xref: /freebsd/contrib/llvm-project/clang/lib/AST/FormatString.cpp (revision 770cf0a5f02dc8983a89c6568d741fbc25baa999) 
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 #include <optional>
19 
20 using clang::analyze_format_string::ArgType;
21 using clang::analyze_format_string::FormatStringHandler;
22 using clang::analyze_format_string::FormatSpecifier;
23 using clang::analyze_format_string::LengthModifier;
24 using clang::analyze_format_string::OptionalAmount;
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 if (I != E && *I == 'l' && LO.OpenCL) {
227         ++I;
228         lmKind = LengthModifier::AsShortLong;
229       } else {
230         lmKind = LengthModifier::AsShort;
231       }
232       break;
233     case 'l':
234       ++I;
235       if (I != E && *I == 'l') {
236         ++I;
237         lmKind = LengthModifier::AsLongLong;
238       } else {
239         lmKind = LengthModifier::AsLong;
240       }
241       break;
242     case 'j': lmKind = LengthModifier::AsIntMax;     ++I; break;
243     case 'z': lmKind = LengthModifier::AsSizeT;      ++I; break;
244     case 't': lmKind = LengthModifier::AsPtrDiff;    ++I; break;
245     case 'L': lmKind = LengthModifier::AsLongDouble; ++I; break;
246     case 'q': lmKind = LengthModifier::AsQuad;       ++I; break;
247     case 'a':
248       if (IsScanf && !LO.C99 && !LO.CPlusPlus11) {
249         // For scanf in C90, look at the next character to see if this should
250         // be parsed as the GNU extension 'a' length modifier. If not, this
251         // will be parsed as a conversion specifier.
252         ++I;
253         if (I != E && (*I == 's' || *I == 'S' || *I == '[')) {
254           lmKind = LengthModifier::AsAllocate;
255           break;
256         }
257         --I;
258       }
259       return false;
260     case 'm':
261       if (IsScanf) {
262         lmKind = LengthModifier::AsMAllocate;
263         ++I;
264         break;
265       }
266       return false;
267     // printf: AsInt64, AsInt32, AsInt3264
268     // scanf:  AsInt64
269     case 'I':
270       if (I + 1 != E && I + 2 != E) {
271         if (I[1] == '6' && I[2] == '4') {
272           I += 3;
273           lmKind = LengthModifier::AsInt64;
274           break;
275         }
276         if (IsScanf)
277           return false;
278 
279         if (I[1] == '3' && I[2] == '2') {
280           I += 3;
281           lmKind = LengthModifier::AsInt32;
282           break;
283         }
284       }
285       ++I;
286       lmKind = LengthModifier::AsInt3264;
287       break;
288     case 'w':
289       lmKind = LengthModifier::AsWide; ++I; break;
290   }
291   LengthModifier lm(lmPosition, lmKind);
292   FS.setLengthModifier(lm);
293   return true;
294 }
295 
296 bool clang::analyze_format_string::ParseUTF8InvalidSpecifier(
297     const char *SpecifierBegin, const char *FmtStrEnd, unsigned &Len) {
298   if (SpecifierBegin + 1 >= FmtStrEnd)
299     return false;
300 
301   const llvm::UTF8 *SB =
302       reinterpret_cast<const llvm::UTF8 *>(SpecifierBegin + 1);
303   const llvm::UTF8 *SE = reinterpret_cast<const llvm::UTF8 *>(FmtStrEnd);
304   const char FirstByte = *SB;
305 
306   // If the invalid specifier is a multibyte UTF-8 string, return the
307   // total length accordingly so that the conversion specifier can be
308   // properly updated to reflect a complete UTF-8 specifier.
309   unsigned NumBytes = llvm::getNumBytesForUTF8(FirstByte);
310   if (NumBytes == 1)
311     return false;
312   if (SB + NumBytes > SE)
313     return false;
314 
315   Len = NumBytes + 1;
316   return true;
317 }
318 
319 //===----------------------------------------------------------------------===//
320 // Methods on ArgType.
321 //===----------------------------------------------------------------------===//
322 
323 clang::analyze_format_string::ArgType::MatchKind
324 ArgType::matchesType(ASTContext &C, QualType argTy) const {
325   // When using the format attribute in C++, you can receive a function or an
326   // array that will necessarily decay to a pointer when passed to the final
327   // format consumer. Apply decay before type comparison.
328   if (argTy->canDecayToPointerType())
329     argTy = C.getDecayedType(argTy);
330 
331   if (Ptr) {
332     // It has to be a pointer.
333     const PointerType *PT = argTy->getAs<PointerType>();
334     if (!PT)
335       return NoMatch;
336 
337     // We cannot write through a const qualified pointer.
338     if (PT->getPointeeType().isConstQualified())
339       return NoMatch;
340 
341     argTy = PT->getPointeeType();
342   }
343 
344   switch (K) {
345     case InvalidTy:
346       llvm_unreachable("ArgType must be valid");
347 
348     case UnknownTy:
349       return Match;
350 
351     case AnyCharTy: {
352       if (const auto *ETy = argTy->getAs<EnumType>()) {
353         // If the enum is incomplete we know nothing about the underlying type.
354         // Assume that it's 'int'. Do not use the underlying type for a scoped
355         // enumeration.
356         if (!ETy->getDecl()->isComplete())
357           return NoMatch;
358         if (ETy->isUnscopedEnumerationType())
359           argTy = ETy->getDecl()->getIntegerType();
360       }
361 
362       if (const auto *BT = argTy->getAs<BuiltinType>()) {
363         // The types are perfectly matched?
364         switch (BT->getKind()) {
365         default:
366           break;
367         case BuiltinType::Char_S:
368         case BuiltinType::SChar:
369         case BuiltinType::UChar:
370         case BuiltinType::Char_U:
371             return Match;
372         case BuiltinType::Bool:
373           if (!Ptr)
374             return Match;
375           break;
376         }
377         // "Partially matched" because of promotions?
378         if (!Ptr) {
379           switch (BT->getKind()) {
380           default:
381             break;
382           case BuiltinType::Int:
383           case BuiltinType::UInt:
384             return MatchPromotion;
385           case BuiltinType::Short:
386           case BuiltinType::UShort:
387           case BuiltinType::WChar_S:
388           case BuiltinType::WChar_U:
389             return NoMatchPromotionTypeConfusion;
390           }
391         }
392       }
393       return NoMatch;
394     }
395 
396     case SpecificTy: {
397       if (const EnumType *ETy = argTy->getAs<EnumType>()) {
398         // If the enum is incomplete we know nothing about the underlying type.
399         // Assume that it's 'int'. Do not use the underlying type for a scoped
400         // enumeration as that needs an exact match.
401         if (!ETy->getDecl()->isComplete())
402           argTy = C.IntTy;
403         else if (ETy->isUnscopedEnumerationType())
404           argTy = ETy->getDecl()->getIntegerType();
405       }
406 
407       if (argTy->isSaturatedFixedPointType())
408         argTy = C.getCorrespondingUnsaturatedType(argTy);
409 
410       argTy = C.getCanonicalType(argTy).getUnqualifiedType();
411 
412       if (T == argTy)
413         return Match;
414       if (const auto *BT = argTy->getAs<BuiltinType>()) {
415         // Check if the only difference between them is signed vs unsigned
416         // if true, return match signedness.
417         switch (BT->getKind()) {
418           default:
419             break;
420           case BuiltinType::Bool:
421             if (Ptr && (T == C.UnsignedCharTy || T == C.SignedCharTy))
422               return NoMatch;
423             [[fallthrough]];
424           case BuiltinType::Char_S:
425           case BuiltinType::SChar:
426             if (T == C.UnsignedShortTy || T == C.ShortTy)
427               return NoMatchTypeConfusion;
428             if (T == C.UnsignedCharTy)
429               return NoMatchSignedness;
430             if (T == C.SignedCharTy)
431               return Match;
432             break;
433           case BuiltinType::Char_U:
434           case BuiltinType::UChar:
435             if (T == C.UnsignedShortTy || T == C.ShortTy)
436               return NoMatchTypeConfusion;
437             if (T == C.UnsignedCharTy)
438               return Match;
439             if (T == C.SignedCharTy)
440               return NoMatchSignedness;
441             break;
442           case BuiltinType::Short:
443             if (T == C.UnsignedShortTy)
444               return NoMatchSignedness;
445             break;
446           case BuiltinType::UShort:
447             if (T == C.ShortTy)
448               return NoMatchSignedness;
449             break;
450           case BuiltinType::Int:
451             if (T == C.UnsignedIntTy)
452               return NoMatchSignedness;
453             break;
454           case BuiltinType::UInt:
455             if (T == C.IntTy)
456               return NoMatchSignedness;
457             break;
458           case BuiltinType::Long:
459             if (T == C.UnsignedLongTy)
460               return NoMatchSignedness;
461             break;
462           case BuiltinType::ULong:
463             if (T == C.LongTy)
464               return NoMatchSignedness;
465             break;
466           case BuiltinType::LongLong:
467             if (T == C.UnsignedLongLongTy)
468               return NoMatchSignedness;
469             break;
470           case BuiltinType::ULongLong:
471             if (T == C.LongLongTy)
472               return NoMatchSignedness;
473             break;
474           }
475           // "Partially matched" because of promotions?
476           if (!Ptr) {
477             switch (BT->getKind()) {
478             default:
479               break;
480             case BuiltinType::Bool:
481               if (T == C.IntTy || T == C.UnsignedIntTy)
482                 return MatchPromotion;
483               break;
484             case BuiltinType::Int:
485             case BuiltinType::UInt:
486               if (T == C.SignedCharTy || T == C.UnsignedCharTy ||
487                   T == C.ShortTy || T == C.UnsignedShortTy || T == C.WCharTy ||
488                   T == C.WideCharTy)
489                 return MatchPromotion;
490               break;
491             case BuiltinType::Char_U:
492               if (T == C.UnsignedIntTy)
493                 return MatchPromotion;
494               if (T == C.UnsignedShortTy)
495                 return NoMatchPromotionTypeConfusion;
496               break;
497             case BuiltinType::Char_S:
498               if (T == C.IntTy)
499                 return MatchPromotion;
500               if (T == C.ShortTy)
501                 return NoMatchPromotionTypeConfusion;
502               break;
503             case BuiltinType::Half:
504             case BuiltinType::Float:
505               if (T == C.DoubleTy)
506                 return MatchPromotion;
507               break;
508             case BuiltinType::Short:
509             case BuiltinType::UShort:
510               if (T == C.SignedCharTy || T == C.UnsignedCharTy)
511                 return NoMatchPromotionTypeConfusion;
512               break;
513             case BuiltinType::WChar_U:
514             case BuiltinType::WChar_S:
515               if (T != C.WCharTy && T != C.WideCharTy)
516                 return NoMatchPromotionTypeConfusion;
517             }
518           }
519       }
520       return NoMatch;
521     }
522 
523     case CStrTy:
524       if (const auto *PT = argTy->getAs<PointerType>();
525           PT && PT->getPointeeType()->isCharType())
526         return Match;
527       return NoMatch;
528 
529     case WCStrTy:
530       if (const auto *PT = argTy->getAs<PointerType>();
531           PT &&
532           C.hasSameUnqualifiedType(PT->getPointeeType(), C.getWideCharType()))
533         return Match;
534       return NoMatch;
535 
536     case WIntTy: {
537       QualType WInt = C.getCanonicalType(C.getWIntType()).getUnqualifiedType();
538 
539       if (C.getCanonicalType(argTy).getUnqualifiedType() == WInt)
540         return Match;
541 
542       QualType PromoArg = C.isPromotableIntegerType(argTy)
543                               ? C.getPromotedIntegerType(argTy)
544                               : argTy;
545       PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType();
546 
547       // If the promoted argument is the corresponding signed type of the
548       // wint_t type, then it should match.
549       if (PromoArg->hasSignedIntegerRepresentation() &&
550           C.getCorrespondingUnsignedType(PromoArg) == WInt)
551         return Match;
552 
553       return WInt == PromoArg ? Match : NoMatch;
554     }
555 
556     case CPointerTy:
557       if (const auto *PT = argTy->getAs<PointerType>()) {
558         QualType PointeeTy = PT->getPointeeType();
559         if (PointeeTy->isVoidType() || (!Ptr && PointeeTy->isCharType()))
560           return Match;
561         return NoMatchPedantic;
562       }
563 
564       // nullptr_t* is not a double pointer, so reject when something like
565       // void** is expected.
566       // In C++, nullptr is promoted to void*. In C23, va_arg(ap, void*) is not
567       // undefined when the next argument is of type nullptr_t.
568       if (!Ptr && argTy->isNullPtrType())
569         return C.getLangOpts().CPlusPlus ? MatchPromotion : Match;
570 
571       if (argTy->isObjCObjectPointerType() || argTy->isBlockPointerType())
572         return NoMatchPedantic;
573 
574       return NoMatch;
575 
576     case ObjCPointerTy: {
577       if (argTy->getAs<ObjCObjectPointerType>() ||
578           argTy->getAs<BlockPointerType>())
579         return Match;
580 
581       // Handle implicit toll-free bridging.
582       if (const PointerType *PT = argTy->getAs<PointerType>()) {
583         // Things such as CFTypeRef are really just opaque pointers
584         // to C structs representing CF types that can often be bridged
585         // to Objective-C objects.  Since the compiler doesn't know which
586         // structs can be toll-free bridged, we just accept them all.
587         QualType pointee = PT->getPointeeType();
588         if (pointee->getAsStructureType() || pointee->isVoidType())
589           return Match;
590       }
591       return NoMatch;
592     }
593   }
594 
595   llvm_unreachable("Invalid ArgType Kind!");
596 }
597 
598 static analyze_format_string::ArgType::MatchKind
599 integerTypeMatch(ASTContext &C, QualType A, QualType B, bool CheckSign) {
600   using MK = analyze_format_string::ArgType::MatchKind;
601 
602   uint64_t IntSize = C.getTypeSize(C.IntTy);
603   uint64_t ASize = C.getTypeSize(A);
604   uint64_t BSize = C.getTypeSize(B);
605   if (std::max(ASize, IntSize) != std::max(BSize, IntSize))
606     return MK::NoMatch;
607   if (CheckSign && A->isSignedIntegerType() != B->isSignedIntegerType())
608     return MK::NoMatchSignedness;
609   if (ASize != BSize)
610     return MK::MatchPromotion;
611   return MK::Match;
612 }
613 
614 analyze_format_string::ArgType::MatchKind
615 ArgType::matchesArgType(ASTContext &C, const ArgType &Other) const {
616   using AK = analyze_format_string::ArgType::Kind;
617 
618   // Per matchesType.
619   if (K == AK::InvalidTy || Other.K == AK::InvalidTy)
620     return NoMatch;
621   if (K == AK::UnknownTy || Other.K == AK::UnknownTy)
622     return Match;
623 
624   // Handle whether either (or both, or neither) sides has Ptr set,
625   // in addition to whether either (or both, or neither) sides is a SpecificTy
626   // that is a pointer.
627   ArgType Left = *this;
628   bool LeftWasPointer = false;
629   ArgType Right = Other;
630   bool RightWasPointer = false;
631   if (Left.Ptr) {
632     Left.Ptr = false;
633     LeftWasPointer = true;
634   } else if (Left.K == AK::SpecificTy && Left.T->isPointerType()) {
635     Left.T = Left.T->getPointeeType();
636     LeftWasPointer = true;
637   }
638   if (Right.Ptr) {
639     Right.Ptr = false;
640     RightWasPointer = true;
641   } else if (Right.K == AK::SpecificTy && Right.T->isPointerType()) {
642     Right.T = Right.T->getPointeeType();
643     RightWasPointer = true;
644   }
645 
646   if (LeftWasPointer != RightWasPointer)
647     return NoMatch;
648 
649   // Ensure that if at least one side is a SpecificTy, then Left is a
650   // SpecificTy.
651   if (Right.K == AK::SpecificTy)
652     std::swap(Left, Right);
653 
654   if (Left.K == AK::SpecificTy) {
655     if (Right.K == AK::SpecificTy) {
656       auto Canon1 = C.getCanonicalType(Left.T);
657       auto Canon2 = C.getCanonicalType(Right.T);
658       if (Canon1 == Canon2)
659         return Match;
660 
661       auto *BT1 = QualType(Canon1)->getAs<BuiltinType>();
662       auto *BT2 = QualType(Canon2)->getAs<BuiltinType>();
663       if (BT1 == nullptr || BT2 == nullptr)
664         return NoMatch;
665       if (BT1 == BT2)
666         return Match;
667 
668       if (!LeftWasPointer && BT1->isInteger() && BT2->isInteger())
669         return integerTypeMatch(C, Canon1, Canon2, true);
670       return NoMatch;
671     } else if (Right.K == AK::AnyCharTy) {
672       if (!LeftWasPointer && Left.T->isIntegerType())
673         return integerTypeMatch(C, Left.T, C.CharTy, false);
674       return NoMatch;
675     } else if (Right.K == AK::WIntTy) {
676       if (!LeftWasPointer && Left.T->isIntegerType())
677         return integerTypeMatch(C, Left.T, C.WIntTy, true);
678       return NoMatch;
679     }
680     // It's hypothetically possible to create an AK::SpecificTy ArgType
681     // that matches another kind of ArgType, but in practice Clang doesn't
682     // do that, so ignore that case.
683     return NoMatch;
684   }
685 
686   return Left.K == Right.K ? Match : NoMatch;
687 }
688 
689 ArgType ArgType::makeVectorType(ASTContext &C, unsigned NumElts) const {
690   // Check for valid vector element types.
691   if (T.isNull())
692     return ArgType::Invalid();
693 
694   QualType Vec = C.getExtVectorType(T, NumElts);
695   return ArgType(Vec, Name);
696 }
697 
698 QualType ArgType::getRepresentativeType(ASTContext &C) const {
699   QualType Res;
700   switch (K) {
701     case InvalidTy:
702       llvm_unreachable("No representative type for Invalid ArgType");
703     case UnknownTy:
704       llvm_unreachable("No representative type for Unknown ArgType");
705     case AnyCharTy:
706       Res = C.CharTy;
707       break;
708     case SpecificTy:
709       Res = T;
710       break;
711     case CStrTy:
712       Res = C.getPointerType(C.CharTy);
713       break;
714     case WCStrTy:
715       Res = C.getPointerType(C.getWideCharType());
716       break;
717     case ObjCPointerTy:
718       Res = C.ObjCBuiltinIdTy;
719       break;
720     case CPointerTy:
721       Res = C.VoidPtrTy;
722       break;
723     case WIntTy: {
724       Res = C.getWIntType();
725       break;
726     }
727   }
728 
729   if (Ptr)
730     Res = C.getPointerType(Res);
731   return Res;
732 }
733 
734 std::string ArgType::getRepresentativeTypeName(ASTContext &C) const {
735   std::string S = getRepresentativeType(C).getAsString(C.getPrintingPolicy());
736 
737   std::string Alias;
738   if (Name) {
739     // Use a specific name for this type, e.g. "size_t".
740     Alias = Name;
741     if (Ptr) {
742       // If ArgType is actually a pointer to T, append an asterisk.
743       Alias += (Alias[Alias.size()-1] == '*') ? "*" : " *";
744     }
745     // If Alias is the same as the underlying type, e.g. wchar_t, then drop it.
746     if (S == Alias)
747       Alias.clear();
748   }
749 
750   if (!Alias.empty())
751     return std::string("'") + Alias + "' (aka '" + S + "')";
752   return std::string("'") + S + "'";
753 }
754 
755 
756 //===----------------------------------------------------------------------===//
757 // Methods on OptionalAmount.
758 //===----------------------------------------------------------------------===//
759 
760 ArgType
761 analyze_format_string::OptionalAmount::getArgType(ASTContext &Ctx) const {
762   return Ctx.IntTy;
763 }
764 
765 //===----------------------------------------------------------------------===//
766 // Methods on LengthModifier.
767 //===----------------------------------------------------------------------===//
768 
769 const char *
770 analyze_format_string::LengthModifier::toString() const {
771   switch (kind) {
772   case AsChar:
773     return "hh";
774   case AsShort:
775     return "h";
776   case AsShortLong:
777     return "hl";
778   case AsLong: // or AsWideChar
779     return "l";
780   case AsLongLong:
781     return "ll";
782   case AsQuad:
783     return "q";
784   case AsIntMax:
785     return "j";
786   case AsSizeT:
787     return "z";
788   case AsPtrDiff:
789     return "t";
790   case AsInt32:
791     return "I32";
792   case AsInt3264:
793     return "I";
794   case AsInt64:
795     return "I64";
796   case AsLongDouble:
797     return "L";
798   case AsAllocate:
799     return "a";
800   case AsMAllocate:
801     return "m";
802   case AsWide:
803     return "w";
804   case None:
805     return "";
806   }
807   return nullptr;
808 }
809 
810 //===----------------------------------------------------------------------===//
811 // Methods on ConversionSpecifier.
812 //===----------------------------------------------------------------------===//
813 
814 const char *ConversionSpecifier::toString() const {
815   switch (kind) {
816   case bArg: return "b";
817   case BArg: return "B";
818   case dArg: return "d";
819   case DArg: return "D";
820   case iArg: return "i";
821   case oArg: return "o";
822   case OArg: return "O";
823   case uArg: return "u";
824   case UArg: return "U";
825   case xArg: return "x";
826   case XArg: return "X";
827   case fArg: return "f";
828   case FArg: return "F";
829   case eArg: return "e";
830   case EArg: return "E";
831   case gArg: return "g";
832   case GArg: return "G";
833   case aArg: return "a";
834   case AArg: return "A";
835   case cArg: return "c";
836   case sArg: return "s";
837   case pArg: return "p";
838   case PArg:
839     return "P";
840   case nArg: return "n";
841   case PercentArg:  return "%";
842   case ScanListArg: return "[";
843   case InvalidSpecifier: return nullptr;
844 
845   // POSIX unicode extensions.
846   case CArg: return "C";
847   case SArg: return "S";
848 
849   // Objective-C specific specifiers.
850   case ObjCObjArg: return "@";
851 
852   // FreeBSD kernel specific specifiers.
853   case FreeBSDbArg: return "b";
854   case FreeBSDDArg: return "D";
855   case FreeBSDrArg: return "r";
856   case FreeBSDyArg: return "y";
857 
858   // GlibC specific specifiers.
859   case PrintErrno: return "m";
860 
861   // MS specific specifiers.
862   case ZArg: return "Z";
863 
864   // ISO/IEC TR 18037 (fixed-point) specific specifiers.
865   case rArg:
866     return "r";
867   case RArg:
868     return "R";
869   case kArg:
870     return "k";
871   case KArg:
872     return "K";
873   }
874   return nullptr;
875 }
876 
877 std::optional<ConversionSpecifier>
878 ConversionSpecifier::getStandardSpecifier() const {
879   ConversionSpecifier::Kind NewKind;
880 
881   switch (getKind()) {
882   default:
883     return std::nullopt;
884   case DArg:
885     NewKind = dArg;
886     break;
887   case UArg:
888     NewKind = uArg;
889     break;
890   case OArg:
891     NewKind = oArg;
892     break;
893   }
894 
895   ConversionSpecifier FixedCS(*this);
896   FixedCS.setKind(NewKind);
897   return FixedCS;
898 }
899 
900 //===----------------------------------------------------------------------===//
901 // Methods on OptionalAmount.
902 //===----------------------------------------------------------------------===//
903 
904 void OptionalAmount::toString(raw_ostream &os) const {
905   switch (hs) {
906   case Invalid:
907   case NotSpecified:
908     return;
909   case Arg:
910     if (UsesDotPrefix)
911         os << ".";
912     if (usesPositionalArg())
913       os << "*" << getPositionalArgIndex() << "$";
914     else
915       os << "*";
916     break;
917   case Constant:
918     if (UsesDotPrefix)
919         os << ".";
920     os << amt;
921     break;
922   }
923 }
924 
925 bool FormatSpecifier::hasValidLengthModifier(const TargetInfo &Target,
926                                              const LangOptions &LO) const {
927   switch (LM.getKind()) {
928     case LengthModifier::None:
929       return true;
930 
931     // Handle most integer flags
932     case LengthModifier::AsShort:
933       // Length modifier only applies to FP vectors.
934       if (LO.OpenCL && CS.isDoubleArg())
935         return !VectorNumElts.isInvalid();
936 
937       if (CS.isFixedPointArg())
938         return true;
939 
940       if (Target.getTriple().isOSMSVCRT()) {
941         switch (CS.getKind()) {
942           case ConversionSpecifier::cArg:
943           case ConversionSpecifier::CArg:
944           case ConversionSpecifier::sArg:
945           case ConversionSpecifier::SArg:
946           case ConversionSpecifier::ZArg:
947             return true;
948           default:
949             break;
950         }
951       }
952       [[fallthrough]];
953     case LengthModifier::AsChar:
954     case LengthModifier::AsLongLong:
955     case LengthModifier::AsQuad:
956     case LengthModifier::AsIntMax:
957     case LengthModifier::AsSizeT:
958     case LengthModifier::AsPtrDiff:
959       switch (CS.getKind()) {
960         case ConversionSpecifier::bArg:
961         case ConversionSpecifier::BArg:
962         case ConversionSpecifier::dArg:
963         case ConversionSpecifier::DArg:
964         case ConversionSpecifier::iArg:
965         case ConversionSpecifier::oArg:
966         case ConversionSpecifier::OArg:
967         case ConversionSpecifier::uArg:
968         case ConversionSpecifier::UArg:
969         case ConversionSpecifier::xArg:
970         case ConversionSpecifier::XArg:
971         case ConversionSpecifier::nArg:
972           return true;
973         case ConversionSpecifier::FreeBSDrArg:
974         case ConversionSpecifier::FreeBSDyArg:
975           return Target.getTriple().isOSFreeBSD() || Target.getTriple().isPS();
976         default:
977           return false;
978       }
979 
980     case LengthModifier::AsShortLong:
981       return LO.OpenCL && !VectorNumElts.isInvalid();
982 
983     // Handle 'l' flag
984     case LengthModifier::AsLong: // or AsWideChar
985       if (CS.isDoubleArg()) {
986         // Invalid for OpenCL FP scalars.
987         if (LO.OpenCL && VectorNumElts.isInvalid())
988           return false;
989         return true;
990       }
991 
992       if (CS.isFixedPointArg())
993         return true;
994 
995       switch (CS.getKind()) {
996         case ConversionSpecifier::bArg:
997         case ConversionSpecifier::BArg:
998         case ConversionSpecifier::dArg:
999         case ConversionSpecifier::DArg:
1000         case ConversionSpecifier::iArg:
1001         case ConversionSpecifier::oArg:
1002         case ConversionSpecifier::OArg:
1003         case ConversionSpecifier::uArg:
1004         case ConversionSpecifier::UArg:
1005         case ConversionSpecifier::xArg:
1006         case ConversionSpecifier::XArg:
1007         case ConversionSpecifier::nArg:
1008         case ConversionSpecifier::cArg:
1009         case ConversionSpecifier::sArg:
1010         case ConversionSpecifier::ScanListArg:
1011         case ConversionSpecifier::ZArg:
1012           return true;
1013         case ConversionSpecifier::FreeBSDrArg:
1014         case ConversionSpecifier::FreeBSDyArg:
1015           return Target.getTriple().isOSFreeBSD() || Target.getTriple().isPS();
1016         default:
1017           return false;
1018       }
1019 
1020     case LengthModifier::AsLongDouble:
1021       switch (CS.getKind()) {
1022         case ConversionSpecifier::aArg:
1023         case ConversionSpecifier::AArg:
1024         case ConversionSpecifier::fArg:
1025         case ConversionSpecifier::FArg:
1026         case ConversionSpecifier::eArg:
1027         case ConversionSpecifier::EArg:
1028         case ConversionSpecifier::gArg:
1029         case ConversionSpecifier::GArg:
1030           return true;
1031         // GNU libc extension.
1032         case ConversionSpecifier::dArg:
1033         case ConversionSpecifier::iArg:
1034         case ConversionSpecifier::oArg:
1035         case ConversionSpecifier::uArg:
1036         case ConversionSpecifier::xArg:
1037         case ConversionSpecifier::XArg:
1038           return !Target.getTriple().isOSDarwin() &&
1039                  !Target.getTriple().isOSWindows();
1040         default:
1041           return false;
1042       }
1043 
1044     case LengthModifier::AsAllocate:
1045       switch (CS.getKind()) {
1046         case ConversionSpecifier::sArg:
1047         case ConversionSpecifier::SArg:
1048         case ConversionSpecifier::ScanListArg:
1049           return true;
1050         default:
1051           return false;
1052       }
1053 
1054     case LengthModifier::AsMAllocate:
1055       switch (CS.getKind()) {
1056         case ConversionSpecifier::cArg:
1057         case ConversionSpecifier::CArg:
1058         case ConversionSpecifier::sArg:
1059         case ConversionSpecifier::SArg:
1060         case ConversionSpecifier::ScanListArg:
1061           return true;
1062         default:
1063           return false;
1064       }
1065     case LengthModifier::AsInt32:
1066     case LengthModifier::AsInt3264:
1067     case LengthModifier::AsInt64:
1068       switch (CS.getKind()) {
1069         case ConversionSpecifier::dArg:
1070         case ConversionSpecifier::iArg:
1071         case ConversionSpecifier::oArg:
1072         case ConversionSpecifier::uArg:
1073         case ConversionSpecifier::xArg:
1074         case ConversionSpecifier::XArg:
1075           return Target.getTriple().isOSMSVCRT();
1076         default:
1077           return false;
1078       }
1079     case LengthModifier::AsWide:
1080       switch (CS.getKind()) {
1081         case ConversionSpecifier::cArg:
1082         case ConversionSpecifier::CArg:
1083         case ConversionSpecifier::sArg:
1084         case ConversionSpecifier::SArg:
1085         case ConversionSpecifier::ZArg:
1086           return Target.getTriple().isOSMSVCRT();
1087         default:
1088           return false;
1089       }
1090   }
1091   llvm_unreachable("Invalid LengthModifier Kind!");
1092 }
1093 
1094 bool FormatSpecifier::hasStandardLengthModifier() const {
1095   switch (LM.getKind()) {
1096     case LengthModifier::None:
1097     case LengthModifier::AsChar:
1098     case LengthModifier::AsShort:
1099     case LengthModifier::AsLong:
1100     case LengthModifier::AsLongLong:
1101     case LengthModifier::AsIntMax:
1102     case LengthModifier::AsSizeT:
1103     case LengthModifier::AsPtrDiff:
1104     case LengthModifier::AsLongDouble:
1105       return true;
1106     case LengthModifier::AsAllocate:
1107     case LengthModifier::AsMAllocate:
1108     case LengthModifier::AsQuad:
1109     case LengthModifier::AsInt32:
1110     case LengthModifier::AsInt3264:
1111     case LengthModifier::AsInt64:
1112     case LengthModifier::AsWide:
1113     case LengthModifier::AsShortLong: // ???
1114       return false;
1115   }
1116   llvm_unreachable("Invalid LengthModifier Kind!");
1117 }
1118 
1119 bool FormatSpecifier::hasStandardConversionSpecifier(
1120     const LangOptions &LangOpt) const {
1121   switch (CS.getKind()) {
1122     case ConversionSpecifier::bArg:
1123     case ConversionSpecifier::BArg:
1124     case ConversionSpecifier::cArg:
1125     case ConversionSpecifier::dArg:
1126     case ConversionSpecifier::iArg:
1127     case ConversionSpecifier::oArg:
1128     case ConversionSpecifier::uArg:
1129     case ConversionSpecifier::xArg:
1130     case ConversionSpecifier::XArg:
1131     case ConversionSpecifier::fArg:
1132     case ConversionSpecifier::FArg:
1133     case ConversionSpecifier::eArg:
1134     case ConversionSpecifier::EArg:
1135     case ConversionSpecifier::gArg:
1136     case ConversionSpecifier::GArg:
1137     case ConversionSpecifier::aArg:
1138     case ConversionSpecifier::AArg:
1139     case ConversionSpecifier::sArg:
1140     case ConversionSpecifier::pArg:
1141     case ConversionSpecifier::nArg:
1142     case ConversionSpecifier::ObjCObjArg:
1143     case ConversionSpecifier::ScanListArg:
1144     case ConversionSpecifier::PercentArg:
1145     case ConversionSpecifier::PArg:
1146       return true;
1147     case ConversionSpecifier::CArg:
1148     case ConversionSpecifier::SArg:
1149       return LangOpt.ObjC;
1150     case ConversionSpecifier::InvalidSpecifier:
1151     case ConversionSpecifier::FreeBSDbArg:
1152     case ConversionSpecifier::FreeBSDDArg:
1153     case ConversionSpecifier::FreeBSDrArg:
1154     case ConversionSpecifier::FreeBSDyArg:
1155     case ConversionSpecifier::PrintErrno:
1156     case ConversionSpecifier::DArg:
1157     case ConversionSpecifier::OArg:
1158     case ConversionSpecifier::UArg:
1159     case ConversionSpecifier::ZArg:
1160       return false;
1161     case ConversionSpecifier::rArg:
1162     case ConversionSpecifier::RArg:
1163     case ConversionSpecifier::kArg:
1164     case ConversionSpecifier::KArg:
1165       return LangOpt.FixedPoint;
1166   }
1167   llvm_unreachable("Invalid ConversionSpecifier Kind!");
1168 }
1169 
1170 bool FormatSpecifier::hasStandardLengthConversionCombination() const {
1171   if (LM.getKind() == LengthModifier::AsLongDouble) {
1172     switch(CS.getKind()) {
1173         case ConversionSpecifier::dArg:
1174         case ConversionSpecifier::iArg:
1175         case ConversionSpecifier::oArg:
1176         case ConversionSpecifier::uArg:
1177         case ConversionSpecifier::xArg:
1178         case ConversionSpecifier::XArg:
1179           return false;
1180         default:
1181           return true;
1182     }
1183   }
1184   return true;
1185 }
1186 
1187 std::optional<LengthModifier>
1188 FormatSpecifier::getCorrectedLengthModifier() const {
1189   if (CS.isAnyIntArg() || CS.getKind() == ConversionSpecifier::nArg) {
1190     if (LM.getKind() == LengthModifier::AsLongDouble ||
1191         LM.getKind() == LengthModifier::AsQuad) {
1192       LengthModifier FixedLM(LM);
1193       FixedLM.setKind(LengthModifier::AsLongLong);
1194       return FixedLM;
1195     }
1196   }
1197 
1198   return std::nullopt;
1199 }
1200 
1201 bool FormatSpecifier::namedTypeToLengthModifier(QualType QT,
1202                                                 LengthModifier &LM) {
1203   for (/**/; const auto *TT = QT->getAs<TypedefType>();
1204        QT = TT->getDecl()->getUnderlyingType()) {
1205     const TypedefNameDecl *Typedef = TT->getDecl();
1206     const IdentifierInfo *Identifier = Typedef->getIdentifier();
1207     if (Identifier->getName() == "size_t") {
1208       LM.setKind(LengthModifier::AsSizeT);
1209       return true;
1210     } else if (Identifier->getName() == "ssize_t") {
1211       // Not C99, but common in Unix.
1212       LM.setKind(LengthModifier::AsSizeT);
1213       return true;
1214     } else if (Identifier->getName() == "intmax_t") {
1215       LM.setKind(LengthModifier::AsIntMax);
1216       return true;
1217     } else if (Identifier->getName() == "uintmax_t") {
1218       LM.setKind(LengthModifier::AsIntMax);
1219       return true;
1220     } else if (Identifier->getName() == "ptrdiff_t") {
1221       LM.setKind(LengthModifier::AsPtrDiff);
1222       return true;
1223     }
1224   }
1225   return false;
1226 }
1227