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llvm-project/clang/lib/AST/ScanfFormatString.cpp

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//= ScanfFormatString.cpp - Analysis of printf 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
//
//===----------------------------------------------------------------------===//
//
// Handling of format string in scanf and friends. The structure of format
// strings for fscanf() are described in C99 7.19.6.2.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/FormatString.h"
#include "FormatStringParsing.h"
#include "clang/Basic/TargetInfo.h"
using clang::analyze_format_string::ArgType;
using clang::analyze_format_string::FormatStringHandler;
using clang::analyze_format_string::LengthModifier;
using clang::analyze_format_string::OptionalAmount;
using clang::analyze_format_string::ConversionSpecifier;
using clang::analyze_scanf::ScanfConversionSpecifier;
using clang::analyze_scanf::ScanfSpecifier;
using clang::UpdateOnReturn;
using namespace clang;
typedef clang::analyze_format_string::SpecifierResult<ScanfSpecifier>
ScanfSpecifierResult;
static bool ParseScanList(FormatStringHandler &H,
ScanfConversionSpecifier &CS,
const char *&Beg, const char *E) {
const char *I = Beg;
const char *start = I - 1;
UpdateOnReturn <const char*> UpdateBeg(Beg, I);
// No more characters?
if (I == E) {
H.HandleIncompleteScanList(start, I);
return true;
}
// Special case: ']' is the first character.
if (*I == ']') {
if (++I == E) {
H.HandleIncompleteScanList(start, I - 1);
return true;
}
}
// Special case: "^]" are the first characters.
if (I + 1 != E && I[0] == '^' && I[1] == ']') {
I += 2;
if (I == E) {
H.HandleIncompleteScanList(start, I - 1);
return true;
}
}
// Look for a ']' character which denotes the end of the scan list.
while (*I != ']') {
if (++I == E) {
H.HandleIncompleteScanList(start, I - 1);
return true;
}
}
CS.setEndScanList(I);
return false;
}
// FIXME: Much of this is copy-paste from ParsePrintfSpecifier.
// We can possibly refactor.
static ScanfSpecifierResult ParseScanfSpecifier(FormatStringHandler &H,
const char *&Beg,
const char *E,
unsigned &argIndex,
const LangOptions &LO,
const TargetInfo &Target) {
using namespace clang::analyze_format_string;
using namespace clang::analyze_scanf;
const char *I = Beg;
const char *Start = nullptr;
UpdateOnReturn <const char*> UpdateBeg(Beg, I);
// Look for a '%' character that indicates the start of a format specifier.
for ( ; I != E ; ++I) {
char c = *I;
if (c == '\0') {
// Detect spurious null characters, which are likely errors.
H.HandleNullChar(I);
return true;
}
if (c == '%') {
Start = I++; // Record the start of the format specifier.
break;
}
}
// No format specifier found?
if (!Start)
return false;
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
ScanfSpecifier FS;
if (ParseArgPosition(H, FS, Start, I, E))
return true;
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
// Look for '*' flag if it is present.
if (*I == '*') {
FS.setSuppressAssignment(I);
if (++I == E) {
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
}
// Look for the field width (if any). Unlike printf, this is either
// a fixed integer or isn't present.
const OptionalAmount &Amt = clang::analyze_format_string::ParseAmount(I, E);
if (Amt.getHowSpecified() != OptionalAmount::NotSpecified) {
assert(Amt.getHowSpecified() == OptionalAmount::Constant);
FS.setFieldWidth(Amt);
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
}
// Look for the length modifier.
if (ParseLengthModifier(FS, I, E, LO, /*IsScanf=*/true) && I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
// Detect spurious null characters, which are likely errors.
if (*I == '\0') {
H.HandleNullChar(I);
return true;
}
// Finally, look for the conversion specifier.
const char *conversionPosition = I++;
ScanfConversionSpecifier::Kind k = ScanfConversionSpecifier::InvalidSpecifier;
switch (*conversionPosition) {
default:
break;
case '%': k = ConversionSpecifier::PercentArg; break;
case 'A': k = ConversionSpecifier::AArg; break;
case 'E': k = ConversionSpecifier::EArg; break;
case 'F': k = ConversionSpecifier::FArg; break;
case 'G': k = ConversionSpecifier::GArg; break;
case 'X': k = ConversionSpecifier::XArg; break;
case 'a': k = ConversionSpecifier::aArg; break;
case 'd': k = ConversionSpecifier::dArg; break;
case 'e': k = ConversionSpecifier::eArg; break;
case 'f': k = ConversionSpecifier::fArg; break;
case 'g': k = ConversionSpecifier::gArg; break;
case 'i': k = ConversionSpecifier::iArg; break;
case 'n': k = ConversionSpecifier::nArg; break;
case 'c': k = ConversionSpecifier::cArg; break;
case 'C': k = ConversionSpecifier::CArg; break;
case 'S': k = ConversionSpecifier::SArg; break;
case '[': k = ConversionSpecifier::ScanListArg; break;
case 'u': k = ConversionSpecifier::uArg; break;
case 'x': k = ConversionSpecifier::xArg; break;
case 'o': k = ConversionSpecifier::oArg; break;
case 's': k = ConversionSpecifier::sArg; break;
case 'p': k = ConversionSpecifier::pArg; break;
// Apple extensions
// Apple-specific
case 'D':
if (Target.getTriple().isOSDarwin())
k = ConversionSpecifier::DArg;
break;
case 'O':
if (Target.getTriple().isOSDarwin())
k = ConversionSpecifier::OArg;
break;
case 'U':
if (Target.getTriple().isOSDarwin())
k = ConversionSpecifier::UArg;
break;
}
ScanfConversionSpecifier CS(conversionPosition, k);
if (k == ScanfConversionSpecifier::ScanListArg) {
if (ParseScanList(H, CS, I, E))
return true;
}
FS.setConversionSpecifier(CS);
if (CS.consumesDataArgument() && !FS.getSuppressAssignment()
&& !FS.usesPositionalArg())
FS.setArgIndex(argIndex++);
// FIXME: '%' and '*' doesn't make sense. Issue a warning.
// FIXME: 'ConsumedSoFar' and '*' doesn't make sense.
if (k == ScanfConversionSpecifier::InvalidSpecifier) {
unsigned Len = I - Beg;
if (ParseUTF8InvalidSpecifier(Beg, E, Len)) {
CS.setEndScanList(Beg + Len);
FS.setConversionSpecifier(CS);
}
// Assume the conversion takes one argument.
return !H.HandleInvalidScanfConversionSpecifier(FS, Beg, Len);
}
return ScanfSpecifierResult(Start, FS);
}
ArgType ScanfSpecifier::getArgType(ASTContext &Ctx) const {
const ScanfConversionSpecifier &CS = getConversionSpecifier();
if (!CS.consumesDataArgument())
return ArgType::Invalid();
switch(CS.getKind()) {
// Signed int.
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.IntTy);
case LengthModifier::AsChar:
return ArgType::PtrTo(ArgType::AnyCharTy);
case LengthModifier::AsShort:
return ArgType::PtrTo(Ctx.ShortTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.LongTy);
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return ArgType::PtrTo(Ctx.LongLongTy);
case LengthModifier::AsInt64:
return ArgType::PtrTo(ArgType(Ctx.LongLongTy, "__int64"));
case LengthModifier::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
case LengthModifier::AsPtrDiff:
return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
case LengthModifier::AsLongDouble:
// GNU extension.
return ArgType::PtrTo(Ctx.LongLongTy);
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
case LengthModifier::AsInt32:
case LengthModifier::AsInt3264:
case LengthModifier::AsWide:
case LengthModifier::AsShortLong:
return ArgType::Invalid();
}
llvm_unreachable("Unsupported LengthModifier Type");
// Unsigned int.
case ConversionSpecifier::oArg:
case ConversionSpecifier::OArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::UArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.UnsignedIntTy);
case LengthModifier::AsChar:
return ArgType::PtrTo(Ctx.UnsignedCharTy);
case LengthModifier::AsShort:
return ArgType::PtrTo(Ctx.UnsignedShortTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.UnsignedLongTy);
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return ArgType::PtrTo(Ctx.UnsignedLongLongTy);
case LengthModifier::AsInt64:
return ArgType::PtrTo(ArgType(Ctx.UnsignedLongLongTy, "unsigned __int64"));
case LengthModifier::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getUIntMaxType(), "uintmax_t"));
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSizeType(), "size_t"));
case LengthModifier::AsPtrDiff:
return ArgType::PtrTo(
ArgType(Ctx.getUnsignedPointerDiffType(), "unsigned ptrdiff_t"));
case LengthModifier::AsLongDouble:
// GNU extension.
return ArgType::PtrTo(Ctx.UnsignedLongLongTy);
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
case LengthModifier::AsInt32:
case LengthModifier::AsInt3264:
case LengthModifier::AsWide:
case LengthModifier::AsShortLong:
return ArgType::Invalid();
}
llvm_unreachable("Unsupported LengthModifier Type");
// Float.
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.FloatTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.DoubleTy);
case LengthModifier::AsLongDouble:
return ArgType::PtrTo(Ctx.LongDoubleTy);
default:
return ArgType::Invalid();
}
// Char, string and scanlist.
case ConversionSpecifier::cArg:
case ConversionSpecifier::sArg:
case ConversionSpecifier::ScanListArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(ArgType::AnyCharTy);
case LengthModifier::AsLong:
case LengthModifier::AsWide:
return ArgType::PtrTo(ArgType(Ctx.getWideCharType(), "wchar_t"));
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
return ArgType::PtrTo(ArgType::CStrTy);
case LengthModifier::AsShort:
if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
return ArgType::PtrTo(ArgType::AnyCharTy);
LLVM_FALLTHROUGH;
default:
return ArgType::Invalid();
}
case ConversionSpecifier::CArg:
case ConversionSpecifier::SArg:
// FIXME: Mac OS X specific?
switch (LM.getKind()) {
case LengthModifier::None:
case LengthModifier::AsWide:
return ArgType::PtrTo(ArgType(Ctx.getWideCharType(), "wchar_t"));
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
return ArgType::PtrTo(ArgType(ArgType::WCStrTy, "wchar_t *"));
case LengthModifier::AsShort:
if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
return ArgType::PtrTo(ArgType::AnyCharTy);
LLVM_FALLTHROUGH;
default:
return ArgType::Invalid();
}
// Pointer.
case ConversionSpecifier::pArg:
return ArgType::PtrTo(ArgType::CPointerTy);
// Write-back.
case ConversionSpecifier::nArg:
switch (LM.getKind()) {
case LengthModifier::None:
return ArgType::PtrTo(Ctx.IntTy);
case LengthModifier::AsChar:
return ArgType::PtrTo(Ctx.SignedCharTy);
case LengthModifier::AsShort:
return ArgType::PtrTo(Ctx.ShortTy);
case LengthModifier::AsLong:
return ArgType::PtrTo(Ctx.LongTy);
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return ArgType::PtrTo(Ctx.LongLongTy);
case LengthModifier::AsInt64:
return ArgType::PtrTo(ArgType(Ctx.LongLongTy, "__int64"));
case LengthModifier::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
case LengthModifier::AsPtrDiff:
return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
case LengthModifier::AsLongDouble:
return ArgType(); // FIXME: Is this a known extension?
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
case LengthModifier::AsInt32:
case LengthModifier::AsInt3264:
case LengthModifier::AsWide:
case LengthModifier::AsShortLong:
return ArgType::Invalid();
}
default:
break;
}
return ArgType();
}
bool ScanfSpecifier::fixType(QualType QT, QualType RawQT,
const LangOptions &LangOpt,
ASTContext &Ctx) {
// %n is different from other conversion specifiers; don't try to fix it.
if (CS.getKind() == ConversionSpecifier::nArg)
return false;
if (!QT->isPointerType())
return false;
QualType PT = QT->getPointeeType();
// If it's an enum, get its underlying type.
if (const EnumType *ETy = PT->getAs<EnumType>()) {
// Don't try to fix incomplete enums.
if (!ETy->getDecl()->isComplete())
return false;
PT = ETy->getDecl()->getIntegerType();
}
const BuiltinType *BT = PT->getAs<BuiltinType>();
if (!BT)
return false;
// Pointer to a character.
if (PT->isAnyCharacterType()) {
CS.setKind(ConversionSpecifier::sArg);
if (PT->isWideCharType())
LM.setKind(LengthModifier::AsWideChar);
else
LM.setKind(LengthModifier::None);
// If we know the target array length, we can use it as a field width.
if (const ConstantArrayType *CAT = Ctx.getAsConstantArrayType(RawQT)) {
if (CAT->getSizeModifier() == ArrayType::Normal)
FieldWidth = OptionalAmount(OptionalAmount::Constant,
CAT->getSize().getZExtValue() - 1,
"", 0, false);
}
return true;
}
// Figure out the length modifier.
switch (BT->getKind()) {
// no modifier
case BuiltinType::UInt:
case BuiltinType::Int:
case BuiltinType::Float:
LM.setKind(LengthModifier::None);
break;
// hh
case BuiltinType::Char_U:
case BuiltinType::UChar:
case BuiltinType::Char_S:
case BuiltinType::SChar:
LM.setKind(LengthModifier::AsChar);
break;
// h
case BuiltinType::Short:
case BuiltinType::UShort:
LM.setKind(LengthModifier::AsShort);
break;
// l
case BuiltinType::Long:
case BuiltinType::ULong:
case BuiltinType::Double:
LM.setKind(LengthModifier::AsLong);
break;
// ll
case BuiltinType::LongLong:
case BuiltinType::ULongLong:
LM.setKind(LengthModifier::AsLongLong);
break;
// L
case BuiltinType::LongDouble:
LM.setKind(LengthModifier::AsLongDouble);
break;
// Don't know.
default:
return false;
}
// Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99.
if (isa<TypedefType>(PT) && (LangOpt.C99 || LangOpt.CPlusPlus11))
namedTypeToLengthModifier(PT, LM);
// If fixing the length modifier was enough, we are done.
if (hasValidLengthModifier(Ctx.getTargetInfo(), LangOpt)) {
const analyze_scanf::ArgType &AT = getArgType(Ctx);
if (AT.isValid() && AT.matchesType(Ctx, QT))
return true;
}
// Figure out the conversion specifier.
if (PT->isRealFloatingType())
CS.setKind(ConversionSpecifier::fArg);
else if (PT->isSignedIntegerType())
CS.setKind(ConversionSpecifier::dArg);
else if (PT->isUnsignedIntegerType())
CS.setKind(ConversionSpecifier::uArg);
else
llvm_unreachable("Unexpected type");
return true;
}
void ScanfSpecifier::toString(raw_ostream &os) const {
os << "%";
if (usesPositionalArg())
os << getPositionalArgIndex() << "$";
if (SuppressAssignment)
os << "*";
FieldWidth.toString(os);
os << LM.toString();
os << CS.toString();
}
bool clang::analyze_format_string::ParseScanfString(FormatStringHandler &H,
const char *I,
const char *E,
const LangOptions &LO,
const TargetInfo &Target) {
unsigned argIndex = 0;
// Keep looking for a format specifier until we have exhausted the string.
while (I != E) {
const ScanfSpecifierResult &FSR = ParseScanfSpecifier(H, I, E, argIndex,
LO, Target);
// Did a fail-stop error of any kind occur when parsing the specifier?
// If so, don't do any more processing.
if (FSR.shouldStop())
return true;
// Did we exhaust the string or encounter an error that
// we can recover from?
if (!FSR.hasValue())
continue;
// We have a format specifier. Pass it to the callback.
if (!H.HandleScanfSpecifier(FSR.getValue(), FSR.getStart(),
I - FSR.getStart())) {
return true;
}
}
assert(I == E && "Format string not exhausted");
return false;
}
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