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llvm-project/clang/lib/Analysis/FormatString.cpp

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// FormatString.cpp - Common stuff for handling printf/scanf formats -*- C++ -*-
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Shared details for processing format strings of printf and scanf
// (and friends).
//
//===----------------------------------------------------------------------===//
#include "FormatStringParsing.h"
#include "clang/Basic/LangOptions.h"
using clang::analyze_format_string::ArgTypeResult;
using clang::analyze_format_string::FormatStringHandler;
using clang::analyze_format_string::FormatSpecifier;
using clang::analyze_format_string::LengthModifier;
using clang::analyze_format_string::OptionalAmount;
using clang::analyze_format_string::PositionContext;
using clang::analyze_format_string::ConversionSpecifier;
using namespace clang;
// Key function to FormatStringHandler.
FormatStringHandler::~FormatStringHandler() {}
//===----------------------------------------------------------------------===//
// Functions for parsing format strings components in both printf and
// scanf format strings.
//===----------------------------------------------------------------------===//
OptionalAmount
clang::analyze_format_string::ParseAmount(const char *&Beg, const char *E) {
const char *I = Beg;
UpdateOnReturn <const char*> UpdateBeg(Beg, I);
unsigned accumulator = 0;
bool hasDigits = false;
for ( ; I != E; ++I) {
char c = *I;
if (c >= '0' && c <= '9') {
hasDigits = true;
accumulator = (accumulator * 10) + (c - '0');
continue;
}
if (hasDigits)
return OptionalAmount(OptionalAmount::Constant, accumulator, Beg, I - Beg,
false);
break;
}
return OptionalAmount();
}
OptionalAmount
clang::analyze_format_string::ParseNonPositionAmount(const char *&Beg,
const char *E,
unsigned &argIndex) {
if (*Beg == '*') {
++Beg;
return OptionalAmount(OptionalAmount::Arg, argIndex++, Beg, 0, false);
}
return ParseAmount(Beg, E);
}
OptionalAmount
clang::analyze_format_string::ParsePositionAmount(FormatStringHandler &H,
const char *Start,
const char *&Beg,
const char *E,
PositionContext p) {
if (*Beg == '*') {
const char *I = Beg + 1;
const OptionalAmount &Amt = ParseAmount(I, E);
if (Amt.getHowSpecified() == OptionalAmount::NotSpecified) {
H.HandleInvalidPosition(Beg, I - Beg, p);
return OptionalAmount(false);
}
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return OptionalAmount(false);
}
assert(Amt.getHowSpecified() == OptionalAmount::Constant);
if (*I == '$') {
// Handle positional arguments
// Special case: '*0$', since this is an easy mistake.
if (Amt.getConstantAmount() == 0) {
H.HandleZeroPosition(Beg, I - Beg + 1);
return OptionalAmount(false);
}
const char *Tmp = Beg;
Beg = ++I;
return OptionalAmount(OptionalAmount::Arg, Amt.getConstantAmount() - 1,
Tmp, 0, true);
}
H.HandleInvalidPosition(Beg, I - Beg, p);
return OptionalAmount(false);
}
return ParseAmount(Beg, E);
}
bool
clang::analyze_format_string::ParseFieldWidth(FormatStringHandler &H,
FormatSpecifier &CS,
const char *Start,
const char *&Beg, const char *E,
unsigned *argIndex) {
// FIXME: Support negative field widths.
if (argIndex) {
CS.setFieldWidth(ParseNonPositionAmount(Beg, E, *argIndex));
}
else {
const OptionalAmount Amt =
ParsePositionAmount(H, Start, Beg, E,
analyze_format_string::FieldWidthPos);
if (Amt.isInvalid())
return true;
CS.setFieldWidth(Amt);
}
return false;
}
bool
clang::analyze_format_string::ParseArgPosition(FormatStringHandler &H,
FormatSpecifier &FS,
const char *Start,
const char *&Beg,
const char *E) {
const char *I = Beg;
const OptionalAmount &Amt = ParseAmount(I, E);
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
if (Amt.getHowSpecified() == OptionalAmount::Constant && *(I++) == '$') {
// Special case: '%0$', since this is an easy mistake.
if (Amt.getConstantAmount() == 0) {
H.HandleZeroPosition(Start, I - Start);
return true;
}
FS.setArgIndex(Amt.getConstantAmount() - 1);
FS.setUsesPositionalArg();
// Update the caller's pointer if we decided to consume
// these characters.
Beg = I;
return false;
}
return false;
}
bool
clang::analyze_format_string::ParseLengthModifier(FormatSpecifier &FS,
const char *&I,
const char *E,
const LangOptions &LO,
bool IsScanf) {
LengthModifier::Kind lmKind = LengthModifier::None;
const char *lmPosition = I;
switch (*I) {
default:
return false;
case 'h':
++I;
lmKind = (I != E && *I == 'h') ? (++I, LengthModifier::AsChar)
: LengthModifier::AsShort;
break;
case 'l':
++I;
lmKind = (I != E && *I == 'l') ? (++I, LengthModifier::AsLongLong)
: LengthModifier::AsLong;
break;
case 'j': lmKind = LengthModifier::AsIntMax; ++I; break;
case 'z': lmKind = LengthModifier::AsSizeT; ++I; break;
case 't': lmKind = LengthModifier::AsPtrDiff; ++I; break;
case 'L': lmKind = LengthModifier::AsLongDouble; ++I; break;
case 'q': lmKind = LengthModifier::AsLongLong; ++I; break;
case 'a':
if (IsScanf && !LO.C99 && !LO.CPlusPlus0x) {
// For scanf in C90, look at the next character to see if this should
// be parsed as the GNU extension 'a' length modifier. If not, this
// will be parsed as a conversion specifier.
++I;
if (I != E && (*I == 's' || *I == 'S' || *I == '[')) {
lmKind = LengthModifier::AsAllocate;
break;
}
--I;
}
return false;
}
LengthModifier lm(lmPosition, lmKind);
FS.setLengthModifier(lm);
return true;
}
//===----------------------------------------------------------------------===//
// Methods on ArgTypeResult.
//===----------------------------------------------------------------------===//
bool ArgTypeResult::matchesType(ASTContext &C, QualType argTy) const {
switch (K) {
case InvalidTy:
llvm_unreachable("ArgTypeResult must be valid");
case UnknownTy:
return true;
case AnyCharTy: {
if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
switch (BT->getKind()) {
default:
break;
case BuiltinType::Char_S:
case BuiltinType::SChar:
case BuiltinType::UChar:
case BuiltinType::Char_U:
return true;
}
return false;
}
case SpecificTy: {
argTy = C.getCanonicalType(argTy).getUnqualifiedType();
if (T == argTy)
return true;
// Check for "compatible types".
if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
switch (BT->getKind()) {
default:
break;
case BuiltinType::Char_S:
case BuiltinType::SChar:
return T == C.UnsignedCharTy;
case BuiltinType::Char_U:
case BuiltinType::UChar:
return T == C.SignedCharTy;
case BuiltinType::Short:
return T == C.UnsignedShortTy;
case BuiltinType::UShort:
return T == C.ShortTy;
case BuiltinType::Int:
return T == C.UnsignedIntTy;
case BuiltinType::UInt:
return T == C.IntTy;
case BuiltinType::Long:
return T == C.UnsignedLongTy;
case BuiltinType::ULong:
return T == C.LongTy;
case BuiltinType::LongLong:
return T == C.UnsignedLongLongTy;
case BuiltinType::ULongLong:
return T == C.LongLongTy;
}
return false;
}
case CStrTy: {
const PointerType *PT = argTy->getAs<PointerType>();
if (!PT)
return false;
QualType pointeeTy = PT->getPointeeType();
if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>())
switch (BT->getKind()) {
case BuiltinType::Void:
case BuiltinType::Char_U:
case BuiltinType::UChar:
case BuiltinType::Char_S:
case BuiltinType::SChar:
return true;
default:
break;
}
return false;
}
case WCStrTy: {
const PointerType *PT = argTy->getAs<PointerType>();
if (!PT)
return false;
QualType pointeeTy =
C.getCanonicalType(PT->getPointeeType()).getUnqualifiedType();
return pointeeTy == C.getWCharType();
}
case WIntTy: {
// Instead of doing a lookup for the definition of 'wint_t' (which
// is defined by the system headers) instead see if wchar_t and
// the argument type promote to the same type.
QualType PromoWChar =
C.getWCharType()->isPromotableIntegerType()
? C.getPromotedIntegerType(C.getWCharType()) : C.getWCharType();
QualType PromoArg =
argTy->isPromotableIntegerType()
? C.getPromotedIntegerType(argTy) : argTy;
PromoWChar = C.getCanonicalType(PromoWChar).getUnqualifiedType();
PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType();
return PromoWChar == PromoArg;
}
case CPointerTy:
return argTy->isPointerType() || argTy->isObjCObjectPointerType() ||
argTy->isNullPtrType();
case ObjCPointerTy:
return argTy->getAs<ObjCObjectPointerType>() != NULL;
}
// FIXME: Should be unreachable, but Clang is currently emitting
// a warning.
return false;
}
QualType ArgTypeResult::getRepresentativeType(ASTContext &C) const {
switch (K) {
case InvalidTy:
llvm_unreachable("No representative type for Invalid ArgTypeResult");
case UnknownTy:
return QualType();
case AnyCharTy:
return C.CharTy;
case SpecificTy:
return T;
case CStrTy:
return C.getPointerType(C.CharTy);
case WCStrTy:
return C.getPointerType(C.getWCharType());
case ObjCPointerTy:
return C.ObjCBuiltinIdTy;
case CPointerTy:
return C.VoidPtrTy;
case WIntTy: {
QualType WC = C.getWCharType();
return WC->isPromotableIntegerType() ? C.getPromotedIntegerType(WC) : WC;
}
}
// FIXME: Should be unreachable, but Clang is currently emitting
// a warning.
return QualType();
}
std::string ArgTypeResult::getRepresentativeTypeName(ASTContext &C) const {
std::string S = getRepresentativeType(C).getAsString();
if (Name)
return std::string("'") + Name + "' (aka '" + S + "')";
return std::string("'") + S + "'";
}
//===----------------------------------------------------------------------===//
// Methods on OptionalAmount.
//===----------------------------------------------------------------------===//
ArgTypeResult
analyze_format_string::OptionalAmount::getArgType(ASTContext &Ctx) const {
return Ctx.IntTy;
}
//===----------------------------------------------------------------------===//
// Methods on LengthModifier.
//===----------------------------------------------------------------------===//
const char *
analyze_format_string::LengthModifier::toString() const {
switch (kind) {
case AsChar:
return "hh";
case AsShort:
return "h";
case AsLong: // or AsWideChar
return "l";
case AsLongLong:
return "ll";
case AsIntMax:
return "j";
case AsSizeT:
return "z";
case AsPtrDiff:
return "t";
case AsLongDouble:
return "L";
case AsAllocate:
return "a";
case None:
return "";
}
return NULL;
}
//===----------------------------------------------------------------------===//
// Methods on ConversionSpecifier.
//===----------------------------------------------------------------------===//
const char *ConversionSpecifier::toString() const {
switch (kind) {
case dArg: return "d";
case iArg: return "i";
case oArg: return "o";
case uArg: return "u";
case xArg: return "x";
case XArg: return "X";
case fArg: return "f";
case FArg: return "F";
case eArg: return "e";
case EArg: return "E";
case gArg: return "g";
case GArg: return "G";
case aArg: return "a";
case AArg: return "A";
case cArg: return "c";
case sArg: return "s";
case pArg: return "p";
case nArg: return "n";
case PercentArg: return "%";
case ScanListArg: return "[";
case InvalidSpecifier: return NULL;
// MacOS X unicode extensions.
case CArg: return "C";
case SArg: return "S";
// Objective-C specific specifiers.
case ObjCObjArg: return "@";
// GlibC specific specifiers.
case PrintErrno: return "m";
}
return NULL;
}
//===----------------------------------------------------------------------===//
// Methods on OptionalAmount.
//===----------------------------------------------------------------------===//
void OptionalAmount::toString(raw_ostream &os) const {
switch (hs) {
case Invalid:
case NotSpecified:
return;
case Arg:
if (UsesDotPrefix)
os << ".";
if (usesPositionalArg())
os << "*" << getPositionalArgIndex() << "$";
else
os << "*";
break;
case Constant:
if (UsesDotPrefix)
os << ".";
os << amt;
break;
}
}
bool FormatSpecifier::hasValidLengthModifier() const {
switch (LM.getKind()) {
case LengthModifier::None:
return true;
// Handle most integer flags
case LengthModifier::AsChar:
case LengthModifier::AsShort:
case LengthModifier::AsLongLong:
case LengthModifier::AsIntMax:
case LengthModifier::AsSizeT:
case LengthModifier::AsPtrDiff:
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::oArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
case ConversionSpecifier::nArg:
return true;
default:
return false;
}
// Handle 'l' flag
case LengthModifier::AsLong:
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::oArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
case ConversionSpecifier::nArg:
case ConversionSpecifier::cArg:
case ConversionSpecifier::sArg:
return true;
default:
return false;
}
case LengthModifier::AsLongDouble:
switch (CS.getKind()) {
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
return true;
default:
return false;
}
case LengthModifier::AsAllocate:
switch (CS.getKind()) {
case ConversionSpecifier::sArg:
case ConversionSpecifier::SArg:
return true;
default:
return false;
}
}
return false;
}
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