1 //== PrintfFormatString.cpp - Analysis of printf format strings --*- 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 // Handling of format string in printf and friends.  The structure of format
10 // strings for fprintf() are described in C99 7.19.6.1.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "clang/AST/FormatString.h"
15 #include "clang/AST/OSLog.h"
16 #include "FormatStringParsing.h"
17 #include "clang/Basic/TargetInfo.h"
18 
19 using clang::analyze_format_string::ArgType;
20 using clang::analyze_format_string::FormatStringHandler;
21 using clang::analyze_format_string::LengthModifier;
22 using clang::analyze_format_string::OptionalAmount;
23 using clang::analyze_format_string::ConversionSpecifier;
24 using clang::analyze_printf::PrintfSpecifier;
25 
26 using namespace clang;
27 
28 typedef clang::analyze_format_string::SpecifierResult<PrintfSpecifier>
29         PrintfSpecifierResult;
30 
31 //===----------------------------------------------------------------------===//
32 // Methods for parsing format strings.
33 //===----------------------------------------------------------------------===//
34 
35 using analyze_format_string::ParseNonPositionAmount;
36 
37 static bool ParsePrecision(FormatStringHandler &H, PrintfSpecifier &FS,
38                            const char *Start, const char *&Beg, const char *E,
39                            unsigned *argIndex) {
40   if (argIndex) {
41     FS.setPrecision(ParseNonPositionAmount(Beg, E, *argIndex));
42   } else {
43     const OptionalAmount Amt = ParsePositionAmount(H, Start, Beg, E,
44                                            analyze_format_string::PrecisionPos);
45     if (Amt.isInvalid())
46       return true;
47     FS.setPrecision(Amt);
48   }
49   return false;
50 }
51 
52 static bool ParseObjCFlags(FormatStringHandler &H, PrintfSpecifier &FS,
53                            const char *FlagBeg, const char *E, bool Warn) {
54    StringRef Flag(FlagBeg, E - FlagBeg);
55    // Currently there is only one flag.
56    if (Flag == "tt") {
57      FS.setHasObjCTechnicalTerm(FlagBeg);
58      return false;
59    }
60    // Handle either the case of no flag or an invalid flag.
61    if (Warn) {
62      if (Flag == "")
63        H.HandleEmptyObjCModifierFlag(FlagBeg, E  - FlagBeg);
64      else
65        H.HandleInvalidObjCModifierFlag(FlagBeg, E  - FlagBeg);
66    }
67    return true;
68 }
69 
70 static PrintfSpecifierResult ParsePrintfSpecifier(FormatStringHandler &H,
71                                                   const char *&Beg,
72                                                   const char *E,
73                                                   unsigned &argIndex,
74                                                   const LangOptions &LO,
75                                                   const TargetInfo &Target,
76                                                   bool Warn,
77                                                   bool isFreeBSDKPrintf) {
78 
79   using namespace clang::analyze_format_string;
80   using namespace clang::analyze_printf;
81 
82   const char *I = Beg;
83   const char *Start = nullptr;
84   UpdateOnReturn <const char*> UpdateBeg(Beg, I);
85 
86   // Look for a '%' character that indicates the start of a format specifier.
87   for ( ; I != E ; ++I) {
88     char c = *I;
89     if (c == '\0') {
90       // Detect spurious null characters, which are likely errors.
91       H.HandleNullChar(I);
92       return true;
93     }
94     if (c == '%') {
95       Start = I++;  // Record the start of the format specifier.
96       break;
97     }
98   }
99 
100   // No format specifier found?
101   if (!Start)
102     return false;
103 
104   if (I == E) {
105     // No more characters left?
106     if (Warn)
107       H.HandleIncompleteSpecifier(Start, E - Start);
108     return true;
109   }
110 
111   PrintfSpecifier FS;
112   if (ParseArgPosition(H, FS, Start, I, E))
113     return true;
114 
115   if (I == E) {
116     // No more characters left?
117     if (Warn)
118       H.HandleIncompleteSpecifier(Start, E - Start);
119     return true;
120   }
121 
122   if (*I == '{') {
123     ++I;
124     unsigned char PrivacyFlags = 0;
125     StringRef MatchedStr;
126 
127     do {
128       StringRef Str(I, E - I);
129       std::string Match = "^[[:space:]]*"
130                           "(private|public|sensitive|mask\\.[^[:space:],}]*)"
131                           "[[:space:]]*(,|})";
132       llvm::Regex R(Match);
133       SmallVector<StringRef, 2> Matches;
134 
135       if (R.match(Str, &Matches)) {
136         MatchedStr = Matches[1];
137         I += Matches[0].size();
138 
139         // Set the privacy flag if the privacy annotation in the
140         // comma-delimited segment is at least as strict as the privacy
141         // annotations in previous comma-delimited segments.
142         if (MatchedStr.startswith("mask")) {
143           StringRef MaskType = MatchedStr.substr(sizeof("mask.") - 1);
144           unsigned Size = MaskType.size();
145           if (Warn && (Size == 0 || Size > 8))
146             H.handleInvalidMaskType(MaskType);
147           FS.setMaskType(MaskType);
148         } else if (MatchedStr.equals("sensitive"))
149           PrivacyFlags = clang::analyze_os_log::OSLogBufferItem::IsSensitive;
150         else if (PrivacyFlags !=
151                  clang::analyze_os_log::OSLogBufferItem::IsSensitive &&
152                  MatchedStr.equals("private"))
153           PrivacyFlags = clang::analyze_os_log::OSLogBufferItem::IsPrivate;
154         else if (PrivacyFlags == 0 && MatchedStr.equals("public"))
155           PrivacyFlags = clang::analyze_os_log::OSLogBufferItem::IsPublic;
156       } else {
157         size_t CommaOrBracePos =
158             Str.find_if([](char c) { return c == ',' || c == '}'; });
159 
160         if (CommaOrBracePos == StringRef::npos) {
161           // Neither a comma nor the closing brace was found.
162           if (Warn)
163             H.HandleIncompleteSpecifier(Start, E - Start);
164           return true;
165         }
166 
167         I += CommaOrBracePos + 1;
168       }
169       // Continue until the closing brace is found.
170     } while (*(I - 1) == ',');
171 
172     // Set the privacy flag.
173     switch (PrivacyFlags) {
174     case 0:
175       break;
176     case clang::analyze_os_log::OSLogBufferItem::IsPrivate:
177       FS.setIsPrivate(MatchedStr.data());
178       break;
179     case clang::analyze_os_log::OSLogBufferItem::IsPublic:
180       FS.setIsPublic(MatchedStr.data());
181       break;
182     case clang::analyze_os_log::OSLogBufferItem::IsSensitive:
183       FS.setIsSensitive(MatchedStr.data());
184       break;
185     default:
186       llvm_unreachable("Unexpected privacy flag value");
187     }
188   }
189 
190   // Look for flags (if any).
191   bool hasMore = true;
192   for ( ; I != E; ++I) {
193     switch (*I) {
194       default: hasMore = false; break;
195       case '\'':
196         // FIXME: POSIX specific.  Always accept?
197         FS.setHasThousandsGrouping(I);
198         break;
199       case '-': FS.setIsLeftJustified(I); break;
200       case '+': FS.setHasPlusPrefix(I); break;
201       case ' ': FS.setHasSpacePrefix(I); break;
202       case '#': FS.setHasAlternativeForm(I); break;
203       case '0': FS.setHasLeadingZeros(I); break;
204     }
205     if (!hasMore)
206       break;
207   }
208 
209   if (I == E) {
210     // No more characters left?
211     if (Warn)
212       H.HandleIncompleteSpecifier(Start, E - Start);
213     return true;
214   }
215 
216   // Look for the field width (if any).
217   if (ParseFieldWidth(H, FS, Start, I, E,
218                       FS.usesPositionalArg() ? nullptr : &argIndex))
219     return true;
220 
221   if (I == E) {
222     // No more characters left?
223     if (Warn)
224       H.HandleIncompleteSpecifier(Start, E - Start);
225     return true;
226   }
227 
228   // Look for the precision (if any).
229   if (*I == '.') {
230     ++I;
231     if (I == E) {
232       if (Warn)
233         H.HandleIncompleteSpecifier(Start, E - Start);
234       return true;
235     }
236 
237     if (ParsePrecision(H, FS, Start, I, E,
238                        FS.usesPositionalArg() ? nullptr : &argIndex))
239       return true;
240 
241     if (I == E) {
242       // No more characters left?
243       if (Warn)
244         H.HandleIncompleteSpecifier(Start, E - Start);
245       return true;
246     }
247   }
248 
249   if (ParseVectorModifier(H, FS, I, E, LO))
250     return true;
251 
252   // Look for the length modifier.
253   if (ParseLengthModifier(FS, I, E, LO) && I == E) {
254     // No more characters left?
255     if (Warn)
256       H.HandleIncompleteSpecifier(Start, E - Start);
257     return true;
258   }
259 
260   // Look for the Objective-C modifier flags, if any.
261   // We parse these here, even if they don't apply to
262   // the conversion specifier, and then emit an error
263   // later if the conversion specifier isn't '@'.  This
264   // enables better recovery, and we don't know if
265   // these flags are applicable until later.
266   const char *ObjCModifierFlagsStart = nullptr,
267              *ObjCModifierFlagsEnd = nullptr;
268   if (*I == '[') {
269     ObjCModifierFlagsStart = I;
270     ++I;
271     auto flagStart = I;
272     for (;; ++I) {
273       ObjCModifierFlagsEnd = I;
274       if (I == E) {
275         if (Warn)
276           H.HandleIncompleteSpecifier(Start, E - Start);
277         return true;
278       }
279       // Did we find the closing ']'?
280       if (*I == ']') {
281         if (ParseObjCFlags(H, FS, flagStart, I, Warn))
282           return true;
283         ++I;
284         break;
285       }
286       // There are no separators defined yet for multiple
287       // Objective-C modifier flags.  When those are
288       // defined, this is the place to check.
289     }
290   }
291 
292   if (*I == '\0') {
293     // Detect spurious null characters, which are likely errors.
294     H.HandleNullChar(I);
295     return true;
296   }
297 
298   // Finally, look for the conversion specifier.
299   const char *conversionPosition = I++;
300   ConversionSpecifier::Kind k = ConversionSpecifier::InvalidSpecifier;
301   switch (*conversionPosition) {
302     default:
303       break;
304     // C99: 7.19.6.1 (section 8).
305     case '%': k = ConversionSpecifier::PercentArg;   break;
306     case 'A': k = ConversionSpecifier::AArg; break;
307     case 'E': k = ConversionSpecifier::EArg; break;
308     case 'F': k = ConversionSpecifier::FArg; break;
309     case 'G': k = ConversionSpecifier::GArg; break;
310     case 'X': k = ConversionSpecifier::XArg; break;
311     case 'a': k = ConversionSpecifier::aArg; break;
312     case 'c': k = ConversionSpecifier::cArg; break;
313     case 'd': k = ConversionSpecifier::dArg; break;
314     case 'e': k = ConversionSpecifier::eArg; break;
315     case 'f': k = ConversionSpecifier::fArg; break;
316     case 'g': k = ConversionSpecifier::gArg; break;
317     case 'i': k = ConversionSpecifier::iArg; break;
318     case 'n': k = ConversionSpecifier::nArg; break;
319     case 'o': k = ConversionSpecifier::oArg; break;
320     case 'p': k = ConversionSpecifier::pArg; break;
321     case 's': k = ConversionSpecifier::sArg; break;
322     case 'u': k = ConversionSpecifier::uArg; break;
323     case 'x': k = ConversionSpecifier::xArg; break;
324     // POSIX specific.
325     case 'C': k = ConversionSpecifier::CArg; break;
326     case 'S': k = ConversionSpecifier::SArg; break;
327     // Apple extension for os_log
328     case 'P':
329       k = ConversionSpecifier::PArg;
330       break;
331     // Objective-C.
332     case '@': k = ConversionSpecifier::ObjCObjArg; break;
333     // Glibc specific.
334     case 'm': k = ConversionSpecifier::PrintErrno; break;
335     // FreeBSD kernel specific.
336     case 'b':
337       if (isFreeBSDKPrintf)
338         k = ConversionSpecifier::FreeBSDbArg; // int followed by char *
339       break;
340     case 'r':
341       if (isFreeBSDKPrintf)
342         k = ConversionSpecifier::FreeBSDrArg; // int
343       break;
344     case 'y':
345       if (isFreeBSDKPrintf)
346         k = ConversionSpecifier::FreeBSDyArg; // int
347       break;
348     // Apple-specific.
349     case 'D':
350       if (isFreeBSDKPrintf)
351         k = ConversionSpecifier::FreeBSDDArg; // void * followed by char *
352       else if (Target.getTriple().isOSDarwin())
353         k = ConversionSpecifier::DArg;
354       break;
355     case 'O':
356       if (Target.getTriple().isOSDarwin())
357         k = ConversionSpecifier::OArg;
358       break;
359     case 'U':
360       if (Target.getTriple().isOSDarwin())
361         k = ConversionSpecifier::UArg;
362       break;
363     // MS specific.
364     case 'Z':
365       if (Target.getTriple().isOSMSVCRT())
366         k = ConversionSpecifier::ZArg;
367       break;
368   }
369 
370   // Check to see if we used the Objective-C modifier flags with
371   // a conversion specifier other than '@'.
372   if (k != ConversionSpecifier::ObjCObjArg &&
373       k != ConversionSpecifier::InvalidSpecifier &&
374       ObjCModifierFlagsStart) {
375     H.HandleObjCFlagsWithNonObjCConversion(ObjCModifierFlagsStart,
376                                            ObjCModifierFlagsEnd + 1,
377                                            conversionPosition);
378     return true;
379   }
380 
381   PrintfConversionSpecifier CS(conversionPosition, k);
382   FS.setConversionSpecifier(CS);
383   if (CS.consumesDataArgument() && !FS.usesPositionalArg())
384     FS.setArgIndex(argIndex++);
385   // FreeBSD kernel specific.
386   if (k == ConversionSpecifier::FreeBSDbArg ||
387       k == ConversionSpecifier::FreeBSDDArg)
388     argIndex++;
389 
390   if (k == ConversionSpecifier::InvalidSpecifier) {
391     unsigned Len = I - Start;
392     if (ParseUTF8InvalidSpecifier(Start, E, Len)) {
393       CS.setEndScanList(Start + Len);
394       FS.setConversionSpecifier(CS);
395     }
396     // Assume the conversion takes one argument.
397     return !H.HandleInvalidPrintfConversionSpecifier(FS, Start, Len);
398   }
399   return PrintfSpecifierResult(Start, FS);
400 }
401 
402 bool clang::analyze_format_string::ParsePrintfString(FormatStringHandler &H,
403                                                      const char *I,
404                                                      const char *E,
405                                                      const LangOptions &LO,
406                                                      const TargetInfo &Target,
407                                                      bool isFreeBSDKPrintf) {
408 
409   unsigned argIndex = 0;
410 
411   // Keep looking for a format specifier until we have exhausted the string.
412   while (I != E) {
413     const PrintfSpecifierResult &FSR = ParsePrintfSpecifier(H, I, E, argIndex,
414                                                             LO, Target, true,
415                                                             isFreeBSDKPrintf);
416     // Did a fail-stop error of any kind occur when parsing the specifier?
417     // If so, don't do any more processing.
418     if (FSR.shouldStop())
419       return true;
420     // Did we exhaust the string or encounter an error that
421     // we can recover from?
422     if (!FSR.hasValue())
423       continue;
424     // We have a format specifier.  Pass it to the callback.
425     if (!H.HandlePrintfSpecifier(FSR.getValue(), FSR.getStart(),
426                                  I - FSR.getStart()))
427       return true;
428   }
429   assert(I == E && "Format string not exhausted");
430   return false;
431 }
432 
433 bool clang::analyze_format_string::ParseFormatStringHasSArg(const char *I,
434                                                             const char *E,
435                                                             const LangOptions &LO,
436                                                             const TargetInfo &Target) {
437 
438   unsigned argIndex = 0;
439 
440   // Keep looking for a %s format specifier until we have exhausted the string.
441   FormatStringHandler H;
442   while (I != E) {
443     const PrintfSpecifierResult &FSR = ParsePrintfSpecifier(H, I, E, argIndex,
444                                                             LO, Target, false,
445                                                             false);
446     // Did a fail-stop error of any kind occur when parsing the specifier?
447     // If so, don't do any more processing.
448     if (FSR.shouldStop())
449       return false;
450     // Did we exhaust the string or encounter an error that
451     // we can recover from?
452     if (!FSR.hasValue())
453       continue;
454     const analyze_printf::PrintfSpecifier &FS = FSR.getValue();
455     // Return true if this a %s format specifier.
456     if (FS.getConversionSpecifier().getKind() == ConversionSpecifier::Kind::sArg)
457       return true;
458   }
459   return false;
460 }
461 
462 //===----------------------------------------------------------------------===//
463 // Methods on PrintfSpecifier.
464 //===----------------------------------------------------------------------===//
465 
466 ArgType PrintfSpecifier::getScalarArgType(ASTContext &Ctx,
467                                           bool IsObjCLiteral) const {
468   if (CS.getKind() == ConversionSpecifier::cArg)
469     switch (LM.getKind()) {
470       case LengthModifier::None:
471         return Ctx.IntTy;
472       case LengthModifier::AsLong:
473       case LengthModifier::AsWide:
474         return ArgType(ArgType::WIntTy, "wint_t");
475       case LengthModifier::AsShort:
476         if (Ctx.getTargetInfo().getTriple().isOSMSVCRT())
477           return Ctx.IntTy;
478         LLVM_FALLTHROUGH;
479       default:
480         return ArgType::Invalid();
481     }
482 
483   if (CS.isIntArg())
484     switch (LM.getKind()) {
485       case LengthModifier::AsLongDouble:
486         // GNU extension.
487         return Ctx.LongLongTy;
488       case LengthModifier::None:
489         return Ctx.IntTy;
490       case LengthModifier::AsInt32:
491         return ArgType(Ctx.IntTy, "__int32");
492       case LengthModifier::AsChar: return ArgType::AnyCharTy;
493       case LengthModifier::AsShort: return Ctx.ShortTy;
494       case LengthModifier::AsLong: return Ctx.LongTy;
495       case LengthModifier::AsLongLong:
496       case LengthModifier::AsQuad:
497         return Ctx.LongLongTy;
498       case LengthModifier::AsInt64:
499         return ArgType(Ctx.LongLongTy, "__int64");
500       case LengthModifier::AsIntMax:
501         return ArgType(Ctx.getIntMaxType(), "intmax_t");
502       case LengthModifier::AsSizeT:
503         return ArgType::makeSizeT(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
504       case LengthModifier::AsInt3264:
505         return Ctx.getTargetInfo().getTriple().isArch64Bit()
506                    ? ArgType(Ctx.LongLongTy, "__int64")
507                    : ArgType(Ctx.IntTy, "__int32");
508       case LengthModifier::AsPtrDiff:
509         return ArgType::makePtrdiffT(
510             ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
511       case LengthModifier::AsAllocate:
512       case LengthModifier::AsMAllocate:
513       case LengthModifier::AsWide:
514         return ArgType::Invalid();
515     }
516 
517   if (CS.isUIntArg())
518     switch (LM.getKind()) {
519       case LengthModifier::AsLongDouble:
520         // GNU extension.
521         return Ctx.UnsignedLongLongTy;
522       case LengthModifier::None:
523         return Ctx.UnsignedIntTy;
524       case LengthModifier::AsInt32:
525         return ArgType(Ctx.UnsignedIntTy, "unsigned __int32");
526       case LengthModifier::AsChar: return Ctx.UnsignedCharTy;
527       case LengthModifier::AsShort: return Ctx.UnsignedShortTy;
528       case LengthModifier::AsLong: return Ctx.UnsignedLongTy;
529       case LengthModifier::AsLongLong:
530       case LengthModifier::AsQuad:
531         return Ctx.UnsignedLongLongTy;
532       case LengthModifier::AsInt64:
533         return ArgType(Ctx.UnsignedLongLongTy, "unsigned __int64");
534       case LengthModifier::AsIntMax:
535         return ArgType(Ctx.getUIntMaxType(), "uintmax_t");
536       case LengthModifier::AsSizeT:
537         return ArgType::makeSizeT(ArgType(Ctx.getSizeType(), "size_t"));
538       case LengthModifier::AsInt3264:
539         return Ctx.getTargetInfo().getTriple().isArch64Bit()
540                    ? ArgType(Ctx.UnsignedLongLongTy, "unsigned __int64")
541                    : ArgType(Ctx.UnsignedIntTy, "unsigned __int32");
542       case LengthModifier::AsPtrDiff:
543         return ArgType::makePtrdiffT(
544             ArgType(Ctx.getUnsignedPointerDiffType(), "unsigned ptrdiff_t"));
545       case LengthModifier::AsAllocate:
546       case LengthModifier::AsMAllocate:
547       case LengthModifier::AsWide:
548         return ArgType::Invalid();
549     }
550 
551   if (CS.isDoubleArg()) {
552     if (LM.getKind() == LengthModifier::AsLongDouble)
553       return Ctx.LongDoubleTy;
554     return Ctx.DoubleTy;
555   }
556 
557   if (CS.getKind() == ConversionSpecifier::nArg) {
558     switch (LM.getKind()) {
559       case LengthModifier::None:
560         return ArgType::PtrTo(Ctx.IntTy);
561       case LengthModifier::AsChar:
562         return ArgType::PtrTo(Ctx.SignedCharTy);
563       case LengthModifier::AsShort:
564         return ArgType::PtrTo(Ctx.ShortTy);
565       case LengthModifier::AsLong:
566         return ArgType::PtrTo(Ctx.LongTy);
567       case LengthModifier::AsLongLong:
568       case LengthModifier::AsQuad:
569         return ArgType::PtrTo(Ctx.LongLongTy);
570       case LengthModifier::AsIntMax:
571         return ArgType::PtrTo(ArgType(Ctx.getIntMaxType(), "intmax_t"));
572       case LengthModifier::AsSizeT:
573         return ArgType::PtrTo(ArgType(Ctx.getSignedSizeType(), "ssize_t"));
574       case LengthModifier::AsPtrDiff:
575         return ArgType::PtrTo(ArgType(Ctx.getPointerDiffType(), "ptrdiff_t"));
576       case LengthModifier::AsLongDouble:
577         return ArgType(); // FIXME: Is this a known extension?
578       case LengthModifier::AsAllocate:
579       case LengthModifier::AsMAllocate:
580       case LengthModifier::AsInt32:
581       case LengthModifier::AsInt3264:
582       case LengthModifier::AsInt64:
583       case LengthModifier::AsWide:
584         return ArgType::Invalid();
585     }
586   }
587 
588   switch (CS.getKind()) {
589     case ConversionSpecifier::sArg:
590       if (LM.getKind() == LengthModifier::AsWideChar) {
591         if (IsObjCLiteral)
592           return ArgType(Ctx.getPointerType(Ctx.UnsignedShortTy.withConst()),
593                          "const unichar *");
594         return ArgType(ArgType::WCStrTy, "wchar_t *");
595       }
596       if (LM.getKind() == LengthModifier::AsWide)
597         return ArgType(ArgType::WCStrTy, "wchar_t *");
598       return ArgType::CStrTy;
599     case ConversionSpecifier::SArg:
600       if (IsObjCLiteral)
601         return ArgType(Ctx.getPointerType(Ctx.UnsignedShortTy.withConst()),
602                        "const unichar *");
603       if (Ctx.getTargetInfo().getTriple().isOSMSVCRT() &&
604           LM.getKind() == LengthModifier::AsShort)
605         return ArgType::CStrTy;
606       return ArgType(ArgType::WCStrTy, "wchar_t *");
607     case ConversionSpecifier::CArg:
608       if (IsObjCLiteral)
609         return ArgType(Ctx.UnsignedShortTy, "unichar");
610       if (Ctx.getTargetInfo().getTriple().isOSMSVCRT() &&
611           LM.getKind() == LengthModifier::AsShort)
612         return Ctx.IntTy;
613       return ArgType(Ctx.WideCharTy, "wchar_t");
614     case ConversionSpecifier::pArg:
615     case ConversionSpecifier::PArg:
616       return ArgType::CPointerTy;
617     case ConversionSpecifier::ObjCObjArg:
618       return ArgType::ObjCPointerTy;
619     default:
620       break;
621   }
622 
623   // FIXME: Handle other cases.
624   return ArgType();
625 }
626 
627 
628 ArgType PrintfSpecifier::getArgType(ASTContext &Ctx,
629                                     bool IsObjCLiteral) const {
630   const PrintfConversionSpecifier &CS = getConversionSpecifier();
631 
632   if (!CS.consumesDataArgument())
633     return ArgType::Invalid();
634 
635   ArgType ScalarTy = getScalarArgType(Ctx, IsObjCLiteral);
636   if (!ScalarTy.isValid() || VectorNumElts.isInvalid())
637     return ScalarTy;
638 
639   return ScalarTy.makeVectorType(Ctx, VectorNumElts.getConstantAmount());
640 }
641 
642 bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt,
643                               ASTContext &Ctx, bool IsObjCLiteral) {
644   // %n is different from other conversion specifiers; don't try to fix it.
645   if (CS.getKind() == ConversionSpecifier::nArg)
646     return false;
647 
648   // Handle Objective-C objects first. Note that while the '%@' specifier will
649   // not warn for structure pointer or void pointer arguments (because that's
650   // how CoreFoundation objects are implemented), we only show a fixit for '%@'
651   // if we know it's an object (block, id, class, or __attribute__((NSObject))).
652   if (QT->isObjCRetainableType()) {
653     if (!IsObjCLiteral)
654       return false;
655 
656     CS.setKind(ConversionSpecifier::ObjCObjArg);
657 
658     // Disable irrelevant flags
659     HasThousandsGrouping = false;
660     HasPlusPrefix = false;
661     HasSpacePrefix = false;
662     HasAlternativeForm = false;
663     HasLeadingZeroes = false;
664     Precision.setHowSpecified(OptionalAmount::NotSpecified);
665     LM.setKind(LengthModifier::None);
666 
667     return true;
668   }
669 
670   // Handle strings next (char *, wchar_t *)
671   if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) {
672     CS.setKind(ConversionSpecifier::sArg);
673 
674     // Disable irrelevant flags
675     HasAlternativeForm = 0;
676     HasLeadingZeroes = 0;
677 
678     // Set the long length modifier for wide characters
679     if (QT->getPointeeType()->isWideCharType())
680       LM.setKind(LengthModifier::AsWideChar);
681     else
682       LM.setKind(LengthModifier::None);
683 
684     return true;
685   }
686 
687   // If it's an enum, get its underlying type.
688   if (const EnumType *ETy = QT->getAs<EnumType>())
689     QT = ETy->getDecl()->getIntegerType();
690 
691   const BuiltinType *BT = QT->getAs<BuiltinType>();
692   if (!BT) {
693     const VectorType *VT = QT->getAs<VectorType>();
694     if (VT) {
695       QT = VT->getElementType();
696       BT = QT->getAs<BuiltinType>();
697       VectorNumElts = OptionalAmount(VT->getNumElements());
698     }
699   }
700 
701   // We can only work with builtin types.
702   if (!BT)
703     return false;
704 
705   // Set length modifier
706   switch (BT->getKind()) {
707   case BuiltinType::Bool:
708   case BuiltinType::WChar_U:
709   case BuiltinType::WChar_S:
710   case BuiltinType::Char8: // FIXME: Treat like 'char'?
711   case BuiltinType::Char16:
712   case BuiltinType::Char32:
713   case BuiltinType::UInt128:
714   case BuiltinType::Int128:
715   case BuiltinType::Half:
716   case BuiltinType::Float16:
717   case BuiltinType::Float128:
718   case BuiltinType::ShortAccum:
719   case BuiltinType::Accum:
720   case BuiltinType::LongAccum:
721   case BuiltinType::UShortAccum:
722   case BuiltinType::UAccum:
723   case BuiltinType::ULongAccum:
724   case BuiltinType::ShortFract:
725   case BuiltinType::Fract:
726   case BuiltinType::LongFract:
727   case BuiltinType::UShortFract:
728   case BuiltinType::UFract:
729   case BuiltinType::ULongFract:
730   case BuiltinType::SatShortAccum:
731   case BuiltinType::SatAccum:
732   case BuiltinType::SatLongAccum:
733   case BuiltinType::SatUShortAccum:
734   case BuiltinType::SatUAccum:
735   case BuiltinType::SatULongAccum:
736   case BuiltinType::SatShortFract:
737   case BuiltinType::SatFract:
738   case BuiltinType::SatLongFract:
739   case BuiltinType::SatUShortFract:
740   case BuiltinType::SatUFract:
741   case BuiltinType::SatULongFract:
742     // Various types which are non-trivial to correct.
743     return false;
744 
745 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
746   case BuiltinType::Id:
747 #include "clang/Basic/OpenCLImageTypes.def"
748 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
749   case BuiltinType::Id:
750 #include "clang/Basic/OpenCLExtensionTypes.def"
751 #define SIGNED_TYPE(Id, SingletonId)
752 #define UNSIGNED_TYPE(Id, SingletonId)
753 #define FLOATING_TYPE(Id, SingletonId)
754 #define BUILTIN_TYPE(Id, SingletonId) \
755   case BuiltinType::Id:
756 #include "clang/AST/BuiltinTypes.def"
757     // Misc other stuff which doesn't make sense here.
758     return false;
759 
760   case BuiltinType::UInt:
761   case BuiltinType::Int:
762   case BuiltinType::Float:
763   case BuiltinType::Double:
764     LM.setKind(LengthModifier::None);
765     break;
766 
767   case BuiltinType::Char_U:
768   case BuiltinType::UChar:
769   case BuiltinType::Char_S:
770   case BuiltinType::SChar:
771     LM.setKind(LengthModifier::AsChar);
772     break;
773 
774   case BuiltinType::Short:
775   case BuiltinType::UShort:
776     LM.setKind(LengthModifier::AsShort);
777     break;
778 
779   case BuiltinType::Long:
780   case BuiltinType::ULong:
781     LM.setKind(LengthModifier::AsLong);
782     break;
783 
784   case BuiltinType::LongLong:
785   case BuiltinType::ULongLong:
786     LM.setKind(LengthModifier::AsLongLong);
787     break;
788 
789   case BuiltinType::LongDouble:
790     LM.setKind(LengthModifier::AsLongDouble);
791     break;
792   }
793 
794   // Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99.
795   if (isa<TypedefType>(QT) && (LangOpt.C99 || LangOpt.CPlusPlus11))
796     namedTypeToLengthModifier(QT, LM);
797 
798   // If fixing the length modifier was enough, we might be done.
799   if (hasValidLengthModifier(Ctx.getTargetInfo())) {
800     // If we're going to offer a fix anyway, make sure the sign matches.
801     switch (CS.getKind()) {
802     case ConversionSpecifier::uArg:
803     case ConversionSpecifier::UArg:
804       if (QT->isSignedIntegerType())
805         CS.setKind(clang::analyze_format_string::ConversionSpecifier::dArg);
806       break;
807     case ConversionSpecifier::dArg:
808     case ConversionSpecifier::DArg:
809     case ConversionSpecifier::iArg:
810       if (QT->isUnsignedIntegerType() && !HasPlusPrefix)
811         CS.setKind(clang::analyze_format_string::ConversionSpecifier::uArg);
812       break;
813     default:
814       // Other specifiers do not have signed/unsigned variants.
815       break;
816     }
817 
818     const analyze_printf::ArgType &ATR = getArgType(Ctx, IsObjCLiteral);
819     if (ATR.isValid() && ATR.matchesType(Ctx, QT))
820       return true;
821   }
822 
823   // Set conversion specifier and disable any flags which do not apply to it.
824   // Let typedefs to char fall through to int, as %c is silly for uint8_t.
825   if (!isa<TypedefType>(QT) && QT->isCharType()) {
826     CS.setKind(ConversionSpecifier::cArg);
827     LM.setKind(LengthModifier::None);
828     Precision.setHowSpecified(OptionalAmount::NotSpecified);
829     HasAlternativeForm = 0;
830     HasLeadingZeroes = 0;
831     HasPlusPrefix = 0;
832   }
833   // Test for Floating type first as LongDouble can pass isUnsignedIntegerType
834   else if (QT->isRealFloatingType()) {
835     CS.setKind(ConversionSpecifier::fArg);
836   }
837   else if (QT->isSignedIntegerType()) {
838     CS.setKind(ConversionSpecifier::dArg);
839     HasAlternativeForm = 0;
840   }
841   else if (QT->isUnsignedIntegerType()) {
842     CS.setKind(ConversionSpecifier::uArg);
843     HasAlternativeForm = 0;
844     HasPlusPrefix = 0;
845   } else {
846     llvm_unreachable("Unexpected type");
847   }
848 
849   return true;
850 }
851 
852 void PrintfSpecifier::toString(raw_ostream &os) const {
853   // Whilst some features have no defined order, we are using the order
854   // appearing in the C99 standard (ISO/IEC 9899:1999 (E) 7.19.6.1)
855   os << "%";
856 
857   // Positional args
858   if (usesPositionalArg()) {
859     os << getPositionalArgIndex() << "$";
860   }
861 
862   // Conversion flags
863   if (IsLeftJustified)    os << "-";
864   if (HasPlusPrefix)      os << "+";
865   if (HasSpacePrefix)     os << " ";
866   if (HasAlternativeForm) os << "#";
867   if (HasLeadingZeroes)   os << "0";
868 
869   // Minimum field width
870   FieldWidth.toString(os);
871   // Precision
872   Precision.toString(os);
873 
874   // Vector modifier
875   if (!VectorNumElts.isInvalid())
876     os << 'v' << VectorNumElts.getConstantAmount();
877 
878   // Length modifier
879   os << LM.toString();
880   // Conversion specifier
881   os << CS.toString();
882 }
883 
884 bool PrintfSpecifier::hasValidPlusPrefix() const {
885   if (!HasPlusPrefix)
886     return true;
887 
888   // The plus prefix only makes sense for signed conversions
889   switch (CS.getKind()) {
890   case ConversionSpecifier::dArg:
891   case ConversionSpecifier::DArg:
892   case ConversionSpecifier::iArg:
893   case ConversionSpecifier::fArg:
894   case ConversionSpecifier::FArg:
895   case ConversionSpecifier::eArg:
896   case ConversionSpecifier::EArg:
897   case ConversionSpecifier::gArg:
898   case ConversionSpecifier::GArg:
899   case ConversionSpecifier::aArg:
900   case ConversionSpecifier::AArg:
901   case ConversionSpecifier::FreeBSDrArg:
902   case ConversionSpecifier::FreeBSDyArg:
903     return true;
904 
905   default:
906     return false;
907   }
908 }
909 
910 bool PrintfSpecifier::hasValidAlternativeForm() const {
911   if (!HasAlternativeForm)
912     return true;
913 
914   // Alternate form flag only valid with the oxXaAeEfFgG conversions
915   switch (CS.getKind()) {
916   case ConversionSpecifier::oArg:
917   case ConversionSpecifier::OArg:
918   case ConversionSpecifier::xArg:
919   case ConversionSpecifier::XArg:
920   case ConversionSpecifier::aArg:
921   case ConversionSpecifier::AArg:
922   case ConversionSpecifier::eArg:
923   case ConversionSpecifier::EArg:
924   case ConversionSpecifier::fArg:
925   case ConversionSpecifier::FArg:
926   case ConversionSpecifier::gArg:
927   case ConversionSpecifier::GArg:
928   case ConversionSpecifier::FreeBSDrArg:
929   case ConversionSpecifier::FreeBSDyArg:
930     return true;
931 
932   default:
933     return false;
934   }
935 }
936 
937 bool PrintfSpecifier::hasValidLeadingZeros() const {
938   if (!HasLeadingZeroes)
939     return true;
940 
941   // Leading zeroes flag only valid with the diouxXaAeEfFgG conversions
942   switch (CS.getKind()) {
943   case ConversionSpecifier::dArg:
944   case ConversionSpecifier::DArg:
945   case ConversionSpecifier::iArg:
946   case ConversionSpecifier::oArg:
947   case ConversionSpecifier::OArg:
948   case ConversionSpecifier::uArg:
949   case ConversionSpecifier::UArg:
950   case ConversionSpecifier::xArg:
951   case ConversionSpecifier::XArg:
952   case ConversionSpecifier::aArg:
953   case ConversionSpecifier::AArg:
954   case ConversionSpecifier::eArg:
955   case ConversionSpecifier::EArg:
956   case ConversionSpecifier::fArg:
957   case ConversionSpecifier::FArg:
958   case ConversionSpecifier::gArg:
959   case ConversionSpecifier::GArg:
960   case ConversionSpecifier::FreeBSDrArg:
961   case ConversionSpecifier::FreeBSDyArg:
962     return true;
963 
964   default:
965     return false;
966   }
967 }
968 
969 bool PrintfSpecifier::hasValidSpacePrefix() const {
970   if (!HasSpacePrefix)
971     return true;
972 
973   // The space prefix only makes sense for signed conversions
974   switch (CS.getKind()) {
975   case ConversionSpecifier::dArg:
976   case ConversionSpecifier::DArg:
977   case ConversionSpecifier::iArg:
978   case ConversionSpecifier::fArg:
979   case ConversionSpecifier::FArg:
980   case ConversionSpecifier::eArg:
981   case ConversionSpecifier::EArg:
982   case ConversionSpecifier::gArg:
983   case ConversionSpecifier::GArg:
984   case ConversionSpecifier::aArg:
985   case ConversionSpecifier::AArg:
986   case ConversionSpecifier::FreeBSDrArg:
987   case ConversionSpecifier::FreeBSDyArg:
988     return true;
989 
990   default:
991     return false;
992   }
993 }
994 
995 bool PrintfSpecifier::hasValidLeftJustified() const {
996   if (!IsLeftJustified)
997     return true;
998 
999   // The left justified flag is valid for all conversions except n
1000   switch (CS.getKind()) {
1001   case ConversionSpecifier::nArg:
1002     return false;
1003 
1004   default:
1005     return true;
1006   }
1007 }
1008 
1009 bool PrintfSpecifier::hasValidThousandsGroupingPrefix() const {
1010   if (!HasThousandsGrouping)
1011     return true;
1012 
1013   switch (CS.getKind()) {
1014     case ConversionSpecifier::dArg:
1015     case ConversionSpecifier::DArg:
1016     case ConversionSpecifier::iArg:
1017     case ConversionSpecifier::uArg:
1018     case ConversionSpecifier::UArg:
1019     case ConversionSpecifier::fArg:
1020     case ConversionSpecifier::FArg:
1021     case ConversionSpecifier::gArg:
1022     case ConversionSpecifier::GArg:
1023       return true;
1024     default:
1025       return false;
1026   }
1027 }
1028 
1029 bool PrintfSpecifier::hasValidPrecision() const {
1030   if (Precision.getHowSpecified() == OptionalAmount::NotSpecified)
1031     return true;
1032 
1033   // Precision is only valid with the diouxXaAeEfFgGsP conversions
1034   switch (CS.getKind()) {
1035   case ConversionSpecifier::dArg:
1036   case ConversionSpecifier::DArg:
1037   case ConversionSpecifier::iArg:
1038   case ConversionSpecifier::oArg:
1039   case ConversionSpecifier::OArg:
1040   case ConversionSpecifier::uArg:
1041   case ConversionSpecifier::UArg:
1042   case ConversionSpecifier::xArg:
1043   case ConversionSpecifier::XArg:
1044   case ConversionSpecifier::aArg:
1045   case ConversionSpecifier::AArg:
1046   case ConversionSpecifier::eArg:
1047   case ConversionSpecifier::EArg:
1048   case ConversionSpecifier::fArg:
1049   case ConversionSpecifier::FArg:
1050   case ConversionSpecifier::gArg:
1051   case ConversionSpecifier::GArg:
1052   case ConversionSpecifier::sArg:
1053   case ConversionSpecifier::FreeBSDrArg:
1054   case ConversionSpecifier::FreeBSDyArg:
1055   case ConversionSpecifier::PArg:
1056     return true;
1057 
1058   default:
1059     return false;
1060   }
1061 }
1062 bool PrintfSpecifier::hasValidFieldWidth() const {
1063   if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified)
1064       return true;
1065 
1066   // The field width is valid for all conversions except n
1067   switch (CS.getKind()) {
1068   case ConversionSpecifier::nArg:
1069     return false;
1070 
1071   default:
1072     return true;
1073   }
1074 }
1075