NoReturnFunctionChecker.cpp revision a5b6469a55fb8796353b073f6c12694b0adc77c2 
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/AST/Attr.h"
17#include "clang/StaticAnalyzer/Core/Checker.h"
18#include "clang/StaticAnalyzer/Core/CheckerManager.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
21#include "llvm/ADT/StringSwitch.h"
22#include <cstdarg>
23
24using namespace clang;
25using namespace ento;
26
27namespace {
28
29class NoReturnFunctionChecker : public Checker< check::PostStmt<CallExpr>,
30                                                check::PostObjCMessage > {
31public:
32  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
33  void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
34};
35
36}
37
38void NoReturnFunctionChecker::checkPostStmt(const CallExpr *CE,
39                                            CheckerContext &C) const {
40  ProgramStateRef state = C.getState();
41  const Expr *Callee = CE->getCallee();
42
43  bool BuildSinks = getFunctionExtInfo(Callee->getType()).getNoReturn();
44
45  if (!BuildSinks) {
46    SVal L = state->getSVal(Callee, C.getLocationContext());
47    const FunctionDecl *FD = L.getAsFunctionDecl();
48    if (!FD)
49      return;
50
51    if (FD->getAttr<AnalyzerNoReturnAttr>() || FD->isNoReturn())
52      BuildSinks = true;
53    else if (const IdentifierInfo *II = FD->getIdentifier()) {
54      // HACK: Some functions are not marked noreturn, and don't return.
55      //  Here are a few hardwired ones.  If this takes too long, we can
56      //  potentially cache these results.
57      BuildSinks
58        = llvm::StringSwitch<bool>(StringRef(II->getName()))
59            .Case("exit", true)
60            .Case("panic", true)
61            .Case("error", true)
62            .Case("Assert", true)
63            // FIXME: This is just a wrapper around throwing an exception.
64            //  Eventually inter-procedural analysis should handle this easily.
65            .Case("ziperr", true)
66            .Case("assfail", true)
67            .Case("db_error", true)
68            .Case("__assert", true)
69            .Case("__assert_rtn", true)
70            .Case("__assert_fail", true)
71            .Case("dtrace_assfail", true)
72            .Case("yy_fatal_error", true)
73            .Case("_XCAssertionFailureHandler", true)
74            .Case("_DTAssertionFailureHandler", true)
75            .Case("_TSAssertionFailureHandler", true)
76            .Default(false);
77    }
78  }
79
80  if (BuildSinks)
81    C.generateSink();
82}
83
84static bool END_WITH_NULL isMultiArgSelector(const Selector *Sel, ...) {
85  va_list argp;
86  va_start(argp, Sel);
87
88  unsigned Slot = 0;
89  const char *Arg;
90  while ((Arg = va_arg(argp, const char *))) {
91    if (!Sel->getNameForSlot(Slot).equals(Arg))
92      break; // still need to va_end!
93    ++Slot;
94  }
95
96  va_end(argp);
97
98  // We only succeeded if we made it to the end of the argument list.
99  return (Arg == NULL);
100}
101
102void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg,
103                                                   CheckerContext &C) const {
104  // Check if the method is annotated with analyzer_noreturn.
105  const ObjCMethodDecl *MD = Msg.getDecl()->getCanonicalDecl();
106  if (MD->hasAttr<AnalyzerNoReturnAttr>()) {
107    C.generateSink();
108    return;
109  }
110
111  // HACK: This entire check is to handle two messages in the Cocoa frameworks:
112  // -[NSAssertionHandler
113  //    handleFailureInMethod:object:file:lineNumber:description:]
114  // -[NSAssertionHandler
115  //    handleFailureInFunction:file:lineNumber:description:]
116  // Eventually these should be annotated with __attribute__((noreturn)).
117  // Because ObjC messages use dynamic dispatch, it is not generally safe to
118  // assume certain methods can't return. In cases where it is definitely valid,
119  // see if you can mark the methods noreturn or analyzer_noreturn instead of
120  // adding more explicit checks to this method.
121
122  if (!Msg.isInstanceMessage())
123    return;
124
125  const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface();
126  if (!Receiver)
127    return;
128  if (!Receiver->getIdentifier()->isStr("NSAssertionHandler"))
129    return;
130
131  Selector Sel = Msg.getSelector();
132  switch (Sel.getNumArgs()) {
133  default:
134    return;
135  case 4:
136    if (!isMultiArgSelector(&Sel, "handleFailureInFunction", "file",
137                            "lineNumber", "description", NULL))
138      return;
139    break;
140  case 5:
141    if (!isMultiArgSelector(&Sel, "handleFailureInMethod", "object", "file",
142                            "lineNumber", "description", NULL))
143      return;
144    break;
145  }
146
147  // If we got here, it's one of the messages we care about.
148  C.generateSink();
149}
150
151
152void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {
153  mgr.registerChecker<NoReturnFunctionChecker>();
154}
155