[clang] 1246b64 - [clang][analyzer] Change modeling of 'fileno' in checkers. (#81842)
via cfe-commits
cfe-commits at lists.llvm.org
Wed Feb 21 00:18:04 PST 2024
Author: Balázs Kéri
Date: 2024-02-21T09:18:01+01:00
New Revision: 1246b64faa5eea1553c1c1aad425c31b701fa6ea
URL: https://github.com/llvm/llvm-project/commit/1246b64faa5eea1553c1c1aad425c31b701fa6ea
DIFF: https://github.com/llvm/llvm-project/commit/1246b64faa5eea1553c1c1aad425c31b701fa6ea.diff
LOG: [clang][analyzer] Change modeling of 'fileno' in checkers. (#81842)
Function 'fileno' fails only if invalid pointer is passed, this is a
case that is often ignored in source code. The failure case leads to
many "false positive" reports when `fileno` returns -1 and this is not
checked in the program. Because this, the function is now assumed
to not fail (this is assumption that the passed file pointer is correct).
The change affects `StdCLibraryFunctionsChecker` and
`StreamChecker`.
Added:
Modified:
clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
clang/test/Analysis/std-c-library-functions-path-notes.c
clang/test/Analysis/stream-errno-note.c
clang/test/Analysis/stream-errno.c
clang/test/Analysis/stream-error.c
clang/test/Analysis/stream-noopen.c
Removed:
################################################################################
diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 6b8ac2629453d4..6cc88679458140 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -2388,12 +2388,15 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
.ArgConstraint(NotNull(ArgNo(0))));
// int fileno(FILE *stream);
+ // According to POSIX 'fileno' may fail and set 'errno'.
+ // But in Linux it may fail only if the specified file pointer is invalid.
+ // At many places 'fileno' is used without check for failure and a failure
+ // case here would produce a large amount of likely false positive warnings.
+ // To avoid this, we assume here that it does not fail.
addToFunctionSummaryMap(
"fileno", Signature(ArgTypes{FilePtrTy}, RetType{IntTy}),
Summary(NoEvalCall)
- .Case(ReturnsValidFileDescriptor, ErrnoMustNotBeChecked,
- GenericSuccessMsg)
- .Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant, GenericFailureMsg)
+ .Case(ReturnsValidFileDescriptor, ErrnoUnchanged, GenericSuccessMsg)
.ArgConstraint(NotNull(ArgNo(0))));
// void rewind(FILE *stream);
diff --git a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
index 7e7e3f0eee2b48..a070f451694a3b 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
@@ -249,6 +249,10 @@ struct StreamOperationEvaluator {
bool isStreamEof() const { return SS->ErrorState == ErrorFEof; }
+ NonLoc getZeroVal(const CallEvent &Call) {
+ return *SVB.makeZeroVal(Call.getResultType()).getAs<NonLoc>();
+ }
+
ProgramStateRef setStreamState(ProgramStateRef State,
const StreamState &NewSS) {
return State->set<StreamMap>(StreamSym, NewSS);
@@ -390,7 +394,8 @@ class StreamChecker : public Checker<check::PreCall, eval::Call,
{&StreamChecker::preDefault,
std::bind(&StreamChecker::evalFeofFerror, _1, _2, _3, _4, ErrorFError),
0}},
- {{{"fileno"}, 1}, {&StreamChecker::preDefault, nullptr, 0}},
+ {{{"fileno"}, 1},
+ {&StreamChecker::preDefault, &StreamChecker::evalFileno, 0}},
};
CallDescriptionMap<FnDescription> FnTestDescriptions = {
@@ -486,6 +491,9 @@ class StreamChecker : public Checker<check::PreCall, eval::Call,
void evalFflush(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const;
+ void evalFileno(const FnDescription *Desc, const CallEvent &Call,
+ CheckerContext &C) 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
@@ -929,8 +937,7 @@ void StreamChecker::evalFputx(const FnDescription *Desc, const CallEvent &Call,
ProgramStateRef StateNotFailed =
State->BindExpr(E.CE, C.getLocationContext(), RetVal);
StateNotFailed =
- E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal,
- *E.SVB.makeZeroVal(E.ACtx.IntTy).getAs<NonLoc>());
+ E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal, E.getZeroVal(Call));
if (!StateNotFailed)
return;
StateNotFailed =
@@ -1003,8 +1010,7 @@ void StreamChecker::evalFscanf(const FnDescription *Desc, const CallEvent &Call,
ProgramStateRef StateNotFailed =
State->BindExpr(E.CE, C.getLocationContext(), RetVal);
StateNotFailed =
- E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal,
- *E.SVB.makeZeroVal(E.ACtx.IntTy).getAs<NonLoc>());
+ E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal, E.getZeroVal(Call));
if (StateNotFailed)
C.addTransition(StateNotFailed);
}
@@ -1073,8 +1079,7 @@ void StreamChecker::evalGetdelim(const FnDescription *Desc,
ProgramStateRef StateNotFailed =
State->BindExpr(E.CE, C.getLocationContext(), RetVal);
StateNotFailed =
- E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal,
- *E.SVB.makeZeroVal(E.CE->getType()).getAs<NonLoc>());
+ E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal, E.getZeroVal(Call));
if (!StateNotFailed)
return;
C.addTransition(StateNotFailed);
@@ -1200,8 +1205,7 @@ void StreamChecker::evalFtell(const FnDescription *Desc, const CallEvent &Call,
ProgramStateRef StateNotFailed =
State->BindExpr(E.CE, C.getLocationContext(), RetVal);
StateNotFailed =
- E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal,
- *E.SVB.makeZeroVal(Call.getResultType()).getAs<NonLoc>());
+ E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal, E.getZeroVal(Call));
if (!StateNotFailed)
return;
@@ -1226,79 +1230,6 @@ void StreamChecker::evalRewind(const FnDescription *Desc, const CallEvent &Call,
C.addTransition(State);
}
-void StreamChecker::evalClearerr(const FnDescription *Desc,
- const CallEvent &Call,
- CheckerContext &C) const {
- ProgramStateRef State = C.getState();
- StreamOperationEvaluator E(C);
- if (!E.Init(Desc, Call, C, State))
- return;
-
- // FilePositionIndeterminate is not cleared.
- State = E.setStreamState(
- State,
- StreamState::getOpened(Desc, ErrorNone, E.SS->FilePositionIndeterminate));
- C.addTransition(State);
-}
-
-void StreamChecker::evalFeofFerror(const FnDescription *Desc,
- const CallEvent &Call, CheckerContext &C,
- const StreamErrorState &ErrorKind) const {
- ProgramStateRef State = C.getState();
- StreamOperationEvaluator E(C);
- if (!E.Init(Desc, Call, C, State))
- return;
-
- if (E.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, E.CE);
- C.addTransition(E.setStreamState(
- TrueState, StreamState::getOpened(Desc, ErrorKind,
- E.SS->FilePositionIndeterminate &&
- !ErrorKind.isFEof())));
- }
- if (StreamErrorState NewES = E.SS->ErrorState & (~ErrorKind)) {
- // Execution path(s) with ErrorKind not set.
- // Function returns false.
- // New error state is everything before minus ErrorKind.
- ProgramStateRef FalseState = E.bindReturnValue(State, C, 0);
- C.addTransition(E.setStreamState(
- FalseState,
- StreamState::getOpened(
- Desc, NewES, E.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);
-}
-
void StreamChecker::preFflush(const FnDescription *Desc, const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
@@ -1377,6 +1308,104 @@ void StreamChecker::evalFflush(const FnDescription *Desc, const CallEvent &Call,
C.addTransition(StateFailed);
}
+void StreamChecker::evalClearerr(const FnDescription *Desc,
+ const CallEvent &Call,
+ CheckerContext &C) const {
+ ProgramStateRef State = C.getState();
+ StreamOperationEvaluator E(C);
+ if (!E.Init(Desc, Call, C, State))
+ return;
+
+ // FilePositionIndeterminate is not cleared.
+ State = E.setStreamState(
+ State,
+ StreamState::getOpened(Desc, ErrorNone, E.SS->FilePositionIndeterminate));
+ C.addTransition(State);
+}
+
+void StreamChecker::evalFeofFerror(const FnDescription *Desc,
+ const CallEvent &Call, CheckerContext &C,
+ const StreamErrorState &ErrorKind) const {
+ ProgramStateRef State = C.getState();
+ StreamOperationEvaluator E(C);
+ if (!E.Init(Desc, Call, C, State))
+ return;
+
+ if (E.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, E.CE);
+ C.addTransition(E.setStreamState(
+ TrueState, StreamState::getOpened(Desc, ErrorKind,
+ E.SS->FilePositionIndeterminate &&
+ !ErrorKind.isFEof())));
+ }
+ if (StreamErrorState NewES = E.SS->ErrorState & (~ErrorKind)) {
+ // Execution path(s) with ErrorKind not set.
+ // Function returns false.
+ // New error state is everything before minus ErrorKind.
+ ProgramStateRef FalseState = E.bindReturnValue(State, C, 0);
+ C.addTransition(E.setStreamState(
+ FalseState,
+ StreamState::getOpened(
+ Desc, NewES, E.SS->FilePositionIndeterminate && !NewES.isFEof())));
+ }
+}
+
+void StreamChecker::evalFileno(const FnDescription *Desc, const CallEvent &Call,
+ CheckerContext &C) const {
+ // Fileno should fail only if the passed pointer is invalid.
+ // Some of the preconditions are checked already in preDefault.
+ // Here we can assume that the operation does not fail, because if we
+ // introduced a separate branch where fileno() returns -1, then it would cause
+ // many unexpected and unwanted warnings in situations where fileno() is
+ // called on valid streams.
+ // The stream error states are not modified by 'fileno', and 'errno' is also
+ // left unchanged (so this evalCall does not invalidate it, but we have a
+ // custom evalCall instead of the default that would invalidate it).
+ ProgramStateRef State = C.getState();
+ StreamOperationEvaluator E(C);
+ if (!E.Init(Desc, Call, C, State))
+ return;
+
+ NonLoc RetVal = makeRetVal(C, E.CE).castAs<NonLoc>();
+ State = State->BindExpr(E.CE, C.getLocationContext(), RetVal);
+ State = E.assumeBinOpNN(State, BO_GE, RetVal, E.getZeroVal(Call));
+ if (!State)
+ return;
+
+ C.addTransition(State);
+}
+
+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,
diff --git a/clang/test/Analysis/std-c-library-functions-path-notes.c b/clang/test/Analysis/std-c-library-functions-path-notes.c
index 4df00fe1e60646..6449b71928fa7c 100644
--- a/clang/test/Analysis/std-c-library-functions-path-notes.c
+++ b/clang/test/Analysis/std-c-library-functions-path-notes.c
@@ -61,24 +61,22 @@ int test_islower(int *x) {
}
int test_bugpath_notes(FILE *f1, char c, FILE *f2) {
- int f = fileno(f2);
- if (f == -1) // \
+ // This test has the purpose of checking that notes appear at correct place.
+ long a = ftell(f2); // no note
+ if (a == -1) // \
// expected-note{{Taking false branch}}
- return 0;
- int l = islower(c);
- f = fileno(f1); // \
- // expected-note{{Value assigned to 'f'}} \
- // expected-note{{Assuming that 'fileno' fails}}
- return dup(f); // \
+ return -1;
+ int l = islower(c); // no note
+ a = ftell(f1); // \
+ // expected-note{{Value assigned to 'a'}} \
+ // expected-note{{Assuming that 'ftell' fails}}
+ return dup(a); // \
// expected-warning{{The 1st argument to 'dup' is -1 but should be >= 0}} \
// expected-note{{The 1st argument to 'dup' is -1 but should be >= 0}}
}
int test_fileno_arg_note(FILE *f1) {
- return dup(fileno(f1)); // \
- // expected-warning{{The 1st argument to 'dup' is < 0 but should be >= 0}} \
- // expected-note{{The 1st argument to 'dup' is < 0 but should be >= 0}} \
- // expected-note{{Assuming that 'fileno' fails}}
+ return dup(fileno(f1)); // no warning
}
int test_readlink_bufsize_zero(char *Buf, size_t Bufsize) {
diff --git a/clang/test/Analysis/stream-errno-note.c b/clang/test/Analysis/stream-errno-note.c
index 2531e26e200385..2411a2d9a00a72 100644
--- a/clang/test/Analysis/stream-errno-note.c
+++ b/clang/test/Analysis/stream-errno-note.c
@@ -141,16 +141,8 @@ void check_rewind_errnocheck(void) {
}
void check_fileno(void) {
- FILE *F = tmpfile();
- // expected-note at +2{{'F' is non-null}}
- // expected-note at +1{{Taking false branch}}
- if (!F)
- return;
- fileno(F);
- // expected-note at -1{{Assuming that 'fileno' is successful; 'errno' becomes undefined after the call}}
- if (errno) {} // expected-warning{{An undefined value may be read from 'errno'}}
- // expected-note at -1{{An undefined value may be read from 'errno'}}
- (void)fclose(F);
+ // nothing to check: checker assumes that 'fileno' is always successful
+ // (and does not change 'errno')
}
void check_fwrite_zeroarg(size_t Siz) {
diff --git a/clang/test/Analysis/stream-errno.c b/clang/test/Analysis/stream-errno.c
index fab6a58b3275a8..5f0a58032fa263 100644
--- a/clang/test/Analysis/stream-errno.c
+++ b/clang/test/Analysis/stream-errno.c
@@ -173,6 +173,8 @@ void check_no_errno_change(void) {
if (errno) {} // no-warning
ferror(F);
if (errno) {} // no-warning
+ fileno(F);
+ if (errno) {} // no-warning
clang_analyzer_eval(errno == 1); // expected-warning{{TRUE}}
fclose(F);
}
@@ -250,20 +252,6 @@ void check_rewind(void) {
fclose(F);
}
-void check_fileno(void) {
- FILE *F = tmpfile();
- if (!F)
- return;
- int N = fileno(F);
- if (N == -1) {
- clang_analyzer_eval(errno != 0); // expected-warning{{TRUE}}
- if (errno) {} // no-warning
- fclose(F);
- return;
- }
- if (errno) {} // expected-warning{{An undefined value may be read from 'errno'}}
-}
-
void check_fflush_opened_file(void) {
FILE *F = tmpfile();
if (!F)
diff --git a/clang/test/Analysis/stream-error.c b/clang/test/Analysis/stream-error.c
index 4bab07577ccd53..ac31083bfc691f 100644
--- a/clang/test/Analysis/stream-error.c
+++ b/clang/test/Analysis/stream-error.c
@@ -491,6 +491,24 @@ void error_ftello(void) {
fclose(F);
}
+void error_fileno(void) {
+ FILE *F = fopen("file", "r");
+ if (!F)
+ return;
+ int N = fileno(F);
+ clang_analyzer_eval(N >= 0); // expected-warning {{TRUE}}
+ clang_analyzer_eval(feof(F) && ferror(F)); // expected-warning {{FALSE}}
+ StreamTesterChecker_make_feof_stream(F);
+ N = fileno(F);
+ clang_analyzer_eval(feof(F)); // expected-warning {{TRUE}}
+ clang_analyzer_eval(ferror(F)); // expected-warning {{FALSE}}
+ StreamTesterChecker_make_ferror_stream(F);
+ N = fileno(F);
+ clang_analyzer_eval(feof(F)); // expected-warning {{FALSE}}
+ clang_analyzer_eval(ferror(F)); // expected-warning {{TRUE}}
+ fclose(F);
+}
+
void error_fflush_on_non_null_stream_clear_error_states(void) {
FILE *F0 = tmpfile(), *F1 = tmpfile();
// `fflush` clears a non-EOF stream's error state.
diff --git a/clang/test/Analysis/stream-noopen.c b/clang/test/Analysis/stream-noopen.c
index 8bd01a90cf8596..644c699d05e246 100644
--- a/clang/test/Analysis/stream-noopen.c
+++ b/clang/test/Analysis/stream-noopen.c
@@ -268,6 +268,16 @@ void test_clearerr(FILE *F) {
// expected-warning at -1{{FALSE}}
}
+void test_fileno(FILE *F) {
+ errno = 0;
+ int A = fileno(F);
+ clang_analyzer_eval(F != NULL); // expected-warning{{TRUE}}
+ clang_analyzer_eval(A >= 0); // expected-warning{{TRUE}}
+ if (errno) {} // no-warning
+ clang_analyzer_eval(errno == 0); // expected-warning{{TRUE}}
+ // expected-warning at -1{{FALSE}}
+}
+
void freadwrite_zerosize(FILE *F) {
fwrite(WBuf, 1, 0, F);
clang_analyzer_eval(feof(F)); // expected-warning {{UNKNOWN}}
More information about the cfe-commits
mailing list