PrintfFormatString.cpp revision bd18d4584aae0ed6f7111ef5713784cf29fe663f
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 } 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 52static PrintfSpecifierResult ParsePrintfSpecifier(FormatStringHandler &H, 53 const char *&Beg, 54 const char *E, 55 unsigned &argIndex) { 56 57 using namespace clang::analyze_format_string; 58 using namespace clang::analyze_printf; 59 60 const char *I = Beg; 61 const char *Start = 0; 62 UpdateOnReturn <const char*> UpdateBeg(Beg, I); 63 64 // Look for a '%' character that indicates the start of a format specifier. 65 for ( ; I != E ; ++I) { 66 char c = *I; 67 if (c == '\0') { 68 // Detect spurious null characters, which are likely errors. 69 H.HandleNullChar(I); 70 return true; 71 } 72 if (c == '%') { 73 Start = I++; // Record the start of the format specifier. 74 break; 75 } 76 } 77 78 // No format specifier found? 79 if (!Start) 80 return false; 81 82 if (I == E) { 83 // No more characters left? 84 H.HandleIncompleteSpecifier(Start, E - Start); 85 return true; 86 } 87 88 PrintfSpecifier FS; 89 if (ParseArgPosition(H, FS, Start, I, E)) 90 return true; 91 92 if (I == E) { 93 // No more characters left? 94 H.HandleIncompleteSpecifier(Start, E - Start); 95 return true; 96 } 97 98 // Look for flags (if any). 99 bool hasMore = true; 100 for ( ; I != E; ++I) { 101 switch (*I) { 102 default: hasMore = false; break; 103 case '\'': 104 // FIXME: POSIX specific. Always accept? 105 FS.setHasThousandsGrouping(I); 106 break; 107 case '-': FS.setIsLeftJustified(I); break; 108 case '+': FS.setHasPlusPrefix(I); break; 109 case ' ': FS.setHasSpacePrefix(I); break; 110 case '#': FS.setHasAlternativeForm(I); break; 111 case '0': FS.setHasLeadingZeros(I); break; 112 } 113 if (!hasMore) 114 break; 115 } 116 117 if (I == E) { 118 // No more characters left? 119 H.HandleIncompleteSpecifier(Start, E - Start); 120 return true; 121 } 122 123 // Look for the field width (if any). 124 if (ParseFieldWidth(H, FS, Start, I, E, 125 FS.usesPositionalArg() ? 0 : &argIndex)) 126 return true; 127 128 if (I == E) { 129 // No more characters left? 130 H.HandleIncompleteSpecifier(Start, E - Start); 131 return true; 132 } 133 134 // Look for the precision (if any). 135 if (*I == '.') { 136 ++I; 137 if (I == E) { 138 H.HandleIncompleteSpecifier(Start, E - Start); 139 return true; 140 } 141 142 if (ParsePrecision(H, FS, Start, I, E, 143 FS.usesPositionalArg() ? 0 : &argIndex)) 144 return true; 145 146 if (I == E) { 147 // No more characters left? 148 H.HandleIncompleteSpecifier(Start, E - Start); 149 return true; 150 } 151 } 152 153 // Look for the length modifier. 154 if (ParseLengthModifier(FS, I, E) && I == E) { 155 // No more characters left? 156 H.HandleIncompleteSpecifier(Start, E - Start); 157 return true; 158 } 159 160 if (*I == '\0') { 161 // Detect spurious null characters, which are likely errors. 162 H.HandleNullChar(I); 163 return true; 164 } 165 166 // Finally, look for the conversion specifier. 167 const char *conversionPosition = I++; 168 ConversionSpecifier::Kind k = ConversionSpecifier::InvalidSpecifier; 169 switch (*conversionPosition) { 170 default: 171 break; 172 // C99: 7.19.6.1 (section 8). 173 case '%': k = ConversionSpecifier::PercentArg; break; 174 case 'A': k = ConversionSpecifier::AArg; break; 175 case 'E': k = ConversionSpecifier::EArg; break; 176 case 'F': k = ConversionSpecifier::FArg; break; 177 case 'G': k = ConversionSpecifier::GArg; break; 178 case 'X': k = ConversionSpecifier::XArg; break; 179 case 'a': k = ConversionSpecifier::aArg; break; 180 case 'c': k = ConversionSpecifier::cArg; break; 181 case 'd': k = ConversionSpecifier::dArg; break; 182 case 'e': k = ConversionSpecifier::eArg; break; 183 case 'f': k = ConversionSpecifier::fArg; break; 184 case 'g': k = ConversionSpecifier::gArg; break; 185 case 'i': k = ConversionSpecifier::iArg; break; 186 case 'n': k = ConversionSpecifier::nArg; break; 187 case 'o': k = ConversionSpecifier::oArg; break; 188 case 'p': k = ConversionSpecifier::pArg; break; 189 case 's': k = ConversionSpecifier::sArg; break; 190 case 'u': k = ConversionSpecifier::uArg; break; 191 case 'x': k = ConversionSpecifier::xArg; break; 192 // POSIX specific. 193 case 'C': k = ConversionSpecifier::CArg; break; 194 case 'S': k = ConversionSpecifier::SArg; break; 195 // Objective-C. 196 case '@': k = ConversionSpecifier::ObjCObjArg; break; 197 // Glibc specific. 198 case 'm': k = ConversionSpecifier::PrintErrno; break; 199 } 200 PrintfConversionSpecifier CS(conversionPosition, k); 201 FS.setConversionSpecifier(CS); 202 if (CS.consumesDataArgument() && !FS.usesPositionalArg()) 203 FS.setArgIndex(argIndex++); 204 205 if (k == ConversionSpecifier::InvalidSpecifier) { 206 // Assume the conversion takes one argument. 207 return !H.HandleInvalidPrintfConversionSpecifier(FS, Start, I - Start); 208 } 209 return PrintfSpecifierResult(Start, FS); 210} 211 212bool clang::analyze_format_string::ParsePrintfString(FormatStringHandler &H, 213 const char *I, 214 const char *E) { 215 216 unsigned argIndex = 0; 217 218 // Keep looking for a format specifier until we have exhausted the string. 219 while (I != E) { 220 const PrintfSpecifierResult &FSR = ParsePrintfSpecifier(H, I, E, argIndex); 221 // Did a fail-stop error of any kind occur when parsing the specifier? 222 // If so, don't do any more processing. 223 if (FSR.shouldStop()) 224 return true;; 225 // Did we exhaust the string or encounter an error that 226 // we can recover from? 227 if (!FSR.hasValue()) 228 continue; 229 // We have a format specifier. Pass it to the callback. 230 if (!H.HandlePrintfSpecifier(FSR.getValue(), FSR.getStart(), 231 I - FSR.getStart())) 232 return true; 233 } 234 assert(I == E && "Format string not exhausted"); 235 return false; 236} 237 238//===----------------------------------------------------------------------===// 239// Methods on ConversionSpecifier. 240//===----------------------------------------------------------------------===// 241const char *ConversionSpecifier::toString() const { 242 switch (kind) { 243 case dArg: return "d"; 244 case iArg: return "i"; 245 case oArg: return "o"; 246 case uArg: return "u"; 247 case xArg: return "x"; 248 case XArg: return "X"; 249 case fArg: return "f"; 250 case FArg: return "F"; 251 case eArg: return "e"; 252 case EArg: return "E"; 253 case gArg: return "g"; 254 case GArg: return "G"; 255 case aArg: return "a"; 256 case AArg: return "A"; 257 case cArg: return "c"; 258 case sArg: return "s"; 259 case pArg: return "p"; 260 case nArg: return "n"; 261 case PercentArg: return "%"; 262 case ScanListArg: return "["; 263 case InvalidSpecifier: return NULL; 264 265 // MacOS X unicode extensions. 266 case CArg: return "C"; 267 case SArg: return "S"; 268 269 // Objective-C specific specifiers. 270 case ObjCObjArg: return "@"; 271 272 // GlibC specific specifiers. 273 case PrintErrno: return "m"; 274 } 275 return NULL; 276} 277 278//===----------------------------------------------------------------------===// 279// Methods on PrintfSpecifier. 280//===----------------------------------------------------------------------===// 281 282ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx) const { 283 const PrintfConversionSpecifier &CS = getConversionSpecifier(); 284 285 if (!CS.consumesDataArgument()) 286 return ArgTypeResult::Invalid(); 287 288 if (CS.getKind() == ConversionSpecifier::cArg) 289 switch (LM.getKind()) { 290 case LengthModifier::None: return Ctx.IntTy; 291 case LengthModifier::AsLong: return ArgTypeResult::WIntTy; 292 default: 293 return ArgTypeResult::Invalid(); 294 } 295 296 if (CS.isIntArg()) 297 switch (LM.getKind()) { 298 case LengthModifier::AsLongDouble: 299 return ArgTypeResult::Invalid(); 300 case LengthModifier::None: return Ctx.IntTy; 301 case LengthModifier::AsChar: return Ctx.SignedCharTy; 302 case LengthModifier::AsShort: return Ctx.ShortTy; 303 case LengthModifier::AsLong: return Ctx.LongTy; 304 case LengthModifier::AsLongLong: return Ctx.LongLongTy; 305 case LengthModifier::AsIntMax: 306 // FIXME: Return unknown for now. 307 return ArgTypeResult(); 308 case LengthModifier::AsSizeT: return Ctx.getSizeType(); 309 case LengthModifier::AsPtrDiff: return Ctx.getPointerDiffType(); 310 } 311 312 if (CS.isUIntArg()) 313 switch (LM.getKind()) { 314 case LengthModifier::AsLongDouble: 315 return ArgTypeResult::Invalid(); 316 case LengthModifier::None: return Ctx.UnsignedIntTy; 317 case LengthModifier::AsChar: return Ctx.UnsignedCharTy; 318 case LengthModifier::AsShort: return Ctx.UnsignedShortTy; 319 case LengthModifier::AsLong: return Ctx.UnsignedLongTy; 320 case LengthModifier::AsLongLong: return Ctx.UnsignedLongLongTy; 321 case LengthModifier::AsIntMax: 322 // FIXME: Return unknown for now. 323 return ArgTypeResult(); 324 case LengthModifier::AsSizeT: 325 // FIXME: How to get the corresponding unsigned 326 // version of size_t? 327 return ArgTypeResult(); 328 case LengthModifier::AsPtrDiff: 329 // FIXME: How to get the corresponding unsigned 330 // version of ptrdiff_t? 331 return ArgTypeResult(); 332 } 333 334 if (CS.isDoubleArg()) { 335 if (LM.getKind() == LengthModifier::AsLongDouble) 336 return Ctx.LongDoubleTy; 337 return Ctx.DoubleTy; 338 } 339 340 switch (CS.getKind()) { 341 case ConversionSpecifier::sArg: 342 return ArgTypeResult(LM.getKind() == LengthModifier::AsWideChar ? 343 ArgTypeResult::WCStrTy : ArgTypeResult::CStrTy); 344 case ConversionSpecifier::SArg: 345 // FIXME: This appears to be Mac OS X specific. 346 return ArgTypeResult::WCStrTy; 347 case ConversionSpecifier::CArg: 348 return Ctx.WCharTy; 349 case ConversionSpecifier::pArg: 350 return ArgTypeResult::CPointerTy; 351 default: 352 break; 353 } 354 355 // FIXME: Handle other cases. 356 return ArgTypeResult(); 357} 358 359bool PrintfSpecifier::fixType(QualType QT) { 360 // Handle strings first (char *, wchar_t *) 361 if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) { 362 CS.setKind(ConversionSpecifier::sArg); 363 364 // Disable irrelevant flags 365 HasAlternativeForm = 0; 366 HasLeadingZeroes = 0; 367 368 // Set the long length modifier for wide characters 369 if (QT->getPointeeType()->isWideCharType()) 370 LM.setKind(LengthModifier::AsWideChar); 371 372 return true; 373 } 374 375 // We can only work with builtin types. 376 if (!QT->isBuiltinType()) 377 return false; 378 379 // Everything else should be a base type 380 const BuiltinType *BT = QT->getAs<BuiltinType>(); 381 382 // Set length modifier 383 switch (BT->getKind()) { 384 default: 385 // The rest of the conversions are either optional or for non-builtin types 386 LM.setKind(LengthModifier::None); 387 break; 388 389 case BuiltinType::Char_U: 390 case BuiltinType::UChar: 391 case BuiltinType::Char_S: 392 case BuiltinType::SChar: 393 LM.setKind(LengthModifier::AsChar); 394 break; 395 396 case BuiltinType::Short: 397 case BuiltinType::UShort: 398 LM.setKind(LengthModifier::AsShort); 399 break; 400 401 case BuiltinType::WChar_S: 402 case BuiltinType::WChar_U: 403 case BuiltinType::Long: 404 case BuiltinType::ULong: 405 LM.setKind(LengthModifier::AsLong); 406 break; 407 408 case BuiltinType::LongLong: 409 case BuiltinType::ULongLong: 410 LM.setKind(LengthModifier::AsLongLong); 411 break; 412 413 case BuiltinType::LongDouble: 414 LM.setKind(LengthModifier::AsLongDouble); 415 break; 416 } 417 418 // Set conversion specifier and disable any flags which do not apply to it. 419 // Let typedefs to char fall through to int, as %c is silly for uint8_t. 420 if (isa<TypedefType>(QT) && QT->isAnyCharacterType()) { 421 CS.setKind(ConversionSpecifier::cArg); 422 LM.setKind(LengthModifier::None); 423 Precision.setHowSpecified(OptionalAmount::NotSpecified); 424 HasAlternativeForm = 0; 425 HasLeadingZeroes = 0; 426 HasPlusPrefix = 0; 427 } 428 // Test for Floating type first as LongDouble can pass isUnsignedIntegerType 429 else if (QT->isRealFloatingType()) { 430 CS.setKind(ConversionSpecifier::fArg); 431 } 432 else if (QT->isPointerType()) { 433 CS.setKind(ConversionSpecifier::pArg); 434 Precision.setHowSpecified(OptionalAmount::NotSpecified); 435 HasAlternativeForm = 0; 436 HasLeadingZeroes = 0; 437 HasPlusPrefix = 0; 438 } 439 else if (QT->isSignedIntegerType()) { 440 CS.setKind(ConversionSpecifier::dArg); 441 HasAlternativeForm = 0; 442 } 443 else if (QT->isUnsignedIntegerType()) { 444 CS.setKind(ConversionSpecifier::uArg); 445 HasAlternativeForm = 0; 446 HasPlusPrefix = 0; 447 } 448 else { 449 return false; 450 } 451 452 return true; 453} 454 455void PrintfSpecifier::toString(llvm::raw_ostream &os) const { 456 // Whilst some features have no defined order, we are using the order 457 // appearing in the C99 standard (ISO/IEC 9899:1999 (E) ¤7.19.6.1) 458 os << "%"; 459 460 // Positional args 461 if (usesPositionalArg()) { 462 os << getPositionalArgIndex() << "$"; 463 } 464 465 // Conversion flags 466 if (IsLeftJustified) os << "-"; 467 if (HasPlusPrefix) os << "+"; 468 if (HasSpacePrefix) os << " "; 469 if (HasAlternativeForm) os << "#"; 470 if (HasLeadingZeroes) os << "0"; 471 472 // Minimum field width 473 FieldWidth.toString(os); 474 // Precision 475 Precision.toString(os); 476 // Length modifier 477 os << LM.toString(); 478 // Conversion specifier 479 os << CS.toString(); 480} 481 482bool PrintfSpecifier::hasValidPlusPrefix() const { 483 if (!HasPlusPrefix) 484 return true; 485 486 // The plus prefix only makes sense for signed conversions 487 switch (CS.getKind()) { 488 case ConversionSpecifier::dArg: 489 case ConversionSpecifier::iArg: 490 case ConversionSpecifier::fArg: 491 case ConversionSpecifier::FArg: 492 case ConversionSpecifier::eArg: 493 case ConversionSpecifier::EArg: 494 case ConversionSpecifier::gArg: 495 case ConversionSpecifier::GArg: 496 case ConversionSpecifier::aArg: 497 case ConversionSpecifier::AArg: 498 return true; 499 500 default: 501 return false; 502 } 503} 504 505bool PrintfSpecifier::hasValidAlternativeForm() const { 506 if (!HasAlternativeForm) 507 return true; 508 509 // Alternate form flag only valid with the oxXaAeEfFgG conversions 510 switch (CS.getKind()) { 511 case ConversionSpecifier::oArg: 512 case ConversionSpecifier::xArg: 513 case ConversionSpecifier::XArg: 514 case ConversionSpecifier::aArg: 515 case ConversionSpecifier::AArg: 516 case ConversionSpecifier::eArg: 517 case ConversionSpecifier::EArg: 518 case ConversionSpecifier::fArg: 519 case ConversionSpecifier::FArg: 520 case ConversionSpecifier::gArg: 521 case ConversionSpecifier::GArg: 522 return true; 523 524 default: 525 return false; 526 } 527} 528 529bool PrintfSpecifier::hasValidLeadingZeros() const { 530 if (!HasLeadingZeroes) 531 return true; 532 533 // Leading zeroes flag only valid with the diouxXaAeEfFgG conversions 534 switch (CS.getKind()) { 535 case ConversionSpecifier::dArg: 536 case ConversionSpecifier::iArg: 537 case ConversionSpecifier::oArg: 538 case ConversionSpecifier::uArg: 539 case ConversionSpecifier::xArg: 540 case ConversionSpecifier::XArg: 541 case ConversionSpecifier::aArg: 542 case ConversionSpecifier::AArg: 543 case ConversionSpecifier::eArg: 544 case ConversionSpecifier::EArg: 545 case ConversionSpecifier::fArg: 546 case ConversionSpecifier::FArg: 547 case ConversionSpecifier::gArg: 548 case ConversionSpecifier::GArg: 549 return true; 550 551 default: 552 return false; 553 } 554} 555 556bool PrintfSpecifier::hasValidSpacePrefix() const { 557 if (!HasSpacePrefix) 558 return true; 559 560 // The space prefix only makes sense for signed conversions 561 switch (CS.getKind()) { 562 case ConversionSpecifier::dArg: 563 case ConversionSpecifier::iArg: 564 case ConversionSpecifier::fArg: 565 case ConversionSpecifier::FArg: 566 case ConversionSpecifier::eArg: 567 case ConversionSpecifier::EArg: 568 case ConversionSpecifier::gArg: 569 case ConversionSpecifier::GArg: 570 case ConversionSpecifier::aArg: 571 case ConversionSpecifier::AArg: 572 return true; 573 574 default: 575 return false; 576 } 577} 578 579bool PrintfSpecifier::hasValidLeftJustified() const { 580 if (!IsLeftJustified) 581 return true; 582 583 // The left justified flag is valid for all conversions except n 584 switch (CS.getKind()) { 585 case ConversionSpecifier::nArg: 586 return false; 587 588 default: 589 return true; 590 } 591} 592 593bool PrintfSpecifier::hasValidPrecision() const { 594 if (Precision.getHowSpecified() == OptionalAmount::NotSpecified) 595 return true; 596 597 // Precision is only valid with the diouxXaAeEfFgGs conversions 598 switch (CS.getKind()) { 599 case ConversionSpecifier::dArg: 600 case ConversionSpecifier::iArg: 601 case ConversionSpecifier::oArg: 602 case ConversionSpecifier::uArg: 603 case ConversionSpecifier::xArg: 604 case ConversionSpecifier::XArg: 605 case ConversionSpecifier::aArg: 606 case ConversionSpecifier::AArg: 607 case ConversionSpecifier::eArg: 608 case ConversionSpecifier::EArg: 609 case ConversionSpecifier::fArg: 610 case ConversionSpecifier::FArg: 611 case ConversionSpecifier::gArg: 612 case ConversionSpecifier::GArg: 613 case ConversionSpecifier::sArg: 614 return true; 615 616 default: 617 return false; 618 } 619} 620bool PrintfSpecifier::hasValidFieldWidth() const { 621 if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified) 622 return true; 623 624 // The field width is valid for all conversions except n 625 switch (CS.getKind()) { 626 case ConversionSpecifier::nArg: 627 return false; 628 629 default: 630 return true; 631 } 632} 633