Add UnixAPIChecker, a meta checker to include various precondition checks for calls
to various unix/posix functions, e.g. 'open()'.
As a first check, check that when 'open()' is passed 'O_CREAT' that it has
a third argument.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97086 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/CMakeLists.txt b/lib/Checker/CMakeLists.txt
index 7b21d08..0e95b08 100644
--- a/lib/Checker/CMakeLists.txt
+++ b/lib/Checker/CMakeLists.txt
@@ -62,6 +62,7 @@
UndefResultChecker.cpp
UndefinedArraySubscriptChecker.cpp
UndefinedAssignmentChecker.cpp
+ UnixAPIChecker.cpp
VLASizeChecker.cpp
ValueManager.cpp
)
diff --git a/lib/Checker/GRExprEngine.cpp b/lib/Checker/GRExprEngine.cpp
index 7f86319..3872856 100644
--- a/lib/Checker/GRExprEngine.cpp
+++ b/lib/Checker/GRExprEngine.cpp
@@ -318,6 +318,7 @@
RegisterNoReturnFunctionChecker(Eng);
RegisterBuiltinFunctionChecker(Eng);
RegisterOSAtomicChecker(Eng);
+ RegisterUnixAPIChecker(Eng);
}
GRExprEngine::GRExprEngine(AnalysisManager &mgr, GRTransferFuncs *tf)
diff --git a/lib/Checker/GRExprEngineInternalChecks.h b/lib/Checker/GRExprEngineInternalChecks.h
index 9877626..a4bcd72 100644
--- a/lib/Checker/GRExprEngineInternalChecks.h
+++ b/lib/Checker/GRExprEngineInternalChecks.h
@@ -44,6 +44,7 @@
// API checks.
void RegisterOSAtomicChecker(GRExprEngine &Eng);
+void RegisterUnixAPIChecker(GRExprEngine &Eng);
} // end clang namespace
#endif
diff --git a/lib/Checker/UnixAPIChecker.cpp b/lib/Checker/UnixAPIChecker.cpp
new file mode 100644
index 0000000..b80f784
--- /dev/null
+++ b/lib/Checker/UnixAPIChecker.cpp
@@ -0,0 +1,151 @@
+//= UnixAPIChecker.h - Checks preconditions for various Unix APIs --*- C++ -*-//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines UnixAPIChecker, which is an assortment of checks on calls
+// to various, widely used UNIX/Posix functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Checker/PathSensitive/CheckerVisitor.h"
+#include "clang/Checker/BugReporter/BugReporter.h"
+#include "clang/Checker/PathSensitive/GRStateTrait.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "GRExprEngineInternalChecks.h"
+#include <fcntl.h>
+
+using namespace clang;
+
+namespace {
+class UnixAPIChecker : public CheckerVisitor<UnixAPIChecker> {
+ enum SubChecks {
+ OpenFn = 0,
+ NumChecks
+ };
+
+ BugType *BTypes[NumChecks];
+
+public:
+ UnixAPIChecker() { memset(BTypes, 0, sizeof(*BTypes) * NumChecks); }
+ static void *getTag() { static unsigned tag = 0; return &tag; }
+
+ void PreVisitCallExpr(CheckerContext &C, const CallExpr *CE);
+};
+} //end anonymous namespace
+
+void clang::RegisterUnixAPIChecker(GRExprEngine &Eng) {
+ Eng.registerCheck(new UnixAPIChecker());
+}
+
+//===----------------------------------------------------------------------===//
+// Utility functions.
+//===----------------------------------------------------------------------===//
+
+static inline void LazyInitialize(BugType *&BT, const char *name) {
+ if (BT)
+ return;
+ BT = new BugType(name, "Unix API");
+}
+
+//===----------------------------------------------------------------------===//
+// "open" (man 2 open)
+//===----------------------------------------------------------------------===//
+
+static void CheckOpen(CheckerContext &C, const CallExpr *CE, BugType *&BT) {
+ LazyInitialize(BT, "Improper use of 'open'");
+
+ // Look at the 'oflags' argument for the O_CREAT flag.
+ const GRState *state = C.getState();
+
+ if (CE->getNumArgs() < 2) {
+ // The frontend should issue a warning for this case, so this is a sanity
+ // check.
+ return;
+ }
+
+ // Now check if oflags has O_CREAT set.
+ const Expr *oflagsEx = CE->getArg(1);
+ const SVal V = state->getSVal(oflagsEx);
+ if (!isa<NonLoc>(V)) {
+ // The case where 'V' can be a location can only be due to a bad header,
+ // so in this case bail out.
+ return;
+ }
+ NonLoc oflags = cast<NonLoc>(V);
+ NonLoc ocreateFlag =
+ cast<NonLoc>(C.getValueManager().makeIntVal((uint64_t) O_CREAT,
+ oflagsEx->getType()));
+ SVal maskedFlagsUC = C.getSValuator().EvalBinOpNN(state, BinaryOperator::And,
+ oflags, ocreateFlag,
+ oflagsEx->getType());
+ if (maskedFlagsUC.isUnknownOrUndef())
+ return;
+ DefinedSVal maskedFlags = cast<DefinedSVal>(maskedFlagsUC);
+
+ // Check if maskedFlags is non-zero.
+ const GRState *trueState, *falseState;
+ llvm::tie(trueState, falseState) = state->Assume(maskedFlags);
+
+ // Only emit an error if the value of 'maskedFlags' is properly
+ // constrained;
+ if (!(trueState && !falseState))
+ return;
+
+ if (CE->getNumArgs() < 3) {
+ ExplodedNode *N = C.GenerateSink(trueState);
+ EnhancedBugReport *report =
+ new EnhancedBugReport(*BT,
+ "Call to 'open' requires a third argument when "
+ "the 'O_CREAT' flag is set", N);
+ report->addRange(oflagsEx->getSourceRange());
+ C.EmitReport(report);
+ }
+}
+
+//===----------------------------------------------------------------------===//
+// Central dispatch function.
+//===----------------------------------------------------------------------===//
+
+typedef void (*SubChecker)(CheckerContext &C, const CallExpr *CE, BugType *&BT);
+namespace {
+ class SubCheck {
+ SubChecker SC;
+ BugType **BT;
+ public:
+ SubCheck(SubChecker sc, BugType *& bt) : SC(sc), BT(&bt) {}
+ SubCheck() : SC(NULL), BT(NULL) {}
+
+ void run(CheckerContext &C, const CallExpr *CE) const {
+ if (SC)
+ SC(C, CE, *BT);
+ }
+ };
+} // end anonymous namespace
+
+void UnixAPIChecker::PreVisitCallExpr(CheckerContext &C, const CallExpr *CE) {
+ // Get the callee. All the functions we care about are C functions
+ // with simple identifiers.
+ const GRState *state = C.getState();
+ const Expr *Callee = CE->getCallee();
+ const FunctionTextRegion *Fn =
+ dyn_cast_or_null<FunctionTextRegion>(state->getSVal(Callee).getAsRegion());
+
+ if (!Fn)
+ return;
+
+ const IdentifierInfo *FI = Fn->getDecl()->getIdentifier();
+ if (!FI)
+ return;
+
+ const SubCheck &SC =
+ llvm::StringSwitch<SubCheck>(FI->getName())
+ .Case("open", SubCheck(CheckOpen, BTypes[OpenFn]))
+ .Default(SubCheck());
+
+ SC.run(C, CE);
+}
diff --git a/test/Analysis/unix-fns.c b/test/Analysis/unix-fns.c
new file mode 100644
index 0000000..2bc2efa
--- /dev/null
+++ b/test/Analysis/unix-fns.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -analyze -analyzer-check-objc-mem %s -analyzer-store=region
+// RUN: %clang_cc1 -analyze -analyzer-check-objc-mem %s -analyzer-store=basic
+
+#include <fcntl.h>
+
+void test_open(const char *path) {
+ int fd;
+ fd = open(path, O_RDONLY); // no-warning
+ if (!fd)
+ close(fd);
+
+ fd = open(path, O_CREAT); // expected-warning{{Call to 'open' requires a third argument when the 'O_CREAT' flag is set}}
+ if (!fd)
+ close(fd);
+}