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llvm-project/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp

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//===-- StreamChecker.cpp -----------------------------------------*- C++ -*--//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines checkers that model and check stream handling functions.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
#include <functional>
using namespace clang;
using namespace ento;
using namespace std::placeholders;
//===----------------------------------------------------------------------===//
// Definition of state data structures.
//===----------------------------------------------------------------------===//
namespace {
struct FnDescription;
/// State of the stream error flags.
/// Sometimes it is not known to the checker what error flags are set.
/// This is indicated by setting more than one flag to true.
/// This is an optimization to avoid state splits.
/// A stream can either be in FEOF or FERROR but not both at the same time.
/// Multiple flags are set to handle the corresponding states together.
struct StreamErrorState {
/// The stream can be in state where none of the error flags set.
bool NoError = true;
/// The stream can be in state where the EOF indicator is set.
bool FEof = false;
/// The stream can be in state where the error indicator is set.
bool FError = false;
bool isNoError() const { return NoError && !FEof && !FError; }
bool isFEof() const { return !NoError && FEof && !FError; }
bool isFError() const { return !NoError && !FEof && FError; }
bool operator==(const StreamErrorState &ES) const {
return NoError == ES.NoError && FEof == ES.FEof && FError == ES.FError;
}
bool operator!=(const StreamErrorState &ES) const { return !(*this == ES); }
StreamErrorState operator|(const StreamErrorState &E) const {
return {NoError || E.NoError, FEof || E.FEof, FError || E.FError};
}
StreamErrorState operator&(const StreamErrorState &E) const {
return {NoError && E.NoError, FEof && E.FEof, FError && E.FError};
}
StreamErrorState operator~() const { return {!NoError, !FEof, !FError}; }
/// Returns if the StreamErrorState is a valid object.
operator bool() const { return NoError || FEof || FError; }
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.AddBoolean(NoError);
ID.AddBoolean(FEof);
ID.AddBoolean(FError);
}
};
const StreamErrorState ErrorNone{true, false, false};
const StreamErrorState ErrorFEof{false, true, false};
const StreamErrorState ErrorFError{false, false, true};
/// Full state information about a stream pointer.
struct StreamState {
/// The last file operation called in the stream.
const FnDescription *LastOperation;
/// State of a stream symbol.
/// FIXME: We need maybe an "escaped" state later.
enum KindTy {
Opened, /// Stream is opened.
Closed, /// Closed stream (an invalid stream pointer after it was closed).
OpenFailed /// The last open operation has failed.
} State;
/// State of the error flags.
/// Ignored in non-opened stream state but must be NoError.
StreamErrorState const ErrorState;
/// Indicate if the file has an "indeterminate file position indicator".
/// This can be set at a failing read or write or seek operation.
/// If it is set no more read or write is allowed.
/// This value is not dependent on the stream error flags:
/// The error flag may be cleared with `clearerr` but the file position
/// remains still indeterminate.
/// This value applies to all error states in ErrorState except FEOF.
/// An EOF+indeterminate state is the same as EOF state.
bool const FilePositionIndeterminate = false;
StreamState(const FnDescription *L, KindTy S, const StreamErrorState &ES,
bool IsFilePositionIndeterminate)
: LastOperation(L), State(S), ErrorState(ES),
FilePositionIndeterminate(IsFilePositionIndeterminate) {
assert((!ES.isFEof() || !IsFilePositionIndeterminate) &&
"FilePositionIndeterminate should be false in FEof case.");
assert((State == Opened || ErrorState.isNoError()) &&
"ErrorState should be None in non-opened stream state.");
}
bool isOpened() const { return State == Opened; }
bool isClosed() const { return State == Closed; }
bool isOpenFailed() const { return State == OpenFailed; }
bool operator==(const StreamState &X) const {
// In not opened state error state should always NoError, so comparison
// here is no problem.
return LastOperation == X.LastOperation && State == X.State &&
ErrorState == X.ErrorState &&
FilePositionIndeterminate == X.FilePositionIndeterminate;
}
static StreamState getOpened(const FnDescription *L,
const StreamErrorState &ES = ErrorNone,
bool IsFilePositionIndeterminate = false) {
return StreamState{L, Opened, ES, IsFilePositionIndeterminate};
}
static StreamState getClosed(const FnDescription *L) {
return StreamState{L, Closed, {}, false};
}
static StreamState getOpenFailed(const FnDescription *L) {
return StreamState{L, OpenFailed, {}, false};
}
void Profile(llvm::FoldingSetNodeID &ID) const {
ID.AddPointer(LastOperation);
ID.AddInteger(State);
ID.AddInteger(ErrorState);
ID.AddBoolean(FilePositionIndeterminate);
}
};
} // namespace
//===----------------------------------------------------------------------===//
// StreamChecker class and utility functions.
//===----------------------------------------------------------------------===//
namespace {
class StreamChecker;
using FnCheck = std::function<void(const StreamChecker *, const FnDescription *,
const CallEvent &, CheckerContext &)>;
using ArgNoTy = unsigned int;
static const ArgNoTy ArgNone = std::numeric_limits<ArgNoTy>::max();
struct FnDescription {
FnCheck PreFn;
FnCheck EvalFn;
ArgNoTy StreamArgNo;
};
/// Get the value of the stream argument out of the passed call event.
/// The call should contain a function that is described by Desc.
SVal getStreamArg(const FnDescription *Desc, const CallEvent &Call) {
assert(Desc && Desc->StreamArgNo != ArgNone &&
"Try to get a non-existing stream argument.");
return Call.getArgSVal(Desc->StreamArgNo);
}
/// Create a conjured symbol return value for a call expression.
DefinedSVal makeRetVal(CheckerContext &C, const CallExpr *CE) {
assert(CE && "Expecting a call expression.");
const LocationContext *LCtx = C.getLocationContext();
return C.getSValBuilder()
.conjureSymbolVal(nullptr, CE, LCtx, C.blockCount())
.castAs<DefinedSVal>();
}
ProgramStateRef bindAndAssumeTrue(ProgramStateRef State, CheckerContext &C,
const CallExpr *CE) {
DefinedSVal RetVal = makeRetVal(C, CE);
State = State->BindExpr(CE, C.getLocationContext(), RetVal);
State = State->assume(RetVal, true);
assert(State && "Assumption on new value should not fail.");
return State;
}
ProgramStateRef bindInt(uint64_t Value, ProgramStateRef State,
CheckerContext &C, const CallExpr *CE) {
State = State->BindExpr(CE, C.getLocationContext(),
C.getSValBuilder().makeIntVal(Value, false));
return State;
}
class StreamChecker : public Checker<check::PreCall, eval::Call,
check::DeadSymbols, check::PointerEscape> {
BugType BT_FileNull{this, "NULL stream pointer", "Stream handling error"};
BugType BT_UseAfterClose{this, "Closed stream", "Stream handling error"};
BugType BT_UseAfterOpenFailed{this, "Invalid stream",
"Stream handling error"};
BugType BT_IndeterminatePosition{this, "Invalid stream state",
"Stream handling error"};
BugType BT_IllegalWhence{this, "Illegal whence argument",
"Stream handling error"};
BugType BT_StreamEof{this, "Stream already in EOF", "Stream handling error"};
BugType BT_ResourceLeak{this, "Resource leak", "Stream handling error",
/*SuppressOnSink =*/true};
public:
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
bool evalCall(const CallEvent &Call, CheckerContext &C) const;
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
ProgramStateRef checkPointerEscape(ProgramStateRef State,
const InvalidatedSymbols &Escaped,
const CallEvent *Call,
PointerEscapeKind Kind) const;
/// If true, evaluate special testing stream functions.
bool TestMode = false;
const BugType *getBT_StreamEof() const { return &BT_StreamEof; }
private:
CallDescriptionMap<FnDescription> FnDescriptions = {
{{"fopen"}, {nullptr, &StreamChecker::evalFopen, ArgNone}},
{{"freopen", 3},
{&StreamChecker::preFreopen, &StreamChecker::evalFreopen, 2}},
{{"tmpfile"}, {nullptr, &StreamChecker::evalFopen, ArgNone}},
{{"fclose", 1},
{&StreamChecker::preDefault, &StreamChecker::evalFclose, 0}},
{{"fread", 4},
{&StreamChecker::preFread,
std::bind(&StreamChecker::evalFreadFwrite, _1, _2, _3, _4, true), 3}},
{{"fwrite", 4},
{&StreamChecker::preFwrite,
std::bind(&StreamChecker::evalFreadFwrite, _1, _2, _3, _4, false), 3}},
{{"fseek", 3}, {&StreamChecker::preFseek, &StreamChecker::evalFseek, 0}},
{{"ftell", 1}, {&StreamChecker::preDefault, nullptr, 0}},
{{"rewind", 1}, {&StreamChecker::preDefault, nullptr, 0}},
{{"fgetpos", 2}, {&StreamChecker::preDefault, nullptr, 0}},
{{"fsetpos", 2}, {&StreamChecker::preDefault, nullptr, 0}},
{{"clearerr", 1},
{&StreamChecker::preDefault, &StreamChecker::evalClearerr, 0}},
{{"feof", 1},
{&StreamChecker::preDefault,
std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFEof),
0}},
{{"ferror", 1},
{&StreamChecker::preDefault,
std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFError),
0}},
{{"fileno", 1}, {&StreamChecker::preDefault, nullptr, 0}},
};
CallDescriptionMap<FnDescription> FnTestDescriptions = {
{{"StreamTesterChecker_make_feof_stream", 1},
{nullptr,
std::bind(&StreamChecker::evalSetFeofFerror, _1, _2, _3, _4, ErrorFEof),
0}},
{{"StreamTesterChecker_make_ferror_stream", 1},
{nullptr,
std::bind(&StreamChecker::evalSetFeofFerror, _1, _2, _3, _4,
ErrorFError),
0}},
};
void evalFopen(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void preFreopen(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void evalFreopen(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void evalFclose(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void preFread(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void preFwrite(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void evalFreadFwrite(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C, bool IsFread) const;
void preFseek(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void evalFseek(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void preDefault(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void evalClearerr(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
void evalFeofFerror(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C,
const StreamErrorState &ErrorKind) const;
void evalSetFeofFerror(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C,
const StreamErrorState &ErrorKind) const;
/// Check that the stream (in StreamVal) is not NULL.
/// If it can only be NULL a fatal error is emitted and nullptr returned.
/// Otherwise the return value is a new state where the stream is constrained
/// to be non-null.
ProgramStateRef ensureStreamNonNull(SVal StreamVal, const Expr *StreamE,
CheckerContext &C,
ProgramStateRef State) const;
/// Check that the stream is the opened state.
/// If the stream is known to be not opened an error is generated
/// and nullptr returned, otherwise the original state is returned.
ProgramStateRef ensureStreamOpened(SVal StreamVal, CheckerContext &C,
ProgramStateRef State) const;
/// Check that the stream has not an invalid ("indeterminate") file position,
/// generate warning for it.
/// (EOF is not an invalid position.)
/// The returned state can be nullptr if a fatal error was generated.
/// It can return non-null state if the stream has not an invalid position or
/// there is execution path with non-invalid position.
ProgramStateRef
ensureNoFilePositionIndeterminate(SVal StreamVal, CheckerContext &C,
ProgramStateRef State) const;
/// Check the legality of the 'whence' argument of 'fseek'.
/// Generate error and return nullptr if it is found to be illegal.
/// Otherwise returns the state.
/// (State is not changed here because the "whence" value is already known.)
ProgramStateRef ensureFseekWhenceCorrect(SVal WhenceVal, CheckerContext &C,
ProgramStateRef State) const;
/// Generate warning about stream in EOF state.
/// There will be always a state transition into the passed State,
/// by the new non-fatal error node or (if failed) a normal transition,
/// to ensure uniform handling.
void reportFEofWarning(SymbolRef StreamSym, CheckerContext &C,
ProgramStateRef State) const;
/// Emit resource leak warnings for the given symbols.
/// Createn a non-fatal error node for these, and returns it (if any warnings
/// were generated). Return value is non-null.
ExplodedNode *reportLeaks(const SmallVector<SymbolRef, 2> &LeakedSyms,
CheckerContext &C, ExplodedNode *Pred) const;
/// Find the description data of the function called by a call event.
/// Returns nullptr if no function is recognized.
const FnDescription *lookupFn(const CallEvent &Call) const {
// Recognize "global C functions" with only integral or pointer arguments
// (and matching name) as stream functions.
if (!Call.isGlobalCFunction())
return nullptr;
for (auto P : Call.parameters()) {
QualType T = P->getType();
if (!T->isIntegralOrEnumerationType() && !T->isPointerType())
return nullptr;
}
return FnDescriptions.lookup(Call);
}
/// Generate a message for BugReporterVisitor if the stored symbol is
/// marked as interesting by the actual bug report.
// FIXME: Use lambda instead.
struct NoteFn {
const BugType *BT_ResourceLeak;
SymbolRef StreamSym;
std::string Message;
std::string operator()(PathSensitiveBugReport &BR) const {
if (BR.isInteresting(StreamSym) && &BR.getBugType() == BT_ResourceLeak)
return Message;
return "";
}
};
const NoteTag *constructNoteTag(CheckerContext &C, SymbolRef StreamSym,
const std::string &Message) const {
return C.getNoteTag(NoteFn{&BT_ResourceLeak, StreamSym, Message});
}
const NoteTag *constructSetEofNoteTag(CheckerContext &C,
SymbolRef StreamSym) const {
return C.getNoteTag([this, StreamSym](PathSensitiveBugReport &BR) {
if (!BR.isInteresting(StreamSym) ||
&BR.getBugType() != this->getBT_StreamEof())
return "";
BR.markNotInteresting(StreamSym);
return "Assuming stream reaches end-of-file here";
});
}
/// Searches for the ExplodedNode where the file descriptor was acquired for
/// StreamSym.
static const ExplodedNode *getAcquisitionSite(const ExplodedNode *N,
SymbolRef StreamSym,
CheckerContext &C);
};
} // end anonymous namespace
// This map holds the state of a stream.
// The stream is identified with a SymbolRef that is created when a stream
// opening function is modeled by the checker.
REGISTER_MAP_WITH_PROGRAMSTATE(StreamMap, SymbolRef, StreamState)
inline void assertStreamStateOpened(const StreamState *SS) {
assert(SS->isOpened() &&
"Previous create of error node for non-opened stream failed?");
}
const ExplodedNode *StreamChecker::getAcquisitionSite(const ExplodedNode *N,
SymbolRef StreamSym,
CheckerContext &C) {
ProgramStateRef State = N->getState();
// When bug type is resource leak, exploded node N may not have state info
// for leaked file descriptor, but predecessor should have it.
if (!State->get<StreamMap>(StreamSym))
N = N->getFirstPred();
const ExplodedNode *Pred = N;
while (N) {
State = N->getState();
if (!State->get<StreamMap>(StreamSym))
return Pred;
Pred = N;
N = N->getFirstPred();
}
return nullptr;
}
//===----------------------------------------------------------------------===//
// Methods of StreamChecker.
//===----------------------------------------------------------------------===//
void StreamChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
const FnDescription *Desc = lookupFn(Call);
if (!Desc || !Desc->PreFn)
return;
Desc->PreFn(this, Desc, Call, C);
}
bool StreamChecker::evalCall(const CallEvent &Call, CheckerContext &C) const {
const FnDescription *Desc = lookupFn(Call);
if (!Desc && TestMode)
Desc = FnTestDescriptions.lookup(Call);
if (!Desc || !Desc->EvalFn)
return false;
Desc->EvalFn(this, Desc, Call, C);
return C.isDifferent();
}
void StreamChecker::evalFopen(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
if (!CE)
return;
DefinedSVal RetVal = makeRetVal(C, CE);
SymbolRef RetSym = RetVal.getAsSymbol();
assert(RetSym && "RetVal must be a symbol here.");
State = State->BindExpr(CE, C.getLocationContext(), RetVal);
// Bifurcate the state into two: one with a valid FILE* pointer, the other
// with a NULL.
ProgramStateRef StateNotNull, StateNull;
std::tie(StateNotNull, StateNull) =
C.getConstraintManager().assumeDual(State, RetVal);
StateNotNull =
StateNotNull->set<StreamMap>(RetSym, StreamState::getOpened(Desc));
StateNull =
StateNull->set<StreamMap>(RetSym, StreamState::getOpenFailed(Desc));
C.addTransition(StateNotNull,
constructNoteTag(C, RetSym, "Stream opened here"));
C.addTransition(StateNull);
}
void StreamChecker::preFreopen(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
// Do not allow NULL as passed stream pointer but allow a closed stream.
ProgramStateRef State = C.getState();
State = ensureStreamNonNull(getStreamArg(Desc, Call),
Call.getArgExpr(Desc->StreamArgNo), C, State);
if (!State)
return;
C.addTransition(State);
}
void StreamChecker::evalFreopen(const FnDescription *Desc,
const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
auto *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
if (!CE)
return;
Optional<DefinedSVal> StreamVal =
getStreamArg(Desc, Call).getAs<DefinedSVal>();
if (!StreamVal)
return;
SymbolRef StreamSym = StreamVal->getAsSymbol();
// Do not care about concrete values for stream ("(FILE *)0x12345"?).
// FIXME: Can be stdin, stdout, stderr such values?
if (!StreamSym)
return;
// Do not handle untracked stream. It is probably escaped.
if (!State->get<StreamMap>(StreamSym))
return;
// Generate state for non-failed case.
// Return value is the passed stream pointer.
// According to the documentations, the stream is closed first
// but any close error is ignored. The state changes to (or remains) opened.
ProgramStateRef StateRetNotNull =
State->BindExpr(CE, C.getLocationContext(), *StreamVal);
// Generate state for NULL return value.
// Stream switches to OpenFailed state.
ProgramStateRef StateRetNull = State->BindExpr(CE, C.getLocationContext(),
C.getSValBuilder().makeNull());
StateRetNotNull =
StateRetNotNull->set<StreamMap>(StreamSym, StreamState::getOpened(Desc));
StateRetNull =
StateRetNull->set<StreamMap>(StreamSym, StreamState::getOpenFailed(Desc));
C.addTransition(StateRetNotNull,
constructNoteTag(C, StreamSym, "Stream reopened here"));
C.addTransition(StateRetNull);
}
void StreamChecker::evalFclose(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SymbolRef Sym = getStreamArg(Desc, Call).getAsSymbol();
if (!Sym)
return;
const StreamState *SS = State->get<StreamMap>(Sym);
if (!SS)
return;
assertStreamStateOpened(SS);
// Close the File Descriptor.
// Regardless if the close fails or not, stream becomes "closed"
// and can not be used any more.
State = State->set<StreamMap>(Sym, StreamState::getClosed(Desc));
C.addTransition(State);
}
void StreamChecker::preFread(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SVal StreamVal = getStreamArg(Desc, Call);
State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
State);
if (!State)
return;
State = ensureStreamOpened(StreamVal, C, State);
if (!State)
return;
State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
if (!State)
return;
SymbolRef Sym = StreamVal.getAsSymbol();
if (Sym && State->get<StreamMap>(Sym)) {
const StreamState *SS = State->get<StreamMap>(Sym);
if (SS->ErrorState & ErrorFEof)
reportFEofWarning(Sym, C, State);
} else {
C.addTransition(State);
}
}
void StreamChecker::preFwrite(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SVal StreamVal = getStreamArg(Desc, Call);
State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
State);
if (!State)
return;
State = ensureStreamOpened(StreamVal, C, State);
if (!State)
return;
State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
if (!State)
return;
C.addTransition(State);
}
void StreamChecker::evalFreadFwrite(const FnDescription *Desc,
const CallEvent &Call, CheckerContext &C,
bool IsFread) const {
ProgramStateRef State = C.getState();
SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
if (!StreamSym)
return;
const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
if (!CE)
return;
Optional<NonLoc> SizeVal = Call.getArgSVal(1).getAs<NonLoc>();
if (!SizeVal)
return;
Optional<NonLoc> NMembVal = Call.getArgSVal(2).getAs<NonLoc>();
if (!NMembVal)
return;
const StreamState *OldSS = State->get<StreamMap>(StreamSym);
if (!OldSS)
return;
assertStreamStateOpened(OldSS);
// C'99 standard, §7.19.8.1.3, the return value of fread:
// The fread function returns the number of elements successfully read, which
// may be less than nmemb if a read error or end-of-file is encountered. If
// size or nmemb is zero, fread returns zero and the contents of the array and
// the state of the stream remain unchanged.
if (State->isNull(*SizeVal).isConstrainedTrue() ||
State->isNull(*NMembVal).isConstrainedTrue()) {
// This is the "size or nmemb is zero" case.
// Just return 0, do nothing more (not clear the error flags).
State = bindInt(0, State, C, CE);
C.addTransition(State);
return;
}
// Generate a transition for the success state.
// If we know the state to be FEOF at fread, do not add a success state.
if (!IsFread || (OldSS->ErrorState != ErrorFEof)) {
ProgramStateRef StateNotFailed =
State->BindExpr(CE, C.getLocationContext(), *NMembVal);
if (StateNotFailed) {
StateNotFailed = StateNotFailed->set<StreamMap>(
StreamSym, StreamState::getOpened(Desc));
C.addTransition(StateNotFailed);
}
}
// Add transition for the failed state.
Optional<NonLoc> RetVal = makeRetVal(C, CE).castAs<NonLoc>();
assert(RetVal && "Value should be NonLoc.");
ProgramStateRef StateFailed =
State->BindExpr(CE, C.getLocationContext(), *RetVal);
if (!StateFailed)
return;
auto Cond = C.getSValBuilder()
.evalBinOpNN(State, BO_LT, *RetVal, *NMembVal,
C.getASTContext().IntTy)
.getAs<DefinedOrUnknownSVal>();
if (!Cond)
return;
StateFailed = StateFailed->assume(*Cond, true);
if (!StateFailed)
return;
StreamErrorState NewES;
if (IsFread)
NewES =
(OldSS->ErrorState == ErrorFEof) ? ErrorFEof : ErrorFEof | ErrorFError;
else
NewES = ErrorFError;
// If a (non-EOF) error occurs, the resulting value of the file position
// indicator for the stream is indeterminate.
StreamState NewSS = StreamState::getOpened(Desc, NewES, !NewES.isFEof());
StateFailed = StateFailed->set<StreamMap>(StreamSym, NewSS);
if (IsFread && OldSS->ErrorState != ErrorFEof)
C.addTransition(StateFailed, constructSetEofNoteTag(C, StreamSym));
else
C.addTransition(StateFailed);
}
void StreamChecker::preFseek(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SVal StreamVal = getStreamArg(Desc, Call);
State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
State);
if (!State)
return;
State = ensureStreamOpened(StreamVal, C, State);
if (!State)
return;
State = ensureFseekWhenceCorrect(Call.getArgSVal(2), C, State);
if (!State)
return;
C.addTransition(State);
}
void StreamChecker::evalFseek(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
if (!StreamSym)
return;
const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
if (!CE)
return;
// Ignore the call if the stream is not tracked.
if (!State->get<StreamMap>(StreamSym))
return;
DefinedSVal RetVal = makeRetVal(C, CE);
// Make expression result.
State = State->BindExpr(CE, C.getLocationContext(), RetVal);
// Bifurcate the state into failed and non-failed.
// Return zero on success, nonzero on error.
ProgramStateRef StateNotFailed, StateFailed;
std::tie(StateFailed, StateNotFailed) =
C.getConstraintManager().assumeDual(State, RetVal);
// Reset the state to opened with no error.
StateNotFailed =
StateNotFailed->set<StreamMap>(StreamSym, StreamState::getOpened(Desc));
// We get error.
// It is possible that fseek fails but sets none of the error flags.
// If fseek failed, assume that the file position becomes indeterminate in any
// case.
StateFailed = StateFailed->set<StreamMap>(
StreamSym,
StreamState::getOpened(Desc, ErrorNone | ErrorFEof | ErrorFError, true));
C.addTransition(StateNotFailed);
C.addTransition(StateFailed, constructSetEofNoteTag(C, StreamSym));
}
void StreamChecker::evalClearerr(const FnDescription *Desc,
const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
if (!StreamSym)
return;
const StreamState *SS = State->get<StreamMap>(StreamSym);
if (!SS)
return;
assertStreamStateOpened(SS);
// FilePositionIndeterminate is not cleared.
State = State->set<StreamMap>(
StreamSym,
StreamState::getOpened(Desc, ErrorNone, SS->FilePositionIndeterminate));
C.addTransition(State);
}
void StreamChecker::evalFeofFerror(const FnDescription *Desc,
const CallEvent &Call, CheckerContext &C,
const StreamErrorState &ErrorKind) const {
ProgramStateRef State = C.getState();
SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
if (!StreamSym)
return;
const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
if (!CE)
return;
const StreamState *SS = State->get<StreamMap>(StreamSym);
if (!SS)
return;
assertStreamStateOpened(SS);
if (SS->ErrorState & ErrorKind) {
// Execution path with error of ErrorKind.
// Function returns true.
// From now on it is the only one error state.
ProgramStateRef TrueState = bindAndAssumeTrue(State, C, CE);
C.addTransition(TrueState->set<StreamMap>(
StreamSym, StreamState::getOpened(Desc, ErrorKind,
SS->FilePositionIndeterminate &&
!ErrorKind.isFEof())));
}
if (StreamErrorState NewES = SS->ErrorState & (~ErrorKind)) {
// Execution path(s) with ErrorKind not set.
// Function returns false.
// New error state is everything before minus ErrorKind.
ProgramStateRef FalseState = bindInt(0, State, C, CE);
C.addTransition(FalseState->set<StreamMap>(
StreamSym,
StreamState::getOpened(
Desc, NewES, SS->FilePositionIndeterminate && !NewES.isFEof())));
}
}
void StreamChecker::preDefault(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
SVal StreamVal = getStreamArg(Desc, Call);
State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
State);
if (!State)
return;
State = ensureStreamOpened(StreamVal, C, State);
if (!State)
return;
C.addTransition(State);
}
void StreamChecker::evalSetFeofFerror(const FnDescription *Desc,
const CallEvent &Call, CheckerContext &C,
const StreamErrorState &ErrorKind) const {
ProgramStateRef State = C.getState();
SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
assert(StreamSym && "Operation not permitted on non-symbolic stream value.");
const StreamState *SS = State->get<StreamMap>(StreamSym);
assert(SS && "Stream should be tracked by the checker.");
State = State->set<StreamMap>(
StreamSym, StreamState::getOpened(SS->LastOperation, ErrorKind));
C.addTransition(State);
}
ProgramStateRef
StreamChecker::ensureStreamNonNull(SVal StreamVal, const Expr *StreamE,
CheckerContext &C,
ProgramStateRef State) const {
auto Stream = StreamVal.getAs<DefinedSVal>();
if (!Stream)
return State;
ConstraintManager &CM = C.getConstraintManager();
ProgramStateRef StateNotNull, StateNull;
std::tie(StateNotNull, StateNull) = CM.assumeDual(C.getState(), *Stream);
if (!StateNotNull && StateNull) {
if (ExplodedNode *N = C.generateErrorNode(StateNull)) {
auto R = std::make_unique<PathSensitiveBugReport>(
BT_FileNull, "Stream pointer might be NULL.", N);
if (StreamE)
bugreporter::trackExpressionValue(N, StreamE, *R);
C.emitReport(std::move(R));
}
return nullptr;
}
return StateNotNull;
}
ProgramStateRef StreamChecker::ensureStreamOpened(SVal StreamVal,
CheckerContext &C,
ProgramStateRef State) const {
SymbolRef Sym = StreamVal.getAsSymbol();
if (!Sym)
return State;
const StreamState *SS = State->get<StreamMap>(Sym);
if (!SS)
return State;
if (SS->isClosed()) {
// Using a stream pointer after 'fclose' causes undefined behavior
// according to cppreference.com .
ExplodedNode *N = C.generateErrorNode();
if (N) {
C.emitReport(std::make_unique<PathSensitiveBugReport>(
BT_UseAfterClose,
"Stream might be already closed. Causes undefined behaviour.", N));
return nullptr;
}
return State;
}
if (SS->isOpenFailed()) {
// Using a stream that has failed to open is likely to cause problems.
// This should usually not occur because stream pointer is NULL.
// But freopen can cause a state when stream pointer remains non-null but
// failed to open.
ExplodedNode *N = C.generateErrorNode();
if (N) {
C.emitReport(std::make_unique<PathSensitiveBugReport>(
BT_UseAfterOpenFailed,
"Stream might be invalid after "
"(re-)opening it has failed. "
"Can cause undefined behaviour.",
N));
return nullptr;
}
return State;
}
return State;
}
ProgramStateRef StreamChecker::ensureNoFilePositionIndeterminate(
SVal StreamVal, CheckerContext &C, ProgramStateRef State) const {
static const char *BugMessage =
"File position of the stream might be 'indeterminate' "
"after a failed operation. "
"Can cause undefined behavior.";
SymbolRef Sym = StreamVal.getAsSymbol();
if (!Sym)
return State;
const StreamState *SS = State->get<StreamMap>(Sym);
if (!SS)
return State;
assert(SS->isOpened() && "First ensure that stream is opened.");
if (SS->FilePositionIndeterminate) {
if (SS->ErrorState & ErrorFEof) {
// The error is unknown but may be FEOF.
// Continue analysis with the FEOF error state.
// Report warning because the other possible error states.
ExplodedNode *N = C.generateNonFatalErrorNode(State);
if (!N)
return nullptr;
C.emitReport(std::make_unique<PathSensitiveBugReport>(
BT_IndeterminatePosition, BugMessage, N));
return State->set<StreamMap>(
Sym, StreamState::getOpened(SS->LastOperation, ErrorFEof, false));
}
// Known or unknown error state without FEOF possible.
// Stop analysis, report error.
ExplodedNode *N = C.generateErrorNode(State);
if (N)
C.emitReport(std::make_unique<PathSensitiveBugReport>(
BT_IndeterminatePosition, BugMessage, N));
return nullptr;
}
return State;
}
ProgramStateRef
StreamChecker::ensureFseekWhenceCorrect(SVal WhenceVal, CheckerContext &C,
ProgramStateRef State) const {
Optional<nonloc::ConcreteInt> CI = WhenceVal.getAs<nonloc::ConcreteInt>();
if (!CI)
return State;
int64_t X = CI->getValue().getSExtValue();
if (X >= 0 && X <= 2)
return State;
if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
C.emitReport(std::make_unique<PathSensitiveBugReport>(
BT_IllegalWhence,
"The whence argument to fseek() should be "
"SEEK_SET, SEEK_END, or SEEK_CUR.",
N));
return nullptr;
}
return State;
}
void StreamChecker::reportFEofWarning(SymbolRef StreamSym, CheckerContext &C,
ProgramStateRef State) const {
if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
auto R = std::make_unique<PathSensitiveBugReport>(
BT_StreamEof,
"Read function called when stream is in EOF state. "
"Function has no effect.",
N);
R->markInteresting(StreamSym);
C.emitReport(std::move(R));
return;
}
C.addTransition(State);
}
ExplodedNode *
StreamChecker::reportLeaks(const SmallVector<SymbolRef, 2> &LeakedSyms,
CheckerContext &C, ExplodedNode *Pred) const {
ExplodedNode *Err = C.generateNonFatalErrorNode(C.getState(), Pred);
if (!Err)
return Pred;
for (SymbolRef LeakSym : LeakedSyms) {
// Resource leaks can result in multiple warning that describe the same kind
// of programming error:
// void f() {
// FILE *F = fopen("a.txt");
// if (rand()) // state split
// return; // warning
// } // warning
// While this isn't necessarily true (leaking the same stream could result
// from a different kinds of errors), the reduction in redundant reports
// makes this a worthwhile heuristic.
// FIXME: Add a checker option to turn this uniqueing feature off.
const ExplodedNode *StreamOpenNode = getAcquisitionSite(Err, LeakSym, C);
assert(StreamOpenNode && "Could not find place of stream opening.");
PathDiagnosticLocation LocUsedForUniqueing =
PathDiagnosticLocation::createBegin(
StreamOpenNode->getStmtForDiagnostics(), C.getSourceManager(),
StreamOpenNode->getLocationContext());
std::unique_ptr<PathSensitiveBugReport> R =
std::make_unique<PathSensitiveBugReport>(
BT_ResourceLeak,
"Opened stream never closed. Potential resource leak.", Err,
LocUsedForUniqueing,
StreamOpenNode->getLocationContext()->getDecl());
R->markInteresting(LeakSym);
C.emitReport(std::move(R));
}
return Err;
}
void StreamChecker::checkDeadSymbols(SymbolReaper &SymReaper,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
llvm::SmallVector<SymbolRef, 2> LeakedSyms;
const StreamMapTy &Map = State->get<StreamMap>();
for (const auto &I : Map) {
SymbolRef Sym = I.first;
const StreamState &SS = I.second;
if (!SymReaper.isDead(Sym))
continue;
if (SS.isOpened())
LeakedSyms.push_back(Sym);
State = State->remove<StreamMap>(Sym);
}
ExplodedNode *N = C.getPredecessor();
if (!LeakedSyms.empty())
N = reportLeaks(LeakedSyms, C, N);
C.addTransition(State, N);
}
ProgramStateRef StreamChecker::checkPointerEscape(
ProgramStateRef State, const InvalidatedSymbols &Escaped,
const CallEvent *Call, PointerEscapeKind Kind) const {
// Check for file-handling system call that is not handled by the checker.
// FIXME: The checker should be updated to handle all system calls that take
// 'FILE*' argument. These are now ignored.
if (Kind == PSK_DirectEscapeOnCall && Call->isInSystemHeader())
return State;
for (SymbolRef Sym : Escaped) {
// The symbol escaped.
// From now the stream can be manipulated in unknown way to the checker,
// it is not possible to handle it any more.
// Optimistically, assume that the corresponding file handle will be closed
// somewhere else.
// Remove symbol from state so the following stream calls on this symbol are
// not handled by the checker.
State = State->remove<StreamMap>(Sym);
}
return State;
}
//===----------------------------------------------------------------------===//
// Checker registration.
//===----------------------------------------------------------------------===//
void ento::registerStreamChecker(CheckerManager &Mgr) {
Mgr.registerChecker<StreamChecker>();
}
bool ento::shouldRegisterStreamChecker(const CheckerManager &Mgr) {
return true;
}
void ento::registerStreamTesterChecker(CheckerManager &Mgr) {
auto *Checker = Mgr.getChecker<StreamChecker>();
Checker->TestMode = true;
}
bool ento::shouldRegisterStreamTesterChecker(const CheckerManager &Mgr) {
return true;
}
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