//== 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 "FormatStringParsing.h" using clang::analyze_format_string::ArgTypeResult; 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 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) { using namespace clang::analyze_format_string; using namespace clang::analyze_printf; const char *I = Beg; const char *Start = 0; UpdateOnReturn 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; } 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) { 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); // 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. //===----------------------------------------------------------------------===// ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx, bool IsObjCLiteral) const { const PrintfConversionSpecifier &CS = getConversionSpecifier(); if (!CS.consumesDataArgument()) return ArgTypeResult::Invalid(); if (CS.getKind() == ConversionSpecifier::cArg) switch (LM.getKind()) { case LengthModifier::None: return Ctx.IntTy; case LengthModifier::AsLong: return ArgTypeResult(ArgTypeResult::WIntTy, "wint_t"); default: return ArgTypeResult::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 ArgTypeResult::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 ArgTypeResult(Ctx.getIntMaxType(), "intmax_t"); case LengthModifier::AsSizeT: // FIXME: How to get the corresponding signed version of size_t? return ArgTypeResult(); case LengthModifier::AsPtrDiff: return ArgTypeResult(Ctx.getPointerDiffType(), "ptrdiff_t"); case LengthModifier::AsAllocate: case LengthModifier::AsMAllocate: return ArgTypeResult::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 ArgTypeResult(Ctx.getUIntMaxType(), "uintmax_t"); case LengthModifier::AsSizeT: return ArgTypeResult(Ctx.getSizeType(), "size_t"); case LengthModifier::AsPtrDiff: // FIXME: How to get the corresponding unsigned // version of ptrdiff_t? return ArgTypeResult(); case LengthModifier::AsAllocate: case LengthModifier::AsMAllocate: return ArgTypeResult::Invalid(); } if (CS.isDoubleArg()) { if (LM.getKind() == LengthModifier::AsLongDouble) return Ctx.LongDoubleTy; return Ctx.DoubleTy; } switch (CS.getKind()) { case ConversionSpecifier::sArg: if (LM.getKind() == LengthModifier::AsWideChar) { if (IsObjCLiteral) return Ctx.getPointerType(Ctx.UnsignedShortTy.withConst()); return ArgTypeResult(ArgTypeResult::WCStrTy, "wchar_t *"); } return ArgTypeResult::CStrTy; case ConversionSpecifier::SArg: if (IsObjCLiteral) return Ctx.getPointerType(Ctx.UnsignedShortTy.withConst()); return ArgTypeResult(ArgTypeResult::WCStrTy, "wchar_t *"); case ConversionSpecifier::CArg: if (IsObjCLiteral) return Ctx.UnsignedShortTy; return ArgTypeResult(Ctx.WCharTy, "wchar_t"); case ConversionSpecifier::pArg: return ArgTypeResult::CPointerTy; case ConversionSpecifier::ObjCObjArg: return ArgTypeResult::ObjCPointerTy; default: break; } // FIXME: Handle other cases. return ArgTypeResult(); } bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt, ASTContext &Ctx, bool IsObjCLiteral) { // Handle strings first (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; } // We can only work with builtin types. const BuiltinType *BT = QT->getAs(); 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(QT) && (LangOpt.C99 || LangOpt.CPlusPlus0x)) { const IdentifierInfo *Identifier = QT.getBaseTypeIdentifier(); if (Identifier->getName() == "size_t") { LM.setKind(LengthModifier::AsSizeT); } else if (Identifier->getName() == "ssize_t") { // Not C99, but common in Unix. LM.setKind(LengthModifier::AsSizeT); } else if (Identifier->getName() == "intmax_t") { LM.setKind(LengthModifier::AsIntMax); } else if (Identifier->getName() == "uintmax_t") { LM.setKind(LengthModifier::AsIntMax); } else if (Identifier->getName() == "ptrdiff_t") { LM.setKind(LengthModifier::AsPtrDiff); } } // If fixing the length modifier was enough, we are done. const analyze_printf::ArgTypeResult &ATR = getArgType(Ctx, IsObjCLiteral); if (hasValidLengthModifier() && 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(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::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::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::iArg: case ConversionSpecifier::oArg: 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::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::iArg: 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::iArg: case ConversionSpecifier::oArg: 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; } }