PrintfFormatString.cpp revision b8ec3e35d2d7a56b21cb449d4a7bde8d9d12c2a5
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 PrintfSpecifier. 239//===----------------------------------------------------------------------===// 240 241ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx) const { 242 const PrintfConversionSpecifier &CS = getConversionSpecifier(); 243 244 if (!CS.consumesDataArgument()) 245 return ArgTypeResult::Invalid(); 246 247 if (CS.getKind() == ConversionSpecifier::cArg) 248 switch (LM.getKind()) { 249 case LengthModifier::None: return Ctx.IntTy; 250 case LengthModifier::AsLong: return ArgTypeResult::WIntTy; 251 default: 252 return ArgTypeResult::Invalid(); 253 } 254 255 if (CS.isIntArg()) 256 switch (LM.getKind()) { 257 case LengthModifier::AsLongDouble: 258 return ArgTypeResult::Invalid(); 259 case LengthModifier::None: return Ctx.IntTy; 260 case LengthModifier::AsChar: return ArgTypeResult::AnyCharTy; 261 case LengthModifier::AsShort: return Ctx.ShortTy; 262 case LengthModifier::AsLong: return Ctx.LongTy; 263 case LengthModifier::AsLongLong: return Ctx.LongLongTy; 264 case LengthModifier::AsIntMax: 265 return ArgTypeResult(Ctx.getIntMaxType(), "intmax_t"); 266 case LengthModifier::AsSizeT: 267 // FIXME: How to get the corresponding signed version of size_t? 268 return ArgTypeResult(); 269 case LengthModifier::AsPtrDiff: 270 return ArgTypeResult(Ctx.getPointerDiffType(), "ptrdiff_t"); 271 } 272 273 if (CS.isUIntArg()) 274 switch (LM.getKind()) { 275 case LengthModifier::AsLongDouble: 276 return ArgTypeResult::Invalid(); 277 case LengthModifier::None: return Ctx.UnsignedIntTy; 278 case LengthModifier::AsChar: return Ctx.UnsignedCharTy; 279 case LengthModifier::AsShort: return Ctx.UnsignedShortTy; 280 case LengthModifier::AsLong: return Ctx.UnsignedLongTy; 281 case LengthModifier::AsLongLong: return Ctx.UnsignedLongLongTy; 282 case LengthModifier::AsIntMax: 283 return ArgTypeResult(Ctx.getUIntMaxType(), "uintmax_t"); 284 case LengthModifier::AsSizeT: 285 return ArgTypeResult(Ctx.getSizeType(), "size_t"); 286 case LengthModifier::AsPtrDiff: 287 // FIXME: How to get the corresponding unsigned 288 // version of ptrdiff_t? 289 return ArgTypeResult(); 290 } 291 292 if (CS.isDoubleArg()) { 293 if (LM.getKind() == LengthModifier::AsLongDouble) 294 return Ctx.LongDoubleTy; 295 return Ctx.DoubleTy; 296 } 297 298 switch (CS.getKind()) { 299 case ConversionSpecifier::sArg: 300 return ArgTypeResult(LM.getKind() == LengthModifier::AsWideChar ? 301 ArgTypeResult::WCStrTy : ArgTypeResult::CStrTy); 302 case ConversionSpecifier::SArg: 303 // FIXME: This appears to be Mac OS X specific. 304 return ArgTypeResult::WCStrTy; 305 case ConversionSpecifier::CArg: 306 return Ctx.WCharTy; 307 case ConversionSpecifier::pArg: 308 return ArgTypeResult::CPointerTy; 309 default: 310 break; 311 } 312 313 // FIXME: Handle other cases. 314 return ArgTypeResult(); 315} 316 317bool PrintfSpecifier::fixType(QualType QT, const LangOptions &LangOpt) { 318 // Handle strings first (char *, wchar_t *) 319 if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) { 320 CS.setKind(ConversionSpecifier::sArg); 321 322 // Disable irrelevant flags 323 HasAlternativeForm = 0; 324 HasLeadingZeroes = 0; 325 326 // Set the long length modifier for wide characters 327 if (QT->getPointeeType()->isWideCharType()) 328 LM.setKind(LengthModifier::AsWideChar); 329 else 330 LM.setKind(LengthModifier::None); 331 332 return true; 333 } 334 335 // We can only work with builtin types. 336 const BuiltinType *BT = QT->getAs<BuiltinType>(); 337 if (!BT) 338 return false; 339 340 // Set length modifier 341 switch (BT->getKind()) { 342 case BuiltinType::Bool: 343 case BuiltinType::WChar_U: 344 case BuiltinType::WChar_S: 345 case BuiltinType::Char16: 346 case BuiltinType::Char32: 347 case BuiltinType::UInt128: 348 case BuiltinType::Int128: 349 case BuiltinType::Half: 350 // Various types which are non-trivial to correct. 351 return false; 352 353#define SIGNED_TYPE(Id, SingletonId) 354#define UNSIGNED_TYPE(Id, SingletonId) 355#define FLOATING_TYPE(Id, SingletonId) 356#define BUILTIN_TYPE(Id, SingletonId) \ 357 case BuiltinType::Id: 358#include "clang/AST/BuiltinTypes.def" 359 // Misc other stuff which doesn't make sense here. 360 return false; 361 362 case BuiltinType::UInt: 363 case BuiltinType::Int: 364 case BuiltinType::Float: 365 case BuiltinType::Double: 366 LM.setKind(LengthModifier::None); 367 break; 368 369 case BuiltinType::Char_U: 370 case BuiltinType::UChar: 371 case BuiltinType::Char_S: 372 case BuiltinType::SChar: 373 LM.setKind(LengthModifier::AsChar); 374 break; 375 376 case BuiltinType::Short: 377 case BuiltinType::UShort: 378 LM.setKind(LengthModifier::AsShort); 379 break; 380 381 case BuiltinType::Long: 382 case BuiltinType::ULong: 383 LM.setKind(LengthModifier::AsLong); 384 break; 385 386 case BuiltinType::LongLong: 387 case BuiltinType::ULongLong: 388 LM.setKind(LengthModifier::AsLongLong); 389 break; 390 391 case BuiltinType::LongDouble: 392 LM.setKind(LengthModifier::AsLongDouble); 393 break; 394 } 395 396 // Handle size_t, ptrdiff_t, etc. that have dedicated length modifiers in C99. 397 if (isa<TypedefType>(QT) && (LangOpt.C99 || LangOpt.CPlusPlus0x)) { 398 const IdentifierInfo *Identifier = QT.getBaseTypeIdentifier(); 399 if (Identifier->getName() == "size_t") { 400 LM.setKind(LengthModifier::AsSizeT); 401 } else if (Identifier->getName() == "ssize_t") { 402 // Not C99, but common in Unix. 403 LM.setKind(LengthModifier::AsSizeT); 404 } else if (Identifier->getName() == "intmax_t") { 405 LM.setKind(LengthModifier::AsIntMax); 406 } else if (Identifier->getName() == "uintmax_t") { 407 LM.setKind(LengthModifier::AsIntMax); 408 } else if (Identifier->getName() == "ptrdiff_t") { 409 LM.setKind(LengthModifier::AsPtrDiff); 410 } 411 } 412 413 // Set conversion specifier and disable any flags which do not apply to it. 414 // Let typedefs to char fall through to int, as %c is silly for uint8_t. 415 if (isa<TypedefType>(QT) && QT->isAnyCharacterType()) { 416 CS.setKind(ConversionSpecifier::cArg); 417 LM.setKind(LengthModifier::None); 418 Precision.setHowSpecified(OptionalAmount::NotSpecified); 419 HasAlternativeForm = 0; 420 HasLeadingZeroes = 0; 421 HasPlusPrefix = 0; 422 } 423 // Test for Floating type first as LongDouble can pass isUnsignedIntegerType 424 else if (QT->isRealFloatingType()) { 425 CS.setKind(ConversionSpecifier::fArg); 426 } 427 else if (QT->isSignedIntegerType()) { 428 CS.setKind(ConversionSpecifier::dArg); 429 HasAlternativeForm = 0; 430 } 431 else if (QT->isUnsignedIntegerType()) { 432 // Preserve the original formatting, e.g. 'X', 'o'. 433 if (!cast<PrintfConversionSpecifier>(CS).isUIntArg()) 434 CS.setKind(ConversionSpecifier::uArg); 435 HasAlternativeForm = 0; 436 HasPlusPrefix = 0; 437 } else { 438 llvm_unreachable("Unexpected type"); 439 } 440 441 return true; 442} 443 444void PrintfSpecifier::toString(raw_ostream &os) const { 445 // Whilst some features have no defined order, we are using the order 446 // appearing in the C99 standard (ISO/IEC 9899:1999 (E) 7.19.6.1) 447 os << "%"; 448 449 // Positional args 450 if (usesPositionalArg()) { 451 os << getPositionalArgIndex() << "$"; 452 } 453 454 // Conversion flags 455 if (IsLeftJustified) os << "-"; 456 if (HasPlusPrefix) os << "+"; 457 if (HasSpacePrefix) os << " "; 458 if (HasAlternativeForm) os << "#"; 459 if (HasLeadingZeroes) os << "0"; 460 461 // Minimum field width 462 FieldWidth.toString(os); 463 // Precision 464 Precision.toString(os); 465 // Length modifier 466 os << LM.toString(); 467 // Conversion specifier 468 os << CS.toString(); 469} 470 471bool PrintfSpecifier::hasValidPlusPrefix() const { 472 if (!HasPlusPrefix) 473 return true; 474 475 // The plus prefix only makes sense for signed conversions 476 switch (CS.getKind()) { 477 case ConversionSpecifier::dArg: 478 case ConversionSpecifier::iArg: 479 case ConversionSpecifier::fArg: 480 case ConversionSpecifier::FArg: 481 case ConversionSpecifier::eArg: 482 case ConversionSpecifier::EArg: 483 case ConversionSpecifier::gArg: 484 case ConversionSpecifier::GArg: 485 case ConversionSpecifier::aArg: 486 case ConversionSpecifier::AArg: 487 return true; 488 489 default: 490 return false; 491 } 492} 493 494bool PrintfSpecifier::hasValidAlternativeForm() const { 495 if (!HasAlternativeForm) 496 return true; 497 498 // Alternate form flag only valid with the oxXaAeEfFgG conversions 499 switch (CS.getKind()) { 500 case ConversionSpecifier::oArg: 501 case ConversionSpecifier::xArg: 502 case ConversionSpecifier::XArg: 503 case ConversionSpecifier::aArg: 504 case ConversionSpecifier::AArg: 505 case ConversionSpecifier::eArg: 506 case ConversionSpecifier::EArg: 507 case ConversionSpecifier::fArg: 508 case ConversionSpecifier::FArg: 509 case ConversionSpecifier::gArg: 510 case ConversionSpecifier::GArg: 511 return true; 512 513 default: 514 return false; 515 } 516} 517 518bool PrintfSpecifier::hasValidLeadingZeros() const { 519 if (!HasLeadingZeroes) 520 return true; 521 522 // Leading zeroes flag only valid with the diouxXaAeEfFgG conversions 523 switch (CS.getKind()) { 524 case ConversionSpecifier::dArg: 525 case ConversionSpecifier::iArg: 526 case ConversionSpecifier::oArg: 527 case ConversionSpecifier::uArg: 528 case ConversionSpecifier::xArg: 529 case ConversionSpecifier::XArg: 530 case ConversionSpecifier::aArg: 531 case ConversionSpecifier::AArg: 532 case ConversionSpecifier::eArg: 533 case ConversionSpecifier::EArg: 534 case ConversionSpecifier::fArg: 535 case ConversionSpecifier::FArg: 536 case ConversionSpecifier::gArg: 537 case ConversionSpecifier::GArg: 538 return true; 539 540 default: 541 return false; 542 } 543} 544 545bool PrintfSpecifier::hasValidSpacePrefix() const { 546 if (!HasSpacePrefix) 547 return true; 548 549 // The space prefix only makes sense for signed conversions 550 switch (CS.getKind()) { 551 case ConversionSpecifier::dArg: 552 case ConversionSpecifier::iArg: 553 case ConversionSpecifier::fArg: 554 case ConversionSpecifier::FArg: 555 case ConversionSpecifier::eArg: 556 case ConversionSpecifier::EArg: 557 case ConversionSpecifier::gArg: 558 case ConversionSpecifier::GArg: 559 case ConversionSpecifier::aArg: 560 case ConversionSpecifier::AArg: 561 return true; 562 563 default: 564 return false; 565 } 566} 567 568bool PrintfSpecifier::hasValidLeftJustified() const { 569 if (!IsLeftJustified) 570 return true; 571 572 // The left justified flag is valid for all conversions except n 573 switch (CS.getKind()) { 574 case ConversionSpecifier::nArg: 575 return false; 576 577 default: 578 return true; 579 } 580} 581 582bool PrintfSpecifier::hasValidThousandsGroupingPrefix() const { 583 if (!HasThousandsGrouping) 584 return true; 585 586 switch (CS.getKind()) { 587 case ConversionSpecifier::dArg: 588 case ConversionSpecifier::iArg: 589 case ConversionSpecifier::uArg: 590 case ConversionSpecifier::fArg: 591 case ConversionSpecifier::FArg: 592 case ConversionSpecifier::gArg: 593 case ConversionSpecifier::GArg: 594 return true; 595 default: 596 return false; 597 } 598} 599 600bool PrintfSpecifier::hasValidPrecision() const { 601 if (Precision.getHowSpecified() == OptionalAmount::NotSpecified) 602 return true; 603 604 // Precision is only valid with the diouxXaAeEfFgGs conversions 605 switch (CS.getKind()) { 606 case ConversionSpecifier::dArg: 607 case ConversionSpecifier::iArg: 608 case ConversionSpecifier::oArg: 609 case ConversionSpecifier::uArg: 610 case ConversionSpecifier::xArg: 611 case ConversionSpecifier::XArg: 612 case ConversionSpecifier::aArg: 613 case ConversionSpecifier::AArg: 614 case ConversionSpecifier::eArg: 615 case ConversionSpecifier::EArg: 616 case ConversionSpecifier::fArg: 617 case ConversionSpecifier::FArg: 618 case ConversionSpecifier::gArg: 619 case ConversionSpecifier::GArg: 620 case ConversionSpecifier::sArg: 621 return true; 622 623 default: 624 return false; 625 } 626} 627bool PrintfSpecifier::hasValidFieldWidth() const { 628 if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified) 629 return true; 630 631 // The field width is valid for all conversions except n 632 switch (CS.getKind()) { 633 case ConversionSpecifier::nArg: 634 return false; 635 636 default: 637 return true; 638 } 639} 640