CheckerDocumentation.cpp revision 8919e688dc610d1f632a4d43f7f1489f67255476 
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/Checker.h"
17#include "clang/StaticAnalyzer/Core/CheckerManager.h"
18#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
21
22using namespace clang;
23using 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.
28namespace 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
36class CheckerDocumentation : public Checker< check::PreStmt<DeclStmt>,
37                                       check::PostStmt<CallExpr>,
38                                       check::PreObjCMessage,
39                                       check::PostObjCMessage,
40                                       check::PreCall,
41                                       check::PostCall,
42                                       check::BranchCondition,
43                                       check::Location,
44                                       check::Bind,
45                                       check::DeadSymbols,
46                                       check::EndPath,
47                                       check::EndAnalysis,
48                                       check::EndOfTranslationUnit,
49                                       eval::Call,
50                                       eval::Assume,
51                                       check::LiveSymbols,
52                                       check::RegionChanges,
53                                       check::Event<ImplicitNullDerefEvent>,
54                                       check::ASTDecl<FunctionDecl> > {
55public:
56
57  /// \brief Pre-visit the Statement.
58  ///
59  /// The method will be called before the analyzer core processes the
60  /// statement. The notification is performed for every explored CFGElement,
61  /// which does not include the control flow statements such as IfStmt. The
62  /// callback can be specialized to be called with any subclass of Stmt.
63  ///
64  /// See checkBranchCondition() callback for performing custom processing of
65  /// the branching statements.
66  ///
67  /// check::PreStmt<DeclStmt>
68  void checkPreStmt(const DeclStmt *DS, CheckerContext &C) const {}
69
70  /// \brief Post-visit the Statement.
71  ///
72  /// The method will be called after the analyzer core processes the
73  /// statement. The notification is performed for every explored CFGElement,
74  /// which does not include the control flow statements such as IfStmt. The
75  /// callback can be specialized to be called with any subclass of Stmt.
76  ///
77  /// check::PostStmt<CallExpr>
78  void checkPostStmt(const CallExpr *DS, CheckerContext &C) const;
79
80  /// \brief Pre-visit the Objective C message.
81  ///
82  /// This will be called before the analyzer core processes the method call.
83  /// This is called for any action which produces an Objective-C message send,
84  /// including explicit message syntax and property access.
85  ///
86  /// check::PreObjCMessage
87  void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {}
88
89  /// \brief Post-visit the Objective C message.
90  /// \sa checkPreObjCMessage()
91  ///
92  /// check::PostObjCMessage
93  void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {}
94
95  /// \brief Pre-visit an abstract "call" event.
96  ///
97  /// This is used for checkers that want to check arguments or attributed
98  /// behavior for functions and methods no matter how they are being invoked.
99  ///
100  /// Note that this includes ALL cross-body invocations, so if you want to
101  /// limit your checks to, say, function calls, you can either test for that
102  /// or fall back to the explicit callback (i.e. check::PreStmt).
103  ///
104  /// check::PreCall
105  void checkPreCall(const CallEvent &Call, CheckerContext &C) const {}
106
107  /// \brief Post-visit an abstract "call" event.
108  /// \sa checkPreObjCMessage()
109  ///
110  /// check::PostCall
111  void checkPostCall(const CallEvent &Call, CheckerContext &C) const {}
112
113  /// \brief Pre-visit of the condition statement of a branch (such as IfStmt).
114  void checkBranchCondition(const Stmt *Condition, CheckerContext &Ctx) const {}
115
116  /// \brief Called on a load from and a store to a location.
117  ///
118  /// The method will be called each time a location (pointer) value is
119  /// accessed.
120  /// \param Loc    The value of the location (pointer).
121  /// \param IsLoad The flag specifying if the location is a store or a load.
122  /// \param S      The load is performed while processing the statement.
123  ///
124  /// check::Location
125  void checkLocation(SVal Loc, bool IsLoad, const Stmt *S,
126                     CheckerContext &) const {}
127
128  /// \brief Called on binding of a value to a location.
129  ///
130  /// \param Loc The value of the location (pointer).
131  /// \param Val The value which will be stored at the location Loc.
132  /// \param S   The bind is performed while processing the statement S.
133  ///
134  /// check::Bind
135  void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &) const {}
136
137
138  /// \brief Called whenever a symbol becomes dead.
139  ///
140  /// This callback should be used by the checkers to aggressively clean
141  /// up/reduce the checker state, which is important for reducing the overall
142  /// memory usage. Specifically, if a checker keeps symbol specific information
143  /// in the sate, it can and should be dropped after the symbol becomes dead.
144  /// In addition, reporting a bug as soon as the checker becomes dead leads to
145  /// more precise diagnostics. (For example, one should report that a malloced
146  /// variable is not freed right after it goes out of scope.)
147  ///
148  /// \param SR The SymbolReaper object can be queried to determine which
149  ///           symbols are dead.
150  ///
151  /// check::DeadSymbols
152  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const {}
153
154  /// \brief Called when an end of path is reached in the ExplodedGraph.
155  ///
156  /// This callback should be used to check if the allocated resources are freed.
157  ///
158  /// check::EndPath
159  void checkEndPath(CheckerContext &Ctx) const {}
160
161  /// \brief Called after all the paths in the ExplodedGraph reach end of path
162  /// - the symbolic execution graph is fully explored.
163  ///
164  /// This callback should be used in cases when a checker needs to have a
165  /// global view of the information generated on all paths. For example, to
166  /// compare execution summary/result several paths.
167  /// See IdempotentOperationChecker for a usage example.
168  ///
169  /// check::EndAnalysis
170  void checkEndAnalysis(ExplodedGraph &G,
171                        BugReporter &BR,
172                        ExprEngine &Eng) const {}
173
174  /// \brief Called after analysis of a TranslationUnit is complete.
175  ///
176  /// check::EndOfTranslationUnit
177  void checkEndOfTranslationUnit(const TranslationUnitDecl *TU,
178                                 AnalysisManager &Mgr,
179                                 BugReporter &BR) const {}
180
181
182  /// \brief Evaluates function call.
183  ///
184  /// The analysis core threats all function calls in the same way. However, some
185  /// functions have special meaning, which should be reflected in the program
186  /// state. This callback allows a checker to provide domain specific knowledge
187  /// about the particular functions it knows about.
188  ///
189  /// \returns true if the call has been successfully evaluated
190  /// and false otherwise. Note, that only one checker can evaluate a call. If
191  /// more then one checker claim that they can evaluate the same call the
192  /// first one wins.
193  ///
194  /// eval::Call
195  bool evalCall(const CallExpr *CE, CheckerContext &C) const { return true; }
196
197  /// \brief Handles assumptions on symbolic values.
198  ///
199  /// This method is called when a symbolic expression is assumed to be true or
200  /// false. For example, the assumptions are performed when evaluating a
201  /// condition at a branch. The callback allows checkers track the assumptions
202  /// performed on the symbols of interest and change the state accordingly.
203  ///
204  /// eval::Assume
205  ProgramStateRef evalAssume(ProgramStateRef State,
206                                 SVal Cond,
207                                 bool Assumption) const { return State; }
208
209  /// Allows modifying SymbolReaper object. For example, checkers can explicitly
210  /// register symbols of interest as live. These symbols will not be marked
211  /// dead and removed.
212  ///
213  /// check::LiveSymbols
214  void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const {}
215
216
217  bool wantsRegionChangeUpdate(ProgramStateRef St) const { return true; }
218
219  /// \brief Allows tracking regions which get invalidated.
220  ///
221  /// \param State The current program state.
222  /// \param Invalidated A set of all symbols potentially touched by the change.
223  /// \param ExplicitRegions The regions explicitly requested for invalidation.
224  ///   For example, in the case of a function call, these would be arguments.
225  /// \param Regions The transitive closure of accessible regions,
226  ///   i.e. all regions that may have been touched by this change.
227  /// \param Call The call expression wrapper if the regions are invalidated
228  ///   by a call, 0 otherwise.
229  /// Note, in order to be notified, the checker should also implement the
230  /// wantsRegionChangeUpdate callback.
231  ///
232  /// check::RegionChanges
233  ProgramStateRef
234    checkRegionChanges(ProgramStateRef State,
235                       const StoreManager::InvalidatedSymbols *Invalidated,
236                       ArrayRef<const MemRegion *> ExplicitRegions,
237                       ArrayRef<const MemRegion *> Regions,
238                       const CallEvent *Call) const {
239    return State;
240  }
241
242  /// check::Event<ImplicitNullDerefEvent>
243  void checkEvent(ImplicitNullDerefEvent Event) const {}
244
245  /// \brief Check every declaration in the AST.
246  ///
247  /// An AST traversal callback, which should only be used when the checker is
248  /// not path sensitive. It will be called for every Declaration in the AST and
249  /// can be specialized to only be called on subclasses of Decl, for example,
250  /// FunctionDecl.
251  ///
252  /// check::ASTDecl<FunctionDecl>
253  void checkASTDecl(const FunctionDecl *D,
254                    AnalysisManager &Mgr,
255                    BugReporter &BR) const {}
256
257};
258
259void CheckerDocumentation::checkPostStmt(const CallExpr *DS,
260                                         CheckerContext &C) const {
261  return;
262}
263
264} // end namespace
265