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

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//== PrintfFormatString.cpp - Analysis of printf format strings --*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Handling of format string in printf and friends. The structure of format
// strings for fprintf() are described in C99 7.19.6.1.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/Analyses/FormatString.h"
#include "clang/Basic/TargetInfo.h"
#include "FormatStringParsing.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_printf::PrintfSpecifier;
using namespace clang;
typedef clang::analyze_format_string::SpecifierResult<PrintfSpecifier>
PrintfSpecifierResult;
//===----------------------------------------------------------------------===//
// Methods for parsing format strings.
//===----------------------------------------------------------------------===//
using analyze_format_string::ParseNonPositionAmount;
static bool ParsePrecision(FormatStringHandler &H, PrintfSpecifier &FS,
const char *Start, const char *&Beg, const char *E,
unsigned *argIndex) {
if (argIndex) {
FS.setPrecision(ParseNonPositionAmount(Beg, E, *argIndex));
} else {
const OptionalAmount Amt = ParsePositionAmount(H, Start, Beg, E,
analyze_format_string::PrecisionPos);
if (Amt.isInvalid())
return true;
FS.setPrecision(Amt);
}
return false;
}
static PrintfSpecifierResult ParsePrintfSpecifier(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_printf;
const char *I = Beg;
const char *Start = 0;
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;
}
PrintfSpecifier 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 flags (if any).
bool hasMore = true;
for ( ; I != E; ++I) {
switch (*I) {
default: hasMore = false; break;
case '\'':
// FIXME: POSIX specific. Always accept?
FS.setHasThousandsGrouping(I);
break;
case '-': FS.setIsLeftJustified(I); break;
case '+': FS.setHasPlusPrefix(I); break;
case ' ': FS.setHasSpacePrefix(I); break;
case '#': FS.setHasAlternativeForm(I); break;
case '0': FS.setHasLeadingZeros(I); break;
}
if (!hasMore)
break;
}
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
// Look for the field width (if any).
if (ParseFieldWidth(H, FS, Start, I, E,
FS.usesPositionalArg() ? 0 : &argIndex))
return true;
if (I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
// Look for the precision (if any).
if (*I == '.') {
++I;
if (I == E) {
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
if (ParsePrecision(H, FS, Start, I, E,
FS.usesPositionalArg() ? 0 : &argIndex))
return true;
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) && I == E) {
// No more characters left?
H.HandleIncompleteSpecifier(Start, E - Start);
return true;
}
if (*I == '\0') {
// Detect spurious null characters, which are likely errors.
H.HandleNullChar(I);
return true;
}
// Finally, look for the conversion specifier.
const char *conversionPosition = I++;
ConversionSpecifier::Kind k = ConversionSpecifier::InvalidSpecifier;
switch (*conversionPosition) {
default:
break;
// C99: 7.19.6.1 (section 8).
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 'c': k = ConversionSpecifier::cArg; 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 'o': k = ConversionSpecifier::oArg; break;
case 'p': k = ConversionSpecifier::pArg; break;
case 's': k = ConversionSpecifier::sArg; break;
case 'u': k = ConversionSpecifier::uArg; break;
case 'x': k = ConversionSpecifier::xArg; break;
// POSIX specific.
case 'C': k = ConversionSpecifier::CArg; break;
case 'S': k = ConversionSpecifier::SArg; break;
// Objective-C.
case '@': k = ConversionSpecifier::ObjCObjArg; break;
// Glibc specific.
case 'm': k = ConversionSpecifier::PrintErrno; break;
// 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;
}
PrintfConversionSpecifier CS(conversionPosition, k);
FS.setConversionSpecifier(CS);
if (CS.consumesDataArgument() && !FS.usesPositionalArg())
FS.setArgIndex(argIndex++);
if (k == ConversionSpecifier::InvalidSpecifier) {
// Assume the conversion takes one argument.
return !H.HandleInvalidPrintfConversionSpecifier(FS, Start, I - Start);
}
return PrintfSpecifierResult(Start, FS);
}
bool clang::analyze_format_string::ParsePrintfString(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 PrintfSpecifierResult &FSR = ParsePrintfSpecifier(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.HandlePrintfSpecifier(FSR.getValue(), FSR.getStart(),
I - FSR.getStart()))
return true;
}
assert(I == E && "Format string not exhausted");
return false;
}
//===----------------------------------------------------------------------===//
// Methods on PrintfSpecifier.
//===----------------------------------------------------------------------===//
ArgType PrintfSpecifier::getArgType(ASTContext &Ctx,
bool IsObjCLiteral) const {
const PrintfConversionSpecifier &CS = getConversionSpecifier();
if (!CS.consumesDataArgument())
return ArgType::Invalid();
if (CS.getKind() == ConversionSpecifier::cArg)
switch (LM.getKind()) {
case LengthModifier::None: return Ctx.IntTy;
case LengthModifier::AsLong:
return ArgType(ArgType::WIntTy, "wint_t");
default:
return ArgType::Invalid();
}
if (CS.isIntArg())
switch (LM.getKind()) {
case LengthModifier::AsLongDouble:
// GNU extension.
return Ctx.LongLongTy;
case LengthModifier::None: return Ctx.IntTy;
case LengthModifier::AsChar: return ArgType::AnyCharTy;
case LengthModifier::AsShort: return Ctx.ShortTy;
case LengthModifier::AsLong: return Ctx.LongTy;
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return Ctx.LongLongTy;
case LengthModifier::AsIntMax:
return ArgType(Ctx.getIntMaxType(), "intmax_t");
case LengthModifier::AsSizeT:
// FIXME: How to get the corresponding signed version of size_t?
return ArgType();
case LengthModifier::AsPtrDiff:
return ArgType(Ctx.getPointerDiffType(), "ptrdiff_t");
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
return ArgType::Invalid();
}
if (CS.isUIntArg())
switch (LM.getKind()) {
case LengthModifier::AsLongDouble:
// GNU extension.
return Ctx.UnsignedLongLongTy;
case LengthModifier::None: return Ctx.UnsignedIntTy;
case LengthModifier::AsChar: return Ctx.UnsignedCharTy;
case LengthModifier::AsShort: return Ctx.UnsignedShortTy;
case LengthModifier::AsLong: return Ctx.UnsignedLongTy;
case LengthModifier::AsLongLong:
case LengthModifier::AsQuad:
return Ctx.UnsignedLongLongTy;
case LengthModifier::AsIntMax:
return ArgType(Ctx.getUIntMaxType(), "uintmax_t");
case LengthModifier::AsSizeT:
return ArgType(Ctx.getSizeType(), "size_t");
case LengthModifier::AsPtrDiff:
// FIXME: How to get the corresponding unsigned
// version of ptrdiff_t?
return ArgType();
case LengthModifier::AsAllocate:
case LengthModifier::AsMAllocate:
return ArgType::Invalid();
}
if (CS.isDoubleArg()) {
if (LM.getKind() == LengthModifier::AsLongDouble)
return Ctx.LongDoubleTy;
return Ctx.DoubleTy;
}
if (CS.getKind() == 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::AsIntMax:
return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
case LengthModifier::AsSizeT:
return ArgType(); // FIXME: 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:
return ArgType::Invalid();
}
}
switch (CS.getKind()) {
case ConversionSpecifier::sArg:
if (LM.getKind() == LengthModifier::AsWideChar) {
if (IsObjCLiteral)
return Ctx.getPointerType(Ctx.UnsignedShortTy.withConst());
return ArgType(ArgType::WCStrTy, "wchar_t *");
}
return ArgType::CStrTy;
case ConversionSpecifier::SArg:
if (IsObjCLiteral)
return Ctx.getPointerType(Ctx.UnsignedShortTy.withConst());
return ArgType(ArgType::WCStrTy, "wchar_t *");
case ConversionSpecifier::CArg:
if (IsObjCLiteral)
return Ctx.UnsignedShortTy;
return ArgType(Ctx.WCharTy, "wchar_t");
case ConversionSpecifier::pArg:
return ArgType::CPointerTy;
case ConversionSpecifier::ObjCObjArg:
return ArgType::ObjCPointerTy;
default:
break;
}
// FIXME: Handle other cases.
return ArgType();
}
bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt,
ASTContext &Ctx, bool IsObjCLiteral) {
// %n is different from other conversion specifiers; don't try to fix it.
if (CS.getKind() == ConversionSpecifier::nArg)
return false;
// Handle Objective-C objects first. Note that while the '%@' specifier will
// not warn for structure pointer or void pointer arguments (because that's
// how CoreFoundation objects are implemented), we only show a fixit for '%@'
// if we know it's an object (block, id, class, or __attribute__((NSObject))).
if (QT->isObjCRetainableType()) {
if (!IsObjCLiteral)
return false;
CS.setKind(ConversionSpecifier::ObjCObjArg);
// Disable irrelevant flags
HasThousandsGrouping = false;
HasPlusPrefix = false;
HasSpacePrefix = false;
HasAlternativeForm = false;
HasLeadingZeroes = false;
Precision.setHowSpecified(OptionalAmount::NotSpecified);
LM.setKind(LengthModifier::None);
return true;
}
// Handle strings next (char *, wchar_t *)
if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) {
CS.setKind(ConversionSpecifier::sArg);
// Disable irrelevant flags
HasAlternativeForm = 0;
HasLeadingZeroes = 0;
// Set the long length modifier for wide characters
if (QT->getPointeeType()->isWideCharType())
LM.setKind(LengthModifier::AsWideChar);
else
LM.setKind(LengthModifier::None);
return true;
}
// If it's an enum, get its underlying type.
if (const EnumType *ETy = QT->getAs<EnumType>())
QT = ETy->getDecl()->getIntegerType();
// We can only work with builtin types.
const BuiltinType *BT = QT->getAs<BuiltinType>();
if (!BT)
return false;
// Set length modifier
switch (BT->getKind()) {
case BuiltinType::Bool:
case BuiltinType::WChar_U:
case BuiltinType::WChar_S:
case BuiltinType::Char16:
case BuiltinType::Char32:
case BuiltinType::UInt128:
case BuiltinType::Int128:
case BuiltinType::Half:
// Various types which are non-trivial to correct.
return false;
#define SIGNED_TYPE(Id, SingletonId)
#define UNSIGNED_TYPE(Id, SingletonId)
#define FLOATING_TYPE(Id, SingletonId)
#define BUILTIN_TYPE(Id, SingletonId) \
case BuiltinType::Id:
#include "clang/AST/BuiltinTypes.def"
// Misc other stuff which doesn't make sense here.
return false;
case BuiltinType::UInt:
case BuiltinType::Int:
case BuiltinType::Float:
case BuiltinType::Double:
LM.setKind(LengthModifier::None);
break;
case BuiltinType::Char_U:
case BuiltinType::UChar:
case BuiltinType::Char_S:
case BuiltinType::SChar:
LM.setKind(LengthModifier::AsChar);
break;
case BuiltinType::Short:
case BuiltinType::UShort:
LM.setKind(LengthModifier::AsShort);
break;
case BuiltinType::Long:
case BuiltinType::ULong:
LM.setKind(LengthModifier::AsLong);
break;
case BuiltinType::LongLong:
case BuiltinType::ULongLong:
LM.setKind(LengthModifier::AsLongLong);
break;
case BuiltinType::LongDouble:
LM.setKind(LengthModifier::AsLongDouble);
break;
}
// Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99.
if (isa<TypedefType>(QT) && (LangOpt.C99 || LangOpt.CPlusPlus0x))
namedTypeToLengthModifier(QT, LM);
// If fixing the length modifier was enough, we are done.
if (hasValidLengthModifier(Ctx.getTargetInfo())) {
const analyze_printf::ArgType &ATR = getArgType(Ctx, IsObjCLiteral);
if (ATR.isValid() && ATR.matchesType(Ctx, QT))
return true;
}
// Set conversion specifier and disable any flags which do not apply to it.
// Let typedefs to char fall through to int, as %c is silly for uint8_t.
if (isa<TypedefType>(QT) && QT->isAnyCharacterType()) {
CS.setKind(ConversionSpecifier::cArg);
LM.setKind(LengthModifier::None);
Precision.setHowSpecified(OptionalAmount::NotSpecified);
HasAlternativeForm = 0;
HasLeadingZeroes = 0;
HasPlusPrefix = 0;
}
// Test for Floating type first as LongDouble can pass isUnsignedIntegerType
else if (QT->isRealFloatingType()) {
CS.setKind(ConversionSpecifier::fArg);
}
else if (QT->isSignedIntegerType()) {
CS.setKind(ConversionSpecifier::dArg);
HasAlternativeForm = 0;
}
else if (QT->isUnsignedIntegerType()) {
CS.setKind(ConversionSpecifier::uArg);
HasAlternativeForm = 0;
HasPlusPrefix = 0;
} else {
llvm_unreachable("Unexpected type");
}
return true;
}
void PrintfSpecifier::toString(raw_ostream &os) const {
// Whilst some features have no defined order, we are using the order
// appearing in the C99 standard (ISO/IEC 9899:1999 (E) 7.19.6.1)
os << "%";
// Positional args
if (usesPositionalArg()) {
os << getPositionalArgIndex() << "$";
}
// Conversion flags
if (IsLeftJustified) os << "-";
if (HasPlusPrefix) os << "+";
if (HasSpacePrefix) os << " ";
if (HasAlternativeForm) os << "#";
if (HasLeadingZeroes) os << "0";
// Minimum field width
FieldWidth.toString(os);
// Precision
Precision.toString(os);
// Length modifier
os << LM.toString();
// Conversion specifier
os << CS.toString();
}
bool PrintfSpecifier::hasValidPlusPrefix() const {
if (!HasPlusPrefix)
return true;
// The plus prefix only makes sense for signed conversions
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
return true;
default:
return false;
}
}
bool PrintfSpecifier::hasValidAlternativeForm() const {
if (!HasAlternativeForm)
return true;
// Alternate form flag only valid with the oxXaAeEfFgG conversions
switch (CS.getKind()) {
case ConversionSpecifier::oArg:
case ConversionSpecifier::OArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
return true;
default:
return false;
}
}
bool PrintfSpecifier::hasValidLeadingZeros() const {
if (!HasLeadingZeroes)
return true;
// Leading zeroes flag only valid with the diouxXaAeEfFgG conversions
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::oArg:
case ConversionSpecifier::OArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::UArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
return true;
default:
return false;
}
}
bool PrintfSpecifier::hasValidSpacePrefix() const {
if (!HasSpacePrefix)
return true;
// The space prefix only makes sense for signed conversions
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
return true;
default:
return false;
}
}
bool PrintfSpecifier::hasValidLeftJustified() const {
if (!IsLeftJustified)
return true;
// The left justified flag is valid for all conversions except n
switch (CS.getKind()) {
case ConversionSpecifier::nArg:
return false;
default:
return true;
}
}
bool PrintfSpecifier::hasValidThousandsGroupingPrefix() const {
if (!HasThousandsGrouping)
return true;
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::UArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
return true;
default:
return false;
}
}
bool PrintfSpecifier::hasValidPrecision() const {
if (Precision.getHowSpecified() == OptionalAmount::NotSpecified)
return true;
// Precision is only valid with the diouxXaAeEfFgGs conversions
switch (CS.getKind()) {
case ConversionSpecifier::dArg:
case ConversionSpecifier::DArg:
case ConversionSpecifier::iArg:
case ConversionSpecifier::oArg:
case ConversionSpecifier::OArg:
case ConversionSpecifier::uArg:
case ConversionSpecifier::UArg:
case ConversionSpecifier::xArg:
case ConversionSpecifier::XArg:
case ConversionSpecifier::aArg:
case ConversionSpecifier::AArg:
case ConversionSpecifier::eArg:
case ConversionSpecifier::EArg:
case ConversionSpecifier::fArg:
case ConversionSpecifier::FArg:
case ConversionSpecifier::gArg:
case ConversionSpecifier::GArg:
case ConversionSpecifier::sArg:
return true;
default:
return false;
}
}
bool PrintfSpecifier::hasValidFieldWidth() const {
if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified)
return true;
// The field width is valid for all conversions except n
switch (CS.getKind()) {
case ConversionSpecifier::nArg:
return false;
default:
return true;
}
}
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