1 //==- ExprInspectionChecker.cpp - Used for regression tests ------*- 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 #include "ClangSACheckers.h"
11 #include "clang/StaticAnalyzer/Checkers/SValExplainer.h"
12 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
13 #include "clang/StaticAnalyzer/Core/Checker.h"
14 #include "clang/StaticAnalyzer/Core/IssueHash.h"
15 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
16 #include "llvm/ADT/StringSwitch.h"
17 #include "llvm/Support/ScopedPrinter.h"
18
19 using namespace clang;
20 using namespace ento;
21
22 namespace {
23 class ExprInspectionChecker : public Checker<eval::Call, check::DeadSymbols,
24 check::EndAnalysis> {
25 mutable std::unique_ptr<BugType> BT;
26
27 // These stats are per-analysis, not per-branch, hence they shouldn't
28 // stay inside the program state.
29 struct ReachedStat {
30 ExplodedNode *ExampleNode;
31 unsigned NumTimesReached;
32 };
33 mutable llvm::DenseMap<const CallExpr *, ReachedStat> ReachedStats;
34
35 void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
36 void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
37 void analyzerWarnIfReached(const CallExpr *CE, CheckerContext &C) const;
38 void analyzerNumTimesReached(const CallExpr *CE, CheckerContext &C) const;
39 void analyzerCrash(const CallExpr *CE, CheckerContext &C) const;
40 void analyzerWarnOnDeadSymbol(const CallExpr *CE, CheckerContext &C) const;
41 void analyzerDump(const CallExpr *CE, CheckerContext &C) const;
42 void analyzerExplain(const CallExpr *CE, CheckerContext &C) const;
43 void analyzerPrintState(const CallExpr *CE, CheckerContext &C) const;
44 void analyzerGetExtent(const CallExpr *CE, CheckerContext &C) const;
45 void analyzerHashDump(const CallExpr *CE, CheckerContext &C) const;
46
47 typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
48 CheckerContext &C) const;
49
50 ExplodedNode *reportBug(llvm::StringRef Msg, CheckerContext &C) const;
51 ExplodedNode *reportBug(llvm::StringRef Msg, BugReporter &BR,
52 ExplodedNode *N) const;
53
54 public:
55 bool evalCall(const CallExpr *CE, CheckerContext &C) const;
56 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
57 void checkEndAnalysis(ExplodedGraph &G, BugReporter &BR,
58 ExprEngine &Eng) const;
59 };
60 }
61
REGISTER_SET_WITH_PROGRAMSTATE(MarkedSymbols,SymbolRef)62 REGISTER_SET_WITH_PROGRAMSTATE(MarkedSymbols, SymbolRef)
63
64 bool ExprInspectionChecker::evalCall(const CallExpr *CE,
65 CheckerContext &C) const {
66 // These checks should have no effect on the surrounding environment
67 // (globals should not be invalidated, etc), hence the use of evalCall.
68 FnCheck Handler = llvm::StringSwitch<FnCheck>(C.getCalleeName(CE))
69 .Case("clang_analyzer_eval", &ExprInspectionChecker::analyzerEval)
70 .Case("clang_analyzer_checkInlined",
71 &ExprInspectionChecker::analyzerCheckInlined)
72 .Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
73 .Case("clang_analyzer_warnIfReached",
74 &ExprInspectionChecker::analyzerWarnIfReached)
75 .Case("clang_analyzer_warnOnDeadSymbol",
76 &ExprInspectionChecker::analyzerWarnOnDeadSymbol)
77 .StartsWith("clang_analyzer_explain", &ExprInspectionChecker::analyzerExplain)
78 .StartsWith("clang_analyzer_dump", &ExprInspectionChecker::analyzerDump)
79 .Case("clang_analyzer_getExtent", &ExprInspectionChecker::analyzerGetExtent)
80 .Case("clang_analyzer_printState",
81 &ExprInspectionChecker::analyzerPrintState)
82 .Case("clang_analyzer_numTimesReached",
83 &ExprInspectionChecker::analyzerNumTimesReached)
84 .Case("clang_analyzer_hashDump", &ExprInspectionChecker::analyzerHashDump)
85 .Default(nullptr);
86
87 if (!Handler)
88 return false;
89
90 (this->*Handler)(CE, C);
91 return true;
92 }
93
getArgumentValueString(const CallExpr * CE,CheckerContext & C)94 static const char *getArgumentValueString(const CallExpr *CE,
95 CheckerContext &C) {
96 if (CE->getNumArgs() == 0)
97 return "Missing assertion argument";
98
99 ExplodedNode *N = C.getPredecessor();
100 const LocationContext *LC = N->getLocationContext();
101 ProgramStateRef State = N->getState();
102
103 const Expr *Assertion = CE->getArg(0);
104 SVal AssertionVal = State->getSVal(Assertion, LC);
105
106 if (AssertionVal.isUndef())
107 return "UNDEFINED";
108
109 ProgramStateRef StTrue, StFalse;
110 std::tie(StTrue, StFalse) =
111 State->assume(AssertionVal.castAs<DefinedOrUnknownSVal>());
112
113 if (StTrue) {
114 if (StFalse)
115 return "UNKNOWN";
116 else
117 return "TRUE";
118 } else {
119 if (StFalse)
120 return "FALSE";
121 else
122 llvm_unreachable("Invalid constraint; neither true or false.");
123 }
124 }
125
reportBug(llvm::StringRef Msg,CheckerContext & C) const126 ExplodedNode *ExprInspectionChecker::reportBug(llvm::StringRef Msg,
127 CheckerContext &C) const {
128 ExplodedNode *N = C.generateNonFatalErrorNode();
129 reportBug(Msg, C.getBugReporter(), N);
130 return N;
131 }
132
reportBug(llvm::StringRef Msg,BugReporter & BR,ExplodedNode * N) const133 ExplodedNode *ExprInspectionChecker::reportBug(llvm::StringRef Msg,
134 BugReporter &BR,
135 ExplodedNode *N) const {
136 if (!N)
137 return nullptr;
138
139 if (!BT)
140 BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));
141
142 BR.emitReport(llvm::make_unique<BugReport>(*BT, Msg, N));
143 return N;
144 }
145
analyzerEval(const CallExpr * CE,CheckerContext & C) const146 void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
147 CheckerContext &C) const {
148 const LocationContext *LC = C.getPredecessor()->getLocationContext();
149
150 // A specific instantiation of an inlined function may have more constrained
151 // values than can generally be assumed. Skip the check.
152 if (LC->getStackFrame()->getParent() != nullptr)
153 return;
154
155 reportBug(getArgumentValueString(CE, C), C);
156 }
157
analyzerWarnIfReached(const CallExpr * CE,CheckerContext & C) const158 void ExprInspectionChecker::analyzerWarnIfReached(const CallExpr *CE,
159 CheckerContext &C) const {
160 reportBug("REACHABLE", C);
161 }
162
analyzerNumTimesReached(const CallExpr * CE,CheckerContext & C) const163 void ExprInspectionChecker::analyzerNumTimesReached(const CallExpr *CE,
164 CheckerContext &C) const {
165 ++ReachedStats[CE].NumTimesReached;
166 if (!ReachedStats[CE].ExampleNode) {
167 // Later, in checkEndAnalysis, we'd throw a report against it.
168 ReachedStats[CE].ExampleNode = C.generateNonFatalErrorNode();
169 }
170 }
171
analyzerCheckInlined(const CallExpr * CE,CheckerContext & C) const172 void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
173 CheckerContext &C) const {
174 const LocationContext *LC = C.getPredecessor()->getLocationContext();
175
176 // An inlined function could conceivably also be analyzed as a top-level
177 // function. We ignore this case and only emit a message (TRUE or FALSE)
178 // when we are analyzing it as an inlined function. This means that
179 // clang_analyzer_checkInlined(true) should always print TRUE, but
180 // clang_analyzer_checkInlined(false) should never actually print anything.
181 if (LC->getStackFrame()->getParent() == nullptr)
182 return;
183
184 reportBug(getArgumentValueString(CE, C), C);
185 }
186
analyzerExplain(const CallExpr * CE,CheckerContext & C) const187 void ExprInspectionChecker::analyzerExplain(const CallExpr *CE,
188 CheckerContext &C) const {
189 if (CE->getNumArgs() == 0) {
190 reportBug("Missing argument for explaining", C);
191 return;
192 }
193
194 SVal V = C.getSVal(CE->getArg(0));
195 SValExplainer Ex(C.getASTContext());
196 reportBug(Ex.Visit(V), C);
197 }
198
analyzerDump(const CallExpr * CE,CheckerContext & C) const199 void ExprInspectionChecker::analyzerDump(const CallExpr *CE,
200 CheckerContext &C) const {
201 if (CE->getNumArgs() == 0) {
202 reportBug("Missing argument for dumping", C);
203 return;
204 }
205
206 SVal V = C.getSVal(CE->getArg(0));
207
208 llvm::SmallString<32> Str;
209 llvm::raw_svector_ostream OS(Str);
210 V.dumpToStream(OS);
211 reportBug(OS.str(), C);
212 }
213
analyzerGetExtent(const CallExpr * CE,CheckerContext & C) const214 void ExprInspectionChecker::analyzerGetExtent(const CallExpr *CE,
215 CheckerContext &C) const {
216 if (CE->getNumArgs() == 0) {
217 reportBug("Missing region for obtaining extent", C);
218 return;
219 }
220
221 auto MR = dyn_cast_or_null<SubRegion>(C.getSVal(CE->getArg(0)).getAsRegion());
222 if (!MR) {
223 reportBug("Obtaining extent of a non-region", C);
224 return;
225 }
226
227 ProgramStateRef State = C.getState();
228 State = State->BindExpr(CE, C.getLocationContext(),
229 MR->getExtent(C.getSValBuilder()));
230 C.addTransition(State);
231 }
232
analyzerPrintState(const CallExpr * CE,CheckerContext & C) const233 void ExprInspectionChecker::analyzerPrintState(const CallExpr *CE,
234 CheckerContext &C) const {
235 C.getState()->dump();
236 }
237
analyzerWarnOnDeadSymbol(const CallExpr * CE,CheckerContext & C) const238 void ExprInspectionChecker::analyzerWarnOnDeadSymbol(const CallExpr *CE,
239 CheckerContext &C) const {
240 if (CE->getNumArgs() == 0)
241 return;
242 SVal Val = C.getSVal(CE->getArg(0));
243 SymbolRef Sym = Val.getAsSymbol();
244 if (!Sym)
245 return;
246
247 ProgramStateRef State = C.getState();
248 State = State->add<MarkedSymbols>(Sym);
249 C.addTransition(State);
250 }
251
checkDeadSymbols(SymbolReaper & SymReaper,CheckerContext & C) const252 void ExprInspectionChecker::checkDeadSymbols(SymbolReaper &SymReaper,
253 CheckerContext &C) const {
254 ProgramStateRef State = C.getState();
255 const MarkedSymbolsTy &Syms = State->get<MarkedSymbols>();
256 ExplodedNode *N = C.getPredecessor();
257 for (auto I = Syms.begin(), E = Syms.end(); I != E; ++I) {
258 SymbolRef Sym = *I;
259 if (!SymReaper.isDead(Sym))
260 continue;
261
262 // The non-fatal error node should be the same for all reports.
263 if (ExplodedNode *BugNode = reportBug("SYMBOL DEAD", C))
264 N = BugNode;
265 State = State->remove<MarkedSymbols>(Sym);
266 }
267 C.addTransition(State, N);
268 }
269
checkEndAnalysis(ExplodedGraph & G,BugReporter & BR,ExprEngine & Eng) const270 void ExprInspectionChecker::checkEndAnalysis(ExplodedGraph &G, BugReporter &BR,
271 ExprEngine &Eng) const {
272 for (auto Item: ReachedStats) {
273 unsigned NumTimesReached = Item.second.NumTimesReached;
274 ExplodedNode *N = Item.second.ExampleNode;
275
276 reportBug(llvm::to_string(NumTimesReached), BR, N);
277 }
278 ReachedStats.clear();
279 }
280
analyzerCrash(const CallExpr * CE,CheckerContext & C) const281 void ExprInspectionChecker::analyzerCrash(const CallExpr *CE,
282 CheckerContext &C) const {
283 LLVM_BUILTIN_TRAP;
284 }
285
analyzerHashDump(const CallExpr * CE,CheckerContext & C) const286 void ExprInspectionChecker::analyzerHashDump(const CallExpr *CE,
287 CheckerContext &C) const {
288 const LangOptions &Opts = C.getLangOpts();
289 const SourceManager &SM = C.getSourceManager();
290 FullSourceLoc FL(CE->getArg(0)->getLocStart(), SM);
291 std::string HashContent =
292 GetIssueString(SM, FL, getCheckName().getName(), "Category",
293 C.getLocationContext()->getDecl(), Opts);
294
295 reportBug(HashContent, C);
296 }
297
registerExprInspectionChecker(CheckerManager & Mgr)298 void ento::registerExprInspectionChecker(CheckerManager &Mgr) {
299 Mgr.registerChecker<ExprInspectionChecker>();
300 }
301