FormatString.h

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//= FormatString.h - Analysis of printf/fprintf format strings --*- 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 APIs for analyzing the format strings of printf, fscanf,
// and friends.
//
// The structure of format strings for fprintf are described in C99 7.19.6.1.
//
// The structure of format strings for fscanf are described in C99 7.19.6.2.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_CLANG_AST_FORMATSTRING_H
#define LLVM_CLANG_AST_FORMATSTRING_H
 
#include "clang/AST/CanonicalType.h"
#include "llvm/ADT/StringRef.h"
#include <optional>
 
namespace clang {
 
class TargetInfo;
 
//===----------------------------------------------------------------------===//
/// Common components of both fprintf and fscanf format strings.
namespace analyze_format_string {
 
/// Class representing optional flags with location and representation
/// information.
class OptionalFlag {
public:
  OptionalFlag(const char *Representation)
      : representation(Representation), flag(false) {}
  bool isSet() const { return flag; }
  void set() { flag = true; }
  void clear() { flag = false; }
  void setPosition(const char *position) {
    assert(position);
    flag = true;
    this->position = position;
  }
  const char *getPosition() const {
    assert(position);
    return position;
  }
  const char *toString() const { return representation; }
 
  // Overloaded operators for bool like qualities
  explicit operator bool() const { return flag; }
  OptionalFlag &operator=(const bool &rhs) {
    flag = rhs;
    return *this; // Return a reference to myself.
  }
 
private:
  const char *representation;
  const char *position;
  bool flag;
};
 
/// Represents the length modifier in a format string in scanf/printf.
class LengthModifier {
public:
  enum Kind {
    None,
    AsChar,             // 'hh'
    AsShort,            // 'h'
    AsShortLong,        // 'hl' (OpenCL float/int vector element)
    AsLong,             // 'l'
    AsLongLong,         // 'll'
    AsQuad,             // 'q' (BSD, deprecated, for 64-bit integer types)
    AsIntMax,           // 'j'
    AsSizeT,            // 'z'
    AsPtrDiff,          // 't'
    AsInt32,            // 'I32' (MSVCRT, like __int32)
    AsInt3264,          // 'I'   (MSVCRT, like __int3264 from MIDL)
    AsInt64,            // 'I64' (MSVCRT, like __int64)
    AsLongDouble,       // 'L'
    AsIntN,             // 'wN'
    AsFastIntN,         // 'wfN'
    AsDecimal32,        // 'H'  (C23, _Decimal32)
    AsDecimal64,        // 'D'  (C23, _Decimal64)
    AsDecimal128,       // 'DD' (C23, _Decimal128)
    AsAllocate,         // for '%as', GNU extension to C90 scanf
    AsMAllocate,        // for '%ms', GNU extension to scanf
    AsWide,             // 'w' (MSVCRT, like l but only for c, C, s, S, or Z
    AsWideChar = AsLong // for '%ls', only makes sense for printf
  };
 
  LengthModifier() : Position(nullptr), kind(None) {}
  LengthModifier(const char *pos, Kind k) : Position(pos), kind(k) {}
  LengthModifier(const char *pos, Kind k, unsigned bitWidth, unsigned length)
      : Position(pos), kind(k), BitWidth(bitWidth), ModifierLength(length) {}
 
  const char *getStart() const { return Position; }
 
  unsigned getLength() const {
    switch (kind) {
    default:
      return 1;
    case AsLongLong:
    case AsChar:
    case AsDecimal128:
      return 2;
    case AsIntN:
    case AsFastIntN:
      assert(ModifierLength != 0 &&
             "C23 wN/wfN length modifiers must have a nonzero length");
      return ModifierLength;
    case AsInt32:
    case AsInt64:
      return 3;
    case None:
      return 0;
    }
  }
 
  Kind getKind() const { return kind; }
  void setKind(Kind k) { kind = k; }
 
  unsigned getBitWidth() const { return BitWidth; }
 
  StringRef toString() const;
 
private:
  const char *Position;
  Kind kind;
  unsigned BitWidth = 0;
  unsigned ModifierLength = 0;
};
 
class ConversionSpecifier {
public:
  enum Kind {
    InvalidSpecifier = 0,
    // C99 conversion specifiers.
    cArg,
    dArg,
    DArg, // Apple extension
    iArg,
    // C23 conversion specifiers.
    bArg,
    BArg,
 
    IntArgBeg = dArg,
    IntArgEnd = BArg,
 
    oArg,
    OArg, // Apple extension
    uArg,
    UArg, // Apple extension
    xArg,
    XArg,
    UIntArgBeg = oArg,
    UIntArgEnd = XArg,
 
    fArg,
    FArg,
    eArg,
    EArg,
    gArg,
    GArg,
    aArg,
    AArg,
    DoubleArgBeg = fArg,
    DoubleArgEnd = AArg,
 
    sArg,
    pArg,
    nArg,
    PercentArg,
    CArg,
    SArg,
 
    // Apple extension: P specifies to os_log that the data being pointed to is
    // to be copied by os_log. The precision indicates the number of bytes to
    // copy.
    PArg,
 
    // ** Printf-specific **
 
    ZArg, // MS extension
 
    // ISO/IEC TR 18037 (fixed-point) specific specifiers.
    kArg, // %k for signed accum types
    KArg, // %K for unsigned accum types
    rArg, // %r for signed fract types
    RArg, // %R for unsigned fract types
    FixedPointArgBeg = kArg,
    FixedPointArgEnd = RArg,
 
    // Objective-C specific specifiers.
    ObjCObjArg, // '@'
    ObjCBeg = ObjCObjArg,
    ObjCEnd = ObjCObjArg,
 
    // FreeBSD kernel specific specifiers.
    FreeBSDbArg,
    FreeBSDDArg,
    FreeBSDrArg,
    FreeBSDyArg,
 
    // GlibC specific specifiers.
    PrintErrno, // 'm'
 
    PrintfConvBeg = ObjCObjArg,
    PrintfConvEnd = PrintErrno,
 
    // ** Scanf-specific **
    ScanListArg, // '['
    ScanfConvBeg = ScanListArg,
    ScanfConvEnd = ScanListArg
  };
 
  ConversionSpecifier(bool isPrintf = true)
      : IsPrintf(isPrintf), Position(nullptr), EndScanList(nullptr),
        kind(InvalidSpecifier) {}
 
  ConversionSpecifier(bool isPrintf, const char *pos, Kind k)
      : IsPrintf(isPrintf), Position(pos), EndScanList(nullptr), kind(k) {}
 
  const char *getStart() const { return Position; }
 
  StringRef getCharacters() const { return StringRef(getStart(), getLength()); }
 
  bool consumesDataArgument() const {
    switch (kind) {
    case PrintErrno:
      assert(IsPrintf);
      return false;
    case PercentArg:
      return false;
    case InvalidSpecifier:
      return false;
    default:
      return true;
    }
  }
 
  Kind getKind() const { return kind; }
  void setKind(Kind k) { kind = k; }
  unsigned getLength() const {
    return EndScanList ? EndScanList - Position : 1;
  }
  void setEndScanList(const char *pos) { EndScanList = pos; }
 
  bool isIntArg() const {
    return (kind >= IntArgBeg && kind <= IntArgEnd) || kind == FreeBSDrArg ||
           kind == FreeBSDyArg;
  }
  bool isUIntArg() const { return kind >= UIntArgBeg && kind <= UIntArgEnd; }
  bool isAnyIntArg() const { return kind >= IntArgBeg && kind <= UIntArgEnd; }
  bool isDoubleArg() const {
    return kind >= DoubleArgBeg && kind <= DoubleArgEnd;
  }
  bool isFixedPointArg() const {
    return kind >= FixedPointArgBeg && kind <= FixedPointArgEnd;
  }
 
  const char *toString() const;
 
  bool isPrintfKind() const { return IsPrintf; }
 
  std::optional<ConversionSpecifier> getStandardSpecifier() const;
 
protected:
  bool IsPrintf;
  const char *Position;
  const char *EndScanList;
  Kind kind;
};
 
class ArgType {
public:
  enum Kind {
    UnknownTy,
    InvalidTy,
    UnsupportedTy,
    SpecificTy,
    ObjCPointerTy,
    CPointerTy,
    AnyCharTy,
    CStrTy,
    WCStrTy,
    WIntTy
  };
 
  /// How well a given conversion specifier matches its argument.
  enum MatchKind {
    /// The conversion specifier and the argument types are incompatible. For
    /// instance, "%d" and float.
    NoMatch = 0,
    /// The conversion specifier and the argument type are compatible. For
    /// instance, "%d" and int.
    Match = 1,
    /// The conversion specifier and the argument type are compatible because of
    /// default argument promotions. For instance, "%hhd" and int.
    MatchPromotion,
    /// The conversion specifier and the argument type are compatible but still
    /// seems likely to be an error. For instanace, "%hhd" and short.
    NoMatchPromotionTypeConfusion,
    /// The conversion specifier and the argument type are disallowed by the C
    /// standard, but are in practice harmless. For instance, "%p" and int*.
    NoMatchPedantic,
    /// The conversion specifier and the argument type have different sign.
    NoMatchSignedness,
    /// The conversion specifier and the argument type are compatible, but still
    /// seems likely to be an error. For instance, "%hd" and _Bool.
    NoMatchTypeConfusion,
  };
 
private:
  Kind K;
  QualType T;
  const char *Name = nullptr;
  bool Ptr = false;
 
  /// The TypeKind identifies certain well-known types.
  enum class TypeKind {
    DontCare,
    SizeT,
    PtrdiffT,
    IntN,
    UIntN,
    FastIntN,
    FastUIntN,
  };
  TypeKind TK = TypeKind::DontCare;
  unsigned BitWidth = 0;
 
public:
  ArgType(Kind K = UnknownTy, const char *N = nullptr) : K(K), Name(N) {}
  ArgType(QualType T, const char *N = nullptr) : K(SpecificTy), T(T), Name(N) {}
  ArgType(CanQualType T) : K(SpecificTy), T(T) {}
 
  static ArgType Invalid() { return ArgType(InvalidTy); }
  static ArgType Unsupported(const char *N) {
    ArgType A(UnsupportedTy);
    A.Name = N;
    return A;
  }
  bool isValid() const { return K != InvalidTy; }
  bool isUnsupported() const { return K == UnsupportedTy; }
 
  bool isSizeT() const { return TK == TypeKind::SizeT; }
 
  bool isPtrdiffT() const { return TK == TypeKind::PtrdiffT; }
 
  /// Create an ArgType which corresponds to the type pointer to A.
  static ArgType PtrTo(const ArgType &A) {
    assert(A.K >= InvalidTy && "ArgType cannot be pointer to invalid/unknown");
    ArgType Res = A;
    Res.Ptr = true;
    return Res;
  }
 
  /// Create an ArgType which corresponds to the size_t/ssize_t type.
  static ArgType makeSizeT(const ArgType &A) {
    ArgType Res = A;
    Res.TK = TypeKind::SizeT;
    return Res;
  }
 
  /// Create an ArgType which corresponds to the ptrdiff_t/unsigned ptrdiff_t
  /// type.
  static ArgType makePtrdiffT(const ArgType &A) {
    ArgType Res = A;
    Res.TK = TypeKind::PtrdiffT;
    return Res;
  }
 
  static ArgType makeIntNType(ASTContext &Ctx, const LengthModifier &LengthMod,
                              bool Signed);
 
  MatchKind matchesType(ASTContext &C, QualType argTy) const;
  MatchKind matchesArgType(ASTContext &C, const ArgType &other) const;
 
  QualType getRepresentativeType(ASTContext &C) const;
 
  ArgType makeVectorType(ASTContext &C, unsigned NumElts) const;
 
  std::string getRepresentativeTypeName(ASTContext &C) const;
};
 
class OptionalAmount {
public:
  enum HowSpecified { NotSpecified, Constant, Arg, Invalid };
 
  OptionalAmount(HowSpecified howSpecified, unsigned amount,
                 const char *amountStart, unsigned amountLength,
                 bool usesPositionalArg)
      : start(amountStart), length(amountLength), hs(howSpecified), amt(amount),
        UsesPositionalArg(usesPositionalArg), UsesDotPrefix(false) {}
 
  OptionalAmount(bool valid = true)
      : start(nullptr), length(0), hs(valid ? NotSpecified : Invalid), amt(0),
        UsesPositionalArg(false), UsesDotPrefix(false) {}
 
  explicit OptionalAmount(unsigned Amount)
      : start(nullptr), length(0), hs(Constant), amt(Amount),
        UsesPositionalArg(false), UsesDotPrefix(false) {}
 
  bool isInvalid() const { return hs == Invalid; }
 
  HowSpecified getHowSpecified() const { return hs; }
  void setHowSpecified(HowSpecified h) { hs = h; }
 
  bool hasDataArgument() const { return hs == Arg; }
 
  unsigned getArgIndex() const {
    assert(hasDataArgument());
    return amt;
  }
 
  unsigned getConstantAmount() const {
    assert(hs == Constant);
    return amt;
  }
 
  const char *getStart() const {
    // We include the . character if it is given.
    return start - UsesDotPrefix;
  }
 
  unsigned getConstantLength() const {
    assert(hs == Constant);
    return length + UsesDotPrefix;
  }
 
  StringRef getCharacters() const {
    return StringRef(start - UsesDotPrefix, length + UsesDotPrefix);
  }
 
  ArgType getArgType(ASTContext &Ctx) const;
 
  void toString(raw_ostream &os) const;
 
  bool usesPositionalArg() const { return (bool)UsesPositionalArg; }
  unsigned getPositionalArgIndex() const {
    assert(hasDataArgument());
    return amt + 1;
  }
 
  bool usesDotPrefix() const { return UsesDotPrefix; }
  void setUsesDotPrefix() { UsesDotPrefix = true; }
 
private:
  const char *start;
  unsigned length;
  HowSpecified hs;
  unsigned amt;
  bool UsesPositionalArg : 1;
  bool UsesDotPrefix;
};
 
class FormatSpecifier {
protected:
  LengthModifier LM;
  OptionalAmount FieldWidth;
  ConversionSpecifier CS;
  OptionalAmount VectorNumElts;
 
  /// Positional arguments, an IEEE extension:
  ///  IEEE Std 1003.1, 2004 Edition
  ///  http://www.opengroup.org/onlinepubs/009695399/functions/printf.html
  bool UsesPositionalArg;
  unsigned argIndex;
 
public:
  FormatSpecifier(bool isPrintf)
      : CS(isPrintf), VectorNumElts(false), UsesPositionalArg(false),
        argIndex(0) {}
 
  void setLengthModifier(LengthModifier lm) { LM = lm; }
 
  void setUsesPositionalArg() { UsesPositionalArg = true; }
 
  void setArgIndex(unsigned i) { argIndex = i; }
 
  unsigned getArgIndex() const { return argIndex; }
 
  unsigned getPositionalArgIndex() const { return argIndex + 1; }
 
  const LengthModifier &getLengthModifier() const { return LM; }
 
  const OptionalAmount &getFieldWidth() const { return FieldWidth; }
 
  void setVectorNumElts(const OptionalAmount &Amt) { VectorNumElts = Amt; }
 
  const OptionalAmount &getVectorNumElts() const { return VectorNumElts; }
 
  void setFieldWidth(const OptionalAmount &Amt) { FieldWidth = Amt; }
 
  bool usesPositionalArg() const { return UsesPositionalArg; }
 
  bool hasValidLengthModifier(const TargetInfo &Target,
                              const LangOptions &LO) const;
 
  bool hasStandardLengthModifier() const;
 
  std::optional<LengthModifier> getCorrectedLengthModifier() const;
 
  bool hasStandardConversionSpecifier(const LangOptions &LangOpt) const;
 
  bool hasStandardLengthConversionCombination() const;
 
  /// For a TypedefType QT, if it is a named integer type such as size_t,
  /// assign the appropriate value to LM and return true.
  static bool namedTypeToLengthModifier(ASTContext &Ctx, QualType QT,
                                        LengthModifier &LM);
};
 
} // namespace analyze_format_string
 
//===----------------------------------------------------------------------===//
/// Pieces specific to fprintf format strings.
 
namespace analyze_printf {
 
class PrintfConversionSpecifier
    : public analyze_format_string::ConversionSpecifier {
public:
  PrintfConversionSpecifier()
      : ConversionSpecifier(true, nullptr, InvalidSpecifier) {}
 
  PrintfConversionSpecifier(const char *pos, Kind k)
      : ConversionSpecifier(true, pos, k) {}
 
  bool isObjCArg() const { return kind >= ObjCBeg && kind <= ObjCEnd; }
  bool isDoubleArg() const {
    return kind >= DoubleArgBeg && kind <= DoubleArgEnd;
  }
 
  static bool classof(const analyze_format_string::ConversionSpecifier *CS) {
    return CS->isPrintfKind();
  }
};
 
using analyze_format_string::ArgType;
using analyze_format_string::LengthModifier;
using analyze_format_string::OptionalAmount;
using analyze_format_string::OptionalFlag;
 
class PrintfSpecifier : public analyze_format_string::FormatSpecifier {
  OptionalFlag HasThousandsGrouping; // ''', POSIX extension.
  OptionalFlag IsLeftJustified;      // '-'
  OptionalFlag HasPlusPrefix;        // '+'
  OptionalFlag HasSpacePrefix;       // ' '
  OptionalFlag HasAlternativeForm;   // '#'
  OptionalFlag HasLeadingZeroes;     // '0'
  OptionalFlag HasObjCTechnicalTerm; // '[tt]'
  OptionalFlag IsPrivate;            // '{private}'
  OptionalFlag IsPublic;             // '{public}'
  OptionalFlag IsSensitive;          // '{sensitive}'
  OptionalAmount Precision;
  StringRef MaskType;
 
  ArgType getScalarArgType(ASTContext &Ctx, bool IsObjCLiteral) const;
 
public:
  PrintfSpecifier()
      : FormatSpecifier(/* isPrintf = */ true), HasThousandsGrouping("'"),
        IsLeftJustified("-"), HasPlusPrefix("+"), HasSpacePrefix(" "),
        HasAlternativeForm("#"), HasLeadingZeroes("0"),
        HasObjCTechnicalTerm("tt"), IsPrivate("private"), IsPublic("public"),
        IsSensitive("sensitive") {}
 
  // Methods for incrementally constructing the PrintfSpecifier.
  void setConversionSpecifier(const PrintfConversionSpecifier &cs) { CS = cs; }
  void setHasThousandsGrouping(const char *position) {
    HasThousandsGrouping.setPosition(position);
  }
  void setIsLeftJustified(const char *position) {
    IsLeftJustified.setPosition(position);
  }
  void setHasPlusPrefix(const char *position) {
    HasPlusPrefix.setPosition(position);
  }
  void setHasSpacePrefix(const char *position) {
    HasSpacePrefix.setPosition(position);
  }
  void setHasAlternativeForm(const char *position) {
    HasAlternativeForm.setPosition(position);
  }
  void setHasLeadingZeros(const char *position) {
    HasLeadingZeroes.setPosition(position);
  }
  void setHasObjCTechnicalTerm(const char *position) {
    HasObjCTechnicalTerm.setPosition(position);
  }
  void setIsPrivate(const char *position) { IsPrivate.setPosition(position); }
  void setIsPublic(const char *position) { IsPublic.setPosition(position); }
  void setIsSensitive(const char *position) {
    IsSensitive.setPosition(position);
  }
  void setUsesPositionalArg() { UsesPositionalArg = true; }
 
  // Methods for querying the format specifier.
 
  const PrintfConversionSpecifier &getConversionSpecifier() const {
    return cast<PrintfConversionSpecifier>(CS);
  }
 
  void setPrecision(const OptionalAmount &Amt) {
    Precision = Amt;
    Precision.setUsesDotPrefix();
  }
 
  const OptionalAmount &getPrecision() const { return Precision; }
 
  bool consumesDataArgument() const {
    return getConversionSpecifier().consumesDataArgument();
  }
 
  /// Returns the builtin type that a data argument
  /// paired with this format specifier should have.  This method
  /// will return null if the format specifier does not have
  /// a matching data argument or the matching argument matches
  /// more than one type.
  ArgType getArgType(ASTContext &Ctx, bool IsObjCLiteral) const;
 
  const OptionalFlag &hasThousandsGrouping() const {
    return HasThousandsGrouping;
  }
  const OptionalFlag &isLeftJustified() const { return IsLeftJustified; }
  const OptionalFlag &hasPlusPrefix() const { return HasPlusPrefix; }
  const OptionalFlag &hasAlternativeForm() const { return HasAlternativeForm; }
  const OptionalFlag &hasLeadingZeros() const { return HasLeadingZeroes; }
  const OptionalFlag &hasSpacePrefix() const { return HasSpacePrefix; }
  const OptionalFlag &hasObjCTechnicalTerm() const {
    return HasObjCTechnicalTerm;
  }
  const OptionalFlag &isPrivate() const { return IsPrivate; }
  const OptionalFlag &isPublic() const { return IsPublic; }
  const OptionalFlag &isSensitive() const { return IsSensitive; }
  bool usesPositionalArg() const { return UsesPositionalArg; }
 
  StringRef getMaskType() const { return MaskType; }
  void setMaskType(StringRef S) { MaskType = S; }
 
  /// Changes the specifier and length according to a QualType, retaining any
  /// flags or options. Returns true on success, or false when a conversion
  /// was not successful.
  bool fixType(QualType QT, const LangOptions &LangOpt, ASTContext &Ctx,
               bool IsObjCLiteral);
 
  void toString(raw_ostream &os) const;
 
  // Validation methods - to check if any element results in undefined behavior
  bool hasValidPlusPrefix() const;
  bool hasValidAlternativeForm() const;
  bool hasValidLeadingZeros() const;
  bool hasValidSpacePrefix() const;
  bool hasValidLeftJustified() const;
  bool hasValidThousandsGroupingPrefix() const;
 
  bool hasValidPrecision() const;
  bool hasValidFieldWidth() const;
};
} // namespace analyze_printf
 
//===----------------------------------------------------------------------===//
/// Pieces specific to fscanf format strings.
 
namespace analyze_scanf {
 
class ScanfConversionSpecifier
    : public analyze_format_string::ConversionSpecifier {
public:
  ScanfConversionSpecifier()
      : ConversionSpecifier(false, nullptr, InvalidSpecifier) {}
 
  ScanfConversionSpecifier(const char *pos, Kind k)
      : ConversionSpecifier(false, pos, k) {}
 
  static bool classof(const analyze_format_string::ConversionSpecifier *CS) {
    return !CS->isPrintfKind();
  }
};
 
using analyze_format_string::ArgType;
using analyze_format_string::LengthModifier;
using analyze_format_string::OptionalAmount;
using analyze_format_string::OptionalFlag;
 
class ScanfSpecifier : public analyze_format_string::FormatSpecifier {
  OptionalFlag SuppressAssignment; // '*'
public:
  ScanfSpecifier()
      : FormatSpecifier(/* isPrintf = */ false), SuppressAssignment("*") {}
 
  void setSuppressAssignment(const char *position) {
    SuppressAssignment.setPosition(position);
  }
 
  const OptionalFlag &getSuppressAssignment() const {
    return SuppressAssignment;
  }
 
  void setConversionSpecifier(const ScanfConversionSpecifier &cs) { CS = cs; }
 
  const ScanfConversionSpecifier &getConversionSpecifier() const {
    return cast<ScanfConversionSpecifier>(CS);
  }
 
  bool consumesDataArgument() const {
    return CS.consumesDataArgument() && !SuppressAssignment;
  }
 
  ArgType getArgType(ASTContext &Ctx) const;
 
  bool fixType(QualType QT, QualType RawQT, const LangOptions &LangOpt,
               ASTContext &Ctx);
 
  void toString(raw_ostream &os) const;
};
 
} // namespace analyze_scanf
 
//===----------------------------------------------------------------------===//
// Parsing and processing of format strings (both fprintf and fscanf).
 
namespace analyze_format_string {
 
enum PositionContext { FieldWidthPos = 0, PrecisionPos = 1 };
 
class FormatStringHandler {
public:
  FormatStringHandler() {}
  virtual ~FormatStringHandler();
 
  virtual void HandleNullChar(const char *nullCharacter) {}
 
  virtual void HandlePosition(const char *startPos, unsigned posLen) {}
 
  virtual void HandleInvalidPosition(const char *startPos, unsigned posLen,
                                     PositionContext p) {}
 
  virtual void HandleZeroPosition(const char *startPos, unsigned posLen) {}
 
  virtual void HandleIncompleteSpecifier(const char *startSpecifier,
                                         unsigned specifierLen) {}
 
  virtual void HandleEmptyObjCModifierFlag(const char *startFlags,
                                           unsigned flagsLen) {}
 
  virtual void HandleInvalidObjCModifierFlag(const char *startFlag,
                                             unsigned flagLen) {}
 
  virtual void
  HandleObjCFlagsWithNonObjCConversion(const char *flagsStart,
                                       const char *flagsEnd,
                                       const char *conversionPosition) {}
  // Printf-specific handlers.
 
  virtual bool HandleInvalidPrintfConversionSpecifier(
      const analyze_printf::PrintfSpecifier &FS, const char *startSpecifier,
      unsigned specifierLen) {
    return true;
  }
 
  virtual bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
                                     const char *startSpecifier,
                                     unsigned specifierLen,
                                     const TargetInfo &Target) {
    return true;
  }
 
  /// Handle mask types whose sizes are not between one and eight bytes.
  virtual void handleInvalidMaskType(StringRef MaskType) {}
 
  // Scanf-specific handlers.
 
  virtual bool
  HandleInvalidScanfConversionSpecifier(const analyze_scanf::ScanfSpecifier &FS,
                                        const char *startSpecifier,
                                        unsigned specifierLen) {
    return true;
  }
 
  virtual bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
                                    const char *startSpecifier,
                                    unsigned specifierLen) {
    return true;
  }
 
  virtual void HandleIncompleteScanList(const char *start, const char *end) {}
};
 
bool ParsePrintfString(FormatStringHandler &H, const char *beg, const char *end,
                       const LangOptions &LO, const TargetInfo &Target,
                       bool isFreeBSDKPrintf);
 
bool ParseFormatStringHasSArg(const char *beg, const char *end,
                              const LangOptions &LO, const TargetInfo &Target);
 
bool ParseScanfString(FormatStringHandler &H, const char *beg, const char *end,
                      const LangOptions &LO, const TargetInfo &Target);
 
/// Return true if the given string has at least one formatting specifier.
bool parseFormatStringHasFormattingSpecifiers(const char *Begin,
                                              const char *End,
                                              const LangOptions &LO,
                                              const TargetInfo &Target);
 
} // namespace analyze_format_string
} // namespace clang
#endif