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