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//===- CallDescription.h - 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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_CALLDESCRIPTION_H
#define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_CALLDESCRIPTION_H
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Support/Compiler.h"
#include <optional>
#include <vector>
namespace clang {
class IdentifierInfo;
} // namespace clang
namespace clang {
namespace ento {
/// A `CallDescription` is a pattern that can be used to _match_ calls
/// based on the qualified name and the argument/parameter counts.
class CallDescription {
public:
enum class Mode {
/// Match calls to functions from the C standard library. This also
/// recognizes builtin variants whose name is derived by adding
/// "__builtin", "__inline" or similar prefixes or suffixes; but only
/// matches functions than are externally visible and are declared either
/// directly within a TU or in the namespace 'std'.
/// For the exact heuristics, see CheckerContext::isCLibraryFunction().
CLibrary,
/// An extended version of the `CLibrary` mode that also matches the
/// hardened variants like __FOO_chk() and __builtin__FOO_chk() that take
/// additional arguments compared to the "regular" function FOO().
/// This is not the default behavior of `CLibrary` because in this case the
/// checker code must be prepared to handle the different parametrization.
/// For the exact heuristics, see CheckerContext::isHardenedVariantOf().
CLibraryMaybeHardened,
/// Matches "simple" functions that are not methods. (Static methods are
/// methods.)
SimpleFunc,
/// Matches a C++ method (may be static, may be virtual, may be an
/// overloaded operator, a constructor or a destructor).
CXXMethod,
/// Match any CallEvent that is not an ObjCMethodCall. This should not be
/// used when the checker looks for a concrete function (and knows whether
/// it is a method); but GenericTaintChecker uses this mode to match
/// functions whose name was configured by the user.
Unspecified,
/// FIXME: Add support for ObjCMethodCall events (I'm not adding it because
/// I'm not familiar with Objective-C). Note that currently an early return
/// in `bool matches(const CallEvent &Call) const;` discards all
/// Objective-C method calls.
};
private:
friend class CallEvent;
using MaybeCount = std::optional<unsigned>;
mutable std::optional<const IdentifierInfo *> II;
// The list of the qualified names used to identify the specified CallEvent,
// e.g. "{a, b}" represent the qualified names, like "a::b".
std::vector<std::string> QualifiedName;
MaybeCount RequiredArgs;
MaybeCount RequiredParams;
Mode MatchAs;
public:
/// Constructs a CallDescription object.
///
/// @param MatchAs Specifies the kind of the call that should be matched.
///
/// @param QualifiedName The list of the name qualifiers of the function that
/// will be matched. The user is allowed to skip any of the qualifiers.
/// For example, {"std", "basic_string", "c_str"} would match both
/// std::basic_string<...>::c_str() and std::__1::basic_string<...>::c_str().
///
/// @param RequiredArgs The expected number of arguments that are passed to
/// the function. Omit this parameter (or pass std::nullopt) to match every
/// occurrence without checking the argument count in the call.
///
/// @param RequiredParams The expected number of parameters in the function
/// definition that is called. Omit this parameter to match every occurrence
/// without checking the parameter count in the definition.
CallDescription(Mode MatchAs, ArrayRef<StringRef> QualifiedName,
MaybeCount RequiredArgs = std::nullopt,
MaybeCount RequiredParams = std::nullopt);
/// Get the name of the function that this object matches.
StringRef getFunctionName() const { return QualifiedName.back(); }
/// Get the qualified name parts in reversed order.
/// E.g. { "std", "vector", "data" } -> "vector", "std"
auto begin_qualified_name_parts() const {
return std::next(QualifiedName.rbegin());
}
auto end_qualified_name_parts() const { return QualifiedName.rend(); }
/// It's false, if and only if we expect a single identifier, such as
/// `getenv`. It's true for `std::swap`, or `my::detail::container::data`.
bool hasQualifiedNameParts() const { return QualifiedName.size() > 1; }
/// @name Matching CallDescriptions against a CallEvent
/// @{
/// Returns true if the CallEvent is a call to a function that matches
/// the CallDescription.
///
/// \note This function is not intended to be used to match Obj-C method
/// calls.
bool matches(const CallEvent &Call) const;
/// Returns true whether the CallEvent matches on any of the CallDescriptions
/// supplied.
///
/// \note This function is not intended to be used to match Obj-C method
/// calls.
friend bool matchesAny(const CallEvent &Call, const CallDescription &CD1) {
return CD1.matches(Call);
}
/// \copydoc clang::ento::CallDescription::matchesAny(const CallEvent &, const CallDescription &)
template <typename... Ts>
friend bool matchesAny(const CallEvent &Call, const CallDescription &CD1,
const Ts &...CDs) {
return CD1.matches(Call) || matchesAny(Call, CDs...);
}
/// @}
/// @name Matching CallDescriptions against a CallExpr
/// @{
/// Returns true if the CallExpr is a call to a function that matches the
/// CallDescription.
///
/// When available, always prefer matching with a CallEvent! This function
/// exists only when that is not available, for example, when _only_
/// syntactic check is done on a piece of code.
///
/// Also, StdLibraryFunctionsChecker::Signature is likely a better candicade
/// for syntactic only matching if you are writing a new checker. This is
/// handy if a CallDescriptionMap is already there.
///
/// The function is imprecise because CallEvent may know path sensitive
/// information, such as the precise argument count (see comments for
/// CallEvent::getNumArgs), the called function if it was called through a
/// function pointer, and other information not available syntactically.
bool matchesAsWritten(const CallExpr &CE) const;
/// Returns true whether the CallExpr matches on any of the CallDescriptions
/// supplied.
///
/// \note This function is not intended to be used to match Obj-C method
/// calls.
friend bool matchesAnyAsWritten(const CallExpr &CE,
const CallDescription &CD1) {
return CD1.matchesAsWritten(CE);
}
/// \copydoc clang::ento::CallDescription::matchesAnyAsWritten(const CallExpr &, const CallDescription &)
template <typename... Ts>
friend bool matchesAnyAsWritten(const CallExpr &CE,
const CallDescription &CD1,
const Ts &...CDs) {
return CD1.matchesAsWritten(CE) || matchesAnyAsWritten(CE, CDs...);
}
/// @}
private:
bool matchesImpl(const FunctionDecl *Callee, size_t ArgCount,
size_t ParamCount) const;
bool matchNameOnly(const NamedDecl *ND) const;
bool matchQualifiedNameParts(const Decl *D) const;
};
/// An immutable map from CallDescriptions to arbitrary data. Provides a unified
/// way for checkers to react on function calls.
template <typename T> class CallDescriptionMap {
friend class CallDescriptionSet;
// Some call descriptions aren't easily hashable (eg., the ones with qualified
// names in which some sections are omitted), so let's put them
// in a simple vector and use linear lookup.
// TODO: Implement an actual map for fast lookup for "hashable" call
// descriptions (eg., the ones for C functions that just match the name).
std::vector<std::pair<CallDescription, T>> LinearMap;
public:
CallDescriptionMap(
std::initializer_list<std::pair<CallDescription, T>> &&List)
: LinearMap(List) {}
template <typename InputIt>
CallDescriptionMap(InputIt First, InputIt Last) : LinearMap(First, Last) {}
~CallDescriptionMap() = default;
// These maps are usually stored once per checker, so let's make sure
// we don't do redundant copies.
CallDescriptionMap(const CallDescriptionMap &) = delete;
CallDescriptionMap &operator=(const CallDescription &) = delete;
CallDescriptionMap(CallDescriptionMap &&) = default;
CallDescriptionMap &operator=(CallDescriptionMap &&) = default;
[[nodiscard]] const T *lookup(const CallEvent &Call) const {
// Slow path: linear lookup.
// TODO: Implement some sort of fast path.
for (const std::pair<CallDescription, T> &I : LinearMap)
if (I.first.matches(Call))
return &I.second;
return nullptr;
}
/// When available, always prefer lookup with a CallEvent! This function
/// exists only when that is not available, for example, when _only_
/// syntactic check is done on a piece of code.
///
/// Also, StdLibraryFunctionsChecker::Signature is likely a better candicade
/// for syntactic only matching if you are writing a new checker. This is
/// handy if a CallDescriptionMap is already there.
///
/// The function is imprecise because CallEvent may know path sensitive
/// information, such as the precise argument count (see comments for
/// CallEvent::getNumArgs), the called function if it was called through a
/// function pointer, and other information not available syntactically.
[[nodiscard]] const T *lookupAsWritten(const CallExpr &Call) const {
// Slow path: linear lookup.
// TODO: Implement some sort of fast path.
for (const std::pair<CallDescription, T> &I : LinearMap)
if (I.first.matchesAsWritten(Call))
return &I.second;
return nullptr;
}
};
/// Enumerators of this enum class are used to construct CallDescription
/// objects; in that context the fully qualified name is needlessly verbose.
using CDM = CallDescription::Mode;
/// An immutable set of CallDescriptions.
/// Checkers can efficiently decide if a given CallEvent matches any
/// CallDescription in the set.
class CallDescriptionSet {
CallDescriptionMap<bool /*unused*/> Impl = {};
public:
CallDescriptionSet(std::initializer_list<CallDescription> &&List);
CallDescriptionSet(const CallDescriptionSet &) = delete;
CallDescriptionSet &operator=(const CallDescription &) = delete;
[[nodiscard]] bool contains(const CallEvent &Call) const;
/// When available, always prefer lookup with a CallEvent! This function
/// exists only when that is not available, for example, when _only_
/// syntactic check is done on a piece of code.
///
/// Also, StdLibraryFunctionsChecker::Signature is likely a better candicade
/// for syntactic only matching if you are writing a new checker. This is
/// handy if a CallDescriptionMap is already there.
///
/// The function is imprecise because CallEvent may know path sensitive
/// information, such as the precise argument count (see comments for
/// CallEvent::getNumArgs), the called function if it was called through a
/// function pointer, and other information not available syntactically.
[[nodiscard]] bool containsAsWritten(const CallExpr &CE) const;
};
} // namespace ento
} // namespace clang
#endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_CALLDESCRIPTION_H
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