1 //===- CheckerDocumentation.cpp - Documentation checker ---------*- 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 checker lists all the checker callbacks and provides documentation for 11 // checker writers. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "ClangSACheckers.h" 16 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 17 #include "clang/StaticAnalyzer/Core/Checker.h" 18 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" 21 22 using namespace clang; 23 using namespace ento; 24 25 // All checkers should be placed into anonymous namespace. 26 // We place the CheckerDocumentation inside ento namespace to make the 27 // it visible in doxygen. 28 namespace clang { 29 namespace ento { 30 31 /// This checker documents the callback functions checkers can use to implement 32 /// the custom handling of the specific events during path exploration as well 33 /// as reporting bugs. Most of the callbacks are targeted at path-sensitive 34 /// checking. 35 /// 36 /// \sa CheckerContext 37 class CheckerDocumentation : public Checker< check::PreStmt<ReturnStmt>, 38 check::PostStmt<DeclStmt>, 39 check::PreObjCMessage, 40 check::PostObjCMessage, 41 check::ObjCMessageNil, 42 check::PreCall, 43 check::PostCall, 44 check::BranchCondition, 45 check::NewAllocator, 46 check::Location, 47 check::Bind, 48 check::DeadSymbols, 49 check::BeginFunction, 50 check::EndFunction, 51 check::EndAnalysis, 52 check::EndOfTranslationUnit, 53 eval::Call, 54 eval::Assume, 55 check::LiveSymbols, 56 check::RegionChanges, 57 check::PointerEscape, 58 check::ConstPointerEscape, 59 check::Event<ImplicitNullDerefEvent>, 60 check::ASTDecl<FunctionDecl> > { 61 public: 62 /// Pre-visit the Statement. 63 /// 64 /// The method will be called before the analyzer core processes the 65 /// statement. The notification is performed for every explored CFGElement, 66 /// which does not include the control flow statements such as IfStmt. The 67 /// callback can be specialized to be called with any subclass of Stmt. 68 /// 69 /// See checkBranchCondition() callback for performing custom processing of 70 /// the branching statements. 71 /// 72 /// check::PreStmt<ReturnStmt> 73 void checkPreStmt(const ReturnStmt *DS, CheckerContext &C) const {} 74 75 /// Post-visit the Statement. 76 /// 77 /// The method will be called after the analyzer core processes the 78 /// statement. The notification is performed for every explored CFGElement, 79 /// which does not include the control flow statements such as IfStmt. The 80 /// callback can be specialized to be called with any subclass of Stmt. 81 /// 82 /// check::PostStmt<DeclStmt> 83 void checkPostStmt(const DeclStmt *DS, CheckerContext &C) const; 84 85 /// Pre-visit the Objective C message. 86 /// 87 /// This will be called before the analyzer core processes the method call. 88 /// This is called for any action which produces an Objective-C message send, 89 /// including explicit message syntax and property access. 90 /// 91 /// check::PreObjCMessage 92 void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {} 93 94 /// Post-visit the Objective C message. 95 /// \sa checkPreObjCMessage() 96 /// 97 /// check::PostObjCMessage 98 void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {} 99 100 /// Visit an Objective-C message whose receiver is nil. 101 /// 102 /// This will be called when the analyzer core processes a method call whose 103 /// receiver is definitely nil. In this case, check{Pre/Post}ObjCMessage and 104 /// check{Pre/Post}Call will not be called. 105 /// 106 /// check::ObjCMessageNil 107 void checkObjCMessageNil(const ObjCMethodCall &M, CheckerContext &C) const {} 108 109 /// Pre-visit an abstract "call" event. 110 /// 111 /// This is used for checkers that want to check arguments or attributed 112 /// behavior for functions and methods no matter how they are being invoked. 113 /// 114 /// Note that this includes ALL cross-body invocations, so if you want to 115 /// limit your checks to, say, function calls, you should test for that at the 116 /// beginning of your callback function. 117 /// 118 /// check::PreCall 119 void checkPreCall(const CallEvent &Call, CheckerContext &C) const {} 120 121 /// Post-visit an abstract "call" event. 122 /// \sa checkPreObjCMessage() 123 /// 124 /// check::PostCall 125 void checkPostCall(const CallEvent &Call, CheckerContext &C) const {} 126 127 /// Pre-visit of the condition statement of a branch (such as IfStmt). 128 void checkBranchCondition(const Stmt *Condition, CheckerContext &Ctx) const {} 129 130 /// Post-visit the C++ operator new's allocation call. 131 /// 132 /// Execution of C++ operator new consists of the following phases: (1) call 133 /// default or overridden operator new() to allocate memory (2) cast the 134 /// return value of operator new() from void pointer type to class pointer 135 /// type, (3) assuming that the value is non-null, call the object's 136 /// constructor over this pointer, (4) declare that the value of the 137 /// new-expression is this pointer. This callback is called between steps 138 /// (2) and (3). Post-call for the allocator is called after step (1). 139 /// Pre-statement for the new-expression is called on step (4) when the value 140 /// of the expression is evaluated. 141 /// \param NE The C++ new-expression that triggered the allocation. 142 /// \param Target The allocated region, casted to the class type. 143 void checkNewAllocator(const CXXNewExpr *NE, SVal Target, 144 CheckerContext &) const {} 145 146 /// Called on a load from and a store to a location. 147 /// 148 /// The method will be called each time a location (pointer) value is 149 /// accessed. 150 /// \param Loc The value of the location (pointer). 151 /// \param IsLoad The flag specifying if the location is a store or a load. 152 /// \param S The load is performed while processing the statement. 153 /// 154 /// check::Location 155 void checkLocation(SVal Loc, bool IsLoad, const Stmt *S, 156 CheckerContext &) const {} 157 158 /// Called on binding of a value to a location. 159 /// 160 /// \param Loc The value of the location (pointer). 161 /// \param Val The value which will be stored at the location Loc. 162 /// \param S The bind is performed while processing the statement S. 163 /// 164 /// check::Bind 165 void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &) const {} 166 167 /// Called whenever a symbol becomes dead. 168 /// 169 /// This callback should be used by the checkers to aggressively clean 170 /// up/reduce the checker state, which is important for reducing the overall 171 /// memory usage. Specifically, if a checker keeps symbol specific information 172 /// in the sate, it can and should be dropped after the symbol becomes dead. 173 /// In addition, reporting a bug as soon as the checker becomes dead leads to 174 /// more precise diagnostics. (For example, one should report that a malloced 175 /// variable is not freed right after it goes out of scope.) 176 /// 177 /// \param SR The SymbolReaper object can be queried to determine which 178 /// symbols are dead. 179 /// 180 /// check::DeadSymbols 181 void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const {} 182 183 184 /// Called when the analyzer core starts analyzing a function, 185 /// regardless of whether it is analyzed at the top level or is inlined. 186 /// 187 /// check::BeginFunction 188 void checkBeginFunction(CheckerContext &Ctx) const {} 189 190 /// Called when the analyzer core reaches the end of a 191 /// function being analyzed regardless of whether it is analyzed at the top 192 /// level or is inlined. 193 /// 194 /// check::EndFunction 195 void checkEndFunction(CheckerContext &Ctx) const {} 196 197 /// Called after all the paths in the ExplodedGraph reach end of path 198 /// - the symbolic execution graph is fully explored. 199 /// 200 /// This callback should be used in cases when a checker needs to have a 201 /// global view of the information generated on all paths. For example, to 202 /// compare execution summary/result several paths. 203 /// See IdempotentOperationChecker for a usage example. 204 /// 205 /// check::EndAnalysis 206 void checkEndAnalysis(ExplodedGraph &G, 207 BugReporter &BR, 208 ExprEngine &Eng) const {} 209 210 /// Called after analysis of a TranslationUnit is complete. 211 /// 212 /// check::EndOfTranslationUnit 213 void checkEndOfTranslationUnit(const TranslationUnitDecl *TU, 214 AnalysisManager &Mgr, 215 BugReporter &BR) const {} 216 217 /// Evaluates function call. 218 /// 219 /// The analysis core threats all function calls in the same way. However, some 220 /// functions have special meaning, which should be reflected in the program 221 /// state. This callback allows a checker to provide domain specific knowledge 222 /// about the particular functions it knows about. 223 /// 224 /// \returns true if the call has been successfully evaluated 225 /// and false otherwise. Note, that only one checker can evaluate a call. If 226 /// more than one checker claims that they can evaluate the same call the 227 /// first one wins. 228 /// 229 /// eval::Call 230 bool evalCall(const CallExpr *CE, CheckerContext &C) const { return true; } 231 232 /// Handles assumptions on symbolic values. 233 /// 234 /// This method is called when a symbolic expression is assumed to be true or 235 /// false. For example, the assumptions are performed when evaluating a 236 /// condition at a branch. The callback allows checkers track the assumptions 237 /// performed on the symbols of interest and change the state accordingly. 238 /// 239 /// eval::Assume 240 ProgramStateRef evalAssume(ProgramStateRef State, 241 SVal Cond, 242 bool Assumption) const { return State; } 243 244 /// Allows modifying SymbolReaper object. For example, checkers can explicitly 245 /// register symbols of interest as live. These symbols will not be marked 246 /// dead and removed. 247 /// 248 /// check::LiveSymbols 249 void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const {} 250 251 /// Called when the contents of one or more regions change. 252 /// 253 /// This can occur in many different ways: an explicit bind, a blanket 254 /// invalidation of the region contents, or by passing a region to a function 255 /// call whose behavior the analyzer cannot model perfectly. 256 /// 257 /// \param State The current program state. 258 /// \param Invalidated A set of all symbols potentially touched by the change. 259 /// \param ExplicitRegions The regions explicitly requested for invalidation. 260 /// For a function call, this would be the arguments. For a bind, this 261 /// would be the region being bound to. 262 /// \param Regions The transitive closure of regions accessible from, 263 /// \p ExplicitRegions, i.e. all regions that may have been touched 264 /// by this change. For a simple bind, this list will be the same as 265 /// \p ExplicitRegions, since a bind does not affect the contents of 266 /// anything accessible through the base region. 267 /// \param LCtx LocationContext that is useful for getting various contextual 268 /// info, like callstack, CFG etc. 269 /// \param Call The opaque call triggering this invalidation. Will be 0 if the 270 /// change was not triggered by a call. 271 /// 272 /// check::RegionChanges 273 ProgramStateRef 274 checkRegionChanges(ProgramStateRef State, 275 const InvalidatedSymbols *Invalidated, 276 ArrayRef<const MemRegion *> ExplicitRegions, 277 ArrayRef<const MemRegion *> Regions, 278 const LocationContext *LCtx, 279 const CallEvent *Call) const { 280 return State; 281 } 282 283 /// Called when pointers escape. 284 /// 285 /// This notifies the checkers about pointer escape, which occurs whenever 286 /// the analyzer cannot track the symbol any more. For example, as a 287 /// result of assigning a pointer into a global or when it's passed to a 288 /// function call the analyzer cannot model. 289 /// 290 /// \param State The state at the point of escape. 291 /// \param Escaped The list of escaped symbols. 292 /// \param Call The corresponding CallEvent, if the symbols escape as 293 /// parameters to the given call. 294 /// \param Kind How the symbols have escaped. 295 /// \returns Checkers can modify the state by returning a new state. 296 ProgramStateRef checkPointerEscape(ProgramStateRef State, 297 const InvalidatedSymbols &Escaped, 298 const CallEvent *Call, 299 PointerEscapeKind Kind) const { 300 return State; 301 } 302 303 /// Called when const pointers escape. 304 /// 305 /// Note: in most cases checkPointerEscape callback is sufficient. 306 /// \sa checkPointerEscape 307 ProgramStateRef checkConstPointerEscape(ProgramStateRef State, 308 const InvalidatedSymbols &Escaped, 309 const CallEvent *Call, 310 PointerEscapeKind Kind) const { 311 return State; 312 } 313 314 /// check::Event<ImplicitNullDerefEvent> 315 void checkEvent(ImplicitNullDerefEvent Event) const {} 316 317 /// Check every declaration in the AST. 318 /// 319 /// An AST traversal callback, which should only be used when the checker is 320 /// not path sensitive. It will be called for every Declaration in the AST and 321 /// can be specialized to only be called on subclasses of Decl, for example, 322 /// FunctionDecl. 323 /// 324 /// check::ASTDecl<FunctionDecl> 325 void checkASTDecl(const FunctionDecl *D, 326 AnalysisManager &Mgr, 327 BugReporter &BR) const {} 328 }; 329 330 void CheckerDocumentation::checkPostStmt(const DeclStmt *DS, 331 CheckerContext &C) const { 332 } 333 334 } // end namespace ento 335 } // end namespace clang 336