[cfe-commits] r166976 - in /cfe/trunk: lib/StaticAnalyzer/Checkers/CMakeLists.txt lib/StaticAnalyzer/Checkers/Checkers.td lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp test/Analysis/simple-stream-checks.c
Anna Zaks
ganna at apple.com
Mon Oct 29 15:51:50 PDT 2012
Author: zaks
Date: Mon Oct 29 17:51:50 2012
New Revision: 166976
URL: http://llvm.org/viewvc/llvm-project?rev=166976&view=rev
Log:
[analyzer] Add SimpleStreamChecker.
This is an example checker for catching fopen fclose API misuses.
Added:
cfe/trunk/lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp
cfe/trunk/test/Analysis/simple-stream-checks.c
Modified:
cfe/trunk/lib/StaticAnalyzer/Checkers/CMakeLists.txt
cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td
Modified: cfe/trunk/lib/StaticAnalyzer/Checkers/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Checkers/CMakeLists.txt?rev=166976&r1=166975&r2=166976&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Checkers/CMakeLists.txt (original)
+++ cfe/trunk/lib/StaticAnalyzer/Checkers/CMakeLists.txt Mon Oct 29 17:51:50 2012
@@ -31,6 +31,7 @@
DivZeroChecker.cpp
DynamicTypePropagation.cpp
ExprInspectionChecker.cpp
+ SimpleStreamChecker.cpp
FixedAddressChecker.cpp
GenericTaintChecker.cpp
IdempotentOperationChecker.cpp
Modified: cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td?rev=166976&r1=166975&r2=166976&view=diff
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td (original)
+++ cfe/trunk/lib/StaticAnalyzer/Checkers/Checkers.td Mon Oct 29 17:51:50 2012
@@ -303,6 +303,10 @@
HelpText<"Check stream handling functions">,
DescFile<"StreamChecker.cpp">;
+def SimpleStreamChecker : Checker<"SimpleStream">,
+ HelpText<"Check for misuses of stream APIs">,
+ DescFile<"SimpleStreamChecker.cpp">;
+
} // end "alpha.unix"
let ParentPackage = CString in {
Added: cfe/trunk/lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp?rev=166976&view=auto
==============================================================================
--- cfe/trunk/lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp (added)
+++ cfe/trunk/lib/StaticAnalyzer/Checkers/SimpleStreamChecker.cpp Mon Oct 29 17:51:50 2012
@@ -0,0 +1,229 @@
+//===-- SimpleStreamChecker.cpp -----------------------------------------*- C++ -*--//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines a checker for proper use of fopen/fclose APIs.
+// - If a file has been closed with fclose, it should not be accessed again.
+// Accessing a closed file results in undefined behavior.
+// - If a file was opened with fopen, it must be closed with fclose before
+// the execution ends. Failing to do so results in a resource leak.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+typedef llvm::SmallVector<SymbolRef, 2> SymbolVector;
+
+struct StreamState {
+ enum Kind { Opened, Closed } K;
+
+ StreamState(Kind InK) : K(InK) { }
+
+ bool isOpened() const { return K == Opened; }
+ bool isClosed() const { return K == Closed; }
+
+ static StreamState getOpened() { return StreamState(Opened); }
+ static StreamState getClosed() { return StreamState(Closed); }
+
+ bool operator==(const StreamState &X) const {
+ return K == X.K;
+ }
+ void Profile(llvm::FoldingSetNodeID &ID) const {
+ ID.AddInteger(K);
+ }
+};
+
+class SimpleStreamChecker: public Checker<check::PostStmt<CallExpr>,
+ check::PreStmt<CallExpr>,
+ check::DeadSymbols,
+ eval::Assume > {
+
+ mutable IdentifierInfo *IIfopen, *IIfclose;
+
+ mutable OwningPtr<BugType> DoubleCloseBugType;
+ mutable OwningPtr<BugType> LeakBugType;
+
+ void initIdentifierInfo(ASTContext &Ctx) const;
+
+ void reportDoubleClose(SymbolRef FileDescSym,
+ const CallExpr *Call,
+ CheckerContext &C) const;
+
+ ExplodedNode *reportLeaks(SymbolVector LeakedStreams,
+ CheckerContext &C) const;
+
+public:
+ SimpleStreamChecker() : IIfopen(0), IIfclose(0) {}
+
+ /// Process fopen.
+ void checkPostStmt(const CallExpr *Call, CheckerContext &C) const;
+ /// Process fclose.
+ void checkPreStmt(const CallExpr *Call, CheckerContext &C) const;
+
+ void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
+ ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond,
+ bool Assumption) const;
+
+};
+
+} // end anonymous namespace
+
+/// The state of the checker is a map from tracked stream symbols to their
+/// state. Let's store it in the GDM.
+REGISTER_MAP_WITH_GDM(StreamMap, SymbolRef, StreamState)
+
+void SimpleStreamChecker::checkPostStmt(const CallExpr *Call,
+ CheckerContext &C) const {
+ initIdentifierInfo(C.getASTContext());
+
+ if (C.getCalleeIdentifier(Call) != IIfopen)
+ return;
+
+ // Get the symbolic value corresponding to the file handle.
+ SymbolRef FileDesc = C.getSVal(Call).getAsSymbol();
+ if (!FileDesc)
+ return;
+
+ // Generate the next transition (an edge in the exploded graph).
+ ProgramStateRef State = C.getState();
+ State = State->set<StreamMap>(FileDesc, StreamState::getOpened());
+ C.addTransition(State);
+}
+
+void SimpleStreamChecker::checkPreStmt(const CallExpr *Call,
+ CheckerContext &C) const {
+ initIdentifierInfo(C.getASTContext());
+
+ if (C.getCalleeIdentifier(Call) != IIfclose)
+ return;
+ if (Call->getNumArgs() != 1)
+ return;
+
+ // Get the symbolic value corresponding to the file handle.
+ SymbolRef FileDesc = C.getSVal(Call->getArg(0)).getAsSymbol();
+ if (!FileDesc)
+ return;
+
+ // Check if the stream has already been closed.
+ ProgramStateRef State = C.getState();
+ const StreamState *SS = State->get<StreamMap>(FileDesc);
+ if (SS && SS->isClosed())
+ reportDoubleClose(FileDesc, Call, C);
+
+ // Generate the next transition, in which the stream is closed.
+ State = State->set<StreamMap>(FileDesc, StreamState::getClosed());
+ C.addTransition(State);
+}
+
+void SimpleStreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
+ CheckerContext &C) const {
+ ProgramStateRef State = C.getState();
+ StreamMap TrackedStreams = State->get<StreamMap>();
+ SymbolVector LeakedStreams;
+ for (StreamMap::iterator I = TrackedStreams.begin(),
+ E = TrackedStreams.end(); I != E; ++I) {
+ SymbolRef Sym = I->first;
+ if (SymReaper.isDead(Sym)) {
+ const StreamState &SS = I->second;
+ if (SS.isOpened())
+ LeakedStreams.push_back(Sym);
+
+ // Remove the dead symbol from the streams map.
+ State = State->remove<StreamMap>(Sym);
+ }
+ }
+
+ ExplodedNode *N = reportLeaks(LeakedStreams, C);
+ C.addTransition(State, N);
+}
+
+// If a symbolic region is assumed to NULL (or another constant), stop tracking
+// it - assuming that allocation failed on this path.
+ProgramStateRef SimpleStreamChecker::evalAssume(ProgramStateRef State,
+ SVal Cond,
+ bool Assumption) const {
+ StreamMap TrackedStreams = State->get<StreamMap>();
+ SymbolVector LeakedStreams;
+ for (StreamMap::iterator I = TrackedStreams.begin(),
+ E = TrackedStreams.end(); I != E; ++I) {
+ SymbolRef Sym = I->first;
+ if (State->getConstraintManager().isNull(State, Sym).isTrue())
+ State = State->remove<StreamMap>(Sym);
+ }
+ return State;
+}
+
+void SimpleStreamChecker::reportDoubleClose(SymbolRef FileDescSym,
+ const CallExpr *CallExpr,
+ CheckerContext &C) const {
+ // We reached a bug, stop exploring the path here by generating a sink.
+ ExplodedNode *ErrNode = C.generateSink();
+ // If this error node already exists, return.
+ if (!ErrNode)
+ return;
+
+ // Initialize the bug type.
+ if (!DoubleCloseBugType)
+ DoubleCloseBugType.reset(new BugType("Double fclose",
+ "Unix Stream API Error"));
+ // Generate the report.
+ BugReport *R = new BugReport(*DoubleCloseBugType,
+ "Closing a previously closed file stream", ErrNode);
+ R->addRange(CallExpr->getSourceRange());
+ R->markInteresting(FileDescSym);
+ C.EmitReport(R);
+}
+
+ExplodedNode *SimpleStreamChecker::reportLeaks(SymbolVector LeakedStreams,
+ CheckerContext &C) const {
+ ExplodedNode *Pred = C.getPredecessor();
+ if (LeakedStreams.empty())
+ return Pred;
+
+ // Generate an intermediate node representing the leak point.
+ static SimpleProgramPointTag Tag("StreamChecker : Leak");
+ ExplodedNode *ErrNode = C.addTransition(Pred->getState(), Pred, &Tag);
+ if (!ErrNode)
+ return Pred;
+
+ // Initialize the bug type.
+ if (!LeakBugType) {
+ LeakBugType.reset(new BuiltinBug("Resource Leak",
+ "Unix Stream API Error"));
+ // Sinks are higher importance bugs as well as calls to assert() or exit(0).
+ LeakBugType->setSuppressOnSink(true);
+ }
+
+ // Attach bug reports to the leak node.
+ for (llvm::SmallVector<SymbolRef, 2>::iterator
+ I = LeakedStreams.begin(), E = LeakedStreams.end(); I != E; ++I) {
+ BugReport *R = new BugReport(*LeakBugType,
+ "Opened file is never closed; potential resource leak", ErrNode);
+ C.EmitReport(R);
+ }
+
+ return ErrNode;
+}
+
+void SimpleStreamChecker::initIdentifierInfo(ASTContext &Ctx) const {
+ if (IIfopen)
+ return;
+ IIfopen = &Ctx.Idents.get("fopen");
+ IIfclose = &Ctx.Idents.get("fclose");
+}
+
+void ento::registerSimpleStreamChecker(CheckerManager &mgr) {
+ mgr.registerChecker<SimpleStreamChecker>();
+}
Added: cfe/trunk/test/Analysis/simple-stream-checks.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/simple-stream-checks.c?rev=166976&view=auto
==============================================================================
--- cfe/trunk/test/Analysis/simple-stream-checks.c (added)
+++ cfe/trunk/test/Analysis/simple-stream-checks.c Mon Oct 29 17:51:50 2012
@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,alpha.unix.SimpleStream -verify %s
+
+typedef struct __sFILE {
+ unsigned char *_p;
+} FILE;
+FILE *fopen(const char * restrict, const char * restrict) __asm("_" "fopen" );
+int fputc(int, FILE *);
+int fputs(const char * restrict, FILE * restrict) __asm("_" "fputs" );
+int fclose(FILE *);
+void exit(int);
+
+void checkDoubleFClose(int *Data) {
+ FILE *F = fopen("myfile.txt", "w");
+ if (F != 0) {
+ fputs ("fopen example", F);
+ if (!Data)
+ fclose(F);
+ else
+ fputc(*Data, F);
+ fclose(F); // expected-warning {{Closing a previously closed file stream}}
+ }
+}
+
+int checkLeak(int *Data) {
+ FILE *F = fopen("myfile.txt", "w");
+ if (F != 0) {
+ fputs ("fopen example", F);
+ }
+
+ if (Data) // expected-warning {{Opened file is never closed; potential resource leak}}
+ return *Data;
+ else
+ return 0;
+}
+
+void checkLeakFollowedByAssert(int *Data) {
+ FILE *F = fopen("myfile.txt", "w");
+ if (F != 0) {
+ fputs ("fopen example", F);
+ if (!Data)
+ exit(0);
+ fclose(F);
+ }
+}
More information about the cfe-commits
mailing list