1 // FormatString.cpp - Common stuff for handling printf/scanf formats -*- 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 // Shared details for processing format strings of printf and scanf 11 // (and friends). 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "FormatStringParsing.h" 16 17 using clang::analyze_format_string::ArgTypeResult; 18 using clang::analyze_format_string::FormatStringHandler; 19 using clang::analyze_format_string::FormatSpecifier; 20 using clang::analyze_format_string::LengthModifier; 21 using clang::analyze_format_string::OptionalAmount; 22 using clang::analyze_format_string::PositionContext; 23 using clang::analyze_format_string::ConversionSpecifier; 24 using namespace clang; 25 26 // Key function to FormatStringHandler. 27 FormatStringHandler::~FormatStringHandler() {} 28 29 //===----------------------------------------------------------------------===// 30 // Functions for parsing format strings components in both printf and 31 // scanf format strings. 32 //===----------------------------------------------------------------------===// 33 34 OptionalAmount 35 clang::analyze_format_string::ParseAmount(const char *&Beg, const char *E) { 36 const char *I = Beg; 37 UpdateOnReturn <const char*> UpdateBeg(Beg, I); 38 39 unsigned accumulator = 0; 40 bool hasDigits = false; 41 42 for ( ; I != E; ++I) { 43 char c = *I; 44 if (c >= '0' && c <= '9') { 45 hasDigits = true; 46 accumulator = (accumulator * 10) + (c - '0'); 47 continue; 48 } 49 50 if (hasDigits) 51 return OptionalAmount(OptionalAmount::Constant, accumulator, Beg, I - Beg, 52 false); 53 54 break; 55 } 56 57 return OptionalAmount(); 58 } 59 60 OptionalAmount 61 clang::analyze_format_string::ParseNonPositionAmount(const char *&Beg, 62 const char *E, 63 unsigned &argIndex) { 64 if (*Beg == '*') { 65 ++Beg; 66 return OptionalAmount(OptionalAmount::Arg, argIndex++, Beg, 0, false); 67 } 68 69 return ParseAmount(Beg, E); 70 } 71 72 OptionalAmount 73 clang::analyze_format_string::ParsePositionAmount(FormatStringHandler &H, 74 const char *Start, 75 const char *&Beg, 76 const char *E, 77 PositionContext p) { 78 if (*Beg == '*') { 79 const char *I = Beg + 1; 80 const OptionalAmount &Amt = ParseAmount(I, E); 81 82 if (Amt.getHowSpecified() == OptionalAmount::NotSpecified) { 83 H.HandleInvalidPosition(Beg, I - Beg, p); 84 return OptionalAmount(false); 85 } 86 87 if (I == E) { 88 // No more characters left? 89 H.HandleIncompleteSpecifier(Start, E - Start); 90 return OptionalAmount(false); 91 } 92 93 assert(Amt.getHowSpecified() == OptionalAmount::Constant); 94 95 if (*I == '$') { 96 // Handle positional arguments 97 98 // Special case: '*0$', since this is an easy mistake. 99 if (Amt.getConstantAmount() == 0) { 100 H.HandleZeroPosition(Beg, I - Beg + 1); 101 return OptionalAmount(false); 102 } 103 104 const char *Tmp = Beg; 105 Beg = ++I; 106 107 return OptionalAmount(OptionalAmount::Arg, Amt.getConstantAmount() - 1, 108 Tmp, 0, true); 109 } 110 111 H.HandleInvalidPosition(Beg, I - Beg, p); 112 return OptionalAmount(false); 113 } 114 115 return ParseAmount(Beg, E); 116 } 117 118 119 bool 120 clang::analyze_format_string::ParseFieldWidth(FormatStringHandler &H, 121 FormatSpecifier &CS, 122 const char *Start, 123 const char *&Beg, const char *E, 124 unsigned *argIndex) { 125 // FIXME: Support negative field widths. 126 if (argIndex) { 127 CS.setFieldWidth(ParseNonPositionAmount(Beg, E, *argIndex)); 128 } 129 else { 130 const OptionalAmount Amt = 131 ParsePositionAmount(H, Start, Beg, E, 132 analyze_format_string::FieldWidthPos); 133 134 if (Amt.isInvalid()) 135 return true; 136 CS.setFieldWidth(Amt); 137 } 138 return false; 139 } 140 141 bool 142 clang::analyze_format_string::ParseArgPosition(FormatStringHandler &H, 143 FormatSpecifier &FS, 144 const char *Start, 145 const char *&Beg, 146 const char *E) { 147 const char *I = Beg; 148 149 const OptionalAmount &Amt = ParseAmount(I, E); 150 151 if (I == E) { 152 // No more characters left? 153 H.HandleIncompleteSpecifier(Start, E - Start); 154 return true; 155 } 156 157 if (Amt.getHowSpecified() == OptionalAmount::Constant && *(I++) == '$') { 158 // Special case: '%0$', since this is an easy mistake. 159 if (Amt.getConstantAmount() == 0) { 160 H.HandleZeroPosition(Start, I - Start); 161 return true; 162 } 163 164 FS.setArgIndex(Amt.getConstantAmount() - 1); 165 FS.setUsesPositionalArg(); 166 // Update the caller's pointer if we decided to consume 167 // these characters. 168 Beg = I; 169 return false; 170 } 171 172 return false; 173 } 174 175 bool 176 clang::analyze_format_string::ParseLengthModifier(FormatSpecifier &FS, 177 const char *&I, 178 const char *E) { 179 LengthModifier::Kind lmKind = LengthModifier::None; 180 const char *lmPosition = I; 181 switch (*I) { 182 default: 183 return false; 184 case 'h': 185 ++I; 186 lmKind = (I != E && *I == 'h') ? 187 ++I, LengthModifier::AsChar : LengthModifier::AsShort; 188 break; 189 case 'l': 190 ++I; 191 lmKind = (I != E && *I == 'l') ? 192 ++I, LengthModifier::AsLongLong : LengthModifier::AsLong; 193 break; 194 case 'j': lmKind = LengthModifier::AsIntMax; ++I; break; 195 case 'z': lmKind = LengthModifier::AsSizeT; ++I; break; 196 case 't': lmKind = LengthModifier::AsPtrDiff; ++I; break; 197 case 'L': lmKind = LengthModifier::AsLongDouble; ++I; break; 198 case 'q': lmKind = LengthModifier::AsLongLong; ++I; break; 199 } 200 LengthModifier lm(lmPosition, lmKind); 201 FS.setLengthModifier(lm); 202 return true; 203 } 204 205 //===----------------------------------------------------------------------===// 206 // Methods on ArgTypeResult. 207 //===----------------------------------------------------------------------===// 208 209 bool ArgTypeResult::matchesType(ASTContext &C, QualType argTy) const { 210 switch (K) { 211 case InvalidTy: 212 llvm_unreachable("ArgTypeResult must be valid"); 213 214 case UnknownTy: 215 return true; 216 217 case SpecificTy: { 218 argTy = C.getCanonicalType(argTy).getUnqualifiedType(); 219 if (T == argTy) 220 return true; 221 // Check for "compatible types". 222 if (const BuiltinType *BT = argTy->getAs<BuiltinType>()) 223 switch (BT->getKind()) { 224 default: 225 break; 226 case BuiltinType::Char_S: 227 case BuiltinType::SChar: 228 return T == C.UnsignedCharTy; 229 case BuiltinType::Char_U: 230 case BuiltinType::UChar: 231 return T == C.SignedCharTy; 232 case BuiltinType::Short: 233 return T == C.UnsignedShortTy; 234 case BuiltinType::UShort: 235 return T == C.ShortTy; 236 case BuiltinType::Int: 237 return T == C.UnsignedIntTy; 238 case BuiltinType::UInt: 239 return T == C.IntTy; 240 case BuiltinType::Long: 241 return T == C.UnsignedLongTy; 242 case BuiltinType::ULong: 243 return T == C.LongTy; 244 case BuiltinType::LongLong: 245 return T == C.UnsignedLongLongTy; 246 case BuiltinType::ULongLong: 247 return T == C.LongLongTy; 248 } 249 return false; 250 } 251 252 case CStrTy: { 253 const PointerType *PT = argTy->getAs<PointerType>(); 254 if (!PT) 255 return false; 256 QualType pointeeTy = PT->getPointeeType(); 257 if (const BuiltinType *BT = pointeeTy->getAs<BuiltinType>()) 258 switch (BT->getKind()) { 259 case BuiltinType::Void: 260 case BuiltinType::Char_U: 261 case BuiltinType::UChar: 262 case BuiltinType::Char_S: 263 case BuiltinType::SChar: 264 return true; 265 default: 266 break; 267 } 268 269 return false; 270 } 271 272 case WCStrTy: { 273 const PointerType *PT = argTy->getAs<PointerType>(); 274 if (!PT) 275 return false; 276 QualType pointeeTy = 277 C.getCanonicalType(PT->getPointeeType()).getUnqualifiedType(); 278 return pointeeTy == C.getWCharType(); 279 } 280 281 case WIntTy: { 282 // Instead of doing a lookup for the definition of 'wint_t' (which 283 // is defined by the system headers) instead see if wchar_t and 284 // the argument type promote to the same type. 285 QualType PromoWChar = 286 C.getWCharType()->isPromotableIntegerType() 287 ? C.getPromotedIntegerType(C.getWCharType()) : C.getWCharType(); 288 QualType PromoArg = 289 argTy->isPromotableIntegerType() 290 ? C.getPromotedIntegerType(argTy) : argTy; 291 292 PromoWChar = C.getCanonicalType(PromoWChar).getUnqualifiedType(); 293 PromoArg = C.getCanonicalType(PromoArg).getUnqualifiedType(); 294 295 return PromoWChar == PromoArg; 296 } 297 298 case CPointerTy: 299 return argTy->isPointerType() || argTy->isObjCObjectPointerType() || 300 argTy->isNullPtrType(); 301 302 case ObjCPointerTy: 303 return argTy->getAs<ObjCObjectPointerType>() != NULL; 304 } 305 306 // FIXME: Should be unreachable, but Clang is currently emitting 307 // a warning. 308 return false; 309 } 310 311 QualType ArgTypeResult::getRepresentativeType(ASTContext &C) const { 312 switch (K) { 313 case InvalidTy: 314 llvm_unreachable("No representative type for Invalid ArgTypeResult"); 315 case UnknownTy: 316 return QualType(); 317 case SpecificTy: 318 return T; 319 case CStrTy: 320 return C.getPointerType(C.CharTy); 321 case WCStrTy: 322 return C.getPointerType(C.getWCharType()); 323 case ObjCPointerTy: 324 return C.ObjCBuiltinIdTy; 325 case CPointerTy: 326 return C.VoidPtrTy; 327 case WIntTy: { 328 QualType WC = C.getWCharType(); 329 return WC->isPromotableIntegerType() ? C.getPromotedIntegerType(WC) : WC; 330 } 331 } 332 333 // FIXME: Should be unreachable, but Clang is currently emitting 334 // a warning. 335 return QualType(); 336 } 337 338 //===----------------------------------------------------------------------===// 339 // Methods on OptionalAmount. 340 //===----------------------------------------------------------------------===// 341 342 ArgTypeResult 343 analyze_format_string::OptionalAmount::getArgType(ASTContext &Ctx) const { 344 return Ctx.IntTy; 345 } 346 347 //===----------------------------------------------------------------------===// 348 // Methods on LengthModifier. 349 //===----------------------------------------------------------------------===// 350 351 const char * 352 analyze_format_string::LengthModifier::toString() const { 353 switch (kind) { 354 case AsChar: 355 return "hh"; 356 case AsShort: 357 return "h"; 358 case AsLong: // or AsWideChar 359 return "l"; 360 case AsLongLong: 361 return "ll"; 362 case AsIntMax: 363 return "j"; 364 case AsSizeT: 365 return "z"; 366 case AsPtrDiff: 367 return "t"; 368 case AsLongDouble: 369 return "L"; 370 case None: 371 return ""; 372 } 373 return NULL; 374 } 375 376 //===----------------------------------------------------------------------===// 377 // Methods on OptionalAmount. 378 //===----------------------------------------------------------------------===// 379 380 void OptionalAmount::toString(raw_ostream &os) const { 381 switch (hs) { 382 case Invalid: 383 case NotSpecified: 384 return; 385 case Arg: 386 if (UsesDotPrefix) 387 os << "."; 388 if (usesPositionalArg()) 389 os << "*" << getPositionalArgIndex() << "$"; 390 else 391 os << "*"; 392 break; 393 case Constant: 394 if (UsesDotPrefix) 395 os << "."; 396 os << amt; 397 break; 398 } 399 } 400 401 //===----------------------------------------------------------------------===// 402 // Methods on ConversionSpecifier. 403 //===----------------------------------------------------------------------===// 404 405 bool FormatSpecifier::hasValidLengthModifier() const { 406 switch (LM.getKind()) { 407 case LengthModifier::None: 408 return true; 409 410 // Handle most integer flags 411 case LengthModifier::AsChar: 412 case LengthModifier::AsShort: 413 case LengthModifier::AsLongLong: 414 case LengthModifier::AsIntMax: 415 case LengthModifier::AsSizeT: 416 case LengthModifier::AsPtrDiff: 417 switch (CS.getKind()) { 418 case ConversionSpecifier::dArg: 419 case ConversionSpecifier::iArg: 420 case ConversionSpecifier::oArg: 421 case ConversionSpecifier::uArg: 422 case ConversionSpecifier::xArg: 423 case ConversionSpecifier::XArg: 424 case ConversionSpecifier::nArg: 425 return true; 426 default: 427 return false; 428 } 429 430 // Handle 'l' flag 431 case LengthModifier::AsLong: 432 switch (CS.getKind()) { 433 case ConversionSpecifier::dArg: 434 case ConversionSpecifier::iArg: 435 case ConversionSpecifier::oArg: 436 case ConversionSpecifier::uArg: 437 case ConversionSpecifier::xArg: 438 case ConversionSpecifier::XArg: 439 case ConversionSpecifier::aArg: 440 case ConversionSpecifier::AArg: 441 case ConversionSpecifier::fArg: 442 case ConversionSpecifier::FArg: 443 case ConversionSpecifier::eArg: 444 case ConversionSpecifier::EArg: 445 case ConversionSpecifier::gArg: 446 case ConversionSpecifier::GArg: 447 case ConversionSpecifier::nArg: 448 case ConversionSpecifier::cArg: 449 case ConversionSpecifier::sArg: 450 return true; 451 default: 452 return false; 453 } 454 455 case LengthModifier::AsLongDouble: 456 switch (CS.getKind()) { 457 case ConversionSpecifier::aArg: 458 case ConversionSpecifier::AArg: 459 case ConversionSpecifier::fArg: 460 case ConversionSpecifier::FArg: 461 case ConversionSpecifier::eArg: 462 case ConversionSpecifier::EArg: 463 case ConversionSpecifier::gArg: 464 case ConversionSpecifier::GArg: 465 return true; 466 default: 467 return false; 468 } 469 } 470 return false; 471 } 472 473 474