1// MacOSXAPIChecker.h - Checks proper use of various MacOS X APIs --*- C++ -*-// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This defines MacOSXAPIChecker, which is an assortment of checks on calls 11// to various, widely used Apple APIs. 12// 13// FIXME: What's currently in BasicObjCFoundationChecks.cpp should be migrated 14// to here, using the new Checker interface. 15// 16//===----------------------------------------------------------------------===// 17 18#include "ClangSACheckers.h" 19#include "clang/Basic/TargetInfo.h" 20#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 21#include "clang/StaticAnalyzer/Core/Checker.h" 22#include "clang/StaticAnalyzer/Core/CheckerManager.h" 23#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 24#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" 25#include "llvm/ADT/SmallString.h" 26#include "llvm/ADT/StringSwitch.h" 27#include "llvm/Support/raw_ostream.h" 28 29using namespace clang; 30using namespace ento; 31 32namespace { 33class MacOSXAPIChecker : public Checker< check::PreStmt<CallExpr> > { 34 mutable std::unique_ptr<BugType> BT_dispatchOnce; 35 36public: 37 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const; 38 39 void CheckDispatchOnce(CheckerContext &C, const CallExpr *CE, 40 StringRef FName) const; 41 42 typedef void (MacOSXAPIChecker::*SubChecker)(CheckerContext &, 43 const CallExpr *, 44 StringRef FName) const; 45}; 46} //end anonymous namespace 47 48//===----------------------------------------------------------------------===// 49// dispatch_once and dispatch_once_f 50//===----------------------------------------------------------------------===// 51 52void MacOSXAPIChecker::CheckDispatchOnce(CheckerContext &C, const CallExpr *CE, 53 StringRef FName) const { 54 if (CE->getNumArgs() < 1) 55 return; 56 57 // Check if the first argument is stack allocated. If so, issue a warning 58 // because that's likely to be bad news. 59 ProgramStateRef state = C.getState(); 60 const MemRegion *R = 61 state->getSVal(CE->getArg(0), C.getLocationContext()).getAsRegion(); 62 if (!R || !isa<StackSpaceRegion>(R->getMemorySpace())) 63 return; 64 65 ExplodedNode *N = C.generateErrorNode(state); 66 if (!N) 67 return; 68 69 if (!BT_dispatchOnce) 70 BT_dispatchOnce.reset(new BugType(this, "Improper use of 'dispatch_once'", 71 "API Misuse (Apple)")); 72 73 // Handle _dispatch_once. In some versions of the OS X SDK we have the case 74 // that dispatch_once is a macro that wraps a call to _dispatch_once. 75 // _dispatch_once is then a function which then calls the real dispatch_once. 76 // Users do not care; they just want the warning at the top-level call. 77 if (CE->getLocStart().isMacroID()) { 78 StringRef TrimmedFName = FName.ltrim("_"); 79 if (TrimmedFName != FName) 80 FName = TrimmedFName; 81 } 82 83 SmallString<256> S; 84 llvm::raw_svector_ostream os(S); 85 os << "Call to '" << FName << "' uses"; 86 if (const VarRegion *VR = dyn_cast<VarRegion>(R)) 87 os << " the local variable '" << VR->getDecl()->getName() << '\''; 88 else 89 os << " stack allocated memory"; 90 os << " for the predicate value. Using such transient memory for " 91 "the predicate is potentially dangerous."; 92 if (isa<VarRegion>(R) && isa<StackLocalsSpaceRegion>(R->getMemorySpace())) 93 os << " Perhaps you intended to declare the variable as 'static'?"; 94 95 auto report = llvm::make_unique<BugReport>(*BT_dispatchOnce, os.str(), N); 96 report->addRange(CE->getArg(0)->getSourceRange()); 97 C.emitReport(std::move(report)); 98} 99 100//===----------------------------------------------------------------------===// 101// Central dispatch function. 102//===----------------------------------------------------------------------===// 103 104void MacOSXAPIChecker::checkPreStmt(const CallExpr *CE, 105 CheckerContext &C) const { 106 StringRef Name = C.getCalleeName(CE); 107 if (Name.empty()) 108 return; 109 110 SubChecker SC = 111 llvm::StringSwitch<SubChecker>(Name) 112 .Cases("dispatch_once", 113 "_dispatch_once", 114 "dispatch_once_f", 115 &MacOSXAPIChecker::CheckDispatchOnce) 116 .Default(nullptr); 117 118 if (SC) 119 (this->*SC)(C, CE, Name); 120} 121 122//===----------------------------------------------------------------------===// 123// Registration. 124//===----------------------------------------------------------------------===// 125 126void ento::registerMacOSXAPIChecker(CheckerManager &mgr) { 127 mgr.registerChecker<MacOSXAPIChecker>(); 128} 129