FormatString.cpp revision 15f92bad58c8650b1306729744b1a1230197497a 
1// FormatString.cpp - Common stuff for handling printf/scanf formats -*- C++ -*-
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Shared details for processing format strings of printf and scanf
11// (and friends).
12//
13//===----------------------------------------------------------------------===//
14
15#include "FormatStringParsing.h"
16#include "clang/Basic/LangOptions.h"
17#include "clang/Basic/TargetInfo.h"
18
19using clang::analyze_format_string::ArgType;
20using clang::analyze_format_string::FormatStringHandler;
21using clang::analyze_format_string::FormatSpecifier;
22using clang::analyze_format_string::LengthModifier;
23using clang::analyze_format_string::OptionalAmount;
24using clang::analyze_format_string::PositionContext;
25using clang::analyze_format_string::ConversionSpecifier;
26using namespace clang;
27
28// Key function to FormatStringHandler.
29FormatStringHandler::~FormatStringHandler() {}
30
31//===----------------------------------------------------------------------===//
32// Functions for parsing format strings components in both printf and
33// scanf format strings.
34//===----------------------------------------------------------------------===//
35
36OptionalAmount
37clang::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
62OptionalAmount
63clang::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
74OptionalAmount
75clang::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
121bool
122clang::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
143bool
144clang::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
180bool
181clang::analyze_format_string::ParseLengthModifier(FormatSpecifier &FS,
182                                                  const char *&I,
183                                                  const char *E,
184                                                  const LangOptions &LO,
185                                                  bool IsScanf) {
186  LengthModifier::Kind lmKind = LengthModifier::None;
187  const char *lmPosition = I;
188  switch (*I) {
189    default:
190      return false;
191    case 'h':
192      ++I;
193      lmKind = (I != E && *I == 'h') ? (++I, LengthModifier::AsChar)
194                                     : LengthModifier::AsShort;
195      break;
196    case 'l':
197      ++I;
198      lmKind = (I != E && *I == 'l') ? (++I, LengthModifier::AsLongLong)
199                                     : LengthModifier::AsLong;
200      break;
201    case 'j': lmKind = LengthModifier::AsIntMax;     ++I; break;
202    case 'z': lmKind = LengthModifier::AsSizeT;      ++I; break;
203    case 't': lmKind = LengthModifier::AsPtrDiff;    ++I; break;
204    case 'L': lmKind = LengthModifier::AsLongDouble; ++I; break;
205    case 'q': lmKind = LengthModifier::AsQuad;       ++I; break;
206    case 'a':
207      if (IsScanf && !LO.C99 && !LO.CPlusPlus11) {
208        // For scanf in C90, look at the next character to see if this should
209        // be parsed as the GNU extension 'a' length modifier. If not, this
210        // will be parsed as a conversion specifier.
211        ++I;
212        if (I != E && (*I == 's' || *I == 'S' || *I == '[')) {
213          lmKind = LengthModifier::AsAllocate;
214          break;
215        }
216        --I;
217      }
218      return false;
219    case 'm':
220      if (IsScanf) {
221        lmKind = LengthModifier::AsMAllocate;
222        ++I;
223        break;
224      }
225      return false;
226  }
227  LengthModifier lm(lmPosition, lmKind);
228  FS.setLengthModifier(lm);
229  return true;
230}
231
232//===----------------------------------------------------------------------===//
233// Methods on ArgType.
234//===----------------------------------------------------------------------===//
235
236bool ArgType::matchesType(ASTContext &C, QualType argTy) const {
237  if (Ptr) {
238    // It has to be a pointer.
239    const PointerType *PT = argTy->getAs<PointerType>();
240    if (!PT)
241      return false;
242
243    // We cannot write through a const qualified pointer.
244    if (PT->getPointeeType().isConstQualified())
245      return false;
246
247    argTy = PT->getPointeeType();
248  }
249
250  switch (K) {
251    case InvalidTy:
252      llvm_unreachable("ArgType must be valid");
253
254    case UnknownTy:
255      return true;
256
257    case AnyCharTy: {
258      if (const EnumType *ETy = argTy->getAs<EnumType>())
259        argTy = ETy->getDecl()->getIntegerType();
260
261      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
262        switch (BT->getKind()) {
263          default:
264            break;
265          case BuiltinType::Char_S:
266          case BuiltinType::SChar:
267          case BuiltinType::UChar:
268          case BuiltinType::Char_U:
269            return true;
270        }
271      return false;
272    }
273
274    case SpecificTy: {
275      if (const EnumType *ETy = argTy->getAs<EnumType>())
276        argTy = ETy->getDecl()->getIntegerType();
277      argTy = C.getCanonicalType(argTy).getUnqualifiedType();
278
279      if (T == argTy)
280        return true;
281      // Check for "compatible types".
282      if (const BuiltinType *BT = argTy->getAs<BuiltinType>())
283        switch (BT->getKind()) {
284          default:
285            break;
286          case BuiltinType::Char_S:
287          case BuiltinType::SChar:
288          case BuiltinType::Char_U:
289          case BuiltinType::UChar:
290            return T == C.UnsignedCharTy || T == C.SignedCharTy;
291          case BuiltinType::Short:
292            return T == C.UnsignedShortTy;
293          case BuiltinType::UShort:
294            return T == C.ShortTy;
295          case BuiltinType::Int:
296            return T == C.UnsignedIntTy;
297          case BuiltinType::UInt:
298            return T == C.IntTy;
299          case BuiltinType::Long:
300            return T == C.UnsignedLongTy;
301          case BuiltinType::ULong:
302            return T == C.LongTy;
303          case BuiltinType::LongLong:
304            return T == C.UnsignedLongLongTy;
305          case BuiltinType::ULongLong:
306            return T == C.LongLongTy;
307        }
308      return false;
309    }
310
311    case CStrTy: {
312      const PointerType *PT = argTy->getAs<PointerType>();
313      if (!PT)
314        return false;
315      QualType pointeeTy = PT->getPointeeType();
316      if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>())
317        switch (BT->getKind()) {
318          case BuiltinType::Void:
319          case BuiltinType::Char_U:
320          case BuiltinType::UChar:
321          case BuiltinType::Char_S:
322          case BuiltinType::SChar:
323            return true;
324          default:
325            break;
326        }
327
328      return false;
329    }
330
331    case WCStrTy: {
332      const PointerType *PT = argTy->getAs<PointerType>();
333      if (!PT)
334        return false;
335      QualType pointeeTy =
336        C.getCanonicalType(PT->getPointeeType()).getUnqualifiedType();
337      return pointeeTy == C.getWideCharType();
338    }
339
340    case WIntTy: {
341
342      QualType PromoArg =
343        argTy->isPromotableIntegerType()
344          ? C.getPromotedIntegerType(argTy) : argTy;
345
346      QualType WInt = C.getCanonicalType(C.getWIntType()).getUnqualifiedType();
347      PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType();
348
349      // If the promoted argument is the corresponding signed type of the
350      // wint_t type, then it should match.
351      if (PromoArg->hasSignedIntegerRepresentation() &&
352          C.getCorrespondingUnsignedType(PromoArg) == WInt)
353        return true;
354
355      return WInt == PromoArg;
356    }
357
358    case CPointerTy:
359      return argTy->isPointerType() || argTy->isObjCObjectPointerType() ||
360             argTy->isBlockPointerType() || argTy->isNullPtrType();
361
362    case ObjCPointerTy: {
363      if (argTy->getAs<ObjCObjectPointerType>() ||
364          argTy->getAs<BlockPointerType>())
365        return true;
366
367      // Handle implicit toll-free bridging.
368      if (const PointerType *PT = argTy->getAs<PointerType>()) {
369        // Things such as CFTypeRef are really just opaque pointers
370        // to C structs representing CF types that can often be bridged
371        // to Objective-C objects.  Since the compiler doesn't know which
372        // structs can be toll-free bridged, we just accept them all.
373        QualType pointee = PT->getPointeeType();
374        if (pointee->getAsStructureType() || pointee->isVoidType())
375          return true;
376      }
377      return false;
378    }
379  }
380
381  llvm_unreachable("Invalid ArgType Kind!");
382}
383
384QualType ArgType::getRepresentativeType(ASTContext &C) const {
385  QualType Res;
386  switch (K) {
387    case InvalidTy:
388      llvm_unreachable("No representative type for Invalid ArgType");
389    case UnknownTy:
390      llvm_unreachable("No representative type for Unknown ArgType");
391    case AnyCharTy:
392      Res = C.CharTy;
393      break;
394    case SpecificTy:
395      Res = T;
396      break;
397    case CStrTy:
398      Res = C.getPointerType(C.CharTy);
399      break;
400    case WCStrTy:
401      Res = C.getPointerType(C.getWideCharType());
402      break;
403    case ObjCPointerTy:
404      Res = C.ObjCBuiltinIdTy;
405      break;
406    case CPointerTy:
407      Res = C.VoidPtrTy;
408      break;
409    case WIntTy: {
410      Res = C.getWIntType();
411      break;
412    }
413  }
414
415  if (Ptr)
416    Res = C.getPointerType(Res);
417  return Res;
418}
419
420std::string ArgType::getRepresentativeTypeName(ASTContext &C) const {
421  std::string S = getRepresentativeType(C).getAsString();
422
423  std::string Alias;
424  if (Name) {
425    // Use a specific name for this type, e.g. "size_t".
426    Alias = Name;
427    if (Ptr) {
428      // If ArgType is actually a pointer to T, append an asterisk.
429      Alias += (Alias[Alias.size()-1] == '*') ? "*" : " *";
430    }
431    // If Alias is the same as the underlying type, e.g. wchar_t, then drop it.
432    if (S == Alias)
433      Alias.clear();
434  }
435
436  if (!Alias.empty())
437    return std::string("'") + Alias + "' (aka '" + S + "')";
438  return std::string("'") + S + "'";
439}
440
441
442//===----------------------------------------------------------------------===//
443// Methods on OptionalAmount.
444//===----------------------------------------------------------------------===//
445
446ArgType
447analyze_format_string::OptionalAmount::getArgType(ASTContext &Ctx) const {
448  return Ctx.IntTy;
449}
450
451//===----------------------------------------------------------------------===//
452// Methods on LengthModifier.
453//===----------------------------------------------------------------------===//
454
455const char *
456analyze_format_string::LengthModifier::toString() const {
457  switch (kind) {
458  case AsChar:
459    return "hh";
460  case AsShort:
461    return "h";
462  case AsLong: // or AsWideChar
463    return "l";
464  case AsLongLong:
465    return "ll";
466  case AsQuad:
467    return "q";
468  case AsIntMax:
469    return "j";
470  case AsSizeT:
471    return "z";
472  case AsPtrDiff:
473    return "t";
474  case AsLongDouble:
475    return "L";
476  case AsAllocate:
477    return "a";
478  case AsMAllocate:
479    return "m";
480  case None:
481    return "";
482  }
483  return NULL;
484}
485
486//===----------------------------------------------------------------------===//
487// Methods on ConversionSpecifier.
488//===----------------------------------------------------------------------===//
489
490const char *ConversionSpecifier::toString() const {
491  switch (kind) {
492  case dArg: return "d";
493  case DArg: return "D";
494  case iArg: return "i";
495  case oArg: return "o";
496  case OArg: return "O";
497  case uArg: return "u";
498  case UArg: return "U";
499  case xArg: return "x";
500  case XArg: return "X";
501  case fArg: return "f";
502  case FArg: return "F";
503  case eArg: return "e";
504  case EArg: return "E";
505  case gArg: return "g";
506  case GArg: return "G";
507  case aArg: return "a";
508  case AArg: return "A";
509  case cArg: return "c";
510  case sArg: return "s";
511  case pArg: return "p";
512  case nArg: return "n";
513  case PercentArg:  return "%";
514  case ScanListArg: return "[";
515  case InvalidSpecifier: return NULL;
516
517  // MacOS X unicode extensions.
518  case CArg: return "C";
519  case SArg: return "S";
520
521  // Objective-C specific specifiers.
522  case ObjCObjArg: return "@";
523
524  // GlibC specific specifiers.
525  case PrintErrno: return "m";
526  }
527  return NULL;
528}
529
530Optional<ConversionSpecifier>
531ConversionSpecifier::getStandardSpecifier() const {
532  ConversionSpecifier::Kind NewKind;
533
534  switch (getKind()) {
535  default:
536    return None;
537  case DArg:
538    NewKind = dArg;
539    break;
540  case UArg:
541    NewKind = uArg;
542    break;
543  case OArg:
544    NewKind = oArg;
545    break;
546  }
547
548  ConversionSpecifier FixedCS(*this);
549  FixedCS.setKind(NewKind);
550  return FixedCS;
551}
552
553//===----------------------------------------------------------------------===//
554// Methods on OptionalAmount.
555//===----------------------------------------------------------------------===//
556
557void OptionalAmount::toString(raw_ostream &os) const {
558  switch (hs) {
559  case Invalid:
560  case NotSpecified:
561    return;
562  case Arg:
563    if (UsesDotPrefix)
564        os << ".";
565    if (usesPositionalArg())
566      os << "*" << getPositionalArgIndex() << "$";
567    else
568      os << "*";
569    break;
570  case Constant:
571    if (UsesDotPrefix)
572        os << ".";
573    os << amt;
574    break;
575  }
576}
577
578bool FormatSpecifier::hasValidLengthModifier(const TargetInfo &Target) const {
579  switch (LM.getKind()) {
580    case LengthModifier::None:
581      return true;
582
583    // Handle most integer flags
584    case LengthModifier::AsChar:
585    case LengthModifier::AsShort:
586    case LengthModifier::AsLongLong:
587    case LengthModifier::AsQuad:
588    case LengthModifier::AsIntMax:
589    case LengthModifier::AsSizeT:
590    case LengthModifier::AsPtrDiff:
591      switch (CS.getKind()) {
592        case ConversionSpecifier::dArg:
593        case ConversionSpecifier::DArg:
594        case ConversionSpecifier::iArg:
595        case ConversionSpecifier::oArg:
596        case ConversionSpecifier::OArg:
597        case ConversionSpecifier::uArg:
598        case ConversionSpecifier::UArg:
599        case ConversionSpecifier::xArg:
600        case ConversionSpecifier::XArg:
601        case ConversionSpecifier::nArg:
602          return true;
603        default:
604          return false;
605      }
606
607    // Handle 'l' flag
608    case LengthModifier::AsLong:
609      switch (CS.getKind()) {
610        case ConversionSpecifier::dArg:
611        case ConversionSpecifier::DArg:
612        case ConversionSpecifier::iArg:
613        case ConversionSpecifier::oArg:
614        case ConversionSpecifier::OArg:
615        case ConversionSpecifier::uArg:
616        case ConversionSpecifier::UArg:
617        case ConversionSpecifier::xArg:
618        case ConversionSpecifier::XArg:
619        case ConversionSpecifier::aArg:
620        case ConversionSpecifier::AArg:
621        case ConversionSpecifier::fArg:
622        case ConversionSpecifier::FArg:
623        case ConversionSpecifier::eArg:
624        case ConversionSpecifier::EArg:
625        case ConversionSpecifier::gArg:
626        case ConversionSpecifier::GArg:
627        case ConversionSpecifier::nArg:
628        case ConversionSpecifier::cArg:
629        case ConversionSpecifier::sArg:
630        case ConversionSpecifier::ScanListArg:
631          return true;
632        default:
633          return false;
634      }
635
636    case LengthModifier::AsLongDouble:
637      switch (CS.getKind()) {
638        case ConversionSpecifier::aArg:
639        case ConversionSpecifier::AArg:
640        case ConversionSpecifier::fArg:
641        case ConversionSpecifier::FArg:
642        case ConversionSpecifier::eArg:
643        case ConversionSpecifier::EArg:
644        case ConversionSpecifier::gArg:
645        case ConversionSpecifier::GArg:
646          return true;
647        // GNU libc extension.
648        case ConversionSpecifier::dArg:
649        case ConversionSpecifier::iArg:
650        case ConversionSpecifier::oArg:
651        case ConversionSpecifier::uArg:
652        case ConversionSpecifier::xArg:
653        case ConversionSpecifier::XArg:
654          return !Target.getTriple().isOSDarwin() &&
655                 !Target.getTriple().isOSWindows();
656        default:
657          return false;
658      }
659
660    case LengthModifier::AsAllocate:
661      switch (CS.getKind()) {
662        case ConversionSpecifier::sArg:
663        case ConversionSpecifier::SArg:
664        case ConversionSpecifier::ScanListArg:
665          return true;
666        default:
667          return false;
668      }
669
670    case LengthModifier::AsMAllocate:
671      switch (CS.getKind()) {
672        case ConversionSpecifier::cArg:
673        case ConversionSpecifier::CArg:
674        case ConversionSpecifier::sArg:
675        case ConversionSpecifier::SArg:
676        case ConversionSpecifier::ScanListArg:
677          return true;
678        default:
679          return false;
680      }
681  }
682  llvm_unreachable("Invalid LengthModifier Kind!");
683}
684
685bool FormatSpecifier::hasStandardLengthModifier() const {
686  switch (LM.getKind()) {
687    case LengthModifier::None:
688    case LengthModifier::AsChar:
689    case LengthModifier::AsShort:
690    case LengthModifier::AsLong:
691    case LengthModifier::AsLongLong:
692    case LengthModifier::AsIntMax:
693    case LengthModifier::AsSizeT:
694    case LengthModifier::AsPtrDiff:
695    case LengthModifier::AsLongDouble:
696      return true;
697    case LengthModifier::AsAllocate:
698    case LengthModifier::AsMAllocate:
699    case LengthModifier::AsQuad:
700      return false;
701  }
702  llvm_unreachable("Invalid LengthModifier Kind!");
703}
704
705bool FormatSpecifier::hasStandardConversionSpecifier(const LangOptions &LangOpt) const {
706  switch (CS.getKind()) {
707    case ConversionSpecifier::cArg:
708    case ConversionSpecifier::dArg:
709    case ConversionSpecifier::iArg:
710    case ConversionSpecifier::oArg:
711    case ConversionSpecifier::uArg:
712    case ConversionSpecifier::xArg:
713    case ConversionSpecifier::XArg:
714    case ConversionSpecifier::fArg:
715    case ConversionSpecifier::FArg:
716    case ConversionSpecifier::eArg:
717    case ConversionSpecifier::EArg:
718    case ConversionSpecifier::gArg:
719    case ConversionSpecifier::GArg:
720    case ConversionSpecifier::aArg:
721    case ConversionSpecifier::AArg:
722    case ConversionSpecifier::sArg:
723    case ConversionSpecifier::pArg:
724    case ConversionSpecifier::nArg:
725    case ConversionSpecifier::ObjCObjArg:
726    case ConversionSpecifier::ScanListArg:
727    case ConversionSpecifier::PercentArg:
728      return true;
729    case ConversionSpecifier::CArg:
730    case ConversionSpecifier::SArg:
731      return LangOpt.ObjC1 || LangOpt.ObjC2;
732    case ConversionSpecifier::InvalidSpecifier:
733    case ConversionSpecifier::PrintErrno:
734    case ConversionSpecifier::DArg:
735    case ConversionSpecifier::OArg:
736    case ConversionSpecifier::UArg:
737      return false;
738  }
739  llvm_unreachable("Invalid ConversionSpecifier Kind!");
740}
741
742bool FormatSpecifier::hasStandardLengthConversionCombination() const {
743  if (LM.getKind() == LengthModifier::AsLongDouble) {
744    switch(CS.getKind()) {
745        case ConversionSpecifier::dArg:
746        case ConversionSpecifier::iArg:
747        case ConversionSpecifier::oArg:
748        case ConversionSpecifier::uArg:
749        case ConversionSpecifier::xArg:
750        case ConversionSpecifier::XArg:
751          return false;
752        default:
753          return true;
754    }
755  }
756  return true;
757}
758
759Optional<LengthModifier> FormatSpecifier::getCorrectedLengthModifier() const {
760  if (CS.isAnyIntArg() || CS.getKind() == ConversionSpecifier::nArg) {
761    if (LM.getKind() == LengthModifier::AsLongDouble ||
762        LM.getKind() == LengthModifier::AsQuad) {
763      LengthModifier FixedLM(LM);
764      FixedLM.setKind(LengthModifier::AsLongLong);
765      return FixedLM;
766    }
767  }
768
769  return None;
770}
771
772bool FormatSpecifier::namedTypeToLengthModifier(QualType QT,
773                                                LengthModifier &LM) {
774  assert(isa<TypedefType>(QT) && "Expected a TypedefType");
775  const TypedefNameDecl *Typedef = cast<TypedefType>(QT)->getDecl();
776
777  for (;;) {
778    const IdentifierInfo *Identifier = Typedef->getIdentifier();
779    if (Identifier->getName() == "size_t") {
780      LM.setKind(LengthModifier::AsSizeT);
781      return true;
782    } else if (Identifier->getName() == "ssize_t") {
783      // Not C99, but common in Unix.
784      LM.setKind(LengthModifier::AsSizeT);
785      return true;
786    } else if (Identifier->getName() == "intmax_t") {
787      LM.setKind(LengthModifier::AsIntMax);
788      return true;
789    } else if (Identifier->getName() == "uintmax_t") {
790      LM.setKind(LengthModifier::AsIntMax);
791      return true;
792    } else if (Identifier->getName() == "ptrdiff_t") {
793      LM.setKind(LengthModifier::AsPtrDiff);
794      return true;
795    }
796
797    QualType T = Typedef->getUnderlyingType();
798    if (!isa<TypedefType>(T))
799      break;
800
801    Typedef = cast<TypedefType>(T)->getDecl();
802  }
803  return false;
804}
805