1 //===- CheckerDocumentation.cpp - Documentation checker ---------*- 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 checker lists all the checker callbacks and provides documentation for 10 // checker writers. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" 15 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 16 #include "clang/StaticAnalyzer/Core/Checker.h" 17 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 18 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" 20 21 using namespace clang; 22 using namespace ento; 23 24 // All checkers should be placed into anonymous namespace. 25 // We place the CheckerDocumentation inside ento namespace to make the 26 // it visible in doxygen. 27 namespace clang { 28 namespace ento { 29 30 /// This checker documents the callback functions checkers can use to implement 31 /// the custom handling of the specific events during path exploration as well 32 /// as reporting bugs. Most of the callbacks are targeted at path-sensitive 33 /// checking. 34 /// 35 /// \sa CheckerContext 36 class CheckerDocumentation : public Checker< check::PreStmt<ReturnStmt>, 37 check::PostStmt<DeclStmt>, 38 check::PreObjCMessage, 39 check::PostObjCMessage, 40 check::ObjCMessageNil, 41 check::PreCall, 42 check::PostCall, 43 check::BranchCondition, 44 check::NewAllocator, 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 /// 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 /// 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 /// 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 /// Post-visit the Objective C message. 94 /// \sa checkPreObjCMessage() 95 /// 96 /// check::PostObjCMessage 97 void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {} 98 99 /// 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 /// 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 /// Post-visit an abstract "call" event. 121 /// \sa checkPreObjCMessage() 122 /// 123 /// check::PostCall 124 void checkPostCall(const CallEvent &Call, CheckerContext &C) const {} 125 126 /// Pre-visit of the condition statement of a branch (such as IfStmt). 127 void checkBranchCondition(const Stmt *Condition, CheckerContext &Ctx) const {} 128 129 /// Post-visit the C++ operator new's allocation call. 130 /// 131 /// Execution of C++ operator new consists of the following phases: (1) call 132 /// default or overridden operator new() to allocate memory (2) cast the 133 /// return value of operator new() from void pointer type to class pointer 134 /// type, (3) assuming that the value is non-null, call the object's 135 /// constructor over this pointer, (4) declare that the value of the 136 /// new-expression is this pointer. This callback is called between steps 137 /// (2) and (3). Post-call for the allocator is called after step (1). 138 /// Pre-statement for the new-expression is called on step (4) when the value 139 /// of the expression is evaluated. 140 /// \param NE The C++ new-expression that triggered the allocation. 141 /// \param Target The allocated region, casted to the class type. 142 void checkNewAllocator(const CXXNewExpr *NE, SVal Target, 143 CheckerContext &) const {} 144 145 /// Called on a load from and a store to a location. 146 /// 147 /// The method will be called each time a location (pointer) value is 148 /// accessed. 149 /// \param Loc The value of the location (pointer). 150 /// \param IsLoad The flag specifying if the location is a store or a load. 151 /// \param S The load is performed while processing the statement. 152 /// 153 /// check::Location 154 void checkLocation(SVal Loc, bool IsLoad, const Stmt *S, 155 CheckerContext &) const {} 156 157 /// Called on binding of a value to a location. 158 /// 159 /// \param Loc The value of the location (pointer). 160 /// \param Val The value which will be stored at the location Loc. 161 /// \param S The bind is performed while processing the statement S. 162 /// 163 /// check::Bind 164 void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &) const {} 165 166 /// Called whenever a symbol becomes dead. 167 /// 168 /// This callback should be used by the checkers to aggressively clean 169 /// up/reduce the checker state, which is important for reducing the overall 170 /// memory usage. Specifically, if a checker keeps symbol specific information 171 /// in the state, it can and should be dropped after the symbol becomes dead. 172 /// In addition, reporting a bug as soon as the checker becomes dead leads to 173 /// more precise diagnostics. (For example, one should report that a malloced 174 /// variable is not freed right after it goes out of scope.) 175 /// 176 /// \param SR The SymbolReaper object can be queried to determine which 177 /// symbols are dead. 178 /// 179 /// check::DeadSymbols 180 void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const {} 181 182 183 /// Called when the analyzer core starts analyzing a function, 184 /// regardless of whether it is analyzed at the top level or is inlined. 185 /// 186 /// check::BeginFunction 187 void checkBeginFunction(CheckerContext &Ctx) const {} 188 189 /// Called when the analyzer core reaches the end of a 190 /// function being analyzed regardless of whether it is analyzed at the top 191 /// level or is inlined. 192 /// 193 /// check::EndFunction 194 void checkEndFunction(const ReturnStmt *RS, CheckerContext &Ctx) const {} 195 196 /// Called after all the paths in the ExplodedGraph reach end of path 197 /// - the symbolic execution graph is fully explored. 198 /// 199 /// This callback should be used in cases when a checker needs to have a 200 /// global view of the information generated on all paths. For example, to 201 /// compare execution summary/result several paths. 202 /// See IdempotentOperationChecker for a usage example. 203 /// 204 /// check::EndAnalysis 205 void checkEndAnalysis(ExplodedGraph &G, 206 BugReporter &BR, 207 ExprEngine &Eng) const {} 208 209 /// Called after analysis of a TranslationUnit is complete. 210 /// 211 /// check::EndOfTranslationUnit 212 void checkEndOfTranslationUnit(const TranslationUnitDecl *TU, 213 AnalysisManager &Mgr, 214 BugReporter &BR) const {} 215 216 /// Evaluates function call. 217 /// 218 /// The analysis core treats all function calls in the same way. However, some 219 /// functions have special meaning, which should be reflected in the program 220 /// state. This callback allows a checker to provide domain specific knowledge 221 /// about the particular functions it knows about. 222 /// 223 /// \returns true if the call has been successfully evaluated 224 /// and false otherwise. Note, that only one checker can evaluate a call. If 225 /// more than one checker claims that they can evaluate the same call the 226 /// first one wins. 227 /// 228 /// eval::Call 229 bool evalCall(const CallExpr *CE, CheckerContext &C) const { return true; } 230 231 /// Handles assumptions on symbolic values. 232 /// 233 /// This method is called when a symbolic expression is assumed to be true or 234 /// false. For example, the assumptions are performed when evaluating a 235 /// condition at a branch. The callback allows checkers track the assumptions 236 /// performed on the symbols of interest and change the state accordingly. 237 /// 238 /// eval::Assume 239 ProgramStateRef evalAssume(ProgramStateRef State, 240 SVal Cond, 241 bool Assumption) const { return State; } 242 243 /// Allows modifying SymbolReaper object. For example, checkers can explicitly 244 /// register symbols of interest as live. These symbols will not be marked 245 /// dead and removed. 246 /// 247 /// check::LiveSymbols 248 void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const {} 249 250 /// Called when the contents of one or more regions change. 251 /// 252 /// This can occur in many different ways: an explicit bind, a blanket 253 /// invalidation of the region contents, or by passing a region to a function 254 /// call whose behavior the analyzer cannot model perfectly. 255 /// 256 /// \param State The current program state. 257 /// \param Invalidated A set of all symbols potentially touched by the change. 258 /// \param ExplicitRegions The regions explicitly requested for invalidation. 259 /// For a function call, this would be the arguments. For a bind, this 260 /// would be the region being bound to. 261 /// \param Regions The transitive closure of regions accessible from, 262 /// \p ExplicitRegions, i.e. all regions that may have been touched 263 /// by this change. For a simple bind, this list will be the same as 264 /// \p ExplicitRegions, since a bind does not affect the contents of 265 /// anything accessible through the base region. 266 /// \param LCtx LocationContext that is useful for getting various contextual 267 /// info, like callstack, CFG etc. 268 /// \param Call The opaque call triggering this invalidation. Will be 0 if the 269 /// change was not triggered by a call. 270 /// 271 /// check::RegionChanges 272 ProgramStateRef 273 checkRegionChanges(ProgramStateRef State, 274 const InvalidatedSymbols *Invalidated, 275 ArrayRef<const MemRegion *> ExplicitRegions, 276 ArrayRef<const MemRegion *> Regions, 277 const LocationContext *LCtx, 278 const CallEvent *Call) const { 279 return State; 280 } 281 282 /// Called when pointers escape. 283 /// 284 /// This notifies the checkers about pointer escape, which occurs whenever 285 /// the analyzer cannot track the symbol any more. For example, as a 286 /// result of assigning a pointer into a global or when it's passed to a 287 /// function call the analyzer cannot model. 288 /// 289 /// \param State The state at the point of escape. 290 /// \param Escaped The list of escaped symbols. 291 /// \param Call The corresponding CallEvent, if the symbols escape as 292 /// parameters to the given call. 293 /// \param Kind How the symbols have escaped. 294 /// \returns Checkers can modify the state by returning a new state. 295 ProgramStateRef checkPointerEscape(ProgramStateRef State, 296 const InvalidatedSymbols &Escaped, 297 const CallEvent *Call, 298 PointerEscapeKind Kind) const { 299 return State; 300 } 301 302 /// Called when const pointers escape. 303 /// 304 /// Note: in most cases checkPointerEscape callback is sufficient. 305 /// \sa checkPointerEscape 306 ProgramStateRef checkConstPointerEscape(ProgramStateRef State, 307 const InvalidatedSymbols &Escaped, 308 const CallEvent *Call, 309 PointerEscapeKind Kind) const { 310 return State; 311 } 312 313 /// check::Event<ImplicitNullDerefEvent> 314 void checkEvent(ImplicitNullDerefEvent Event) const {} 315 316 /// Check every declaration in the AST. 317 /// 318 /// An AST traversal callback, which should only be used when the checker is 319 /// not path sensitive. It will be called for every Declaration in the AST and 320 /// can be specialized to only be called on subclasses of Decl, for example, 321 /// FunctionDecl. 322 /// 323 /// check::ASTDecl<FunctionDecl> 324 void checkASTDecl(const FunctionDecl *D, 325 AnalysisManager &Mgr, 326 BugReporter &BR) const {} 327 }; 328 329 void CheckerDocumentation::checkPostStmt(const DeclStmt *DS, 330 CheckerContext &C) const { 331 } 332 333 } // end namespace ento 334 } // end namespace clang 335