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::BeginFunction, 49 check::EndFunction, 50 check::EndAnalysis, 51 check::EndOfTranslationUnit, 52 eval::Call, 53 eval::Assume, 54 check::LiveSymbols, 55 check::RegionChanges, 56 check::PointerEscape, 57 check::ConstPointerEscape, 58 check::Event<ImplicitNullDerefEvent>, 59 check::ASTDecl<FunctionDecl> > { 60 public: 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 /// \brief Called whenever a symbol becomes dead. 151 /// 152 /// This callback should be used by the checkers to aggressively clean 153 /// up/reduce the checker state, which is important for reducing the overall 154 /// memory usage. Specifically, if a checker keeps symbol specific information 155 /// in the sate, it can and should be dropped after the symbol becomes dead. 156 /// In addition, reporting a bug as soon as the checker becomes dead leads to 157 /// more precise diagnostics. (For example, one should report that a malloced 158 /// variable is not freed right after it goes out of scope.) 159 /// 160 /// \param SR The SymbolReaper object can be queried to determine which 161 /// symbols are dead. 162 /// 163 /// check::DeadSymbols 164 void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const {} 165 166 167 /// \brief Called when the analyzer core starts analyzing a function, 168 /// regardless of whether it is analyzed at the top level or is inlined. 169 /// 170 /// check::BeginFunction 171 void checkBeginFunction(CheckerContext &Ctx) const {} 172 173 /// \brief Called when the analyzer core reaches the end of a 174 /// function being analyzed regardless of whether it is analyzed at the top 175 /// level or is inlined. 176 /// 177 /// check::EndFunction 178 void checkEndFunction(CheckerContext &Ctx) const {} 179 180 /// \brief Called after all the paths in the ExplodedGraph reach end of path 181 /// - the symbolic execution graph is fully explored. 182 /// 183 /// This callback should be used in cases when a checker needs to have a 184 /// global view of the information generated on all paths. For example, to 185 /// compare execution summary/result several paths. 186 /// See IdempotentOperationChecker for a usage example. 187 /// 188 /// check::EndAnalysis 189 void checkEndAnalysis(ExplodedGraph &G, 190 BugReporter &BR, 191 ExprEngine &Eng) const {} 192 193 /// \brief Called after analysis of a TranslationUnit is complete. 194 /// 195 /// check::EndOfTranslationUnit 196 void checkEndOfTranslationUnit(const TranslationUnitDecl *TU, 197 AnalysisManager &Mgr, 198 BugReporter &BR) const {} 199 200 /// \brief Evaluates function call. 201 /// 202 /// The analysis core threats all function calls in the same way. However, some 203 /// functions have special meaning, which should be reflected in the program 204 /// state. This callback allows a checker to provide domain specific knowledge 205 /// about the particular functions it knows about. 206 /// 207 /// \returns true if the call has been successfully evaluated 208 /// and false otherwise. Note, that only one checker can evaluate a call. If 209 /// more than one checker claims that they can evaluate the same call the 210 /// first one wins. 211 /// 212 /// eval::Call 213 bool evalCall(const CallExpr *CE, CheckerContext &C) const { return true; } 214 215 /// \brief Handles assumptions on symbolic values. 216 /// 217 /// This method is called when a symbolic expression is assumed to be true or 218 /// false. For example, the assumptions are performed when evaluating a 219 /// condition at a branch. The callback allows checkers track the assumptions 220 /// performed on the symbols of interest and change the state accordingly. 221 /// 222 /// eval::Assume 223 ProgramStateRef evalAssume(ProgramStateRef State, 224 SVal Cond, 225 bool Assumption) const { return State; } 226 227 /// Allows modifying SymbolReaper object. For example, checkers can explicitly 228 /// register symbols of interest as live. These symbols will not be marked 229 /// dead and removed. 230 /// 231 /// check::LiveSymbols 232 void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const {} 233 234 /// \brief Called to determine if the checker currently needs to know if when 235 /// contents of any regions change. 236 /// 237 /// Since it is not necessarily cheap to compute which regions are being 238 /// changed, this allows the analyzer core to skip the more expensive 239 /// #checkRegionChanges when no checkers are tracking any state. 240 bool wantsRegionChangeUpdate(ProgramStateRef St) const { return true; } 241 242 /// \brief Called when the contents of one or more regions change. 243 /// 244 /// This can occur in many different ways: an explicit bind, a blanket 245 /// invalidation of the region contents, or by passing a region to a function 246 /// call whose behavior the analyzer cannot model perfectly. 247 /// 248 /// \param State The current program state. 249 /// \param Invalidated A set of all symbols potentially touched by the change. 250 /// \param ExplicitRegions The regions explicitly requested for invalidation. 251 /// For a function call, this would be the arguments. For a bind, this 252 /// would be the region being bound to. 253 /// \param Regions The transitive closure of regions accessible from, 254 /// \p ExplicitRegions, i.e. all regions that may have been touched 255 /// by this change. For a simple bind, this list will be the same as 256 /// \p ExplicitRegions, since a bind does not affect the contents of 257 /// anything accessible through the base region. 258 /// \param Call The opaque call triggering this invalidation. Will be 0 if the 259 /// change was not triggered by a call. 260 /// 261 /// Note that this callback will not be invoked unless 262 /// #wantsRegionChangeUpdate returns \c true. 263 /// 264 /// check::RegionChanges 265 ProgramStateRef 266 checkRegionChanges(ProgramStateRef State, 267 const InvalidatedSymbols *Invalidated, 268 ArrayRef<const MemRegion *> ExplicitRegions, 269 ArrayRef<const MemRegion *> Regions, 270 const CallEvent *Call) const { 271 return State; 272 } 273 274 /// \brief Called when pointers escape. 275 /// 276 /// This notifies the checkers about pointer escape, which occurs whenever 277 /// the analyzer cannot track the symbol any more. For example, as a 278 /// result of assigning a pointer into a global or when it's passed to a 279 /// function call the analyzer cannot model. 280 /// 281 /// \param State The state at the point of escape. 282 /// \param Escaped The list of escaped symbols. 283 /// \param Call The corresponding CallEvent, if the symbols escape as 284 /// parameters to the given call. 285 /// \param Kind How the symbols have escaped. 286 /// \returns Checkers can modify the state by returning a new state. 287 ProgramStateRef checkPointerEscape(ProgramStateRef State, 288 const InvalidatedSymbols &Escaped, 289 const CallEvent *Call, 290 PointerEscapeKind Kind) const { 291 return State; 292 } 293 294 /// \brief Called when const pointers escape. 295 /// 296 /// Note: in most cases checkPointerEscape callback is sufficient. 297 /// \sa checkPointerEscape 298 ProgramStateRef checkConstPointerEscape(ProgramStateRef State, 299 const InvalidatedSymbols &Escaped, 300 const CallEvent *Call, 301 PointerEscapeKind Kind) const { 302 return State; 303 } 304 305 /// check::Event<ImplicitNullDerefEvent> 306 void checkEvent(ImplicitNullDerefEvent Event) const {} 307 308 /// \brief Check every declaration in the AST. 309 /// 310 /// An AST traversal callback, which should only be used when the checker is 311 /// not path sensitive. It will be called for every Declaration in the AST and 312 /// can be specialized to only be called on subclasses of Decl, for example, 313 /// FunctionDecl. 314 /// 315 /// check::ASTDecl<FunctionDecl> 316 void checkASTDecl(const FunctionDecl *D, 317 AnalysisManager &Mgr, 318 BugReporter &BR) const {} 319 }; 320 321 void CheckerDocumentation::checkPostStmt(const DeclStmt *DS, 322 CheckerContext &C) const { 323 } 324 325 } // end namespace ento 326 } // end namespace clang 327