CheckerDocumentation.cpp revision 66c40400e7d6272b0cd675ada18dd62c1f0362c7 
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::BranchCondition,
41                                       check::Location,
42                                       check::Bind,
43                                       check::DeadSymbols,
44                                       check::EndPath,
45                                       check::EndAnalysis,
46                                       check::EndOfTranslationUnit,
47                                       eval::Call,
48                                       eval::Assume,
49                                       check::LiveSymbols,
50                                       check::RegionChanges,
51                                       check::Event<ImplicitNullDerefEvent>,
52                                       check::ASTDecl<FunctionDecl> > {
53public:
54
55  /// \brief Pre-visit the Statement.
56  ///
57  /// The method will be called before the analyzer core processes the
58  /// statement. The notification is performed for every explored CFGElement,
59  /// which does not include the control flow statements such as IfStmt. The
60  /// callback can be specialized to be called with any subclass of Stmt.
61  ///
62  /// See checkBranchCondition() callback for performing custom processing of
63  /// the branching statements.
64  ///
65  /// check::PreStmt<DeclStmt>
66  void checkPreStmt(const DeclStmt *DS, CheckerContext &C) const {}
67
68  /// \brief Post-visit the Statement.
69  ///
70  /// The method will be called after the analyzer core processes the
71  /// statement. The notification is performed for every explored CFGElement,
72  /// which does not include the control flow statements such as IfStmt. The
73  /// callback can be specialized to be called with any subclass of Stmt.
74  ///
75  /// check::PostStmt<DeclStmt>
76  void checkPostStmt(const CallExpr *DS, CheckerContext &C) const;
77
78  /// \brief Pre-visit the Objective C messages.
79  void checkPreObjCMessage(const ObjCMessage &Msg, CheckerContext &C) const {}
80
81  /// \brief Post-visit the Objective C messages.
82  void checkPostObjCMessage(const ObjCMessage &Msg, CheckerContext &C) const {}
83
84  /// \brief Pre-visit of the condition statement of a branch (such as IfStmt).
85  void checkBranchCondition(const Stmt *Condition, CheckerContext &Ctx) const {}
86
87  /// \brief Called on a load from and a store to a location.
88  ///
89  /// The method will be called each time a location (pointer) value is
90  /// accessed.
91  /// \param Loc    The value of the location (pointer).
92  /// \param IsLoad The flag specifying if the location is a store or a load.
93  /// \param S      The load is performed while processing the statement.
94  ///
95  /// check::Location
96  void checkLocation(SVal Loc, bool IsLoad, const Stmt *S,
97                     CheckerContext &C) const {}
98
99  /// \brief Called on binding of a value to a location.
100  ///
101  /// \param Loc The value of the location (pointer).
102  /// \param Val The value which will be stored at the location Loc.
103  /// \param S   The bind is performed while processing the statement S.
104  ///
105  /// check::Bind
106  void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &C) const {}
107
108
109  /// \brief Called whenever a symbol becomes dead.
110  ///
111  /// This callback should be used by the checkers to aggressively clean
112  /// up/reduce the checker state, which is important for reducing the overall
113  /// memory usage. Specifically, if a checker keeps symbol specific information
114  /// in the sate, it can and should be dropped after the symbol becomes dead.
115  /// In addition, reporting a bug as soon as the checker becomes dead leads to
116  /// more precise diagnostics. (For example, one should report that a malloced
117  /// variable is not freed right after it goes out of scope.)
118  ///
119  /// \param SR The SymbolReaper object can be queried to determine which
120  ///           symbols are dead.
121  ///
122  /// check::DeadSymbols
123  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const {}
124
125  /// \brief Called when an end of path is reached in the ExplodedGraph.
126  ///
127  /// This callback should be used to check if the allocated resources are freed.
128  ///
129  /// check::EndPath
130  void checkEndPath(CheckerContext &Ctx) const {}
131
132  /// \brief Called after all the paths in the ExplodedGraph reach end of path
133  /// - the symbolic execution graph is fully explored.
134  ///
135  /// This callback should be used in cases when a checker needs to have a
136  /// global view of the information generated on all paths. For example, to
137  /// compare execution summary/result several paths.
138  /// See IdempotentOperationChecker for a usage example.
139  ///
140  /// check::EndAnalysis
141  void checkEndAnalysis(ExplodedGraph &G,
142                        BugReporter &BR,
143                        ExprEngine &Eng) const {}
144
145  /// \brief Called after analysis of a TranslationUnit is complete.
146  ///
147  /// check::EndOfTranslationUnit
148  void checkEndTranslationUnit(const TranslationUnitDecl *TU,
149                               AnalysisManager &Mgr,
150                               BugReporter &BR) {}
151
152
153  /// \brief Evaluates function call.
154  ///
155  /// The analysis core threats all function calls in the same way. However, some
156  /// functions have special meaning, which should be reflected in the program
157  /// state. This callback allows a checker to provide domain specific knowledge
158  /// about the particular functions it knows about.
159  ///
160  /// \returns true if the call has been successfully evaluated
161  /// and false otherwise. Note, that only one checker can evaluate a call. If
162  /// more then one checker claim that they can evaluate the same call the
163  /// first one wins.
164  ///
165  /// eval::Call
166  bool evalCall(const CallExpr *CE, CheckerContext &C) const { return true; }
167
168  /// \brief Handles assumptions on symbolic values.
169  ///
170  /// This method is called when a symbolic expression is assumed to be true or
171  /// false. For example, the assumptions are performed when evaluating a
172  /// condition at a branch. The callback allows checkers track the assumptions
173  /// performed on the symbols of interest and change the state accordingly.
174  ///
175  /// eval::Assume
176  ProgramStateRef evalAssume(ProgramStateRef State,
177                                 SVal Cond,
178                                 bool Assumption) const { return State; }
179
180  /// Allows modifying SymbolReaper object. For example, checkers can explicitly
181  /// register symbols of interest as live. These symbols will not be marked
182  /// dead and removed.
183  ///
184  /// check::LiveSymbols
185  void checkLiveSymbols(ProgramStateRef State, SymbolReaper &SR) const {}
186
187
188  bool wantsRegionChangeUpdate(ProgramStateRef St) const { return true; }
189
190  /// check::RegionChanges
191  /// Allows tracking regions which get invalidated.
192  /// \param state The current program state.
193  /// \param invalidated A set of all symbols potentially touched by the change.
194  /// \param ExplicitRegions The regions explicitly requested for invalidation.
195  ///   For example, in the case of a function call, these would be arguments.
196  /// \param Regions The transitive closure of accessible regions,
197  ///   i.e. all regions that may have been touched by this change.
198  /// \param The call expression wrapper if the regions are invalidated by a
199  ///   call, 0 otherwise.
200  /// Note, in order to be notified, the checker should also implement
201  /// wantsRegionChangeUpdate callback.
202  ProgramStateRef
203    checkRegionChanges(ProgramStateRef State,
204                       const StoreManager::InvalidatedSymbols *,
205                       ArrayRef<const MemRegion *> ExplicitRegions,
206                       ArrayRef<const MemRegion *> Regions,
207                       const CallOrObjCMessage *Call) const {
208    return State;
209  }
210
211  /// check::Event<ImplicitNullDerefEvent>
212  void checkEvent(ImplicitNullDerefEvent Event) const {}
213
214  /// \brief Check every declaration in the AST.
215  ///
216  /// An AST traversal callback, which should only be used when the checker is
217  /// not path sensitive. It will be called for every Declaration in the AST and
218  /// can be specialized to only be called on subclasses of Decl, for example,
219  /// FunctionDecl.
220  ///
221  /// check::ASTDecl<FunctionDecl>
222  void checkASTDecl(const FunctionDecl *D,
223                    AnalysisManager &Mgr,
224                    BugReporter &BR) const {}
225
226};
227
228void CheckerDocumentation::checkPostStmt(const CallExpr *DS,
229                                         CheckerContext &C) const {
230  return;
231}
232
233} // end namespace
234