| //= 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 'b': k = ConversionSpecifier::bArg; 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::bArg: |
| 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); |
| [[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); |
| [[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 (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; |
| } |
