1 //== CheckerContext.h - Context info for path-sensitive checkers--*- 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 file defines CheckerContext that provides contextual info for 10 // path-sensitive checkers. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_CHECKERCONTEXT_H 15 #define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_CHECKERCONTEXT_H 16 17 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h" 18 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" 19 20 namespace clang { 21 namespace ento { 22 23 class CheckerContext { 24 ExprEngine &Eng; 25 /// The current exploded(symbolic execution) graph node. 26 ExplodedNode *Pred; 27 /// The flag is true if the (state of the execution) has been modified 28 /// by the checker using this context. For example, a new transition has been 29 /// added or a bug report issued. 30 bool Changed; 31 /// The tagged location, which is used to generate all new nodes. 32 const ProgramPoint Location; 33 NodeBuilder &NB; 34 35 public: 36 /// If we are post visiting a call, this flag will be set if the 37 /// call was inlined. In all other cases it will be false. 38 const bool wasInlined; 39 40 CheckerContext(NodeBuilder &builder, 41 ExprEngine &eng, 42 ExplodedNode *pred, 43 const ProgramPoint &loc, 44 bool wasInlined = false) 45 : Eng(eng), 46 Pred(pred), 47 Changed(false), 48 Location(loc), 49 NB(builder), 50 wasInlined(wasInlined) { 51 assert(Pred->getState() && 52 "We should not call the checkers on an empty state."); 53 } 54 55 AnalysisManager &getAnalysisManager() { 56 return Eng.getAnalysisManager(); 57 } 58 59 ConstraintManager &getConstraintManager() { 60 return Eng.getConstraintManager(); 61 } 62 63 StoreManager &getStoreManager() { 64 return Eng.getStoreManager(); 65 } 66 67 /// Returns the previous node in the exploded graph, which includes 68 /// the state of the program before the checker ran. Note, checkers should 69 /// not retain the node in their state since the nodes might get invalidated. 70 ExplodedNode *getPredecessor() { return Pred; } 71 const ProgramStateRef &getState() const { return Pred->getState(); } 72 73 /// Check if the checker changed the state of the execution; ex: added 74 /// a new transition or a bug report. 75 bool isDifferent() { return Changed; } 76 77 /// Returns the number of times the current block has been visited 78 /// along the analyzed path. 79 unsigned blockCount() const { 80 return NB.getContext().blockCount(); 81 } 82 83 ASTContext &getASTContext() { 84 return Eng.getContext(); 85 } 86 87 const LangOptions &getLangOpts() const { 88 return Eng.getContext().getLangOpts(); 89 } 90 91 const LocationContext *getLocationContext() const { 92 return Pred->getLocationContext(); 93 } 94 95 const StackFrameContext *getStackFrame() const { 96 return Pred->getStackFrame(); 97 } 98 99 /// Return true if the current LocationContext has no caller context. 100 bool inTopFrame() const { return getLocationContext()->inTopFrame(); } 101 102 BugReporter &getBugReporter() { 103 return Eng.getBugReporter(); 104 } 105 106 const SourceManager &getSourceManager() { 107 return getBugReporter().getSourceManager(); 108 } 109 110 SValBuilder &getSValBuilder() { 111 return Eng.getSValBuilder(); 112 } 113 114 SymbolManager &getSymbolManager() { 115 return getSValBuilder().getSymbolManager(); 116 } 117 118 ProgramStateManager &getStateManager() { 119 return Eng.getStateManager(); 120 } 121 122 AnalysisDeclContext *getCurrentAnalysisDeclContext() const { 123 return Pred->getLocationContext()->getAnalysisDeclContext(); 124 } 125 126 /// Get the blockID. 127 unsigned getBlockID() const { 128 return NB.getContext().getBlock()->getBlockID(); 129 } 130 131 /// If the given node corresponds to a PostStore program point, 132 /// retrieve the location region as it was uttered in the code. 133 /// 134 /// This utility can be useful for generating extensive diagnostics, for 135 /// example, for finding variables that the given symbol was assigned to. 136 static const MemRegion *getLocationRegionIfPostStore(const ExplodedNode *N) { 137 ProgramPoint L = N->getLocation(); 138 if (Optional<PostStore> PSL = L.getAs<PostStore>()) 139 return reinterpret_cast<const MemRegion*>(PSL->getLocationValue()); 140 return nullptr; 141 } 142 143 /// Get the value of arbitrary expressions at this point in the path. 144 SVal getSVal(const Stmt *S) const { 145 return Pred->getSVal(S); 146 } 147 148 /// Returns true if the value of \p E is greater than or equal to \p 149 /// Val under unsigned comparison 150 bool isGreaterOrEqual(const Expr *E, unsigned long long Val); 151 152 /// Returns true if the value of \p E is negative. 153 bool isNegative(const Expr *E); 154 155 /// Generates a new transition in the program state graph 156 /// (ExplodedGraph). Uses the default CheckerContext predecessor node. 157 /// 158 /// @param State The state of the generated node. If not specified, the state 159 /// will not be changed, but the new node will have the checker's tag. 160 /// @param Tag The tag is used to uniquely identify the creation site. If no 161 /// tag is specified, a default tag, unique to the given checker, 162 /// will be used. Tags are used to prevent states generated at 163 /// different sites from caching out. 164 ExplodedNode *addTransition(ProgramStateRef State = nullptr, 165 const ProgramPointTag *Tag = nullptr) { 166 return addTransitionImpl(State ? State : getState(), false, nullptr, Tag); 167 } 168 169 /// Generates a new transition with the given predecessor. 170 /// Allows checkers to generate a chain of nodes. 171 /// 172 /// @param State The state of the generated node. 173 /// @param Pred The transition will be generated from the specified Pred node 174 /// to the newly generated node. 175 /// @param Tag The tag to uniquely identify the creation site. 176 ExplodedNode *addTransition(ProgramStateRef State, 177 ExplodedNode *Pred, 178 const ProgramPointTag *Tag = nullptr) { 179 return addTransitionImpl(State, false, Pred, Tag); 180 } 181 182 /// Generate a sink node. Generating a sink stops exploration of the 183 /// given path. To create a sink node for the purpose of reporting an error, 184 /// checkers should use generateErrorNode() instead. 185 ExplodedNode *generateSink(ProgramStateRef State, ExplodedNode *Pred, 186 const ProgramPointTag *Tag = nullptr) { 187 return addTransitionImpl(State ? State : getState(), true, Pred, Tag); 188 } 189 190 /// Generate a transition to a node that will be used to report 191 /// an error. This node will be a sink. That is, it will stop exploration of 192 /// the given path. 193 /// 194 /// @param State The state of the generated node. 195 /// @param Tag The tag to uniquely identify the creation site. If null, 196 /// the default tag for the checker will be used. 197 ExplodedNode *generateErrorNode(ProgramStateRef State = nullptr, 198 const ProgramPointTag *Tag = nullptr) { 199 return generateSink(State, Pred, 200 (Tag ? Tag : Location.getTag())); 201 } 202 203 /// Generate a transition to a node that will be used to report 204 /// an error. This node will not be a sink. That is, exploration will 205 /// continue along this path. 206 /// 207 /// @param State The state of the generated node. 208 /// @param Tag The tag to uniquely identify the creation site. If null, 209 /// the default tag for the checker will be used. 210 ExplodedNode * 211 generateNonFatalErrorNode(ProgramStateRef State = nullptr, 212 const ProgramPointTag *Tag = nullptr) { 213 return addTransition(State, (Tag ? Tag : Location.getTag())); 214 } 215 216 /// Generate a transition to a node that will be used to report 217 /// an error. This node will not be a sink. That is, exploration will 218 /// continue along this path. 219 /// 220 /// @param State The state of the generated node. 221 /// @param Pred The transition will be generated from the specified Pred node 222 /// to the newly generated node. 223 /// @param Tag The tag to uniquely identify the creation site. If null, 224 /// the default tag for the checker will be used. 225 ExplodedNode * 226 generateNonFatalErrorNode(ProgramStateRef State, 227 ExplodedNode *Pred, 228 const ProgramPointTag *Tag = nullptr) { 229 return addTransition(State, Pred, (Tag ? Tag : Location.getTag())); 230 } 231 232 /// Emit the diagnostics report. 233 void emitReport(std::unique_ptr<BugReport> R) { 234 Changed = true; 235 Eng.getBugReporter().emitReport(std::move(R)); 236 } 237 238 /// Produce a program point tag that displays an additional path note 239 /// to the user. This is a lightweight alternative to the 240 /// BugReporterVisitor mechanism: instead of visiting the bug report 241 /// node-by-node to restore the sequence of events that led to discovering 242 /// a bug, you can add notes as you add your transitions. 243 /// 244 /// @param Cb Callback with 'BugReporterContext &, BugReport &' parameters. 245 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 246 /// to omit the note from the report if it would make the displayed 247 /// bug path significantly shorter. 248 const NoteTag *getNoteTag(NoteTag::Callback &&Cb, bool IsPrunable = false) { 249 return Eng.getNoteTags().makeNoteTag(std::move(Cb), IsPrunable); 250 } 251 252 /// A shorthand version of getNoteTag that doesn't require you to accept 253 /// the 'BugReporterContext' argument when you don't need it. 254 /// 255 /// @param Cb Callback only with 'BugReport &' parameter. 256 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 257 /// to omit the note from the report if it would make the displayed 258 /// bug path significantly shorter. 259 const NoteTag *getNoteTag(std::function<std::string(BugReport &)> &&Cb, 260 bool IsPrunable = false) { 261 return getNoteTag( 262 [Cb](BugReporterContext &, BugReport &BR) { return Cb(BR); }, 263 IsPrunable); 264 } 265 266 /// A shorthand version of getNoteTag that doesn't require you to accept 267 /// the arguments when you don't need it. 268 /// 269 /// @param Cb Callback without parameters. 270 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 271 /// to omit the note from the report if it would make the displayed 272 /// bug path significantly shorter. 273 const NoteTag *getNoteTag(std::function<std::string()> &&Cb, 274 bool IsPrunable = false) { 275 return getNoteTag([Cb](BugReporterContext &, BugReport &) { return Cb(); }, 276 IsPrunable); 277 } 278 279 /// A shorthand version of getNoteTag that accepts a plain note. 280 /// 281 /// @param Note The note. 282 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 283 /// to omit the note from the report if it would make the displayed 284 /// bug path significantly shorter. 285 const NoteTag *getNoteTag(StringRef Note, bool IsPrunable = false) { 286 return getNoteTag( 287 [Note](BugReporterContext &, BugReport &) { return Note; }, IsPrunable); 288 } 289 290 /// Returns the word that should be used to refer to the declaration 291 /// in the report. 292 StringRef getDeclDescription(const Decl *D); 293 294 /// Get the declaration of the called function (path-sensitive). 295 const FunctionDecl *getCalleeDecl(const CallExpr *CE) const; 296 297 /// Get the name of the called function (path-sensitive). 298 StringRef getCalleeName(const FunctionDecl *FunDecl) const; 299 300 /// Get the identifier of the called function (path-sensitive). 301 const IdentifierInfo *getCalleeIdentifier(const CallExpr *CE) const { 302 const FunctionDecl *FunDecl = getCalleeDecl(CE); 303 if (FunDecl) 304 return FunDecl->getIdentifier(); 305 else 306 return nullptr; 307 } 308 309 /// Get the name of the called function (path-sensitive). 310 StringRef getCalleeName(const CallExpr *CE) const { 311 const FunctionDecl *FunDecl = getCalleeDecl(CE); 312 return getCalleeName(FunDecl); 313 } 314 315 /// Returns true if the callee is an externally-visible function in the 316 /// top-level namespace, such as \c malloc. 317 /// 318 /// If a name is provided, the function must additionally match the given 319 /// name. 320 /// 321 /// Note that this deliberately excludes C++ library functions in the \c std 322 /// namespace, but will include C library functions accessed through the 323 /// \c std namespace. This also does not check if the function is declared 324 /// as 'extern "C"', or if it uses C++ name mangling. 325 static bool isCLibraryFunction(const FunctionDecl *FD, 326 StringRef Name = StringRef()); 327 328 /// Depending on wither the location corresponds to a macro, return 329 /// either the macro name or the token spelling. 330 /// 331 /// This could be useful when checkers' logic depends on whether a function 332 /// is called with a given macro argument. For example: 333 /// s = socket(AF_INET,..) 334 /// If AF_INET is a macro, the result should be treated as a source of taint. 335 /// 336 /// \sa clang::Lexer::getSpelling(), clang::Lexer::getImmediateMacroName(). 337 StringRef getMacroNameOrSpelling(SourceLocation &Loc); 338 339 private: 340 ExplodedNode *addTransitionImpl(ProgramStateRef State, 341 bool MarkAsSink, 342 ExplodedNode *P = nullptr, 343 const ProgramPointTag *Tag = nullptr) { 344 // The analyzer may stop exploring if it sees a state it has previously 345 // visited ("cache out"). The early return here is a defensive check to 346 // prevent accidental caching out by checker API clients. Unless there is a 347 // tag or the client checker has requested that the generated node be 348 // marked as a sink, we assume that a client requesting a transition to a 349 // state that is the same as the predecessor state has made a mistake. We 350 // return the predecessor rather than cache out. 351 // 352 // TODO: We could potentially change the return to an assertion to alert 353 // clients to their mistake, but several checkers (including 354 // DereferenceChecker, CallAndMessageChecker, and DynamicTypePropagation) 355 // rely upon the defensive behavior and would need to be updated. 356 if (!State || (State == Pred->getState() && !Tag && !MarkAsSink)) 357 return Pred; 358 359 Changed = true; 360 const ProgramPoint &LocalLoc = (Tag ? Location.withTag(Tag) : Location); 361 if (!P) 362 P = Pred; 363 364 ExplodedNode *node; 365 if (MarkAsSink) 366 node = NB.generateSink(LocalLoc, State, P); 367 else 368 node = NB.generateNode(LocalLoc, State, P); 369 return node; 370 } 371 }; 372 373 } // end GR namespace 374 375 } // end clang namespace 376 377 #endif 378