PrintfFormatString.cpp revision 6ecb950c65329f8d6ce9ad0514632df35a5ab61f
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, Beg, I - Beg); 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 InvalidSpecifier: return NULL; 259 260 // MacOS X unicode extensions. 261 case CArg: return "C"; 262 case SArg: return "S"; 263 264 // Objective-C specific specifiers. 265 case ObjCObjArg: return "@"; 266 267 // GlibC specific specifiers. 268 case PrintErrno: return "m"; 269 } 270 return NULL; 271} 272 273//===----------------------------------------------------------------------===// 274// Methods on PrintfSpecifier. 275//===----------------------------------------------------------------------===// 276 277ArgTypeResult PrintfSpecifier::getArgType(ASTContext &Ctx) const { 278 const PrintfConversionSpecifier &CS = getConversionSpecifier(); 279 280 if (!CS.consumesDataArgument()) 281 return ArgTypeResult::Invalid(); 282 283 if (CS.isIntArg()) 284 switch (LM.getKind()) { 285 case LengthModifier::AsLongDouble: 286 return ArgTypeResult::Invalid(); 287 case LengthModifier::None: return Ctx.IntTy; 288 case LengthModifier::AsChar: return Ctx.SignedCharTy; 289 case LengthModifier::AsShort: return Ctx.ShortTy; 290 case LengthModifier::AsLong: return Ctx.LongTy; 291 case LengthModifier::AsLongLong: return Ctx.LongLongTy; 292 case LengthModifier::AsIntMax: 293 // FIXME: Return unknown for now. 294 return ArgTypeResult(); 295 case LengthModifier::AsSizeT: return Ctx.getSizeType(); 296 case LengthModifier::AsPtrDiff: return Ctx.getPointerDiffType(); 297 } 298 299 if (CS.isUIntArg()) 300 switch (LM.getKind()) { 301 case LengthModifier::AsLongDouble: 302 return ArgTypeResult::Invalid(); 303 case LengthModifier::None: return Ctx.UnsignedIntTy; 304 case LengthModifier::AsChar: return Ctx.UnsignedCharTy; 305 case LengthModifier::AsShort: return Ctx.UnsignedShortTy; 306 case LengthModifier::AsLong: return Ctx.UnsignedLongTy; 307 case LengthModifier::AsLongLong: return Ctx.UnsignedLongLongTy; 308 case LengthModifier::AsIntMax: 309 // FIXME: Return unknown for now. 310 return ArgTypeResult(); 311 case LengthModifier::AsSizeT: 312 // FIXME: How to get the corresponding unsigned 313 // version of size_t? 314 return ArgTypeResult(); 315 case LengthModifier::AsPtrDiff: 316 // FIXME: How to get the corresponding unsigned 317 // version of ptrdiff_t? 318 return ArgTypeResult(); 319 } 320 321 if (CS.isDoubleArg()) { 322 if (LM.getKind() == LengthModifier::AsLongDouble) 323 return Ctx.LongDoubleTy; 324 return Ctx.DoubleTy; 325 } 326 327 switch (CS.getKind()) { 328 case ConversionSpecifier::sArg: 329 return ArgTypeResult(LM.getKind() == LengthModifier::AsWideChar ? 330 ArgTypeResult::WCStrTy : ArgTypeResult::CStrTy); 331 case ConversionSpecifier::SArg: 332 // FIXME: This appears to be Mac OS X specific. 333 return ArgTypeResult::WCStrTy; 334 case ConversionSpecifier::CArg: 335 return Ctx.WCharTy; 336 case ConversionSpecifier::pArg: 337 return ArgTypeResult::CPointerTy; 338 default: 339 break; 340 } 341 342 // FIXME: Handle other cases. 343 return ArgTypeResult(); 344} 345 346bool PrintfSpecifier::fixType(QualType QT) { 347 // Handle strings first (char *, wchar_t *) 348 if (QT->isPointerType() && (QT->getPointeeType()->isAnyCharacterType())) { 349 CS.setKind(ConversionSpecifier::sArg); 350 351 // Disable irrelevant flags 352 HasAlternativeForm = 0; 353 HasLeadingZeroes = 0; 354 355 // Set the long length modifier for wide characters 356 if (QT->getPointeeType()->isWideCharType()) 357 LM.setKind(LengthModifier::AsWideChar); 358 359 return true; 360 } 361 362 // We can only work with builtin types. 363 if (!QT->isBuiltinType()) 364 return false; 365 366 // Everything else should be a base type 367 const BuiltinType *BT = QT->getAs<BuiltinType>(); 368 369 // Set length modifier 370 switch (BT->getKind()) { 371 default: 372 // The rest of the conversions are either optional or for non-builtin types 373 LM.setKind(LengthModifier::None); 374 break; 375 376 case BuiltinType::WChar: 377 case BuiltinType::Long: 378 case BuiltinType::ULong: 379 LM.setKind(LengthModifier::AsLong); 380 break; 381 382 case BuiltinType::LongLong: 383 case BuiltinType::ULongLong: 384 LM.setKind(LengthModifier::AsLongLong); 385 break; 386 387 case BuiltinType::LongDouble: 388 LM.setKind(LengthModifier::AsLongDouble); 389 break; 390 } 391 392 // Set conversion specifier and disable any flags which do not apply to it. 393 if (QT->isAnyCharacterType()) { 394 CS.setKind(ConversionSpecifier::cArg); 395 Precision.setHowSpecified(OptionalAmount::NotSpecified); 396 HasAlternativeForm = 0; 397 HasLeadingZeroes = 0; 398 HasPlusPrefix = 0; 399 } 400 // Test for Floating type first as LongDouble can pass isUnsignedIntegerType 401 else if (QT->isRealFloatingType()) { 402 CS.setKind(ConversionSpecifier::fArg); 403 } 404 else if (QT->isPointerType()) { 405 CS.setKind(ConversionSpecifier::pArg); 406 Precision.setHowSpecified(OptionalAmount::NotSpecified); 407 HasAlternativeForm = 0; 408 HasLeadingZeroes = 0; 409 HasPlusPrefix = 0; 410 } 411 else if (QT->isSignedIntegerType()) { 412 CS.setKind(ConversionSpecifier::dArg); 413 HasAlternativeForm = 0; 414 } 415 else if (QT->isUnsignedIntegerType()) { 416 CS.setKind(ConversionSpecifier::uArg); 417 HasAlternativeForm = 0; 418 HasPlusPrefix = 0; 419 } 420 else { 421 return false; 422 } 423 424 return true; 425} 426 427void PrintfSpecifier::toString(llvm::raw_ostream &os) const { 428 // Whilst some features have no defined order, we are using the order 429 // appearing in the C99 standard (ISO/IEC 9899:1999 (E) ¤7.19.6.1) 430 os << "%"; 431 432 // Positional args 433 if (usesPositionalArg()) { 434 os << getPositionalArgIndex() << "$"; 435 } 436 437 // Conversion flags 438 if (IsLeftJustified) os << "-"; 439 if (HasPlusPrefix) os << "+"; 440 if (HasSpacePrefix) os << " "; 441 if (HasAlternativeForm) os << "#"; 442 if (HasLeadingZeroes) os << "0"; 443 444 // Minimum field width 445 FieldWidth.toString(os); 446 // Precision 447 Precision.toString(os); 448 // Length modifier 449 os << LM.toString(); 450 // Conversion specifier 451 os << CS.toString(); 452} 453 454bool PrintfSpecifier::hasValidPlusPrefix() const { 455 if (!HasPlusPrefix) 456 return true; 457 458 // The plus prefix only makes sense for signed conversions 459 switch (CS.getKind()) { 460 case ConversionSpecifier::dArg: 461 case ConversionSpecifier::iArg: 462 case ConversionSpecifier::fArg: 463 case ConversionSpecifier::FArg: 464 case ConversionSpecifier::eArg: 465 case ConversionSpecifier::EArg: 466 case ConversionSpecifier::gArg: 467 case ConversionSpecifier::GArg: 468 case ConversionSpecifier::aArg: 469 case ConversionSpecifier::AArg: 470 return true; 471 472 default: 473 return false; 474 } 475} 476 477bool PrintfSpecifier::hasValidAlternativeForm() const { 478 if (!HasAlternativeForm) 479 return true; 480 481 // Alternate form flag only valid with the oxaAeEfFgG conversions 482 switch (CS.getKind()) { 483 case ConversionSpecifier::oArg: 484 case ConversionSpecifier::xArg: 485 case ConversionSpecifier::aArg: 486 case ConversionSpecifier::AArg: 487 case ConversionSpecifier::eArg: 488 case ConversionSpecifier::EArg: 489 case ConversionSpecifier::fArg: 490 case ConversionSpecifier::FArg: 491 case ConversionSpecifier::gArg: 492 case ConversionSpecifier::GArg: 493 return true; 494 495 default: 496 return false; 497 } 498} 499 500bool PrintfSpecifier::hasValidLeadingZeros() const { 501 if (!HasLeadingZeroes) 502 return true; 503 504 // Leading zeroes flag only valid with the diouxXaAeEfFgG conversions 505 switch (CS.getKind()) { 506 case ConversionSpecifier::dArg: 507 case ConversionSpecifier::iArg: 508 case ConversionSpecifier::oArg: 509 case ConversionSpecifier::uArg: 510 case ConversionSpecifier::xArg: 511 case ConversionSpecifier::XArg: 512 case ConversionSpecifier::aArg: 513 case ConversionSpecifier::AArg: 514 case ConversionSpecifier::eArg: 515 case ConversionSpecifier::EArg: 516 case ConversionSpecifier::fArg: 517 case ConversionSpecifier::FArg: 518 case ConversionSpecifier::gArg: 519 case ConversionSpecifier::GArg: 520 return true; 521 522 default: 523 return false; 524 } 525} 526 527bool PrintfSpecifier::hasValidSpacePrefix() const { 528 if (!HasSpacePrefix) 529 return true; 530 531 // The space prefix only makes sense for signed conversions 532 switch (CS.getKind()) { 533 case ConversionSpecifier::dArg: 534 case ConversionSpecifier::iArg: 535 case ConversionSpecifier::fArg: 536 case ConversionSpecifier::FArg: 537 case ConversionSpecifier::eArg: 538 case ConversionSpecifier::EArg: 539 case ConversionSpecifier::gArg: 540 case ConversionSpecifier::GArg: 541 case ConversionSpecifier::aArg: 542 case ConversionSpecifier::AArg: 543 return true; 544 545 default: 546 return false; 547 } 548} 549 550bool PrintfSpecifier::hasValidLeftJustified() const { 551 if (!IsLeftJustified) 552 return true; 553 554 // The left justified flag is valid for all conversions except n 555 switch (CS.getKind()) { 556 case ConversionSpecifier::nArg: 557 return false; 558 559 default: 560 return true; 561 } 562} 563 564bool PrintfSpecifier::hasValidLengthModifier() const { 565 switch (LM.getKind()) { 566 case LengthModifier::None: 567 return true; 568 569 // Handle most integer flags 570 case LengthModifier::AsChar: 571 case LengthModifier::AsShort: 572 case LengthModifier::AsLongLong: 573 case LengthModifier::AsIntMax: 574 case LengthModifier::AsSizeT: 575 case LengthModifier::AsPtrDiff: 576 switch (CS.getKind()) { 577 case ConversionSpecifier::dArg: 578 case ConversionSpecifier::iArg: 579 case ConversionSpecifier::oArg: 580 case ConversionSpecifier::uArg: 581 case ConversionSpecifier::xArg: 582 case ConversionSpecifier::XArg: 583 case ConversionSpecifier::nArg: 584 return true; 585 default: 586 return false; 587 } 588 589 // Handle 'l' flag 590 case LengthModifier::AsLong: 591 switch (CS.getKind()) { 592 case ConversionSpecifier::dArg: 593 case ConversionSpecifier::iArg: 594 case ConversionSpecifier::oArg: 595 case ConversionSpecifier::uArg: 596 case ConversionSpecifier::xArg: 597 case ConversionSpecifier::XArg: 598 case ConversionSpecifier::aArg: 599 case ConversionSpecifier::AArg: 600 case ConversionSpecifier::fArg: 601 case ConversionSpecifier::FArg: 602 case ConversionSpecifier::eArg: 603 case ConversionSpecifier::EArg: 604 case ConversionSpecifier::gArg: 605 case ConversionSpecifier::GArg: 606 case ConversionSpecifier::nArg: 607 case ConversionSpecifier::cArg: 608 case ConversionSpecifier::sArg: 609 return true; 610 default: 611 return false; 612 } 613 614 case LengthModifier::AsLongDouble: 615 switch (CS.getKind()) { 616 case ConversionSpecifier::aArg: 617 case ConversionSpecifier::AArg: 618 case ConversionSpecifier::fArg: 619 case ConversionSpecifier::FArg: 620 case ConversionSpecifier::eArg: 621 case ConversionSpecifier::EArg: 622 case ConversionSpecifier::gArg: 623 case ConversionSpecifier::GArg: 624 return true; 625 default: 626 return false; 627 } 628 } 629 return false; 630} 631 632bool PrintfSpecifier::hasValidPrecision() const { 633 if (Precision.getHowSpecified() == OptionalAmount::NotSpecified) 634 return true; 635 636 // Precision is only valid with the diouxXaAeEfFgGs conversions 637 switch (CS.getKind()) { 638 case ConversionSpecifier::dArg: 639 case ConversionSpecifier::iArg: 640 case ConversionSpecifier::oArg: 641 case ConversionSpecifier::uArg: 642 case ConversionSpecifier::xArg: 643 case ConversionSpecifier::XArg: 644 case ConversionSpecifier::aArg: 645 case ConversionSpecifier::AArg: 646 case ConversionSpecifier::eArg: 647 case ConversionSpecifier::EArg: 648 case ConversionSpecifier::fArg: 649 case ConversionSpecifier::FArg: 650 case ConversionSpecifier::gArg: 651 case ConversionSpecifier::GArg: 652 case ConversionSpecifier::sArg: 653 return true; 654 655 default: 656 return false; 657 } 658} 659bool PrintfSpecifier::hasValidFieldWidth() const { 660 if (FieldWidth.getHowSpecified() == OptionalAmount::NotSpecified) 661 return true; 662 663 // The field width is valid for all conversions except n 664 switch (CS.getKind()) { 665 case ConversionSpecifier::nArg: 666 return false; 667 668 default: 669 return true; 670 } 671} 672