PrintfFormatString.cpp revision 117348caf0a8f91782e9e32e32a8689576f394d7
1//== PrintfFormatString.cpp - Analysis of printf format strings --*- 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// Handling of format string in printf and friends. The structure of format 11// strings for fprintf() are described in C99 7.19.6.1. 12// 13//===----------------------------------------------------------------------===// 14 15#include "clang/Analysis/Analyses/FormatString.h" 16#include "FormatStringParsing.h" 17 18using clang::analyze_format_string::ArgTypeResult; 19using clang::analyze_format_string::FormatStringHandler; 20using clang::analyze_format_string::LengthModifier; 21using clang::analyze_format_string::OptionalAmount; 22using clang::analyze_format_string::ConversionSpecifier; 23using clang::analyze_printf::PrintfSpecifier; 24 25using namespace clang; 26 27typedef clang::analyze_format_string::SpecifierResult<PrintfSpecifier> 28 PrintfSpecifierResult; 29 30//===----------------------------------------------------------------------===// 31// Methods for parsing format strings. 32//===----------------------------------------------------------------------===// 33 34using analyze_format_string::ParseNonPositionAmount; 35 36static bool ParsePrecision(FormatStringHandler &H, PrintfSpecifier &FS, 37 const char *Start, const char *&Beg, const char *E, 38 unsigned *argIndex) { 39 if (argIndex) { 40 FS.setPrecision(ParseNonPositionAmount(Beg, E, *argIndex)); 41 } else { 42 const OptionalAmount Amt = ParsePositionAmount(H, Start, Beg, E, 43 analyze_format_string::PrecisionPos); 44 if (Amt.isInvalid()) 45 return true; 46 FS.setPrecision(Amt); 47 } 48 return false; 49} 50 51static PrintfSpecifierResult ParsePrintfSpecifier(FormatStringHandler &H, 52 const char *&Beg, 53 const char *E, 54 unsigned &argIndex) { 55 56 using namespace clang::analyze_format_string; 57 using namespace clang::analyze_printf; 58 59 const char *I = Beg; 60 const char *Start = 0; 61 UpdateOnReturn <const char*> UpdateBeg(Beg, I); 62 63 // Look for a '%' character that indicates the start of a format specifier. 64 for ( ; I != E ; ++I) { 65 char c = *I; 66 if (c == '\0') { 67 // Detect spurious null characters, which are likely errors. 68 H.HandleNullChar(I); 69 return true; 70 } 71 if (c == '%') { 72 Start = I++; // Record the start of the format specifier. 73 break; 74 } 75 } 76 77 // No format specifier found? 78 if (!Start) 79 return false; 80 81 if (I == E) { 82 // No more characters left? 83 H.HandleIncompleteSpecifier(Start, E - Start); 84 return true; 85 } 86 87 PrintfSpecifier FS; 88 if (ParseArgPosition(H, FS, Start, I, E)) 89 return true; 90 91 if (I == E) { 92 // No more characters left? 93 H.HandleIncompleteSpecifier(Start, E - Start); 94 return true; 95 } 96 97 // Look for flags (if any). 98 bool hasMore = true; 99 for ( ; I != E; ++I) { 100 switch (*I) { 101 default: hasMore = false; break; 102 case '\'': 103 // FIXME: POSIX specific. Always accept? 104 FS.setHasThousandsGrouping(I); 105 break; 106 case '-': FS.setIsLeftJustified(I); break; 107 case '+': FS.setHasPlusPrefix(I); break; 108 case ' ': FS.setHasSpacePrefix(I); break; 109 case '#': FS.setHasAlternativeForm(I); break; 110 case '0': FS.setHasLeadingZeros(I); break; 111 } 112 if (!hasMore) 113 break; 114 } 115 116 if (I == E) { 117 // No more characters left? 118 H.HandleIncompleteSpecifier(Start, E - Start); 119 return true; 120 } 121 122 // Look for the field width (if any). 123 if (ParseFieldWidth(H, FS, Start, I, E, 124 FS.usesPositionalArg() ? 0 : &argIndex)) 125 return true; 126 127 if (I == E) { 128 // No more characters left? 129 H.HandleIncompleteSpecifier(Start, E - Start); 130 return true; 131 } 132 133 // Look for the precision (if any). 134 if (*I == '.') { 135 ++I; 136 if (I == E) { 137 H.HandleIncompleteSpecifier(Start, E - Start); 138 return true; 139 } 140 141 if (ParsePrecision(H, FS, Start, I, E, 142 FS.usesPositionalArg() ? 0 : &argIndex)) 143 return true; 144 145 if (I == E) { 146 // No more characters left? 147 H.HandleIncompleteSpecifier(Start, E - Start); 148 return true; 149 } 150 } 151 152 // Look for the length modifier. 153 if (ParseLengthModifier(FS, I, E) && I == E) { 154 // No more characters left? 155 H.HandleIncompleteSpecifier(Start, E - Start); 156 return true; 157 } 158 159 if (*I == '\0') { 160 // Detect spurious null characters, which are likely errors. 161 H.HandleNullChar(I); 162 return true; 163 } 164 165 // Finally, look for the conversion specifier. 166 const char *conversionPosition = I++; 167 ConversionSpecifier::Kind k = ConversionSpecifier::InvalidSpecifier; 168 switch (*conversionPosition) { 169 default: 170 break; 171 // C99: 7.19.6.1 (section 8). 172 case '%': k = ConversionSpecifier::PercentArg; break; 173 case 'A': k = ConversionSpecifier::AArg; break; 174 case 'E': k = ConversionSpecifier::EArg; break; 175 case 'F': k = ConversionSpecifier::FArg; break; 176 case 'G': k = ConversionSpecifier::GArg; break; 177 case 'X': k = ConversionSpecifier::XArg; break; 178 case 'a': k = ConversionSpecifier::aArg; break; 179 case 'c': k = ConversionSpecifier::cArg; break; 180 case 'd': k = ConversionSpecifier::dArg; break; 181 case 'e': k = ConversionSpecifier::eArg; break; 182 case 'f': k = ConversionSpecifier::fArg; break; 183 case 'g': k = ConversionSpecifier::gArg; break; 184 case 'i': k = ConversionSpecifier::iArg; break; 185 case 'n': k = ConversionSpecifier::nArg; break; 186 case 'o': k = ConversionSpecifier::oArg; break; 187 case 'p': k = ConversionSpecifier::pArg; break; 188 case 's': k = ConversionSpecifier::sArg; break; 189 case 'u': k = ConversionSpecifier::uArg; break; 190 case 'x': k = ConversionSpecifier::xArg; break; 191 // POSIX specific. 192 case 'C': k = ConversionSpecifier::CArg; break; 193 case 'S': k = ConversionSpecifier::SArg; break; 194 // Objective-C. 195 case '@': k = ConversionSpecifier::ObjCObjArg; break; 196 // Glibc specific. 197 case 'm': k = ConversionSpecifier::PrintErrno; break; 198 } 199 PrintfConversionSpecifier CS(conversionPosition, k); 200 FS.setConversionSpecifier(CS); 201 if (CS.consumesDataArgument() && !FS.usesPositionalArg()) 202 FS.setArgIndex(argIndex++); 203 204 if (k == ConversionSpecifier::InvalidSpecifier) { 205 // Assume the conversion takes one argument. 206 return !H.HandleInvalidPrintfConversionSpecifier(FS, Start, I - Start); 207 } 208 return PrintfSpecifierResult(Start, FS); 209} 210 211bool clang::analyze_format_string::ParsePrintfString(FormatStringHandler &H, 212 const char *I, 213 const char *E) { 214 215 unsigned argIndex = 0; 216 217 // Keep looking for a format specifier until we have exhausted the string. 218 while (I != E) { 219 const PrintfSpecifierResult &FSR = ParsePrintfSpecifier(H, I, E, argIndex); 220 // Did a fail-stop error of any kind occur when parsing the specifier? 221 // If so, don't do any more processing. 222 if (FSR.shouldStop()) 223 return true;; 224 // Did we exhaust the string or encounter an error that 225 // we can recover from? 226 if (!FSR.hasValue()) 227 continue; 228 // We have a format specifier. Pass it to the callback. 229 if (!H.HandlePrintfSpecifier(FSR.getValue(), FSR.getStart(), 230 I - FSR.getStart())) 231 return true; 232 } 233 assert(I == E && "Format string not exhausted"); 234 return false; 235} 236 237//===----------------------------------------------------------------------===// 238// Methods on ConversionSpecifier. 239//===----------------------------------------------------------------------===// 240const char *ConversionSpecifier::toString() const { 241 switch (kind) { 242 case dArg: return "d"; 243 case iArg: return "i"; 244 case oArg: return "o"; 245 case uArg: return "u"; 246 case xArg: return "x"; 247 case XArg: return "X"; 248 case fArg: return "f"; 249 case FArg: return "F"; 250 case eArg: return "e"; 251 case EArg: return "E"; 252 case gArg: return "g"; 253 case GArg: return "G"; 254 case aArg: return "a"; 255 case AArg: return "A"; 256 case cArg: return "c"; 257 case sArg: return "s"; 258 case pArg: return "p"; 259 case nArg: return "n"; 260 case PercentArg: return "%"; 261 case ScanListArg: return "["; 262 case InvalidSpecifier: return NULL; 263 264 // MacOS X unicode extensions. 265 case CArg: return "C"; 266 case SArg: return "S"; 267 268 // Objective-C specific specifiers. 269 case ObjCObjArg: return "@"; 270 271 // GlibC specific specifiers. 272 case PrintErrno: return "m"; 273 } 274 return NULL; 275} 276 277//===----------------------------------------------------------------------===// 278// Methods on PrintfSpecifier. 279//===----------------------------------------------------------------------===// 280 281ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx) const { 282 const PrintfConversionSpecifier &CS = getConversionSpecifier(); 283 284 if (!CS.consumesDataArgument()) 285 return ArgTypeResult::Invalid(); 286 287 if (CS.getKind() == ConversionSpecifier::cArg) 288 switch (LM.getKind()) { 289 case LengthModifier::None: return Ctx.IntTy; 290 case LengthModifier::AsLong: return ArgTypeResult::WIntTy; 291 default: 292 return ArgTypeResult::Invalid(); 293 } 294 295 if (CS.isIntArg()) 296 switch (LM.getKind()) { 297 case LengthModifier::AsLongDouble: 298 return ArgTypeResult::Invalid(); 299 case LengthModifier::None: return Ctx.IntTy; 300 case LengthModifier::AsChar: return ArgTypeResult::AnyCharTy; 301 case LengthModifier::AsShort: return Ctx.ShortTy; 302 case LengthModifier::AsLong: return Ctx.LongTy; 303 case LengthModifier::AsLongLong: return Ctx.LongLongTy; 304 case LengthModifier::AsIntMax: 305 return ArgTypeResult(Ctx.getIntMaxType(), "intmax_t"); 306 case LengthModifier::AsSizeT: 307 // FIXME: How to get the corresponding signed version of size_t? 308 return ArgTypeResult(); 309 case LengthModifier::AsPtrDiff: 310 return ArgTypeResult(Ctx.getPointerDiffType(), "ptrdiff_t"); 311 } 312 313 if (CS.isUIntArg()) 314 switch (LM.getKind()) { 315 case LengthModifier::AsLongDouble: 316 return ArgTypeResult::Invalid(); 317 case LengthModifier::None: return Ctx.UnsignedIntTy; 318 case LengthModifier::AsChar: return Ctx.UnsignedCharTy; 319 case LengthModifier::AsShort: return Ctx.UnsignedShortTy; 320 case LengthModifier::AsLong: return Ctx.UnsignedLongTy; 321 case LengthModifier::AsLongLong: return Ctx.UnsignedLongLongTy; 322 case LengthModifier::AsIntMax: 323 return ArgTypeResult(Ctx.getUIntMaxType(), "uintmax_t"); 324 case LengthModifier::AsSizeT: 325 return ArgTypeResult(Ctx.getSizeType(), "size_t"); 326 case LengthModifier::AsPtrDiff: 327 // FIXME: How to get the corresponding unsigned 328 // version of ptrdiff_t? 329 return ArgTypeResult(); 330 } 331 332 if (CS.isDoubleArg()) { 333 if (LM.getKind() == LengthModifier::AsLongDouble) 334 return Ctx.LongDoubleTy; 335 return Ctx.DoubleTy; 336 } 337 338 switch (CS.getKind()) { 339 case ConversionSpecifier::sArg: 340 return ArgTypeResult(LM.getKind() == LengthModifier::AsWideChar ? 341 ArgTypeResult::WCStrTy : ArgTypeResult::CStrTy); 342 case ConversionSpecifier::SArg: 343 // FIXME: This appears to be Mac OS X specific. 344 return ArgTypeResult::WCStrTy; 345 case ConversionSpecifier::CArg: 346 return Ctx.WCharTy; 347 case ConversionSpecifier::pArg: 348 return ArgTypeResult::CPointerTy; 349 default: 350 break; 351 } 352 353 // FIXME: Handle other cases. 354 return ArgTypeResult(); 355} 356 357bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt) { 358 // Handle strings first (char *, wchar_t *) 359 if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) { 360 CS.setKind(ConversionSpecifier::sArg); 361 362 // Disable irrelevant flags 363 HasAlternativeForm = 0; 364 HasLeadingZeroes = 0; 365 366 // Set the long length modifier for wide characters 367 if (QT->getPointeeType()->isWideCharType()) 368 LM.setKind(LengthModifier::AsWideChar); 369 else 370 LM.setKind(LengthModifier::None); 371 372 return true; 373 } 374 375 // We can only work with builtin types. 376 const BuiltinType *BT = QT->getAs<BuiltinType>(); 377 if (!BT) 378 return false; 379 380 // Set length modifier 381 switch (BT->getKind()) { 382 case BuiltinType::Bool: 383 case BuiltinType::WChar_U: 384 case BuiltinType::WChar_S: 385 case BuiltinType::Char16: 386 case BuiltinType::Char32: 387 case BuiltinType::UInt128: 388 case BuiltinType::Int128: 389 case BuiltinType::Half: 390 // Various types which are non-trivial to correct. 391 return false; 392 393#define SIGNED_TYPE(Id, SingletonId) 394#define UNSIGNED_TYPE(Id, SingletonId) 395#define FLOATING_TYPE(Id, SingletonId) 396#define BUILTIN_TYPE(Id, SingletonId) \ 397 case BuiltinType::Id: 398#include "clang/AST/BuiltinTypes.def" 399 // Misc other stuff which doesn't make sense here. 400 return false; 401 402 case BuiltinType::UInt: 403 case BuiltinType::Int: 404 case BuiltinType::Float: 405 case BuiltinType::Double: 406 LM.setKind(LengthModifier::None); 407 break; 408 409 case BuiltinType::Char_U: 410 case BuiltinType::UChar: 411 case BuiltinType::Char_S: 412 case BuiltinType::SChar: 413 LM.setKind(LengthModifier::AsChar); 414 break; 415 416 case BuiltinType::Short: 417 case BuiltinType::UShort: 418 LM.setKind(LengthModifier::AsShort); 419 break; 420 421 case BuiltinType::Long: 422 case BuiltinType::ULong: 423 LM.setKind(LengthModifier::AsLong); 424 break; 425 426 case BuiltinType::LongLong: 427 case BuiltinType::ULongLong: 428 LM.setKind(LengthModifier::AsLongLong); 429 break; 430 431 case BuiltinType::LongDouble: 432 LM.setKind(LengthModifier::AsLongDouble); 433 break; 434 } 435 436 // Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99. 437 if (isa<TypedefType>(QT) && (LangOpt.C99 || LangOpt.CPlusPlus0x)) { 438 const IdentifierInfo *Identifier = QT.getBaseTypeIdentifier(); 439 if (Identifier->getName() == "size_t") { 440 LM.setKind(LengthModifier::AsSizeT); 441 } else if (Identifier->getName() == "ssize_t") { 442 // Not C99, but common in Unix. 443 LM.setKind(LengthModifier::AsSizeT); 444 } else if (Identifier->getName() == "intmax_t") { 445 LM.setKind(LengthModifier::AsIntMax); 446 } else if (Identifier->getName() == "uintmax_t") { 447 LM.setKind(LengthModifier::AsIntMax); 448 } else if (Identifier->getName() == "ptrdiff_t") { 449 LM.setKind(LengthModifier::AsPtrDiff); 450 } 451 } 452 453 // Set conversion specifier and disable any flags which do not apply to it. 454 // Let typedefs to char fall through to int, as %c is silly for uint8_t. 455 if (isa<TypedefType>(QT) && QT->isAnyCharacterType()) { 456 CS.setKind(ConversionSpecifier::cArg); 457 LM.setKind(LengthModifier::None); 458 Precision.setHowSpecified(OptionalAmount::NotSpecified); 459 HasAlternativeForm = 0; 460 HasLeadingZeroes = 0; 461 HasPlusPrefix = 0; 462 } 463 // Test for Floating type first as LongDouble can pass isUnsignedIntegerType 464 else if (QT->isRealFloatingType()) { 465 CS.setKind(ConversionSpecifier::fArg); 466 } 467 else if (QT->isSignedIntegerType()) { 468 CS.setKind(ConversionSpecifier::dArg); 469 HasAlternativeForm = 0; 470 } 471 else if (QT->isUnsignedIntegerType()) { 472 // Preserve the original formatting, e.g. 'X', 'o'. 473 if (!cast<PrintfConversionSpecifier>(CS).isUIntArg()) 474 CS.setKind(ConversionSpecifier::uArg); 475 HasAlternativeForm = 0; 476 HasPlusPrefix = 0; 477 } else { 478 llvm_unreachable("Unexpected type"); 479 } 480 481 return true; 482} 483 484void PrintfSpecifier::toString(raw_ostream &os) const { 485 // Whilst some features have no defined order, we are using the order 486 // appearing in the C99 standard (ISO/IEC 9899:1999 (E) 7.19.6.1) 487 os << "%"; 488 489 // Positional args 490 if (usesPositionalArg()) { 491 os << getPositionalArgIndex() << "$"; 492 } 493 494 // Conversion flags 495 if (IsLeftJustified) os << "-"; 496 if (HasPlusPrefix) os << "+"; 497 if (HasSpacePrefix) os << " "; 498 if (HasAlternativeForm) os << "#"; 499 if (HasLeadingZeroes) os << "0"; 500 501 // Minimum field width 502 FieldWidth.toString(os); 503 // Precision 504 Precision.toString(os); 505 // Length modifier 506 os << LM.toString(); 507 // Conversion specifier 508 os << CS.toString(); 509} 510 511bool PrintfSpecifier::hasValidPlusPrefix() const { 512 if (!HasPlusPrefix) 513 return true; 514 515 // The plus prefix only makes sense for signed conversions 516 switch (CS.getKind()) { 517 case ConversionSpecifier::dArg: 518 case ConversionSpecifier::iArg: 519 case ConversionSpecifier::fArg: 520 case ConversionSpecifier::FArg: 521 case ConversionSpecifier::eArg: 522 case ConversionSpecifier::EArg: 523 case ConversionSpecifier::gArg: 524 case ConversionSpecifier::GArg: 525 case ConversionSpecifier::aArg: 526 case ConversionSpecifier::AArg: 527 return true; 528 529 default: 530 return false; 531 } 532} 533 534bool PrintfSpecifier::hasValidAlternativeForm() const { 535 if (!HasAlternativeForm) 536 return true; 537 538 // Alternate form flag only valid with the oxXaAeEfFgG conversions 539 switch (CS.getKind()) { 540 case ConversionSpecifier::oArg: 541 case ConversionSpecifier::xArg: 542 case ConversionSpecifier::XArg: 543 case ConversionSpecifier::aArg: 544 case ConversionSpecifier::AArg: 545 case ConversionSpecifier::eArg: 546 case ConversionSpecifier::EArg: 547 case ConversionSpecifier::fArg: 548 case ConversionSpecifier::FArg: 549 case ConversionSpecifier::gArg: 550 case ConversionSpecifier::GArg: 551 return true; 552 553 default: 554 return false; 555 } 556} 557 558bool PrintfSpecifier::hasValidLeadingZeros() const { 559 if (!HasLeadingZeroes) 560 return true; 561 562 // Leading zeroes flag only valid with the diouxXaAeEfFgG conversions 563 switch (CS.getKind()) { 564 case ConversionSpecifier::dArg: 565 case ConversionSpecifier::iArg: 566 case ConversionSpecifier::oArg: 567 case ConversionSpecifier::uArg: 568 case ConversionSpecifier::xArg: 569 case ConversionSpecifier::XArg: 570 case ConversionSpecifier::aArg: 571 case ConversionSpecifier::AArg: 572 case ConversionSpecifier::eArg: 573 case ConversionSpecifier::EArg: 574 case ConversionSpecifier::fArg: 575 case ConversionSpecifier::FArg: 576 case ConversionSpecifier::gArg: 577 case ConversionSpecifier::GArg: 578 return true; 579 580 default: 581 return false; 582 } 583} 584 585bool PrintfSpecifier::hasValidSpacePrefix() const { 586 if (!HasSpacePrefix) 587 return true; 588 589 // The space prefix only makes sense for signed conversions 590 switch (CS.getKind()) { 591 case ConversionSpecifier::dArg: 592 case ConversionSpecifier::iArg: 593 case ConversionSpecifier::fArg: 594 case ConversionSpecifier::FArg: 595 case ConversionSpecifier::eArg: 596 case ConversionSpecifier::EArg: 597 case ConversionSpecifier::gArg: 598 case ConversionSpecifier::GArg: 599 case ConversionSpecifier::aArg: 600 case ConversionSpecifier::AArg: 601 return true; 602 603 default: 604 return false; 605 } 606} 607 608bool PrintfSpecifier::hasValidLeftJustified() const { 609 if (!IsLeftJustified) 610 return true; 611 612 // The left justified flag is valid for all conversions except n 613 switch (CS.getKind()) { 614 case ConversionSpecifier::nArg: 615 return false; 616 617 default: 618 return true; 619 } 620} 621 622bool PrintfSpecifier::hasValidThousandsGroupingPrefix() const { 623 if (!HasThousandsGrouping) 624 return true; 625 626 switch (CS.getKind()) { 627 case ConversionSpecifier::dArg: 628 case ConversionSpecifier::iArg: 629 case ConversionSpecifier::uArg: 630 case ConversionSpecifier::fArg: 631 case ConversionSpecifier::FArg: 632 case ConversionSpecifier::gArg: 633 case ConversionSpecifier::GArg: 634 return true; 635 default: 636 return false; 637 } 638} 639 640bool PrintfSpecifier::hasValidPrecision() const { 641 if (Precision.getHowSpecified() == OptionalAmount::NotSpecified) 642 return true; 643 644 // Precision is only valid with the diouxXaAeEfFgGs conversions 645 switch (CS.getKind()) { 646 case ConversionSpecifier::dArg: 647 case ConversionSpecifier::iArg: 648 case ConversionSpecifier::oArg: 649 case ConversionSpecifier::uArg: 650 case ConversionSpecifier::xArg: 651 case ConversionSpecifier::XArg: 652 case ConversionSpecifier::aArg: 653 case ConversionSpecifier::AArg: 654 case ConversionSpecifier::eArg: 655 case ConversionSpecifier::EArg: 656 case ConversionSpecifier::fArg: 657 case ConversionSpecifier::FArg: 658 case ConversionSpecifier::gArg: 659 case ConversionSpecifier::GArg: 660 case ConversionSpecifier::sArg: 661 return true; 662 663 default: 664 return false; 665 } 666} 667bool PrintfSpecifier::hasValidFieldWidth() const { 668 if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified) 669 return true; 670 671 // The field width is valid for all conversions except n 672 switch (CS.getKind()) { 673 case ConversionSpecifier::nArg: 674 return false; 675 676 default: 677 return true; 678 } 679} 680