1 // FormatString.cpp - Common stuff for handling printf/scanf formats -*- C++ -*-
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Shared details for processing format strings of printf and scanf
10 // (and friends).
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "FormatStringParsing.h"
15 #include "clang/Basic/LangOptions.h"
16 #include "clang/Basic/TargetInfo.h"
17 #include "llvm/Support/ConvertUTF.h"
18 
19 using clang::analyze_format_string::ArgType;
20 using clang::analyze_format_string::FormatStringHandler;
21 using clang::analyze_format_string::FormatSpecifier;
22 using clang::analyze_format_string::LengthModifier;
23 using clang::analyze_format_string::OptionalAmount;
24 using clang::analyze_format_string::PositionContext;
25 using clang::analyze_format_string::ConversionSpecifier;
26 using namespace clang;
27 
28 // Key function to FormatStringHandler.
29 FormatStringHandler::~FormatStringHandler() {}
30 
31 //===----------------------------------------------------------------------===//
32 // Functions for parsing format strings components in both printf and
33 // scanf format strings.
34 //===----------------------------------------------------------------------===//
35 
36 OptionalAmount
37 clang::analyze_format_string::ParseAmount(const char *&Beg, const char *E) {
38   const char *I = Beg;
39   UpdateOnReturn <const char*> UpdateBeg(Beg, I);
40 
41   unsigned accumulator = 0;
42   bool hasDigits = false;
43 
44   for ( ; I != E; ++I) {
45     char c = *I;
46     if (c >= '0' && c <= '9') {
47       hasDigits = true;
48       accumulator = (accumulator * 10) + (c - '0');
49       continue;
50     }
51 
52     if (hasDigits)
53       return OptionalAmount(OptionalAmount::Constant, accumulator, Beg, I - Beg,
54           false);
55 
56     break;
57   }
58 
59   return OptionalAmount();
60 }
61 
62 OptionalAmount
63 clang::analyze_format_string::ParseNonPositionAmount(const char *&Beg,
64                                                      const char *E,
65                                                      unsigned &argIndex) {
66   if (*Beg == '*') {
67     ++Beg;
68     return OptionalAmount(OptionalAmount::Arg, argIndex++, Beg, 0, false);
69   }
70 
71   return ParseAmount(Beg, E);
72 }
73 
74 OptionalAmount
75 clang::analyze_format_string::ParsePositionAmount(FormatStringHandler &H,
76                                                   const char *Start,
77                                                   const char *&Beg,
78                                                   const char *E,
79                                                   PositionContext p) {
80   if (*Beg == '*') {
81     const char *I = Beg + 1;
82     const OptionalAmount &Amt = ParseAmount(I, E);
83 
84     if (Amt.getHowSpecified() == OptionalAmount::NotSpecified) {
85       H.HandleInvalidPosition(Beg, I - Beg, p);
86       return OptionalAmount(false);
87     }
88 
89     if (I == E) {
90       // No more characters left?
91       H.HandleIncompleteSpecifier(Start, E - Start);
92       return OptionalAmount(false);
93     }
94 
95     assert(Amt.getHowSpecified() == OptionalAmount::Constant);
96 
97     if (*I == '$') {
98       // Handle positional arguments
99 
100       // Special case: '*0$', since this is an easy mistake.
101       if (Amt.getConstantAmount() == 0) {
102         H.HandleZeroPosition(Beg, I - Beg + 1);
103         return OptionalAmount(false);
104       }
105 
106       const char *Tmp = Beg;
107       Beg = ++I;
108 
109       return OptionalAmount(OptionalAmount::Arg, Amt.getConstantAmount() - 1,
110                             Tmp, 0, true);
111     }
112 
113     H.HandleInvalidPosition(Beg, I - Beg, p);
114     return OptionalAmount(false);
115   }
116 
117   return ParseAmount(Beg, E);
118 }
119 
120 
121 bool
122 clang::analyze_format_string::ParseFieldWidth(FormatStringHandler &H,
123                                               FormatSpecifier &CS,
124                                               const char *Start,
125                                               const char *&Beg, const char *E,
126                                               unsigned *argIndex) {
127   // FIXME: Support negative field widths.
128   if (argIndex) {
129     CS.setFieldWidth(ParseNonPositionAmount(Beg, E, *argIndex));
130   }
131   else {
132     const OptionalAmount Amt =
133       ParsePositionAmount(H, Start, Beg, E,
134                           analyze_format_string::FieldWidthPos);
135 
136     if (Amt.isInvalid())
137       return true;
138     CS.setFieldWidth(Amt);
139   }
140   return false;
141 }
142 
143 bool
144 clang::analyze_format_string::ParseArgPosition(FormatStringHandler &H,
145                                                FormatSpecifier &FS,
146                                                const char *Start,
147                                                const char *&Beg,
148                                                const char *E) {
149   const char *I = Beg;
150 
151   const OptionalAmount &Amt = ParseAmount(I, E);
152 
153   if (I == E) {
154     // No more characters left?
155     H.HandleIncompleteSpecifier(Start, E - Start);
156     return true;
157   }
158 
159   if (Amt.getHowSpecified() == OptionalAmount::Constant && *(I++) == '$') {
160     // Warn that positional arguments are non-standard.
161     H.HandlePosition(Start, I - Start);
162 
163     // Special case: '%0$', since this is an easy mistake.
164     if (Amt.getConstantAmount() == 0) {
165       H.HandleZeroPosition(Start, I - Start);
166       return true;
167     }
168 
169     FS.setArgIndex(Amt.getConstantAmount() - 1);
170     FS.setUsesPositionalArg();
171     // Update the caller's pointer if we decided to consume
172     // these characters.
173     Beg = I;
174     return false;
175   }
176 
177   return false;
178 }
179 
180 bool
181 clang::analyze_format_string::ParseVectorModifier(FormatStringHandler &H,
182                                                   FormatSpecifier &FS,
183                                                   const char *&I,
184                                                   const char *E,
185                                                   const LangOptions &LO) {
186   if (!LO.OpenCL)
187     return false;
188 
189   const char *Start = I;
190   if (*I == 'v') {
191     ++I;
192 
193     if (I == E) {
194       H.HandleIncompleteSpecifier(Start, E - Start);
195       return true;
196     }
197 
198     OptionalAmount NumElts = ParseAmount(I, E);
199     if (NumElts.getHowSpecified() != OptionalAmount::Constant) {
200       H.HandleIncompleteSpecifier(Start, E - Start);
201       return true;
202     }
203 
204     FS.setVectorNumElts(NumElts);
205   }
206 
207   return false;
208 }
209 
210 bool
211 clang::analyze_format_string::ParseLengthModifier(FormatSpecifier &FS,
212                                                   const char *&I,
213                                                   const char *E,
214                                                   const LangOptions &LO,
215                                                   bool IsScanf) {
216   LengthModifier::Kind lmKind = LengthModifier::None;
217   const char *lmPosition = I;
218   switch (*I) {
219     default:
220       return false;
221     case 'h':
222       ++I;
223       if (I != E && *I == 'h') {
224         ++I;
225         lmKind = LengthModifier::AsChar;
226       } else {
227         lmKind = LengthModifier::AsShort;
228       }
229       break;
230     case 'l':
231       ++I;
232       if (I != E && *I == 'l') {
233         ++I;
234         lmKind = LengthModifier::AsLongLong;
235       } else {
236         lmKind = LengthModifier::AsLong;
237       }
238       break;
239     case 'j': lmKind = LengthModifier::AsIntMax;     ++I; break;
240     case 'z': lmKind = LengthModifier::AsSizeT;      ++I; break;
241     case 't': lmKind = LengthModifier::AsPtrDiff;    ++I; break;
242     case 'L': lmKind = LengthModifier::AsLongDouble; ++I; break;
243     case 'q': lmKind = LengthModifier::AsQuad;       ++I; break;
244     case 'a':
245       if (IsScanf && !LO.C99 && !LO.CPlusPlus11) {
246         // For scanf in C90, look at the next character to see if this should
247         // be parsed as the GNU extension 'a' length modifier. If not, this
248         // will be parsed as a conversion specifier.
249         ++I;
250         if (I != E && (*I == 's' || *I == 'S' || *I == '[')) {
251           lmKind = LengthModifier::AsAllocate;
252           break;
253         }
254         --I;
255       }
256       return false;
257     case 'm':
258       if (IsScanf) {
259         lmKind = LengthModifier::AsMAllocate;
260         ++I;
261         break;
262       }
263       return false;
264     // printf: AsInt64, AsInt32, AsInt3264
265     // scanf:  AsInt64
266     case 'I':
267       if (I + 1 != E && I + 2 != E) {
268         if (I[1] == '6' && I[2] == '4') {
269           I += 3;
270           lmKind = LengthModifier::AsInt64;
271           break;
272         }
273         if (IsScanf)
274           return false;
275 
276         if (I[1] == '3' && I[2] == '2') {
277           I += 3;
278           lmKind = LengthModifier::AsInt32;
279           break;
280         }
281       }
282       ++I;
283       lmKind = LengthModifier::AsInt3264;
284       break;
285     case 'w':
286       lmKind = LengthModifier::AsWide; ++I; break;
287   }
288   LengthModifier lm(lmPosition, lmKind);
289   FS.setLengthModifier(lm);
290   return true;
291 }
292 
293 bool clang::analyze_format_string::ParseUTF8InvalidSpecifier(
294     const char *SpecifierBegin, const char *FmtStrEnd, unsigned &Len) {
295   if (SpecifierBegin + 1 >= FmtStrEnd)
296     return false;
297 
298   const llvm::UTF8 *SB =
299       reinterpret_cast<const llvm::UTF8 *>(SpecifierBegin + 1);
300   const llvm::UTF8 *SE = reinterpret_cast<const llvm::UTF8 *>(FmtStrEnd);
301   const char FirstByte = *SB;
302 
303   // If the invalid specifier is a multibyte UTF-8 string, return the
304   // total length accordingly so that the conversion specifier can be
305   // properly updated to reflect a complete UTF-8 specifier.
306   unsigned NumBytes = llvm::getNumBytesForUTF8(FirstByte);
307   if (NumBytes == 1)
308     return false;
309   if (SB + NumBytes > SE)
310     return false;
311 
312   Len = NumBytes + 1;
313   return true;
314 }
315 
316 //===----------------------------------------------------------------------===//
317 // Methods on ArgType.
318 //===----------------------------------------------------------------------===//
319 
320 clang::analyze_format_string::ArgType::MatchKind
321 ArgType::matchesType(ASTContext &C, QualType argTy) const {
322   if (Ptr) {
323     // It has to be a pointer.
324     const PointerType *PT = argTy->getAs<PointerType>();
325     if (!PT)
326       return NoMatch;
327 
328     // We cannot write through a const qualified pointer.
329     if (PT->getPointeeType().isConstQualified())
330       return NoMatch;
331 
332     argTy = PT->getPointeeType();
333   }
334 
335   switch (K) {
336     case InvalidTy:
337       llvm_unreachable("ArgType must be valid");
338 
339     case UnknownTy:
340       return Match;
341 
342     case AnyCharTy: {
343       if (const EnumType *ETy = argTy->getAs<EnumType>()) {
344         // If the enum is incomplete we know nothing about the underlying type.
345         // Assume that it's 'int'.
346         if (!ETy->getDecl()->isComplete())
347           return NoMatch;
348         argTy = ETy->getDecl()->getIntegerType();
349       }
350 
351       if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
352         switch (BT->getKind()) {
353           default:
354             break;
355           case BuiltinType::Char_S:
356           case BuiltinType::SChar:
357           case BuiltinType::UChar:
358           case BuiltinType::Char_U:
359             return Match;
360         }
361       return NoMatch;
362     }
363 
364     case SpecificTy: {
365       if (const EnumType *ETy = argTy->getAs<EnumType>()) {
366         // If the enum is incomplete we know nothing about the underlying type.
367         // Assume that it's 'int'.
368         if (!ETy->getDecl()->isComplete())
369           argTy = C.IntTy;
370         else
371           argTy = ETy->getDecl()->getIntegerType();
372       }
373       argTy = C.getCanonicalType(argTy).getUnqualifiedType();
374 
375       if (T == argTy)
376         return Match;
377       // Check for "compatible types".
378       if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
379         switch (BT->getKind()) {
380           default:
381             break;
382           case BuiltinType::Char_S:
383           case BuiltinType::SChar:
384           case BuiltinType::Char_U:
385           case BuiltinType::UChar:
386             return T == C.UnsignedCharTy || T == C.SignedCharTy ? Match
387                                                                 : NoMatch;
388           case BuiltinType::Short:
389             return T == C.UnsignedShortTy ? Match : NoMatch;
390           case BuiltinType::UShort:
391             return T == C.ShortTy ? Match : NoMatch;
392           case BuiltinType::Int:
393             return T == C.UnsignedIntTy ? Match : NoMatch;
394           case BuiltinType::UInt:
395             return T == C.IntTy ? Match : NoMatch;
396           case BuiltinType::Long:
397             return T == C.UnsignedLongTy ? Match : NoMatch;
398           case BuiltinType::ULong:
399             return T == C.LongTy ? Match : NoMatch;
400           case BuiltinType::LongLong:
401             return T == C.UnsignedLongLongTy ? Match : NoMatch;
402           case BuiltinType::ULongLong:
403             return T == C.LongLongTy ? Match : NoMatch;
404         }
405       return NoMatch;
406     }
407 
408     case CStrTy: {
409       const PointerType *PT = argTy->getAs<PointerType>();
410       if (!PT)
411         return NoMatch;
412       QualType pointeeTy = PT->getPointeeType();
413       if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>())
414         switch (BT->getKind()) {
415           case BuiltinType::Void:
416           case BuiltinType::Char_U:
417           case BuiltinType::UChar:
418           case BuiltinType::Char_S:
419           case BuiltinType::SChar:
420             return Match;
421           default:
422             break;
423         }
424 
425       return NoMatch;
426     }
427 
428     case WCStrTy: {
429       const PointerType *PT = argTy->getAs<PointerType>();
430       if (!PT)
431         return NoMatch;
432       QualType pointeeTy =
433         C.getCanonicalType(PT->getPointeeType()).getUnqualifiedType();
434       return pointeeTy == C.getWideCharType() ? Match : NoMatch;
435     }
436 
437     case WIntTy: {
438       QualType WInt = C.getCanonicalType(C.getWIntType()).getUnqualifiedType();
439 
440       if (C.getCanonicalType(argTy).getUnqualifiedType() == WInt)
441         return Match;
442 
443       QualType PromoArg = argTy->isPromotableIntegerType()
444                               ? C.getPromotedIntegerType(argTy)
445                               : argTy;
446       PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType();
447 
448       // If the promoted argument is the corresponding signed type of the
449       // wint_t type, then it should match.
450       if (PromoArg->hasSignedIntegerRepresentation() &&
451           C.getCorrespondingUnsignedType(PromoArg) == WInt)
452         return Match;
453 
454       return WInt == PromoArg ? Match : NoMatch;
455     }
456 
457     case CPointerTy:
458       if (argTy->isVoidPointerType()) {
459         return Match;
460       } if (argTy->isPointerType() || argTy->isObjCObjectPointerType() ||
461             argTy->isBlockPointerType() || argTy->isNullPtrType()) {
462         return NoMatchPedantic;
463       } else {
464         return NoMatch;
465       }
466 
467     case ObjCPointerTy: {
468       if (argTy->getAs<ObjCObjectPointerType>() ||
469           argTy->getAs<BlockPointerType>())
470         return Match;
471 
472       // Handle implicit toll-free bridging.
473       if (const PointerType *PT = argTy->getAs<PointerType>()) {
474         // Things such as CFTypeRef are really just opaque pointers
475         // to C structs representing CF types that can often be bridged
476         // to Objective-C objects.  Since the compiler doesn't know which
477         // structs can be toll-free bridged, we just accept them all.
478         QualType pointee = PT->getPointeeType();
479         if (pointee->getAsStructureType() || pointee->isVoidType())
480           return Match;
481       }
482       return NoMatch;
483     }
484   }
485 
486   llvm_unreachable("Invalid ArgType Kind!");
487 }
488 
489 ArgType ArgType::makeVectorType(ASTContext &C, unsigned NumElts) const {
490   if (K != SpecificTy) // Won't be a valid vector element type.
491     return ArgType::Invalid();
492 
493   QualType Vec = C.getExtVectorType(T, NumElts);
494   return ArgType(Vec, Name);
495 }
496 
497 QualType ArgType::getRepresentativeType(ASTContext &C) const {
498   QualType Res;
499   switch (K) {
500     case InvalidTy:
501       llvm_unreachable("No representative type for Invalid ArgType");
502     case UnknownTy:
503       llvm_unreachable("No representative type for Unknown ArgType");
504     case AnyCharTy:
505       Res = C.CharTy;
506       break;
507     case SpecificTy:
508       Res = T;
509       break;
510     case CStrTy:
511       Res = C.getPointerType(C.CharTy);
512       break;
513     case WCStrTy:
514       Res = C.getPointerType(C.getWideCharType());
515       break;
516     case ObjCPointerTy:
517       Res = C.ObjCBuiltinIdTy;
518       break;
519     case CPointerTy:
520       Res = C.VoidPtrTy;
521       break;
522     case WIntTy: {
523       Res = C.getWIntType();
524       break;
525     }
526   }
527 
528   if (Ptr)
529     Res = C.getPointerType(Res);
530   return Res;
531 }
532 
533 std::string ArgType::getRepresentativeTypeName(ASTContext &C) const {
534   std::string S = getRepresentativeType(C).getAsString();
535 
536   std::string Alias;
537   if (Name) {
538     // Use a specific name for this type, e.g. "size_t".
539     Alias = Name;
540     if (Ptr) {
541       // If ArgType is actually a pointer to T, append an asterisk.
542       Alias += (Alias[Alias.size()-1] == '*') ? "*" : " *";
543     }
544     // If Alias is the same as the underlying type, e.g. wchar_t, then drop it.
545     if (S == Alias)
546       Alias.clear();
547   }
548 
549   if (!Alias.empty())
550     return std::string("'") + Alias + "' (aka '" + S + "')";
551   return std::string("'") + S + "'";
552 }
553 
554 
555 //===----------------------------------------------------------------------===//
556 // Methods on OptionalAmount.
557 //===----------------------------------------------------------------------===//
558 
559 ArgType
560 analyze_format_string::OptionalAmount::getArgType(ASTContext &Ctx) const {
561   return Ctx.IntTy;
562 }
563 
564 //===----------------------------------------------------------------------===//
565 // Methods on LengthModifier.
566 //===----------------------------------------------------------------------===//
567 
568 const char *
569 analyze_format_string::LengthModifier::toString() const {
570   switch (kind) {
571   case AsChar:
572     return "hh";
573   case AsShort:
574     return "h";
575   case AsLong: // or AsWideChar
576     return "l";
577   case AsLongLong:
578     return "ll";
579   case AsQuad:
580     return "q";
581   case AsIntMax:
582     return "j";
583   case AsSizeT:
584     return "z";
585   case AsPtrDiff:
586     return "t";
587   case AsInt32:
588     return "I32";
589   case AsInt3264:
590     return "I";
591   case AsInt64:
592     return "I64";
593   case AsLongDouble:
594     return "L";
595   case AsAllocate:
596     return "a";
597   case AsMAllocate:
598     return "m";
599   case AsWide:
600     return "w";
601   case None:
602     return "";
603   }
604   return nullptr;
605 }
606 
607 //===----------------------------------------------------------------------===//
608 // Methods on ConversionSpecifier.
609 //===----------------------------------------------------------------------===//
610 
611 const char *ConversionSpecifier::toString() const {
612   switch (kind) {
613   case dArg: return "d";
614   case DArg: return "D";
615   case iArg: return "i";
616   case oArg: return "o";
617   case OArg: return "O";
618   case uArg: return "u";
619   case UArg: return "U";
620   case xArg: return "x";
621   case XArg: return "X";
622   case fArg: return "f";
623   case FArg: return "F";
624   case eArg: return "e";
625   case EArg: return "E";
626   case gArg: return "g";
627   case GArg: return "G";
628   case aArg: return "a";
629   case AArg: return "A";
630   case cArg: return "c";
631   case sArg: return "s";
632   case pArg: return "p";
633   case PArg:
634     return "P";
635   case nArg: return "n";
636   case PercentArg:  return "%";
637   case ScanListArg: return "[";
638   case InvalidSpecifier: return nullptr;
639 
640   // POSIX unicode extensions.
641   case CArg: return "C";
642   case SArg: return "S";
643 
644   // Objective-C specific specifiers.
645   case ObjCObjArg: return "@";
646 
647   // FreeBSD kernel specific specifiers.
648   case FreeBSDbArg: return "b";
649   case FreeBSDDArg: return "D";
650   case FreeBSDrArg: return "r";
651   case FreeBSDyArg: return "y";
652 
653   // GlibC specific specifiers.
654   case PrintErrno: return "m";
655 
656   // MS specific specifiers.
657   case ZArg: return "Z";
658   }
659   return nullptr;
660 }
661 
662 Optional<ConversionSpecifier>
663 ConversionSpecifier::getStandardSpecifier() const {
664   ConversionSpecifier::Kind NewKind;
665 
666   switch (getKind()) {
667   default:
668     return None;
669   case DArg:
670     NewKind = dArg;
671     break;
672   case UArg:
673     NewKind = uArg;
674     break;
675   case OArg:
676     NewKind = oArg;
677     break;
678   }
679 
680   ConversionSpecifier FixedCS(*this);
681   FixedCS.setKind(NewKind);
682   return FixedCS;
683 }
684 
685 //===----------------------------------------------------------------------===//
686 // Methods on OptionalAmount.
687 //===----------------------------------------------------------------------===//
688 
689 void OptionalAmount::toString(raw_ostream &os) const {
690   switch (hs) {
691   case Invalid:
692   case NotSpecified:
693     return;
694   case Arg:
695     if (UsesDotPrefix)
696         os << ".";
697     if (usesPositionalArg())
698       os << "*" << getPositionalArgIndex() << "$";
699     else
700       os << "*";
701     break;
702   case Constant:
703     if (UsesDotPrefix)
704         os << ".";
705     os << amt;
706     break;
707   }
708 }
709 
710 bool FormatSpecifier::hasValidLengthModifier(const TargetInfo &Target) const {
711   switch (LM.getKind()) {
712     case LengthModifier::None:
713       return true;
714 
715     // Handle most integer flags
716     case LengthModifier::AsShort:
717       if (Target.getTriple().isOSMSVCRT()) {
718         switch (CS.getKind()) {
719           case ConversionSpecifier::cArg:
720           case ConversionSpecifier::CArg:
721           case ConversionSpecifier::sArg:
722           case ConversionSpecifier::SArg:
723           case ConversionSpecifier::ZArg:
724             return true;
725           default:
726             break;
727         }
728       }
729       LLVM_FALLTHROUGH;
730     case LengthModifier::AsChar:
731     case LengthModifier::AsLongLong:
732     case LengthModifier::AsQuad:
733     case LengthModifier::AsIntMax:
734     case LengthModifier::AsSizeT:
735     case LengthModifier::AsPtrDiff:
736       switch (CS.getKind()) {
737         case ConversionSpecifier::dArg:
738         case ConversionSpecifier::DArg:
739         case ConversionSpecifier::iArg:
740         case ConversionSpecifier::oArg:
741         case ConversionSpecifier::OArg:
742         case ConversionSpecifier::uArg:
743         case ConversionSpecifier::UArg:
744         case ConversionSpecifier::xArg:
745         case ConversionSpecifier::XArg:
746         case ConversionSpecifier::nArg:
747           return true;
748         case ConversionSpecifier::FreeBSDrArg:
749         case ConversionSpecifier::FreeBSDyArg:
750           return Target.getTriple().isOSFreeBSD() || Target.getTriple().isPS4();
751         default:
752           return false;
753       }
754 
755     // Handle 'l' flag
756     case LengthModifier::AsLong: // or AsWideChar
757       switch (CS.getKind()) {
758         case ConversionSpecifier::dArg:
759         case ConversionSpecifier::DArg:
760         case ConversionSpecifier::iArg:
761         case ConversionSpecifier::oArg:
762         case ConversionSpecifier::OArg:
763         case ConversionSpecifier::uArg:
764         case ConversionSpecifier::UArg:
765         case ConversionSpecifier::xArg:
766         case ConversionSpecifier::XArg:
767         case ConversionSpecifier::aArg:
768         case ConversionSpecifier::AArg:
769         case ConversionSpecifier::fArg:
770         case ConversionSpecifier::FArg:
771         case ConversionSpecifier::eArg:
772         case ConversionSpecifier::EArg:
773         case ConversionSpecifier::gArg:
774         case ConversionSpecifier::GArg:
775         case ConversionSpecifier::nArg:
776         case ConversionSpecifier::cArg:
777         case ConversionSpecifier::sArg:
778         case ConversionSpecifier::ScanListArg:
779         case ConversionSpecifier::ZArg:
780           return true;
781         case ConversionSpecifier::FreeBSDrArg:
782         case ConversionSpecifier::FreeBSDyArg:
783           return Target.getTriple().isOSFreeBSD() || Target.getTriple().isPS4();
784         default:
785           return false;
786       }
787 
788     case LengthModifier::AsLongDouble:
789       switch (CS.getKind()) {
790         case ConversionSpecifier::aArg:
791         case ConversionSpecifier::AArg:
792         case ConversionSpecifier::fArg:
793         case ConversionSpecifier::FArg:
794         case ConversionSpecifier::eArg:
795         case ConversionSpecifier::EArg:
796         case ConversionSpecifier::gArg:
797         case ConversionSpecifier::GArg:
798           return true;
799         // GNU libc extension.
800         case ConversionSpecifier::dArg:
801         case ConversionSpecifier::iArg:
802         case ConversionSpecifier::oArg:
803         case ConversionSpecifier::uArg:
804         case ConversionSpecifier::xArg:
805         case ConversionSpecifier::XArg:
806           return !Target.getTriple().isOSDarwin() &&
807                  !Target.getTriple().isOSWindows();
808         default:
809           return false;
810       }
811 
812     case LengthModifier::AsAllocate:
813       switch (CS.getKind()) {
814         case ConversionSpecifier::sArg:
815         case ConversionSpecifier::SArg:
816         case ConversionSpecifier::ScanListArg:
817           return true;
818         default:
819           return false;
820       }
821 
822     case LengthModifier::AsMAllocate:
823       switch (CS.getKind()) {
824         case ConversionSpecifier::cArg:
825         case ConversionSpecifier::CArg:
826         case ConversionSpecifier::sArg:
827         case ConversionSpecifier::SArg:
828         case ConversionSpecifier::ScanListArg:
829           return true;
830         default:
831           return false;
832       }
833     case LengthModifier::AsInt32:
834     case LengthModifier::AsInt3264:
835     case LengthModifier::AsInt64:
836       switch (CS.getKind()) {
837         case ConversionSpecifier::dArg:
838         case ConversionSpecifier::iArg:
839         case ConversionSpecifier::oArg:
840         case ConversionSpecifier::uArg:
841         case ConversionSpecifier::xArg:
842         case ConversionSpecifier::XArg:
843           return Target.getTriple().isOSMSVCRT();
844         default:
845           return false;
846       }
847     case LengthModifier::AsWide:
848       switch (CS.getKind()) {
849         case ConversionSpecifier::cArg:
850         case ConversionSpecifier::CArg:
851         case ConversionSpecifier::sArg:
852         case ConversionSpecifier::SArg:
853         case ConversionSpecifier::ZArg:
854           return Target.getTriple().isOSMSVCRT();
855         default:
856           return false;
857       }
858   }
859   llvm_unreachable("Invalid LengthModifier Kind!");
860 }
861 
862 bool FormatSpecifier::hasStandardLengthModifier() const {
863   switch (LM.getKind()) {
864     case LengthModifier::None:
865     case LengthModifier::AsChar:
866     case LengthModifier::AsShort:
867     case LengthModifier::AsLong:
868     case LengthModifier::AsLongLong:
869     case LengthModifier::AsIntMax:
870     case LengthModifier::AsSizeT:
871     case LengthModifier::AsPtrDiff:
872     case LengthModifier::AsLongDouble:
873       return true;
874     case LengthModifier::AsAllocate:
875     case LengthModifier::AsMAllocate:
876     case LengthModifier::AsQuad:
877     case LengthModifier::AsInt32:
878     case LengthModifier::AsInt3264:
879     case LengthModifier::AsInt64:
880     case LengthModifier::AsWide:
881       return false;
882   }
883   llvm_unreachable("Invalid LengthModifier Kind!");
884 }
885 
886 bool FormatSpecifier::hasStandardConversionSpecifier(
887     const LangOptions &LangOpt) const {
888   switch (CS.getKind()) {
889     case ConversionSpecifier::cArg:
890     case ConversionSpecifier::dArg:
891     case ConversionSpecifier::iArg:
892     case ConversionSpecifier::oArg:
893     case ConversionSpecifier::uArg:
894     case ConversionSpecifier::xArg:
895     case ConversionSpecifier::XArg:
896     case ConversionSpecifier::fArg:
897     case ConversionSpecifier::FArg:
898     case ConversionSpecifier::eArg:
899     case ConversionSpecifier::EArg:
900     case ConversionSpecifier::gArg:
901     case ConversionSpecifier::GArg:
902     case ConversionSpecifier::aArg:
903     case ConversionSpecifier::AArg:
904     case ConversionSpecifier::sArg:
905     case ConversionSpecifier::pArg:
906     case ConversionSpecifier::nArg:
907     case ConversionSpecifier::ObjCObjArg:
908     case ConversionSpecifier::ScanListArg:
909     case ConversionSpecifier::PercentArg:
910     case ConversionSpecifier::PArg:
911       return true;
912     case ConversionSpecifier::CArg:
913     case ConversionSpecifier::SArg:
914       return LangOpt.ObjC;
915     case ConversionSpecifier::InvalidSpecifier:
916     case ConversionSpecifier::FreeBSDbArg:
917     case ConversionSpecifier::FreeBSDDArg:
918     case ConversionSpecifier::FreeBSDrArg:
919     case ConversionSpecifier::FreeBSDyArg:
920     case ConversionSpecifier::PrintErrno:
921     case ConversionSpecifier::DArg:
922     case ConversionSpecifier::OArg:
923     case ConversionSpecifier::UArg:
924     case ConversionSpecifier::ZArg:
925       return false;
926   }
927   llvm_unreachable("Invalid ConversionSpecifier Kind!");
928 }
929 
930 bool FormatSpecifier::hasStandardLengthConversionCombination() const {
931   if (LM.getKind() == LengthModifier::AsLongDouble) {
932     switch(CS.getKind()) {
933         case ConversionSpecifier::dArg:
934         case ConversionSpecifier::iArg:
935         case ConversionSpecifier::oArg:
936         case ConversionSpecifier::uArg:
937         case ConversionSpecifier::xArg:
938         case ConversionSpecifier::XArg:
939           return false;
940         default:
941           return true;
942     }
943   }
944   return true;
945 }
946 
947 Optional<LengthModifier> FormatSpecifier::getCorrectedLengthModifier() const {
948   if (CS.isAnyIntArg() || CS.getKind() == ConversionSpecifier::nArg) {
949     if (LM.getKind() == LengthModifier::AsLongDouble ||
950         LM.getKind() == LengthModifier::AsQuad) {
951       LengthModifier FixedLM(LM);
952       FixedLM.setKind(LengthModifier::AsLongLong);
953       return FixedLM;
954     }
955   }
956 
957   return None;
958 }
959 
960 bool FormatSpecifier::namedTypeToLengthModifier(QualType QT,
961                                                 LengthModifier &LM) {
962   assert(isa<TypedefType>(QT) && "Expected a TypedefType");
963   const TypedefNameDecl *Typedef = cast<TypedefType>(QT)->getDecl();
964 
965   for (;;) {
966     const IdentifierInfo *Identifier = Typedef->getIdentifier();
967     if (Identifier->getName() == "size_t") {
968       LM.setKind(LengthModifier::AsSizeT);
969       return true;
970     } else if (Identifier->getName() == "ssize_t") {
971       // Not C99, but common in Unix.
972       LM.setKind(LengthModifier::AsSizeT);
973       return true;
974     } else if (Identifier->getName() == "intmax_t") {
975       LM.setKind(LengthModifier::AsIntMax);
976       return true;
977     } else if (Identifier->getName() == "uintmax_t") {
978       LM.setKind(LengthModifier::AsIntMax);
979       return true;
980     } else if (Identifier->getName() == "ptrdiff_t") {
981       LM.setKind(LengthModifier::AsPtrDiff);
982       return true;
983     }
984 
985     QualType T = Typedef->getUnderlyingType();
986     if (!isa<TypedefType>(T))
987       break;
988 
989     Typedef = cast<TypedefType>(T)->getDecl();
990   }
991   return false;
992 }
993