StreamChecker.cpp revision 785950e59424dca7ce0081bebf13c0acd2c4fff6 
1//===-- StreamChecker.cpp -----------------------------------------*- 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 file defines checkers that model and check stream handling functions.
11//
12//===----------------------------------------------------------------------===//
13
14#include "ClangSACheckers.h"
15#include "clang/StaticAnalyzer/Core/Checker.h"
16#include "clang/StaticAnalyzer/Core/CheckerManager.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
18#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
21#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
22#include "llvm/ADT/ImmutableMap.h"
23
24using namespace clang;
25using namespace ento;
26
27namespace {
28
29struct StreamState {
30  enum Kind { Opened, Closed, OpenFailed, Escaped } K;
31  const Stmt *S;
32
33  StreamState(Kind k, const Stmt *s) : K(k), S(s) {}
34
35  bool isOpened() const { return K == Opened; }
36  bool isClosed() const { return K == Closed; }
37  //bool isOpenFailed() const { return K == OpenFailed; }
38  //bool isEscaped() const { return K == Escaped; }
39
40  bool operator==(const StreamState &X) const {
41    return K == X.K && S == X.S;
42  }
43
44  static StreamState getOpened(const Stmt *s) { return StreamState(Opened, s); }
45  static StreamState getClosed(const Stmt *s) { return StreamState(Closed, s); }
46  static StreamState getOpenFailed(const Stmt *s) {
47    return StreamState(OpenFailed, s);
48  }
49  static StreamState getEscaped(const Stmt *s) {
50    return StreamState(Escaped, s);
51  }
52
53  void Profile(llvm::FoldingSetNodeID &ID) const {
54    ID.AddInteger(K);
55    ID.AddPointer(S);
56  }
57};
58
59class StreamChecker : public Checker<eval::Call,
60                                       check::DeadSymbols,
61                                       check::EndPath,
62                                       check::PreStmt<ReturnStmt> > {
63  mutable IdentifierInfo *II_fopen, *II_tmpfile, *II_fclose, *II_fread,
64                 *II_fwrite,
65                 *II_fseek, *II_ftell, *II_rewind, *II_fgetpos, *II_fsetpos,
66                 *II_clearerr, *II_feof, *II_ferror, *II_fileno;
67  mutable OwningPtr<BuiltinBug> BT_nullfp, BT_illegalwhence,
68                                      BT_doubleclose, BT_ResourceLeak;
69
70public:
71  StreamChecker()
72    : II_fopen(0), II_tmpfile(0) ,II_fclose(0), II_fread(0), II_fwrite(0),
73      II_fseek(0), II_ftell(0), II_rewind(0), II_fgetpos(0), II_fsetpos(0),
74      II_clearerr(0), II_feof(0), II_ferror(0), II_fileno(0) {}
75
76  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
77  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
78  void checkEndPath(CheckerContext &Ctx) const;
79  void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
80
81private:
82  void Fopen(CheckerContext &C, const CallExpr *CE) const;
83  void Tmpfile(CheckerContext &C, const CallExpr *CE) const;
84  void Fclose(CheckerContext &C, const CallExpr *CE) const;
85  void Fread(CheckerContext &C, const CallExpr *CE) const;
86  void Fwrite(CheckerContext &C, const CallExpr *CE) const;
87  void Fseek(CheckerContext &C, const CallExpr *CE) const;
88  void Ftell(CheckerContext &C, const CallExpr *CE) const;
89  void Rewind(CheckerContext &C, const CallExpr *CE) const;
90  void Fgetpos(CheckerContext &C, const CallExpr *CE) const;
91  void Fsetpos(CheckerContext &C, const CallExpr *CE) const;
92  void Clearerr(CheckerContext &C, const CallExpr *CE) const;
93  void Feof(CheckerContext &C, const CallExpr *CE) const;
94  void Ferror(CheckerContext &C, const CallExpr *CE) const;
95  void Fileno(CheckerContext &C, const CallExpr *CE) const;
96
97  void OpenFileAux(CheckerContext &C, const CallExpr *CE) const;
98
99  ProgramStateRef CheckNullStream(SVal SV, ProgramStateRef state,
100                                 CheckerContext &C) const;
101  ProgramStateRef CheckDoubleClose(const CallExpr *CE, ProgramStateRef state,
102                                 CheckerContext &C) const;
103};
104
105} // end anonymous namespace
106
107namespace clang {
108namespace ento {
109  template <>
110  struct ProgramStateTrait<StreamState>
111    : public ProgramStatePartialTrait<llvm::ImmutableMap<SymbolRef, StreamState> > {
112    static void *GDMIndex() { static int x; return &x; }
113  };
114}
115}
116
117bool StreamChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
118  const FunctionDecl *FD = C.getCalleeDecl(CE);
119  if (!FD || FD->getKind() != Decl::Function)
120    return false;
121
122  ASTContext &Ctx = C.getASTContext();
123  if (!II_fopen)
124    II_fopen = &Ctx.Idents.get("fopen");
125  if (!II_tmpfile)
126    II_tmpfile = &Ctx.Idents.get("tmpfile");
127  if (!II_fclose)
128    II_fclose = &Ctx.Idents.get("fclose");
129  if (!II_fread)
130    II_fread = &Ctx.Idents.get("fread");
131  if (!II_fwrite)
132    II_fwrite = &Ctx.Idents.get("fwrite");
133  if (!II_fseek)
134    II_fseek = &Ctx.Idents.get("fseek");
135  if (!II_ftell)
136    II_ftell = &Ctx.Idents.get("ftell");
137  if (!II_rewind)
138    II_rewind = &Ctx.Idents.get("rewind");
139  if (!II_fgetpos)
140    II_fgetpos = &Ctx.Idents.get("fgetpos");
141  if (!II_fsetpos)
142    II_fsetpos = &Ctx.Idents.get("fsetpos");
143  if (!II_clearerr)
144    II_clearerr = &Ctx.Idents.get("clearerr");
145  if (!II_feof)
146    II_feof = &Ctx.Idents.get("feof");
147  if (!II_ferror)
148    II_ferror = &Ctx.Idents.get("ferror");
149  if (!II_fileno)
150    II_fileno = &Ctx.Idents.get("fileno");
151
152  if (FD->getIdentifier() == II_fopen) {
153    Fopen(C, CE);
154    return true;
155  }
156  if (FD->getIdentifier() == II_tmpfile) {
157    Tmpfile(C, CE);
158    return true;
159  }
160  if (FD->getIdentifier() == II_fclose) {
161    Fclose(C, CE);
162    return true;
163  }
164  if (FD->getIdentifier() == II_fread) {
165    Fread(C, CE);
166    return true;
167  }
168  if (FD->getIdentifier() == II_fwrite) {
169    Fwrite(C, CE);
170    return true;
171  }
172  if (FD->getIdentifier() == II_fseek) {
173    Fseek(C, CE);
174    return true;
175  }
176  if (FD->getIdentifier() == II_ftell) {
177    Ftell(C, CE);
178    return true;
179  }
180  if (FD->getIdentifier() == II_rewind) {
181    Rewind(C, CE);
182    return true;
183  }
184  if (FD->getIdentifier() == II_fgetpos) {
185    Fgetpos(C, CE);
186    return true;
187  }
188  if (FD->getIdentifier() == II_fsetpos) {
189    Fsetpos(C, CE);
190    return true;
191  }
192  if (FD->getIdentifier() == II_clearerr) {
193    Clearerr(C, CE);
194    return true;
195  }
196  if (FD->getIdentifier() == II_feof) {
197    Feof(C, CE);
198    return true;
199  }
200  if (FD->getIdentifier() == II_ferror) {
201    Ferror(C, CE);
202    return true;
203  }
204  if (FD->getIdentifier() == II_fileno) {
205    Fileno(C, CE);
206    return true;
207  }
208
209  return false;
210}
211
212void StreamChecker::Fopen(CheckerContext &C, const CallExpr *CE) const {
213  OpenFileAux(C, CE);
214}
215
216void StreamChecker::Tmpfile(CheckerContext &C, const CallExpr *CE) const {
217  OpenFileAux(C, CE);
218}
219
220void StreamChecker::OpenFileAux(CheckerContext &C, const CallExpr *CE) const {
221  ProgramStateRef state = C.getState();
222  SValBuilder &svalBuilder = C.getSValBuilder();
223  const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
224  DefinedSVal RetVal =
225    cast<DefinedSVal>(svalBuilder.conjureSymbolVal(0, CE, LCtx,
226                                                   C.blockCount()));
227  state = state->BindExpr(CE, C.getLocationContext(), RetVal);
228
229  ConstraintManager &CM = C.getConstraintManager();
230  // Bifurcate the state into two: one with a valid FILE* pointer, the other
231  // with a NULL.
232  ProgramStateRef stateNotNull, stateNull;
233  llvm::tie(stateNotNull, stateNull) = CM.assumeDual(state, RetVal);
234
235  if (SymbolRef Sym = RetVal.getAsSymbol()) {
236    // if RetVal is not NULL, set the symbol's state to Opened.
237    stateNotNull =
238      stateNotNull->set<StreamState>(Sym,StreamState::getOpened(CE));
239    stateNull =
240      stateNull->set<StreamState>(Sym, StreamState::getOpenFailed(CE));
241
242    C.addTransition(stateNotNull);
243    C.addTransition(stateNull);
244  }
245}
246
247void StreamChecker::Fclose(CheckerContext &C, const CallExpr *CE) const {
248  ProgramStateRef state = CheckDoubleClose(CE, C.getState(), C);
249  if (state)
250    C.addTransition(state);
251}
252
253void StreamChecker::Fread(CheckerContext &C, const CallExpr *CE) const {
254  ProgramStateRef state = C.getState();
255  if (!CheckNullStream(state->getSVal(CE->getArg(3), C.getLocationContext()),
256                       state, C))
257    return;
258}
259
260void StreamChecker::Fwrite(CheckerContext &C, const CallExpr *CE) const {
261  ProgramStateRef state = C.getState();
262  if (!CheckNullStream(state->getSVal(CE->getArg(3), C.getLocationContext()),
263                       state, C))
264    return;
265}
266
267void StreamChecker::Fseek(CheckerContext &C, const CallExpr *CE) const {
268  ProgramStateRef state = C.getState();
269  if (!(state = CheckNullStream(state->getSVal(CE->getArg(0),
270                                               C.getLocationContext()), state, C)))
271    return;
272  // Check the legality of the 'whence' argument of 'fseek'.
273  SVal Whence = state->getSVal(CE->getArg(2), C.getLocationContext());
274  const nonloc::ConcreteInt *CI = dyn_cast<nonloc::ConcreteInt>(&Whence);
275
276  if (!CI)
277    return;
278
279  int64_t x = CI->getValue().getSExtValue();
280  if (x >= 0 && x <= 2)
281    return;
282
283  if (ExplodedNode *N = C.addTransition(state)) {
284    if (!BT_illegalwhence)
285      BT_illegalwhence.reset(new BuiltinBug("Illegal whence argument",
286					"The whence argument to fseek() should be "
287					"SEEK_SET, SEEK_END, or SEEK_CUR."));
288    BugReport *R = new BugReport(*BT_illegalwhence,
289				 BT_illegalwhence->getDescription(), N);
290    C.emitReport(R);
291  }
292}
293
294void StreamChecker::Ftell(CheckerContext &C, const CallExpr *CE) const {
295  ProgramStateRef state = C.getState();
296  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
297                       state, C))
298    return;
299}
300
301void StreamChecker::Rewind(CheckerContext &C, const CallExpr *CE) const {
302  ProgramStateRef state = C.getState();
303  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
304                       state, C))
305    return;
306}
307
308void StreamChecker::Fgetpos(CheckerContext &C, const CallExpr *CE) const {
309  ProgramStateRef state = C.getState();
310  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
311                       state, C))
312    return;
313}
314
315void StreamChecker::Fsetpos(CheckerContext &C, const CallExpr *CE) const {
316  ProgramStateRef state = C.getState();
317  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
318                       state, C))
319    return;
320}
321
322void StreamChecker::Clearerr(CheckerContext &C, const CallExpr *CE) const {
323  ProgramStateRef state = C.getState();
324  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
325                       state, C))
326    return;
327}
328
329void StreamChecker::Feof(CheckerContext &C, const CallExpr *CE) const {
330  ProgramStateRef state = C.getState();
331  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
332                       state, C))
333    return;
334}
335
336void StreamChecker::Ferror(CheckerContext &C, const CallExpr *CE) const {
337  ProgramStateRef state = C.getState();
338  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
339                       state, C))
340    return;
341}
342
343void StreamChecker::Fileno(CheckerContext &C, const CallExpr *CE) const {
344  ProgramStateRef state = C.getState();
345  if (!CheckNullStream(state->getSVal(CE->getArg(0), C.getLocationContext()),
346                       state, C))
347    return;
348}
349
350ProgramStateRef StreamChecker::CheckNullStream(SVal SV, ProgramStateRef state,
351                                    CheckerContext &C) const {
352  const DefinedSVal *DV = dyn_cast<DefinedSVal>(&SV);
353  if (!DV)
354    return 0;
355
356  ConstraintManager &CM = C.getConstraintManager();
357  ProgramStateRef stateNotNull, stateNull;
358  llvm::tie(stateNotNull, stateNull) = CM.assumeDual(state, *DV);
359
360  if (!stateNotNull && stateNull) {
361    if (ExplodedNode *N = C.generateSink(stateNull)) {
362      if (!BT_nullfp)
363        BT_nullfp.reset(new BuiltinBug("NULL stream pointer",
364                                     "Stream pointer might be NULL."));
365      BugReport *R =new BugReport(*BT_nullfp, BT_nullfp->getDescription(), N);
366      C.emitReport(R);
367    }
368    return 0;
369  }
370  return stateNotNull;
371}
372
373ProgramStateRef StreamChecker::CheckDoubleClose(const CallExpr *CE,
374                                               ProgramStateRef state,
375                                               CheckerContext &C) const {
376  SymbolRef Sym =
377    state->getSVal(CE->getArg(0), C.getLocationContext()).getAsSymbol();
378  if (!Sym)
379    return state;
380
381  const StreamState *SS = state->get<StreamState>(Sym);
382
383  // If the file stream is not tracked, return.
384  if (!SS)
385    return state;
386
387  // Check: Double close a File Descriptor could cause undefined behaviour.
388  // Conforming to man-pages
389  if (SS->isClosed()) {
390    ExplodedNode *N = C.generateSink();
391    if (N) {
392      if (!BT_doubleclose)
393        BT_doubleclose.reset(new BuiltinBug("Double fclose",
394                                        "Try to close a file Descriptor already"
395                                        " closed. Cause undefined behaviour."));
396      BugReport *R = new BugReport(*BT_doubleclose,
397                                   BT_doubleclose->getDescription(), N);
398      C.emitReport(R);
399    }
400    return NULL;
401  }
402
403  // Close the File Descriptor.
404  return state->set<StreamState>(Sym, StreamState::getClosed(CE));
405}
406
407void StreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
408                                     CheckerContext &C) const {
409  // TODO: Clean up the state.
410  for (SymbolReaper::dead_iterator I = SymReaper.dead_begin(),
411         E = SymReaper.dead_end(); I != E; ++I) {
412    SymbolRef Sym = *I;
413    ProgramStateRef state = C.getState();
414    const StreamState *SS = state->get<StreamState>(Sym);
415    // TODO: Shouldn't we have a continue here?
416    if (!SS)
417      return;
418
419    if (SS->isOpened()) {
420      ExplodedNode *N = C.generateSink();
421      if (N) {
422        if (!BT_ResourceLeak)
423          BT_ResourceLeak.reset(new BuiltinBug("Resource Leak",
424                         "Opened File never closed. Potential Resource leak."));
425        BugReport *R = new BugReport(*BT_ResourceLeak,
426                                     BT_ResourceLeak->getDescription(), N);
427        C.emitReport(R);
428      }
429    }
430  }
431}
432
433void StreamChecker::checkEndPath(CheckerContext &Ctx) const {
434  ProgramStateRef state = Ctx.getState();
435  typedef llvm::ImmutableMap<SymbolRef, StreamState> SymMap;
436  SymMap M = state->get<StreamState>();
437
438  for (SymMap::iterator I = M.begin(), E = M.end(); I != E; ++I) {
439    StreamState SS = I->second;
440    if (SS.isOpened()) {
441      ExplodedNode *N = Ctx.addTransition(state);
442      if (N) {
443        if (!BT_ResourceLeak)
444          BT_ResourceLeak.reset(new BuiltinBug("Resource Leak",
445                         "Opened File never closed. Potential Resource leak."));
446        BugReport *R = new BugReport(*BT_ResourceLeak,
447                                     BT_ResourceLeak->getDescription(), N);
448        Ctx.emitReport(R);
449      }
450    }
451  }
452}
453
454void StreamChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const {
455  const Expr *RetE = S->getRetValue();
456  if (!RetE)
457    return;
458
459  ProgramStateRef state = C.getState();
460  SymbolRef Sym = state->getSVal(RetE, C.getLocationContext()).getAsSymbol();
461
462  if (!Sym)
463    return;
464
465  const StreamState *SS = state->get<StreamState>(Sym);
466  if(!SS)
467    return;
468
469  if (SS->isOpened())
470    state = state->set<StreamState>(Sym, StreamState::getEscaped(S));
471
472  C.addTransition(state);
473}
474
475void ento::registerStreamChecker(CheckerManager &mgr) {
476  mgr.registerChecker<StreamChecker>();
477}
478