(); const Variable *var2 = v2.tokvalue->variable(); if (!var1 || !var2) continue; if (v1.tokvalue->varId() == v2.tokvalue->varId()) continue; if (var1->isReference() || var2->isReference()) continue; if (var1->isRValueReference() || var2->isRValueReference()) continue; comparePointersError(tok, &v1, &v2); } } } void CheckOther::comparePointersError(const Token *tok, const ValueFlow::Value *v1, const ValueFlow::Value *v2) { ErrorPath errorPath; std::string verb = "Comparing"; if (Token::simpleMatch(tok, "-")) verb = "Subtracting"; if (v1) { errorPath.emplace_back(v1->tokvalue->variable()->nameToken(), "Variable declared here."); errorPath.insert(errorPath.end(), v1->errorPath.begin(), v1->errorPath.end()); } if (v2) { errorPath.emplace_back(v2->tokvalue->variable()->nameToken(), "Variable declared here."); errorPath.insert(errorPath.end(), v2->errorPath.begin(), v2->errorPath.end()); } errorPath.emplace_back(tok, ""); reportError( errorPath, Severity::error, "comparePointers", verb + " pointers that point to different objects", CWE570, false); }