PrintfFormatString.cpp revision 7966297a70996977f167a8676568f02f4283bdd6
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 '-': FS.setIsLeftJustified(I); break; 104 case '+': FS.setHasPlusPrefix(I); break; 105 case ' ': FS.setHasSpacePrefix(I); break; 106 case '#': FS.setHasAlternativeForm(I); break; 107 case '0': FS.setHasLeadingZeros(I); break; 108 } 109 if (!hasMore) 110 break; 111 } 112 113 if (I == E) { 114 // No more characters left? 115 H.HandleIncompleteSpecifier(Start, E - Start); 116 return true; 117 } 118 119 // Look for the field width (if any). 120 if (ParseFieldWidth(H, FS, Start, I, E, 121 FS.usesPositionalArg() ? 0 : &argIndex)) 122 return true; 123 124 if (I == E) { 125 // No more characters left? 126 H.HandleIncompleteSpecifier(Start, E - Start); 127 return true; 128 } 129 130 // Look for the precision (if any). 131 if (*I == '.') { 132 ++I; 133 if (I == E) { 134 H.HandleIncompleteSpecifier(Start, E - Start); 135 return true; 136 } 137 138 if (ParsePrecision(H, FS, Start, I, E, 139 FS.usesPositionalArg() ? 0 : &argIndex)) 140 return true; 141 142 if (I == E) { 143 // No more characters left? 144 H.HandleIncompleteSpecifier(Start, E - Start); 145 return true; 146 } 147 } 148 149 // Look for the length modifier. 150 if (ParseLengthModifier(FS, I, E) && I == E) { 151 // No more characters left? 152 H.HandleIncompleteSpecifier(Start, E - Start); 153 return true; 154 } 155 156 if (*I == '\0') { 157 // Detect spurious null characters, which are likely errors. 158 H.HandleNullChar(I); 159 return true; 160 } 161 162 // Finally, look for the conversion specifier. 163 const char *conversionPosition = I++; 164 ConversionSpecifier::Kind k = ConversionSpecifier::InvalidSpecifier; 165 switch (*conversionPosition) { 166 default: 167 break; 168 // C99: 7.19.6.1 (section 8). 169 case '%': k = ConversionSpecifier::PercentArg; break; 170 case 'A': k = ConversionSpecifier::AArg; break; 171 case 'E': k = ConversionSpecifier::EArg; break; 172 case 'F': k = ConversionSpecifier::FArg; break; 173 case 'G': k = ConversionSpecifier::GArg; break; 174 case 'X': k = ConversionSpecifier::XArg; break; 175 case 'a': k = ConversionSpecifier::aArg; break; 176 case 'c': k = ConversionSpecifier::cArg; break; 177 case 'd': k = ConversionSpecifier::dArg; break; 178 case 'e': k = ConversionSpecifier::eArg; break; 179 case 'f': k = ConversionSpecifier::fArg; break; 180 case 'g': k = ConversionSpecifier::gArg; break; 181 case 'i': k = ConversionSpecifier::iArg; break; 182 case 'n': k = ConversionSpecifier::nArg; break; 183 case 'o': k = ConversionSpecifier::oArg; break; 184 case 'p': k = ConversionSpecifier::pArg; break; 185 case 's': k = ConversionSpecifier::sArg; break; 186 case 'u': k = ConversionSpecifier::uArg; break; 187 case 'x': k = ConversionSpecifier::xArg; break; 188 // Mac OS X (unicode) specific 189 case 'C': k = ConversionSpecifier::CArg; break; 190 case 'S': k = ConversionSpecifier::SArg; break; 191 // Objective-C. 192 case '@': k = ConversionSpecifier::ObjCObjArg; break; 193 // Glibc specific. 194 case 'm': k = ConversionSpecifier::PrintErrno; break; 195 } 196 PrintfConversionSpecifier CS(conversionPosition, k); 197 FS.setConversionSpecifier(CS); 198 if (CS.consumesDataArgument() && !FS.usesPositionalArg()) 199 FS.setArgIndex(argIndex++); 200 201 if (k == ConversionSpecifier::InvalidSpecifier) { 202 // Assume the conversion takes one argument. 203 return !H.HandleInvalidPrintfConversionSpecifier(FS, Start, I - Start); 204 } 205 return PrintfSpecifierResult(Start, FS); 206} 207 208bool clang::analyze_format_string::ParsePrintfString(FormatStringHandler &H, 209 const char *I, 210 const char *E) { 211 212 unsigned argIndex = 0; 213 214 // Keep looking for a format specifier until we have exhausted the string. 215 while (I != E) { 216 const PrintfSpecifierResult &FSR = ParsePrintfSpecifier(H, I, E, argIndex); 217 // Did a fail-stop error of any kind occur when parsing the specifier? 218 // If so, don't do any more processing. 219 if (FSR.shouldStop()) 220 return true;; 221 // Did we exhaust the string or encounter an error that 222 // we can recover from? 223 if (!FSR.hasValue()) 224 continue; 225 // We have a format specifier. Pass it to the callback. 226 if (!H.HandlePrintfSpecifier(FSR.getValue(), FSR.getStart(), 227 I - FSR.getStart())) 228 return true; 229 } 230 assert(I == E && "Format string not exhausted"); 231 return false; 232} 233 234//===----------------------------------------------------------------------===// 235// Methods on ConversionSpecifier. 236//===----------------------------------------------------------------------===// 237const char *ConversionSpecifier::toString() const { 238 switch (kind) { 239 case dArg: return "d"; 240 case iArg: return "i"; 241 case oArg: return "o"; 242 case uArg: return "u"; 243 case xArg: return "x"; 244 case XArg: return "X"; 245 case fArg: return "f"; 246 case FArg: return "F"; 247 case eArg: return "e"; 248 case EArg: return "E"; 249 case gArg: return "g"; 250 case GArg: return "G"; 251 case aArg: return "a"; 252 case AArg: return "A"; 253 case cArg: return "c"; 254 case sArg: return "s"; 255 case pArg: return "p"; 256 case nArg: return "n"; 257 case PercentArg: return "%"; 258 case ScanListArg: return "["; 259 case InvalidSpecifier: return NULL; 260 261 // MacOS X unicode extensions. 262 case CArg: return "C"; 263 case SArg: return "S"; 264 265 // Objective-C specific specifiers. 266 case ObjCObjArg: return "@"; 267 268 // GlibC specific specifiers. 269 case PrintErrno: return "m"; 270 } 271 return NULL; 272} 273 274//===----------------------------------------------------------------------===// 275// Methods on PrintfSpecifier. 276//===----------------------------------------------------------------------===// 277 278ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx) const { 279 const PrintfConversionSpecifier &CS = getConversionSpecifier(); 280 281 if (!CS.consumesDataArgument()) 282 return ArgTypeResult::Invalid(); 283 284 if (CS.getKind() == ConversionSpecifier::cArg) 285 switch (LM.getKind()) { 286 case LengthModifier::None: return Ctx.IntTy; 287 case LengthModifier::AsLong: return ArgTypeResult::WIntTy; 288 default: 289 return ArgTypeResult::Invalid(); 290 } 291 292 if (CS.isIntArg()) 293 switch (LM.getKind()) { 294 case LengthModifier::AsLongDouble: 295 return ArgTypeResult::Invalid(); 296 case LengthModifier::None: return Ctx.IntTy; 297 case LengthModifier::AsChar: return Ctx.SignedCharTy; 298 case LengthModifier::AsShort: return Ctx.ShortTy; 299 case LengthModifier::AsLong: return Ctx.LongTy; 300 case LengthModifier::AsLongLong: return Ctx.LongLongTy; 301 case LengthModifier::AsIntMax: 302 // FIXME: Return unknown for now. 303 return ArgTypeResult(); 304 case LengthModifier::AsSizeT: return Ctx.getSizeType(); 305 case LengthModifier::AsPtrDiff: return Ctx.getPointerDiffType(); 306 } 307 308 if (CS.isUIntArg()) 309 switch (LM.getKind()) { 310 case LengthModifier::AsLongDouble: 311 return ArgTypeResult::Invalid(); 312 case LengthModifier::None: return Ctx.UnsignedIntTy; 313 case LengthModifier::AsChar: return Ctx.UnsignedCharTy; 314 case LengthModifier::AsShort: return Ctx.UnsignedShortTy; 315 case LengthModifier::AsLong: return Ctx.UnsignedLongTy; 316 case LengthModifier::AsLongLong: return Ctx.UnsignedLongLongTy; 317 case LengthModifier::AsIntMax: 318 // FIXME: Return unknown for now. 319 return ArgTypeResult(); 320 case LengthModifier::AsSizeT: 321 // FIXME: How to get the corresponding unsigned 322 // version of size_t? 323 return ArgTypeResult(); 324 case LengthModifier::AsPtrDiff: 325 // FIXME: How to get the corresponding unsigned 326 // version of ptrdiff_t? 327 return ArgTypeResult(); 328 } 329 330 if (CS.isDoubleArg()) { 331 if (LM.getKind() == LengthModifier::AsLongDouble) 332 return Ctx.LongDoubleTy; 333 return Ctx.DoubleTy; 334 } 335 336 switch (CS.getKind()) { 337 case ConversionSpecifier::sArg: 338 return ArgTypeResult(LM.getKind() == LengthModifier::AsWideChar ? 339 ArgTypeResult::WCStrTy : ArgTypeResult::CStrTy); 340 case ConversionSpecifier::SArg: 341 // FIXME: This appears to be Mac OS X specific. 342 return ArgTypeResult::WCStrTy; 343 case ConversionSpecifier::CArg: 344 return Ctx.WCharTy; 345 case ConversionSpecifier::pArg: 346 return ArgTypeResult::CPointerTy; 347 default: 348 break; 349 } 350 351 // FIXME: Handle other cases. 352 return ArgTypeResult(); 353} 354 355bool PrintfSpecifier::fixType(QualType QT) { 356 // Handle strings first (char *, wchar_t *) 357 if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) { 358 CS.setKind(ConversionSpecifier::sArg); 359 360 // Disable irrelevant flags 361 HasAlternativeForm = 0; 362 HasLeadingZeroes = 0; 363 364 // Set the long length modifier for wide characters 365 if (QT->getPointeeType()->isWideCharType()) 366 LM.setKind(LengthModifier::AsWideChar); 367 368 return true; 369 } 370 371 // We can only work with builtin types. 372 if (!QT->isBuiltinType()) 373 return false; 374 375 // Everything else should be a base type 376 const BuiltinType *BT = QT->getAs<BuiltinType>(); 377 378 // Set length modifier 379 switch (BT->getKind()) { 380 default: 381 // The rest of the conversions are either optional or for non-builtin types 382 LM.setKind(LengthModifier::None); 383 break; 384 385 case BuiltinType::Char_U: 386 case BuiltinType::UChar: 387 case BuiltinType::Char_S: 388 case BuiltinType::SChar: 389 LM.setKind(LengthModifier::AsChar); 390 break; 391 392 case BuiltinType::Short: 393 case BuiltinType::UShort: 394 LM.setKind(LengthModifier::AsShort); 395 break; 396 397 case BuiltinType::WChar: 398 case BuiltinType::Long: 399 case BuiltinType::ULong: 400 LM.setKind(LengthModifier::AsLong); 401 break; 402 403 case BuiltinType::LongLong: 404 case BuiltinType::ULongLong: 405 LM.setKind(LengthModifier::AsLongLong); 406 break; 407 408 case BuiltinType::LongDouble: 409 LM.setKind(LengthModifier::AsLongDouble); 410 break; 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->isPointerType()) { 428 CS.setKind(ConversionSpecifier::pArg); 429 Precision.setHowSpecified(OptionalAmount::NotSpecified); 430 HasAlternativeForm = 0; 431 HasLeadingZeroes = 0; 432 HasPlusPrefix = 0; 433 } 434 else if (QT->isSignedIntegerType()) { 435 CS.setKind(ConversionSpecifier::dArg); 436 HasAlternativeForm = 0; 437 } 438 else if (QT->isUnsignedIntegerType()) { 439 CS.setKind(ConversionSpecifier::uArg); 440 HasAlternativeForm = 0; 441 HasPlusPrefix = 0; 442 } 443 else { 444 return false; 445 } 446 447 return true; 448} 449 450void PrintfSpecifier::toString(llvm::raw_ostream &os) const { 451 // Whilst some features have no defined order, we are using the order 452 // appearing in the C99 standard (ISO/IEC 9899:1999 (E) ¤7.19.6.1) 453 os << "%"; 454 455 // Positional args 456 if (usesPositionalArg()) { 457 os << getPositionalArgIndex() << "$"; 458 } 459 460 // Conversion flags 461 if (IsLeftJustified) os << "-"; 462 if (HasPlusPrefix) os << "+"; 463 if (HasSpacePrefix) os << " "; 464 if (HasAlternativeForm) os << "#"; 465 if (HasLeadingZeroes) os << "0"; 466 467 // Minimum field width 468 FieldWidth.toString(os); 469 // Precision 470 Precision.toString(os); 471 // Length modifier 472 os << LM.toString(); 473 // Conversion specifier 474 os << CS.toString(); 475} 476 477bool PrintfSpecifier::hasValidPlusPrefix() const { 478 if (!HasPlusPrefix) 479 return true; 480 481 // The plus prefix only makes sense for signed conversions 482 switch (CS.getKind()) { 483 case ConversionSpecifier::dArg: 484 case ConversionSpecifier::iArg: 485 case ConversionSpecifier::fArg: 486 case ConversionSpecifier::FArg: 487 case ConversionSpecifier::eArg: 488 case ConversionSpecifier::EArg: 489 case ConversionSpecifier::gArg: 490 case ConversionSpecifier::GArg: 491 case ConversionSpecifier::aArg: 492 case ConversionSpecifier::AArg: 493 return true; 494 495 default: 496 return false; 497 } 498} 499 500bool PrintfSpecifier::hasValidAlternativeForm() const { 501 if (!HasAlternativeForm) 502 return true; 503 504 // Alternate form flag only valid with the oxXaAeEfFgG conversions 505 switch (CS.getKind()) { 506 case ConversionSpecifier::oArg: 507 case ConversionSpecifier::xArg: 508 case ConversionSpecifier::XArg: 509 case ConversionSpecifier::aArg: 510 case ConversionSpecifier::AArg: 511 case ConversionSpecifier::eArg: 512 case ConversionSpecifier::EArg: 513 case ConversionSpecifier::fArg: 514 case ConversionSpecifier::FArg: 515 case ConversionSpecifier::gArg: 516 case ConversionSpecifier::GArg: 517 return true; 518 519 default: 520 return false; 521 } 522} 523 524bool PrintfSpecifier::hasValidLeadingZeros() const { 525 if (!HasLeadingZeroes) 526 return true; 527 528 // Leading zeroes flag only valid with the diouxXaAeEfFgG conversions 529 switch (CS.getKind()) { 530 case ConversionSpecifier::dArg: 531 case ConversionSpecifier::iArg: 532 case ConversionSpecifier::oArg: 533 case ConversionSpecifier::uArg: 534 case ConversionSpecifier::xArg: 535 case ConversionSpecifier::XArg: 536 case ConversionSpecifier::aArg: 537 case ConversionSpecifier::AArg: 538 case ConversionSpecifier::eArg: 539 case ConversionSpecifier::EArg: 540 case ConversionSpecifier::fArg: 541 case ConversionSpecifier::FArg: 542 case ConversionSpecifier::gArg: 543 case ConversionSpecifier::GArg: 544 return true; 545 546 default: 547 return false; 548 } 549} 550 551bool PrintfSpecifier::hasValidSpacePrefix() const { 552 if (!HasSpacePrefix) 553 return true; 554 555 // The space prefix only makes sense for signed conversions 556 switch (CS.getKind()) { 557 case ConversionSpecifier::dArg: 558 case ConversionSpecifier::iArg: 559 case ConversionSpecifier::fArg: 560 case ConversionSpecifier::FArg: 561 case ConversionSpecifier::eArg: 562 case ConversionSpecifier::EArg: 563 case ConversionSpecifier::gArg: 564 case ConversionSpecifier::GArg: 565 case ConversionSpecifier::aArg: 566 case ConversionSpecifier::AArg: 567 return true; 568 569 default: 570 return false; 571 } 572} 573 574bool PrintfSpecifier::hasValidLeftJustified() const { 575 if (!IsLeftJustified) 576 return true; 577 578 // The left justified flag is valid for all conversions except n 579 switch (CS.getKind()) { 580 case ConversionSpecifier::nArg: 581 return false; 582 583 default: 584 return true; 585 } 586} 587 588bool PrintfSpecifier::hasValidPrecision() const { 589 if (Precision.getHowSpecified() == OptionalAmount::NotSpecified) 590 return true; 591 592 // Precision is only valid with the diouxXaAeEfFgGs conversions 593 switch (CS.getKind()) { 594 case ConversionSpecifier::dArg: 595 case ConversionSpecifier::iArg: 596 case ConversionSpecifier::oArg: 597 case ConversionSpecifier::uArg: 598 case ConversionSpecifier::xArg: 599 case ConversionSpecifier::XArg: 600 case ConversionSpecifier::aArg: 601 case ConversionSpecifier::AArg: 602 case ConversionSpecifier::eArg: 603 case ConversionSpecifier::EArg: 604 case ConversionSpecifier::fArg: 605 case ConversionSpecifier::FArg: 606 case ConversionSpecifier::gArg: 607 case ConversionSpecifier::GArg: 608 case ConversionSpecifier::sArg: 609 return true; 610 611 default: 612 return false; 613 } 614} 615bool PrintfSpecifier::hasValidFieldWidth() const { 616 if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified) 617 return true; 618 619 // The field width is valid for all conversions except n 620 switch (CS.getKind()) { 621 case ConversionSpecifier::nArg: 622 return false; 623 624 default: 625 return true; 626 } 627} 628