1//=== NoReturnFunctionChecker.cpp -------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This defines NoReturnFunctionChecker, which evaluates functions that do not
10// return to the caller.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15#include "clang/AST/Attr.h"
16#include "clang/Analysis/SelectorExtras.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::PostCall,
30 check::PostObjCMessage > {
31 mutable Selector HandleFailureInFunctionSel;
32 mutable Selector HandleFailureInMethodSel;
33public:
34 void checkPostCall(const CallEvent &CE, CheckerContext &C) const;
35 void checkPostObjCMessage(const ObjCMethodCall &msg, CheckerContext &C) const;
36};
37
38}
39
40void NoReturnFunctionChecker::checkPostCall(const CallEvent &CE,
41 CheckerContext &C) const {
42 bool BuildSinks = false;
43
44 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(Val: CE.getDecl()))
45 BuildSinks = FD->hasAttr<AnalyzerNoReturnAttr>() || FD->isNoReturn();
46
47 if (const CallExpr *CExpr = dyn_cast_or_null<CallExpr>(Val: CE.getOriginExpr());
48 CExpr && !BuildSinks) {
49 if (const Expr *C = CExpr->getCallee())
50 BuildSinks = getFunctionExtInfo(t: C->getType()).getNoReturn();
51 }
52
53 if (!BuildSinks && CE.isGlobalCFunction()) {
54 if (const IdentifierInfo *II = CE.getCalleeIdentifier()) {
55 // HACK: Some functions are not marked noreturn, and don't return.
56 // Here are a few hardwired ones. If this takes too long, we can
57 // potentially cache these results.
58 BuildSinks
59 = llvm::StringSwitch<bool>(StringRef(II->getName()))
60 .Case(S: "exit", Value: true)
61 .Case(S: "panic", Value: true)
62 .Case(S: "error", Value: true)
63 .Case(S: "Assert", Value: true)
64 // FIXME: This is just a wrapper around throwing an exception.
65 // Eventually inter-procedural analysis should handle this easily.
66 .Case(S: "ziperr", Value: true)
67 .Case(S: "assfail", Value: true)
68 .Case(S: "db_error", Value: true)
69 .Case(S: "__assert", Value: true)
70 .Case(S: "__assert2", Value: true)
71 // For the purpose of static analysis, we do not care that
72 // this MSVC function will return if the user decides to continue.
73 .Case(S: "_wassert", Value: true)
74 .Case(S: "__assert_rtn", Value: true)
75 .Case(S: "__assert_fail", Value: true)
76 .Case(S: "dtrace_assfail", Value: true)
77 .Case(S: "yy_fatal_error", Value: true)
78 .Case(S: "_XCAssertionFailureHandler", Value: true)
79 .Case(S: "_DTAssertionFailureHandler", Value: true)
80 .Case(S: "_TSAssertionFailureHandler", Value: true)
81 .Default(Value: false);
82 }
83 }
84
85 if (BuildSinks)
86 C.generateSink(State: C.getState(), Pred: C.getPredecessor());
87}
88
89void NoReturnFunctionChecker::checkPostObjCMessage(const ObjCMethodCall &Msg,
90 CheckerContext &C) const {
91 // Check if the method is annotated with analyzer_noreturn.
92 if (const ObjCMethodDecl *MD = Msg.getDecl()) {
93 MD = MD->getCanonicalDecl();
94 if (MD->hasAttr<AnalyzerNoReturnAttr>()) {
95 C.generateSink(State: C.getState(), Pred: C.getPredecessor());
96 return;
97 }
98 }
99
100 // HACK: This entire check is to handle two messages in the Cocoa frameworks:
101 // -[NSAssertionHandler
102 // handleFailureInMethod:object:file:lineNumber:description:]
103 // -[NSAssertionHandler
104 // handleFailureInFunction:file:lineNumber:description:]
105 // Eventually these should be annotated with __attribute__((noreturn)).
106 // Because ObjC messages use dynamic dispatch, it is not generally safe to
107 // assume certain methods can't return. In cases where it is definitely valid,
108 // see if you can mark the methods noreturn or analyzer_noreturn instead of
109 // adding more explicit checks to this method.
110
111 if (!Msg.isInstanceMessage())
112 return;
113
114 const ObjCInterfaceDecl *Receiver = Msg.getReceiverInterface();
115 if (!Receiver)
116 return;
117 if (!Receiver->getIdentifier()->isStr(Str: "NSAssertionHandler"))
118 return;
119
120 Selector Sel = Msg.getSelector();
121 switch (Sel.getNumArgs()) {
122 default:
123 return;
124 case 4:
125 lazyInitKeywordSelector(Sel&: HandleFailureInFunctionSel, Ctx&: C.getASTContext(),
126 IIs: "handleFailureInFunction", IIs: "file", IIs: "lineNumber",
127 IIs: "description");
128 if (Sel != HandleFailureInFunctionSel)
129 return;
130 break;
131 case 5:
132 lazyInitKeywordSelector(Sel&: HandleFailureInMethodSel, Ctx&: C.getASTContext(),
133 IIs: "handleFailureInMethod", IIs: "object", IIs: "file",
134 IIs: "lineNumber", IIs: "description");
135 if (Sel != HandleFailureInMethodSel)
136 return;
137 break;
138 }
139
140 // If we got here, it's one of the messages we care about.
141 C.generateSink(State: C.getState(), Pred: C.getPredecessor());
142}
143
144void ento::registerNoReturnFunctionChecker(CheckerManager &mgr) {
145 mgr.registerChecker<NoReturnFunctionChecker>();
146}
147
148bool ento::shouldRegisterNoReturnFunctionChecker(const CheckerManager &mgr) {
149 return true;
150}
151