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//===- CallDescription.cpp - function/method call matching --*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file This file defines a generic mechanism for matching for function and
/// method calls of C, C++, and Objective-C languages. Instances of these
/// classes are frequently used together with the CallEvent classes.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
#include "clang/AST/Decl.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "llvm/ADT/ArrayRef.h"
#include <iterator>
#include <optional>
using namespace llvm;
using namespace clang;
using MaybeCount = std::optional<unsigned>;
// A constructor helper.
static MaybeCount readRequiredParams(MaybeCount RequiredArgs,
MaybeCount RequiredParams) {
if (RequiredParams)
return RequiredParams;
if (RequiredArgs)
return RequiredArgs;
return std::nullopt;
}
ento::CallDescription::CallDescription(Mode MatchAs,
ArrayRef<StringRef> QualifiedName,
MaybeCount RequiredArgs /*= None*/,
MaybeCount RequiredParams /*= None*/)
: RequiredArgs(RequiredArgs),
RequiredParams(readRequiredParams(RequiredArgs, RequiredParams)),
MatchAs(MatchAs) {
assert(!QualifiedName.empty());
this->QualifiedName.reserve(QualifiedName.size());
llvm::transform(QualifiedName, std::back_inserter(this->QualifiedName),
[](StringRef From) { return From.str(); });
}
bool ento::CallDescription::matches(const CallEvent &Call) const {
// FIXME: Add ObjC Message support.
if (Call.getKind() == CE_ObjCMessage)
return false;
const auto *FD = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
if (!FD)
return false;
return matchesImpl(FD, Call.getNumArgs(), Call.parameters().size());
}
bool ento::CallDescription::matchesAsWritten(const CallExpr &CE) const {
const auto *FD = dyn_cast_or_null<FunctionDecl>(CE.getCalleeDecl());
if (!FD)
return false;
return matchesImpl(FD, CE.getNumArgs(), FD->param_size());
}
bool ento::CallDescription::matchNameOnly(const NamedDecl *ND) const {
DeclarationName Name = ND->getDeclName();
if (const auto *NameII = Name.getAsIdentifierInfo()) {
if (!II)
II = &ND->getASTContext().Idents.get(getFunctionName());
return NameII == *II; // Fast case.
}
// Fallback to the slow stringification and comparison for:
// C++ overloaded operators, constructors, destructors, etc.
// FIXME This comparison is way SLOWER than comparing pointers.
// At some point in the future, we should compare FunctionDecl pointers.
return Name.getAsString() == getFunctionName();
}
bool ento::CallDescription::matchQualifiedNameParts(const Decl *D) const {
const auto FindNextNamespaceOrRecord =
[](const DeclContext *Ctx) -> const DeclContext * {
while (Ctx && !isa<NamespaceDecl, RecordDecl>(Ctx))
Ctx = Ctx->getParent();
return Ctx;
};
auto QualifierPartsIt = begin_qualified_name_parts();
const auto QualifierPartsEndIt = end_qualified_name_parts();
// Match namespace and record names. Skip unrelated names if they don't
// match.
const DeclContext *Ctx = FindNextNamespaceOrRecord(D->getDeclContext());
for (; Ctx && QualifierPartsIt != QualifierPartsEndIt;
Ctx = FindNextNamespaceOrRecord(Ctx->getParent())) {
// If not matched just continue and try matching for the next one.
if (cast<NamedDecl>(Ctx)->getName() != *QualifierPartsIt)
continue;
++QualifierPartsIt;
}
// We matched if we consumed all expected qualifier segments.
return QualifierPartsIt == QualifierPartsEndIt;
}
bool ento::CallDescription::matchesImpl(const FunctionDecl *FD, size_t ArgCount,
size_t ParamCount) const {
if (!FD)
return false;
const bool isMethod = isa<CXXMethodDecl>(FD);
if (MatchAs == Mode::SimpleFunc && isMethod)
return false;
if (MatchAs == Mode::CXXMethod && !isMethod)
return false;
if (MatchAs == Mode::CLibraryMaybeHardened) {
// In addition to accepting FOO() with CLibrary rules, we also want to
// accept calls to __FOO_chk() and __builtin___FOO_chk().
if (CheckerContext::isCLibraryFunction(FD) &&
CheckerContext::isHardenedVariantOf(FD, getFunctionName())) {
// Check that the actual argument/parameter counts are greater or equal
// to the required counts. (Setting a requirement to std::nullopt matches
// anything, so in that case value_or ensures that the value is compared
// with itself.)
return (RequiredArgs.value_or(ArgCount) <= ArgCount &&
RequiredParams.value_or(ParamCount) <= ParamCount);
}
}
if (RequiredArgs.value_or(ArgCount) != ArgCount ||
RequiredParams.value_or(ParamCount) != ParamCount)
return false;
if (MatchAs == Mode::CLibrary || MatchAs == Mode::CLibraryMaybeHardened)
return CheckerContext::isCLibraryFunction(FD, getFunctionName());
if (!matchNameOnly(FD))
return false;
if (!hasQualifiedNameParts())
return true;
return matchQualifiedNameParts(FD);
}
ento::CallDescriptionSet::CallDescriptionSet(
std::initializer_list<CallDescription> &&List) {
Impl.LinearMap.reserve(List.size());
for (const CallDescription &CD : List)
Impl.LinearMap.push_back({CD, /*unused*/ true});
}
bool ento::CallDescriptionSet::contains(const CallEvent &Call) const {
return static_cast<bool>(Impl.lookup(Call));
}
bool ento::CallDescriptionSet::containsAsWritten(const CallExpr &CE) const {
return static_cast<bool>(Impl.lookupAsWritten(CE));
}
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