CheckerDocumentation.cpp revision 96479da6ad9d921d875e7be29fe1bfa127be8069 
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. See the subclasses
85  /// of ObjCMethodCall for more details.
86  ///
87  /// check::PreObjCMessage
88  void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {}
89
90  /// \brief Post-visit the Objective C message.
91  /// \sa checkPreObjCMessage()
92  ///
93  /// check::PostObjCMessage
94  void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const {}
95
96  /// \brief Pre-visit an abstract "call" event.
97  ///
98  /// This is used for checkers that want to check arguments or attributed
99  /// behavior for functions and methods no matter how they are being invoked.
100  ///
101  /// Note that this includes ALL cross-body invocations, so if you want to
102  /// limit your checks to, say, function calls, you can either test for that
103  /// or fall back to the explicit callback (i.e. check::PreStmt).
104  ///
105  /// check::PreCall
106  void checkPreCall(const CallEvent &Call, CheckerContext &C) const {}
107
108  /// \brief Post-visit an abstract "call" event.
109  /// \sa checkPreObjCMessage()
110  ///
111  /// check::PostCall
112  void checkPostCall(const CallEvent &Call, CheckerContext &C) const {}
113
114  /// \brief Pre-visit of the condition statement of a branch (such as IfStmt).
115  void checkBranchCondition(const Stmt *Condition, CheckerContext &Ctx) const {}
116
117  /// \brief Called on a load from and a store to a location.
118  ///
119  /// The method will be called each time a location (pointer) value is
120  /// accessed.
121  /// \param Loc    The value of the location (pointer).
122  /// \param IsLoad The flag specifying if the location is a store or a load.
123  /// \param S      The load is performed while processing the statement.
124  ///
125  /// check::Location
126  void checkLocation(SVal Loc, bool IsLoad, const Stmt *S,
127                     CheckerContext &) const {}
128
129  /// \brief Called on binding of a value to a location.
130  ///
131  /// \param Loc The value of the location (pointer).
132  /// \param Val The value which will be stored at the location Loc.
133  /// \param S   The bind is performed while processing the statement S.
134  ///
135  /// check::Bind
136  void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &) const {}
137
138
139  /// \brief Called whenever a symbol becomes dead.
140  ///
141  /// This callback should be used by the checkers to aggressively clean
142  /// up/reduce the checker state, which is important for reducing the overall
143  /// memory usage. Specifically, if a checker keeps symbol specific information
144  /// in the sate, it can and should be dropped after the symbol becomes dead.
145  /// In addition, reporting a bug as soon as the checker becomes dead leads to
146  /// more precise diagnostics. (For example, one should report that a malloced
147  /// variable is not freed right after it goes out of scope.)
148  ///
149  /// \param SR The SymbolReaper object can be queried to determine which
150  ///           symbols are dead.
151  ///
152  /// check::DeadSymbols
153  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const {}
154
155  /// \brief Called when an end of path is reached in the ExplodedGraph.
156  ///
157  /// This callback should be used to check if the allocated resources are freed.
158  ///
159  /// check::EndPath
160  void checkEndPath(CheckerContext &Ctx) const {}
161
162  /// \brief Called after all the paths in the ExplodedGraph reach end of path
163  /// - the symbolic execution graph is fully explored.
164  ///
165  /// This callback should be used in cases when a checker needs to have a
166  /// global view of the information generated on all paths. For example, to
167  /// compare execution summary/result several paths.
168  /// See IdempotentOperationChecker for a usage example.
169  ///
170  /// check::EndAnalysis
171  void checkEndAnalysis(ExplodedGraph &G,
172                        BugReporter &BR,
173                        ExprEngine &Eng) const {}
174
175  /// \brief Called after analysis of a TranslationUnit is complete.
176  ///
177  /// check::EndOfTranslationUnit
178  void checkEndOfTranslationUnit(const TranslationUnitDecl *TU,
179                                 AnalysisManager &Mgr,
180                                 BugReporter &BR) const {}
181
182
183  /// \brief Evaluates function call.
184  ///
185  /// The analysis core threats all function calls in the same way. However, some
186  /// functions have special meaning, which should be reflected in the program
187  /// state. This callback allows a checker to provide domain specific knowledge
188  /// about the particular functions it knows about.
189  ///
190  /// \returns true if the call has been successfully evaluated
191  /// and false otherwise. Note, that only one checker can evaluate a call. If
192  /// more then one checker claim that they can evaluate the same call the
193  /// first one wins.
194  ///
195  /// eval::Call
196  bool evalCall(const CallExpr *CE, CheckerContext &C) const { return true; }
197
198  /// \brief Handles assumptions on symbolic values.
199  ///
200  /// This method is called when a symbolic expression is assumed to be true or
201  /// false. For example, the assumptions are performed when evaluating a
202  /// condition at a branch. The callback allows checkers track the assumptions
203  /// performed on the symbols of interest and change the state accordingly.
204  ///
205  /// eval::Assume
206  ProgramStateRef evalAssume(ProgramStateRef State,
207                                 SVal Cond,
208                                 bool Assumption) const { return State; }
209
210  /// Allows modifying SymbolReaper object. For example, checkers can explicitly
211  /// register symbols of interest as live. These symbols will not be marked
212  /// dead and removed.
213  ///
214  /// check::LiveSymbols
215  void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const {}
216
217
218  bool wantsRegionChangeUpdate(ProgramStateRef St) const { return true; }
219
220  /// \brief Allows tracking regions which get invalidated.
221  ///
222  /// \param State The current program state.
223  /// \param Invalidated A set of all symbols potentially touched by the change.
224  /// \param ExplicitRegions The regions explicitly requested for invalidation.
225  ///   For example, in the case of a function call, these would be arguments.
226  /// \param Regions The transitive closure of accessible regions,
227  ///   i.e. all regions that may have been touched by this change.
228  /// \param Call The call expression wrapper if the regions are invalidated
229  ///   by a call, 0 otherwise.
230  /// Note, in order to be notified, the checker should also implement the
231  /// wantsRegionChangeUpdate callback.
232  ///
233  /// check::RegionChanges
234  ProgramStateRef
235    checkRegionChanges(ProgramStateRef State,
236                       const StoreManager::InvalidatedSymbols *Invalidated,
237                       ArrayRef<const MemRegion *> ExplicitRegions,
238                       ArrayRef<const MemRegion *> Regions,
239                       const CallEvent *Call) const {
240    return State;
241  }
242
243  /// check::Event<ImplicitNullDerefEvent>
244  void checkEvent(ImplicitNullDerefEvent Event) const {}
245
246  /// \brief Check every declaration in the AST.
247  ///
248  /// An AST traversal callback, which should only be used when the checker is
249  /// not path sensitive. It will be called for every Declaration in the AST and
250  /// can be specialized to only be called on subclasses of Decl, for example,
251  /// FunctionDecl.
252  ///
253  /// check::ASTDecl<FunctionDecl>
254  void checkASTDecl(const FunctionDecl *D,
255                    AnalysisManager &Mgr,
256                    BugReporter &BR) const {}
257
258};
259
260void CheckerDocumentation::checkPostStmt(const CallExpr *DS,
261                                         CheckerContext &C) const {
262  return;
263}
264
265} // end namespace
266