[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 20:57:52 PDT 2012
On Oct 29, 2012, at 4:19 PM, Jordan Rose wrote:
>
> On Oct 29, 2012, at 15:51 , Anna Zaks <ganna at apple.com> wrote:
>
>> 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
>
> This list is supposed to be alphabetical (for convenience, not correctness).
>
>
>> 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;
>
> Why generate an intermediate node at all? I feel like we could just generate the transition in the caller and then report all the leaks here.
>
>
>> + // 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).
>
> Perhaps:
> s/are higher importance/represent more important/
>
> …but also assert isn't really a sink.
>
Why not?
>
>> + 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);
>
> No markInteresting?
makrInteresting is easy
> No attempt to say which file it is? …actually, that's rather hard. Hm.
Yes. Error reporting on leaks is not yet done. I'll add a TODO.
>
>> + 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);
>> + }
>> +}
>>
>>
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>
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