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 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 /// Emit the diagnostics report. 217 void emitReport(std::unique_ptr<BugReport> R) { 218 Changed = true; 219 Eng.getBugReporter().emitReport(std::move(R)); 220 } 221 222 /// Produce a program point tag that displays an additional path note 223 /// to the user. This is a lightweight alternative to the 224 /// BugReporterVisitor mechanism: instead of visiting the bug report 225 /// node-by-node to restore the sequence of events that led to discovering 226 /// a bug, you can add notes as you add your transitions. 227 /// 228 /// @param Cb Callback with 'BugReporterContext &, BugReport &' parameters. 229 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 230 /// to omit the note from the report if it would make the displayed 231 /// bug path significantly shorter. 232 const NoteTag *getNoteTag(NoteTag::Callback &&Cb, bool IsPrunable = false) { 233 return Eng.getNoteTags().makeNoteTag(std::move(Cb), IsPrunable); 234 } 235 236 /// A shorthand version of getNoteTag that doesn't require you to accept 237 /// the BugReporterContext arguments when you don't need it. 238 /// 239 /// @param Cb Callback only with 'BugReport &' parameter. 240 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 241 /// to omit the note from the report if it would make the displayed 242 /// bug path significantly shorter. 243 const NoteTag *getNoteTag(std::function<std::string(BugReport &)> &&Cb, 244 bool IsPrunable = false) { 245 return getNoteTag( 246 [Cb](BugReporterContext &, BugReport &BR) { return Cb(BR); }, 247 IsPrunable); 248 } 249 250 /// A shorthand version of getNoteTag that accepts a plain note. 251 /// 252 /// @param Note The note. 253 /// @param IsPrunable Whether the note is prunable. It allows BugReporter 254 /// to omit the note from the report if it would make the displayed 255 /// bug path significantly shorter. 256 const NoteTag *getNoteTag(StringRef Note, bool IsPrunable = false) { 257 return getNoteTag( 258 [Note](BugReporterContext &, BugReport &) { return Note; }, IsPrunable); 259 } 260 261 /// Returns the word that should be used to refer to the declaration 262 /// in the report. 263 StringRef getDeclDescription(const Decl *D); 264 265 /// Get the declaration of the called function (path-sensitive). 266 const FunctionDecl *getCalleeDecl(const CallExpr *CE) const; 267 268 /// Get the name of the called function (path-sensitive). 269 StringRef getCalleeName(const FunctionDecl *FunDecl) const; 270 271 /// Get the identifier of the called function (path-sensitive). 272 const IdentifierInfo *getCalleeIdentifier(const CallExpr *CE) const { 273 const FunctionDecl *FunDecl = getCalleeDecl(CE); 274 if (FunDecl) 275 return FunDecl->getIdentifier(); 276 else 277 return nullptr; 278 } 279 280 /// Get the name of the called function (path-sensitive). 281 StringRef getCalleeName(const CallExpr *CE) const { 282 const FunctionDecl *FunDecl = getCalleeDecl(CE); 283 return getCalleeName(FunDecl); 284 } 285 286 /// Returns true if the callee is an externally-visible function in the 287 /// top-level namespace, such as \c malloc. 288 /// 289 /// If a name is provided, the function must additionally match the given 290 /// name. 291 /// 292 /// Note that this deliberately excludes C++ library functions in the \c std 293 /// namespace, but will include C library functions accessed through the 294 /// \c std namespace. This also does not check if the function is declared 295 /// as 'extern "C"', or if it uses C++ name mangling. 296 static bool isCLibraryFunction(const FunctionDecl *FD, 297 StringRef Name = StringRef()); 298 299 /// Depending on wither the location corresponds to a macro, return 300 /// either the macro name or the token spelling. 301 /// 302 /// This could be useful when checkers' logic depends on whether a function 303 /// is called with a given macro argument. For example: 304 /// s = socket(AF_INET,..) 305 /// If AF_INET is a macro, the result should be treated as a source of taint. 306 /// 307 /// \sa clang::Lexer::getSpelling(), clang::Lexer::getImmediateMacroName(). 308 StringRef getMacroNameOrSpelling(SourceLocation &Loc); 309 310 private: 311 ExplodedNode *addTransitionImpl(ProgramStateRef State, 312 bool MarkAsSink, 313 ExplodedNode *P = nullptr, 314 const ProgramPointTag *Tag = nullptr) { 315 // The analyzer may stop exploring if it sees a state it has previously 316 // visited ("cache out"). The early return here is a defensive check to 317 // prevent accidental caching out by checker API clients. Unless there is a 318 // tag or the client checker has requested that the generated node be 319 // marked as a sink, we assume that a client requesting a transition to a 320 // state that is the same as the predecessor state has made a mistake. We 321 // return the predecessor rather than cache out. 322 // 323 // TODO: We could potentially change the return to an assertion to alert 324 // clients to their mistake, but several checkers (including 325 // DereferenceChecker, CallAndMessageChecker, and DynamicTypePropagation) 326 // rely upon the defensive behavior and would need to be updated. 327 if (!State || (State == Pred->getState() && !Tag && !MarkAsSink)) 328 return Pred; 329 330 Changed = true; 331 const ProgramPoint &LocalLoc = (Tag ? Location.withTag(Tag) : Location); 332 if (!P) 333 P = Pred; 334 335 ExplodedNode *node; 336 if (MarkAsSink) 337 node = NB.generateSink(LocalLoc, State, P); 338 else 339 node = NB.generateNode(LocalLoc, State, P); 340 return node; 341 } 342 }; 343 344 } // end GR namespace 345 346 } // end clang namespace 347 348 #endif 349