NoReturnFunctionChecker.cpp revision f540c54701e3eeb34cb619a3a4eb18f1ac70ef2d 
1//=== NoReturnFunctionChecker.cpp -------------------------------*- 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 NoReturnFunctionChecker, which evaluates functions that do not
11// return to the caller.
12//
13//===----------------------------------------------------------------------===//
14
15#include "ClangSACheckers.h"
16#include "clang/StaticAnalyzer/Core/Checker.h"
17#include "clang/StaticAnalyzer/Core/CheckerManager.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
20#include "llvm/ADT/StringSwitch.h"
21#include <cstdarg>
22
23using namespace clang;
24using namespace ento;
25
26namespace {
27
28class NoReturnFunctionChecker : public Checker< check::PostStmt<CallExpr>,
29                                                check::PostObjCMessage > {
30public:
31  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
32  void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
33};
34
35}
36
37void NoReturnFunctionChecker::checkPostStmt(const CallExpr *CE,
38                                            CheckerContext &C) const {
39  ProgramStateRef state = C.getState();
40  const Expr *Callee = CE->getCallee();
41
42  bool BuildSinks = getFunctionExtInfo(Callee->getType()).getNoReturn();
43
44  if (!BuildSinks) {
45    SVal L = state->getSVal(Callee, C.getLocationContext());
46    const FunctionDecl *FD = L.getAsFunctionDecl();
47    if (!FD)
48      return;
49
50    if (FD->getAttr<AnalyzerNoReturnAttr>())
51      BuildSinks = true;
52    else if (const IdentifierInfo *II = FD->getIdentifier()) {
53      // HACK: Some functions are not marked noreturn, and don't return.
54      //  Here are a few hardwired ones.  If this takes too long, we can
55      //  potentially cache these results.
56      BuildSinks
57        = llvm::StringSwitch<bool>(StringRef(II->getName()))
58            .Case("exit", true)
59            .Case("panic", true)
60            .Case("error", true)
61            .Case("Assert", true)
62            // FIXME: This is just a wrapper around throwing an exception.
63            //  Eventually inter-procedural analysis should handle this easily.
64            .Case("ziperr", true)
65            .Case("assfail", true)
66            .Case("db_error", true)
67            .Case("__assert", true)
68            .Case("__assert_rtn", true)
69            .Case("__assert_fail", true)
70            .Case("dtrace_assfail", true)
71            .Case("yy_fatal_error", true)
72            .Case("_XCAssertionFailureHandler", true)
73            .Case("_DTAssertionFailureHandler", true)
74            .Case("_TSAssertionFailureHandler", true)
75            .Default(false);
76    }
77  }
78
79  if (BuildSinks)
80    C.generateSink();
81}
82
83static bool END_WITH_NULL isMultiArgSelector(const Selector *Sel, ...) {
84  va_list argp;
85  va_start(argp, Sel);
86
87  unsigned Slot = 0;
88  const char *Arg;
89  while ((Arg = va_arg(argp, const char *))) {
90    if (!Sel->getNameForSlot(Slot).equals(Arg))
91      break; // still need to va_end!
92    ++Slot;
93  }
94
95  va_end(argp);
96
97  // We only succeeded if we made it to the end of the argument list.
98  return (Arg == NULL);
99}
100
101void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg,
102                                                   CheckerContext &C) const {
103  // HACK: This entire check is to handle two messages in the Cocoa frameworks:
104  // -[NSAssertionHandler
105  //    handleFailureInMethod:object:file:lineNumber:description:]
106  // -[NSAssertionHandler
107  //    handleFailureInFunction:file:lineNumber:description:]
108  // Eventually these should be annotated with __attribute__((noreturn)).
109  // Because ObjC messages use dynamic dispatch, it is not generally safe to
110  // assume certain methods can't return. In cases where it is definitely valid,
111  // see if you can mark the methods noreturn or analyzer_noreturn instead of
112  // adding more explicit checks to this method.
113
114  if (!Msg.isInstanceMessage())
115    return;
116
117  const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface();
118  if (!Receiver)
119    return;
120  if (!Receiver->getIdentifier()->isStr("NSAssertionHandler"))
121    return;
122
123  Selector Sel = Msg.getSelector();
124  switch (Sel.getNumArgs()) {
125  default:
126    return;
127  case 4:
128    if (!isMultiArgSelector(&Sel, "handleFailureInFunction", "file",
129                            "lineNumber", "description", NULL))
130      return;
131    break;
132  case 5:
133    if (!isMultiArgSelector(&Sel, "handleFailureInMethod", "object", "file",
134                            "lineNumber", "description", NULL))
135      return;
136    break;
137  }
138
139  // If we got here, it's one of the messages we care about.
140  C.generateSink();
141}
142
143
144void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {
145  mgr.registerChecker<NoReturnFunctionChecker>();
146}
147