Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 385 insertions, 0 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp
new file mode 100644
index 0000000..f601431
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/CallAndMessageChecker.cpp
@@ -0,0 +1,385 @@
+//===--- CallAndMessageChecker.cpp ------------------------------*- C++ -*--==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines CallAndMessageChecker, a builtin checker that checks for various
+// errors of call and objc message expressions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/AST/ParentMap.h"
+#include "clang/Basic/TargetInfo.h"
+#include "llvm/ADT/SmallString.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class CallAndMessageChecker
+  : public Checker< check::PreStmt<CallExpr>, check::PreObjCMessage > {
+  mutable OwningPtr<BugType> BT_call_null;
+  mutable OwningPtr<BugType> BT_call_undef;
+  mutable OwningPtr<BugType> BT_call_arg;
+  mutable OwningPtr<BugType> BT_msg_undef;
+  mutable OwningPtr<BugType> BT_objc_prop_undef;
+  mutable OwningPtr<BugType> BT_msg_arg;
+  mutable OwningPtr<BugType> BT_msg_ret;
+public:
+
+  void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
+  void checkPreObjCMessage(ObjCMessage msg, CheckerContext &C) const;
+
+private:
+  static void PreVisitProcessArgs(CheckerContext &C,CallOrObjCMessage callOrMsg,
+                             const char *BT_desc, OwningPtr<BugType> &BT);
+  static bool PreVisitProcessArg(CheckerContext &C, SVal V,SourceRange argRange,
+                                 const Expr *argEx,
+                                 const bool checkUninitFields,
+                                 const char *BT_desc,
+                                 OwningPtr<BugType> &BT);
+
+  static void EmitBadCall(BugType *BT, CheckerContext &C, const CallExpr *CE);
+  void emitNilReceiverBug(CheckerContext &C, const ObjCMessage &msg,
+                          ExplodedNode *N) const;
+
+  void HandleNilReceiver(CheckerContext &C,
+                         ProgramStateRef state,
+                         ObjCMessage msg) const;
+
+  static void LazyInit_BT(const char *desc, OwningPtr<BugType> &BT) {
+    if (!BT)
+      BT.reset(new BuiltinBug(desc));
+  }
+};
+} // end anonymous namespace
+
+void CallAndMessageChecker::EmitBadCall(BugType *BT, CheckerContext &C,
+                                        const CallExpr *CE) {
+  ExplodedNode *N = C.generateSink();
+  if (!N)
+    return;
+
+  BugReport *R = new BugReport(*BT, BT->getName(), N);
+  R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N,
+                               bugreporter::GetCalleeExpr(N), R));
+  C.EmitReport(R);
+}
+
+void CallAndMessageChecker::PreVisitProcessArgs(CheckerContext &C,
+                                                CallOrObjCMessage callOrMsg,
+                                                const char *BT_desc,
+                                                OwningPtr<BugType> &BT) {
+  // Don't check for uninitialized field values in arguments if the
+  // caller has a body that is available and we have the chance to inline it.
+  // This is a hack, but is a reasonable compromise betweens sometimes warning
+  // and sometimes not depending on if we decide to inline a function.
+  const Decl *D = callOrMsg.getDecl();
+  const bool checkUninitFields =
+    !(C.getAnalysisManager().shouldInlineCall() &&
+      (D && D->getBody()));
+  
+  for (unsigned i = 0, e = callOrMsg.getNumArgs(); i != e; ++i)
+    if (PreVisitProcessArg(C, callOrMsg.getArgSVal(i),
+                           callOrMsg.getArgSourceRange(i), callOrMsg.getArg(i),
+                           checkUninitFields,
+                           BT_desc, BT))
+      return;
+}
+
+bool CallAndMessageChecker::PreVisitProcessArg(CheckerContext &C,
+                                               SVal V, SourceRange argRange,
+                                               const Expr *argEx,
+                                               const bool checkUninitFields,
+                                               const char *BT_desc,
+                                               OwningPtr<BugType> &BT) {
+  if (V.isUndef()) {
+    if (ExplodedNode *N = C.generateSink()) {
+      LazyInit_BT(BT_desc, BT);
+
+      // Generate a report for this bug.
+      BugReport *R = new BugReport(*BT, BT->getName(), N);
+      R->addRange(argRange);
+      if (argEx)
+        R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N, argEx,
+                                                                   R));
+      C.EmitReport(R);
+    }
+    return true;
+  }
+
+  if (!checkUninitFields)
+    return false;
+  
+  if (const nonloc::LazyCompoundVal *LV =
+        dyn_cast<nonloc::LazyCompoundVal>(&V)) {
+
+    class FindUninitializedField {
+    public:
+      SmallVector<const FieldDecl *, 10> FieldChain;
+    private:
+      ASTContext &C;
+      StoreManager &StoreMgr;
+      MemRegionManager &MrMgr;
+      Store store;
+    public:
+      FindUninitializedField(ASTContext &c, StoreManager &storeMgr,
+                             MemRegionManager &mrMgr, Store s)
+      : C(c), StoreMgr(storeMgr), MrMgr(mrMgr), store(s) {}
+
+      bool Find(const TypedValueRegion *R) {
+        QualType T = R->getValueType();
+        if (const RecordType *RT = T->getAsStructureType()) {
+          const RecordDecl *RD = RT->getDecl()->getDefinition();
+          assert(RD && "Referred record has no definition");
+          for (RecordDecl::field_iterator I =
+               RD->field_begin(), E = RD->field_end(); I!=E; ++I) {
+            const FieldRegion *FR = MrMgr.getFieldRegion(*I, R);
+            FieldChain.push_back(*I);
+            T = (*I)->getType();
+            if (T->getAsStructureType()) {
+              if (Find(FR))
+                return true;
+            }
+            else {
+              const SVal &V = StoreMgr.getBinding(store, loc::MemRegionVal(FR));
+              if (V.isUndef())
+                return true;
+            }
+            FieldChain.pop_back();
+          }
+        }
+
+        return false;
+      }
+    };
+
+    const LazyCompoundValData *D = LV->getCVData();
+    FindUninitializedField F(C.getASTContext(),
+                             C.getState()->getStateManager().getStoreManager(),
+                             C.getSValBuilder().getRegionManager(),
+                             D->getStore());
+
+    if (F.Find(D->getRegion())) {
+      if (ExplodedNode *N = C.generateSink()) {
+        LazyInit_BT(BT_desc, BT);
+        SmallString<512> Str;
+        llvm::raw_svector_ostream os(Str);
+        os << "Passed-by-value struct argument contains uninitialized data";
+
+        if (F.FieldChain.size() == 1)
+          os << " (e.g., field: '" << *F.FieldChain[0] << "')";
+        else {
+          os << " (e.g., via the field chain: '";
+          bool first = true;
+          for (SmallVectorImpl<const FieldDecl *>::iterator
+               DI = F.FieldChain.begin(), DE = F.FieldChain.end(); DI!=DE;++DI){
+            if (first)
+              first = false;
+            else
+              os << '.';
+            os << **DI;
+          }
+          os << "')";
+        }
+
+        // Generate a report for this bug.
+        BugReport *R = new BugReport(*BT, os.str(), N);
+        R->addRange(argRange);
+
+        // FIXME: enhance track back for uninitialized value for arbitrary
+        // memregions
+        C.EmitReport(R);
+      }
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void CallAndMessageChecker::checkPreStmt(const CallExpr *CE,
+                                         CheckerContext &C) const{
+
+  const Expr *Callee = CE->getCallee()->IgnoreParens();
+  const LocationContext *LCtx = C.getLocationContext();
+  SVal L = C.getState()->getSVal(Callee, LCtx);
+
+  if (L.isUndef()) {
+    if (!BT_call_undef)
+      BT_call_undef.reset(new BuiltinBug("Called function pointer is an "
+                                         "uninitalized pointer value"));
+    EmitBadCall(BT_call_undef.get(), C, CE);
+    return;
+  }
+
+  if (isa<loc::ConcreteInt>(L)) {
+    if (!BT_call_null)
+      BT_call_null.reset(
+        new BuiltinBug("Called function pointer is null (null dereference)"));
+    EmitBadCall(BT_call_null.get(), C, CE);
+  }
+
+  PreVisitProcessArgs(C, CallOrObjCMessage(CE, C.getState(), LCtx),
+                      "Function call argument is an uninitialized value",
+                      BT_call_arg);
+}
+
+void CallAndMessageChecker::checkPreObjCMessage(ObjCMessage msg,
+                                                CheckerContext &C) const {
+
+  ProgramStateRef state = C.getState();
+  const LocationContext *LCtx = C.getLocationContext();
+
+  // FIXME: Handle 'super'?
+  if (const Expr *receiver = msg.getInstanceReceiver()) {
+    SVal recVal = state->getSVal(receiver, LCtx);
+    if (recVal.isUndef()) {
+      if (ExplodedNode *N = C.generateSink()) {
+        BugType *BT = 0;
+        if (msg.isPureMessageExpr()) {
+          if (!BT_msg_undef)
+            BT_msg_undef.reset(new BuiltinBug("Receiver in message expression "
+                                              "is an uninitialized value"));
+          BT = BT_msg_undef.get();
+        }
+        else {
+          if (!BT_objc_prop_undef)
+            BT_objc_prop_undef.reset(new BuiltinBug("Property access on an "
+                                              "uninitialized object pointer"));
+          BT = BT_objc_prop_undef.get();
+        }
+        BugReport *R =
+          new BugReport(*BT, BT->getName(), N);
+        R->addRange(receiver->getSourceRange());
+        R->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N,
+                                                                   receiver,
+                                                                   R));
+        C.EmitReport(R);
+      }
+      return;
+    } else {
+      // Bifurcate the state into nil and non-nil ones.
+      DefinedOrUnknownSVal receiverVal = cast<DefinedOrUnknownSVal>(recVal);
+  
+      ProgramStateRef notNilState, nilState;
+      llvm::tie(notNilState, nilState) = state->assume(receiverVal);
+  
+      // Handle receiver must be nil.
+      if (nilState && !notNilState) {
+        HandleNilReceiver(C, state, msg);
+        return;
+      }
+    }
+  }
+
+  const char *bugDesc = msg.isPropertySetter() ?
+                     "Argument for property setter is an uninitialized value"
+                   : "Argument in message expression is an uninitialized value";
+  // Check for any arguments that are uninitialized/undefined.
+  PreVisitProcessArgs(C, CallOrObjCMessage(msg, state, LCtx),
+                      bugDesc, BT_msg_arg);
+}
+
+void CallAndMessageChecker::emitNilReceiverBug(CheckerContext &C,
+                                               const ObjCMessage &msg,
+                                               ExplodedNode *N) const {
+
+  if (!BT_msg_ret)
+    BT_msg_ret.reset(
+      new BuiltinBug("Receiver in message expression is "
+                     "'nil' and returns a garbage value"));
+
+  SmallString<200> buf;
+  llvm::raw_svector_ostream os(buf);
+  os << "The receiver of message '" << msg.getSelector().getAsString()
+     << "' is nil and returns a value of type '"
+     << msg.getType(C.getASTContext()).getAsString() << "' that will be garbage";
+
+  BugReport *report = new BugReport(*BT_msg_ret, os.str(), N);
+  if (const Expr *receiver = msg.getInstanceReceiver()) {
+    report->addRange(receiver->getSourceRange());
+    report->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N,
+                                                                    receiver,
+                                                                    report));
+  }
+  C.EmitReport(report);
+}
+
+static bool supportsNilWithFloatRet(const llvm::Triple &triple) {
+  return (triple.getVendor() == llvm::Triple::Apple &&
+          (triple.getOS() == llvm::Triple::IOS ||
+           !triple.isMacOSXVersionLT(10,5)));
+}
+
+void CallAndMessageChecker::HandleNilReceiver(CheckerContext &C,
+                                              ProgramStateRef state,
+                                              ObjCMessage msg) const {
+  ASTContext &Ctx = C.getASTContext();
+
+  // Check the return type of the message expression.  A message to nil will
+  // return different values depending on the return type and the architecture.
+  QualType RetTy = msg.getType(Ctx);
+  CanQualType CanRetTy = Ctx.getCanonicalType(RetTy);
+  const LocationContext *LCtx = C.getLocationContext();
+
+  if (CanRetTy->isStructureOrClassType()) {
+    // Structure returns are safe since the compiler zeroes them out.
+    SVal V = C.getSValBuilder().makeZeroVal(msg.getType(Ctx));
+    C.addTransition(state->BindExpr(msg.getMessageExpr(), LCtx, V));
+    return;
+  }
+
+  // Other cases: check if sizeof(return type) > sizeof(void*)
+  if (CanRetTy != Ctx.VoidTy && C.getLocationContext()->getParentMap()
+                                  .isConsumedExpr(msg.getMessageExpr())) {
+    // Compute: sizeof(void *) and sizeof(return type)
+    const uint64_t voidPtrSize = Ctx.getTypeSize(Ctx.VoidPtrTy);
+    const uint64_t returnTypeSize = Ctx.getTypeSize(CanRetTy);
+
+    if (voidPtrSize < returnTypeSize &&
+        !(supportsNilWithFloatRet(Ctx.getTargetInfo().getTriple()) &&
+          (Ctx.FloatTy == CanRetTy ||
+           Ctx.DoubleTy == CanRetTy ||
+           Ctx.LongDoubleTy == CanRetTy ||
+           Ctx.LongLongTy == CanRetTy ||
+           Ctx.UnsignedLongLongTy == CanRetTy))) {
+      if (ExplodedNode *N = C.generateSink(state))
+        emitNilReceiverBug(C, msg, N);
+      return;
+    }
+
+    // Handle the safe cases where the return value is 0 if the
+    // receiver is nil.
+    //
+    // FIXME: For now take the conservative approach that we only
+    // return null values if we *know* that the receiver is nil.
+    // This is because we can have surprises like:
+    //
+    //   ... = [[NSScreens screens] objectAtIndex:0];
+    //
+    // What can happen is that [... screens] could return nil, but
+    // it most likely isn't nil.  We should assume the semantics
+    // of this case unless we have *a lot* more knowledge.
+    //
+    SVal V = C.getSValBuilder().makeZeroVal(msg.getType(Ctx));
+    C.addTransition(state->BindExpr(msg.getMessageExpr(), LCtx, V));
+    return;
+  }
+
+  C.addTransition(state);
+}
+
+void ento::registerCallAndMessageChecker(CheckerManager &mgr) {
+  mgr.registerChecker<CallAndMessageChecker>();
+}