NoReturnFunctionChecker.cpp revision d9f5a709ddbffe35dcc419c9c3fa6a852e833f7a 
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/CheckerContext.h"
19#include "llvm/ADT/StringSwitch.h"
20#include <cstdarg>
21
22using namespace clang;
23using namespace ento;
24
25namespace {
26
27class NoReturnFunctionChecker : public Checker< check::PostStmt<CallExpr>,
28                                                check::PostObjCMessage > {
29public:
30  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
31  void checkPostObjCMessage(const ObjCMessage &msg, CheckerContext &C) const;
32};
33
34}
35
36void NoReturnFunctionChecker::checkPostStmt(const CallExpr *CE,
37                                            CheckerContext &C) const {
38  const ProgramState *state = C.getState();
39  const Expr *Callee = CE->getCallee();
40
41  bool BuildSinks = getFunctionExtInfo(Callee->getType()).getNoReturn();
42
43  if (!BuildSinks) {
44    SVal L = state->getSVal(Callee);
45    const FunctionDecl *FD = L.getAsFunctionDecl();
46    if (!FD)
47      return;
48
49    if (FD->getAttr<AnalyzerNoReturnAttr>())
50      BuildSinks = true;
51    else if (const IdentifierInfo *II = FD->getIdentifier()) {
52      // HACK: Some functions are not marked noreturn, and don't return.
53      //  Here are a few hardwired ones.  If this takes too long, we can
54      //  potentially cache these results.
55      BuildSinks
56        = llvm::StringSwitch<bool>(StringRef(II->getName()))
57            .Case("exit", true)
58            .Case("panic", true)
59            .Case("error", true)
60            .Case("Assert", true)
61            // FIXME: This is just a wrapper around throwing an exception.
62            //  Eventually inter-procedural analysis should handle this easily.
63            .Case("ziperr", true)
64            .Case("assfail", true)
65            .Case("db_error", true)
66            .Case("__assert", true)
67            .Case("__assert_rtn", true)
68            .Case("__assert_fail", true)
69            .Case("dtrace_assfail", true)
70            .Case("yy_fatal_error", true)
71            .Case("_XCAssertionFailureHandler", true)
72            .Case("_DTAssertionFailureHandler", true)
73            .Case("_TSAssertionFailureHandler", true)
74            .Default(false);
75    }
76  }
77
78  if (BuildSinks)
79    C.generateSink(CE);
80}
81
82static bool END_WITH_NULL isMultiArgSelector(Selector Sel, ...) {
83  va_list argp;
84  va_start(argp, Sel);
85
86  unsigned Slot = 0;
87  const char *Arg;
88  while ((Arg = va_arg(argp, const char *))) {
89    if (!Sel.getNameForSlot(Slot).equals(Arg))
90      break; // still need to va_end!
91    ++Slot;
92  }
93
94  va_end(argp);
95
96  // We only succeeded if we made it to the end of the argument list.
97  return (Arg == NULL);
98}
99
100void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMessage &Msg,
101                                                   CheckerContext &C) const {
102  // HACK: This entire check is to handle two messages in the Cocoa frameworks:
103  // -[NSAssertionHandler
104  //    handleFailureInMethod:object:file:lineNumber:description:]
105  // -[NSAssertionHandler
106  //    handleFailureInFunction:file:lineNumber:description:]
107  // Eventually these should be annotated with __attribute__((noreturn)).
108  // Because ObjC messages use dynamic dispatch, it is not generally safe to
109  // assume certain methods can't return. In cases where it is definitely valid,
110  // see if you can mark the methods noreturn or analyzer_noreturn instead of
111  // adding more explicit checks to this method.
112
113  if (!Msg.isInstanceMessage())
114    return;
115
116  const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface();
117  if (!Receiver)
118    return;
119  if (!Receiver->getIdentifier()->isStr("NSAssertionHandler"))
120    return;
121
122  Selector Sel = Msg.getSelector();
123  switch (Sel.getNumArgs()) {
124  default:
125    return;
126  case 4:
127    if (!isMultiArgSelector(Sel, "handleFailureInFunction", "file",
128                            "lineNumber", "description", NULL))
129      return;
130    break;
131  case 5:
132    if (!isMultiArgSelector(Sel, "handleFailureInMethod", "object", "file",
133                            "lineNumber", "description", NULL))
134      return;
135    break;
136  }
137
138  // If we got here, it's one of the messages we care about.
139  C.generateSink();
140}
141
142
143void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {
144  mgr.registerChecker<NoReturnFunctionChecker>();
145}
146