1 //===--- FileManager.cpp - File System Probing and Caching ----------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the FileManager interface. 10 // 11 //===----------------------------------------------------------------------===// 12 // 13 // TODO: This should index all interesting directories with dirent calls. 14 // getdirentries ? 15 // opendir/readdir_r/closedir ? 16 // 17 //===----------------------------------------------------------------------===// 18 19 #include "clang/Basic/FileManager.h" 20 #include "clang/Basic/FileSystemStatCache.h" 21 #include "llvm/ADT/STLExtras.h" 22 #include "llvm/ADT/SmallString.h" 23 #include "llvm/ADT/Statistic.h" 24 #include "llvm/Config/llvm-config.h" 25 #include "llvm/Support/FileSystem.h" 26 #include "llvm/Support/MemoryBuffer.h" 27 #include "llvm/Support/Path.h" 28 #include "llvm/Support/raw_ostream.h" 29 #include <algorithm> 30 #include <cassert> 31 #include <climits> 32 #include <cstdint> 33 #include <cstdlib> 34 #include <string> 35 #include <utility> 36 37 using namespace clang; 38 39 #define DEBUG_TYPE "file-search" 40 41 ALWAYS_ENABLED_STATISTIC(NumDirLookups, "Number of directory lookups."); 42 ALWAYS_ENABLED_STATISTIC(NumFileLookups, "Number of file lookups."); 43 ALWAYS_ENABLED_STATISTIC(NumDirCacheMisses, 44 "Number of directory cache misses."); 45 ALWAYS_ENABLED_STATISTIC(NumFileCacheMisses, "Number of file cache misses."); 46 47 //===----------------------------------------------------------------------===// 48 // Common logic. 49 //===----------------------------------------------------------------------===// 50 51 FileManager::FileManager(const FileSystemOptions &FSO, 52 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) 53 : FS(std::move(FS)), FileSystemOpts(FSO), SeenDirEntries(64), 54 SeenFileEntries(64), NextFileUID(0) { 55 // If the caller doesn't provide a virtual file system, just grab the real 56 // file system. 57 if (!this->FS) 58 this->FS = llvm::vfs::getRealFileSystem(); 59 } 60 61 FileManager::~FileManager() = default; 62 63 void FileManager::setStatCache(std::unique_ptr<FileSystemStatCache> statCache) { 64 assert(statCache && "No stat cache provided?"); 65 StatCache = std::move(statCache); 66 } 67 68 void FileManager::clearStatCache() { StatCache.reset(); } 69 70 /// Retrieve the directory that the given file name resides in. 71 /// Filename can point to either a real file or a virtual file. 72 static llvm::ErrorOr<const DirectoryEntry *> 73 getDirectoryFromFile(FileManager &FileMgr, StringRef Filename, 74 bool CacheFailure) { 75 if (Filename.empty()) 76 return std::errc::no_such_file_or_directory; 77 78 if (llvm::sys::path::is_separator(Filename[Filename.size() - 1])) 79 return std::errc::is_a_directory; 80 81 StringRef DirName = llvm::sys::path::parent_path(Filename); 82 // Use the current directory if file has no path component. 83 if (DirName.empty()) 84 DirName = "."; 85 86 return FileMgr.getDirectory(DirName, CacheFailure); 87 } 88 89 /// Add all ancestors of the given path (pointing to either a file or 90 /// a directory) as virtual directories. 91 void FileManager::addAncestorsAsVirtualDirs(StringRef Path) { 92 StringRef DirName = llvm::sys::path::parent_path(Path); 93 if (DirName.empty()) 94 DirName = "."; 95 96 auto &NamedDirEnt = *SeenDirEntries.insert( 97 {DirName, std::errc::no_such_file_or_directory}).first; 98 99 // When caching a virtual directory, we always cache its ancestors 100 // at the same time. Therefore, if DirName is already in the cache, 101 // we don't need to recurse as its ancestors must also already be in 102 // the cache (or it's a known non-virtual directory). 103 if (NamedDirEnt.second) 104 return; 105 106 // Add the virtual directory to the cache. 107 auto UDE = std::make_unique<DirectoryEntry>(); 108 UDE->Name = NamedDirEnt.first(); 109 NamedDirEnt.second = *UDE.get(); 110 VirtualDirectoryEntries.push_back(std::move(UDE)); 111 112 // Recursively add the other ancestors. 113 addAncestorsAsVirtualDirs(DirName); 114 } 115 116 llvm::Expected<DirectoryEntryRef> 117 FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) { 118 // stat doesn't like trailing separators except for root directory. 119 // At least, on Win32 MSVCRT, stat() cannot strip trailing '/'. 120 // (though it can strip '\\') 121 if (DirName.size() > 1 && 122 DirName != llvm::sys::path::root_path(DirName) && 123 llvm::sys::path::is_separator(DirName.back())) 124 DirName = DirName.substr(0, DirName.size()-1); 125 #ifdef _WIN32 126 // Fixing a problem with "clang C:test.c" on Windows. 127 // Stat("C:") does not recognize "C:" as a valid directory 128 std::string DirNameStr; 129 if (DirName.size() > 1 && DirName.back() == ':' && 130 DirName.equals_lower(llvm::sys::path::root_name(DirName))) { 131 DirNameStr = DirName.str() + '.'; 132 DirName = DirNameStr; 133 } 134 #endif 135 136 ++NumDirLookups; 137 138 // See if there was already an entry in the map. Note that the map 139 // contains both virtual and real directories. 140 auto SeenDirInsertResult = 141 SeenDirEntries.insert({DirName, std::errc::no_such_file_or_directory}); 142 if (!SeenDirInsertResult.second) { 143 if (SeenDirInsertResult.first->second) 144 return DirectoryEntryRef(&*SeenDirInsertResult.first); 145 return llvm::errorCodeToError(SeenDirInsertResult.first->second.getError()); 146 } 147 148 // We've not seen this before. Fill it in. 149 ++NumDirCacheMisses; 150 auto &NamedDirEnt = *SeenDirInsertResult.first; 151 assert(!NamedDirEnt.second && "should be newly-created"); 152 153 // Get the null-terminated directory name as stored as the key of the 154 // SeenDirEntries map. 155 StringRef InterndDirName = NamedDirEnt.first(); 156 157 // Check to see if the directory exists. 158 llvm::vfs::Status Status; 159 auto statError = getStatValue(InterndDirName, Status, false, 160 nullptr /*directory lookup*/); 161 if (statError) { 162 // There's no real directory at the given path. 163 if (CacheFailure) 164 NamedDirEnt.second = statError; 165 else 166 SeenDirEntries.erase(DirName); 167 return llvm::errorCodeToError(statError); 168 } 169 170 // It exists. See if we have already opened a directory with the 171 // same inode (this occurs on Unix-like systems when one dir is 172 // symlinked to another, for example) or the same path (on 173 // Windows). 174 DirectoryEntry &UDE = UniqueRealDirs[Status.getUniqueID()]; 175 176 NamedDirEnt.second = UDE; 177 if (UDE.getName().empty()) { 178 // We don't have this directory yet, add it. We use the string 179 // key from the SeenDirEntries map as the string. 180 UDE.Name = InterndDirName; 181 } 182 183 return DirectoryEntryRef(&NamedDirEnt); 184 } 185 186 llvm::ErrorOr<const DirectoryEntry *> 187 FileManager::getDirectory(StringRef DirName, bool CacheFailure) { 188 auto Result = getDirectoryRef(DirName, CacheFailure); 189 if (Result) 190 return &Result->getDirEntry(); 191 return llvm::errorToErrorCode(Result.takeError()); 192 } 193 194 llvm::ErrorOr<const FileEntry *> 195 FileManager::getFile(StringRef Filename, bool openFile, bool CacheFailure) { 196 auto Result = getFileRef(Filename, openFile, CacheFailure); 197 if (Result) 198 return &Result->getFileEntry(); 199 return llvm::errorToErrorCode(Result.takeError()); 200 } 201 202 llvm::Expected<FileEntryRef> 203 FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) { 204 ++NumFileLookups; 205 206 // See if there is already an entry in the map. 207 auto SeenFileInsertResult = 208 SeenFileEntries.insert({Filename, std::errc::no_such_file_or_directory}); 209 if (!SeenFileInsertResult.second) { 210 if (!SeenFileInsertResult.first->second) 211 return llvm::errorCodeToError( 212 SeenFileInsertResult.first->second.getError()); 213 // Construct and return and FileEntryRef, unless it's a redirect to another 214 // filename. 215 SeenFileEntryOrRedirect Value = *SeenFileInsertResult.first->second; 216 FileEntry *FE; 217 if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>())) 218 return FileEntryRef(SeenFileInsertResult.first->first(), *FE); 219 return getFileRef(*Value.get<const StringRef *>(), openFile, CacheFailure); 220 } 221 222 // We've not seen this before. Fill it in. 223 ++NumFileCacheMisses; 224 auto &NamedFileEnt = *SeenFileInsertResult.first; 225 assert(!NamedFileEnt.second && "should be newly-created"); 226 227 // Get the null-terminated file name as stored as the key of the 228 // SeenFileEntries map. 229 StringRef InterndFileName = NamedFileEnt.first(); 230 231 // Look up the directory for the file. When looking up something like 232 // sys/foo.h we'll discover all of the search directories that have a 'sys' 233 // subdirectory. This will let us avoid having to waste time on known-to-fail 234 // searches when we go to find sys/bar.h, because all the search directories 235 // without a 'sys' subdir will get a cached failure result. 236 auto DirInfoOrErr = getDirectoryFromFile(*this, Filename, CacheFailure); 237 if (!DirInfoOrErr) { // Directory doesn't exist, file can't exist. 238 if (CacheFailure) 239 NamedFileEnt.second = DirInfoOrErr.getError(); 240 else 241 SeenFileEntries.erase(Filename); 242 243 return llvm::errorCodeToError(DirInfoOrErr.getError()); 244 } 245 const DirectoryEntry *DirInfo = *DirInfoOrErr; 246 247 // FIXME: Use the directory info to prune this, before doing the stat syscall. 248 // FIXME: This will reduce the # syscalls. 249 250 // Check to see if the file exists. 251 std::unique_ptr<llvm::vfs::File> F; 252 llvm::vfs::Status Status; 253 auto statError = getStatValue(InterndFileName, Status, true, 254 openFile ? &F : nullptr); 255 if (statError) { 256 // There's no real file at the given path. 257 if (CacheFailure) 258 NamedFileEnt.second = statError; 259 else 260 SeenFileEntries.erase(Filename); 261 262 return llvm::errorCodeToError(statError); 263 } 264 265 assert((openFile || !F) && "undesired open file"); 266 267 // It exists. See if we have already opened a file with the same inode. 268 // This occurs when one dir is symlinked to another, for example. 269 FileEntry &UFE = UniqueRealFiles[Status.getUniqueID()]; 270 271 NamedFileEnt.second = &UFE; 272 273 // If the name returned by getStatValue is different than Filename, re-intern 274 // the name. 275 if (Status.getName() != Filename) { 276 auto &NewNamedFileEnt = 277 *SeenFileEntries.insert({Status.getName(), &UFE}).first; 278 assert((*NewNamedFileEnt.second).get<FileEntry *>() == &UFE && 279 "filename from getStatValue() refers to wrong file"); 280 InterndFileName = NewNamedFileEnt.first().data(); 281 // In addition to re-interning the name, construct a redirecting seen file 282 // entry, that will point to the name the filesystem actually wants to use. 283 StringRef *Redirect = new (CanonicalNameStorage) StringRef(InterndFileName); 284 NamedFileEnt.second = Redirect; 285 } 286 287 if (UFE.isValid()) { // Already have an entry with this inode, return it. 288 289 // FIXME: this hack ensures that if we look up a file by a virtual path in 290 // the VFS that the getDir() will have the virtual path, even if we found 291 // the file by a 'real' path first. This is required in order to find a 292 // module's structure when its headers/module map are mapped in the VFS. 293 // We should remove this as soon as we can properly support a file having 294 // multiple names. 295 if (DirInfo != UFE.Dir && Status.IsVFSMapped) 296 UFE.Dir = DirInfo; 297 298 // Always update the name to use the last name by which a file was accessed. 299 // FIXME: Neither this nor always using the first name is correct; we want 300 // to switch towards a design where we return a FileName object that 301 // encapsulates both the name by which the file was accessed and the 302 // corresponding FileEntry. 303 // FIXME: The Name should be removed from FileEntry once all clients 304 // adopt FileEntryRef. 305 UFE.Name = InterndFileName; 306 307 return FileEntryRef(InterndFileName, UFE); 308 } 309 310 // Otherwise, we don't have this file yet, add it. 311 UFE.Name = InterndFileName; 312 UFE.Size = Status.getSize(); 313 UFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime()); 314 UFE.Dir = DirInfo; 315 UFE.UID = NextFileUID++; 316 UFE.UniqueID = Status.getUniqueID(); 317 UFE.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file; 318 UFE.File = std::move(F); 319 UFE.IsValid = true; 320 321 if (UFE.File) { 322 if (auto PathName = UFE.File->getName()) 323 fillRealPathName(&UFE, *PathName); 324 } else if (!openFile) { 325 // We should still fill the path even if we aren't opening the file. 326 fillRealPathName(&UFE, InterndFileName); 327 } 328 return FileEntryRef(InterndFileName, UFE); 329 } 330 331 const FileEntry * 332 FileManager::getVirtualFile(StringRef Filename, off_t Size, 333 time_t ModificationTime) { 334 ++NumFileLookups; 335 336 // See if there is already an entry in the map for an existing file. 337 auto &NamedFileEnt = *SeenFileEntries.insert( 338 {Filename, std::errc::no_such_file_or_directory}).first; 339 if (NamedFileEnt.second) { 340 SeenFileEntryOrRedirect Value = *NamedFileEnt.second; 341 FileEntry *FE; 342 if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>())) 343 return FE; 344 return getVirtualFile(*Value.get<const StringRef *>(), Size, 345 ModificationTime); 346 } 347 348 // We've not seen this before, or the file is cached as non-existent. 349 ++NumFileCacheMisses; 350 addAncestorsAsVirtualDirs(Filename); 351 FileEntry *UFE = nullptr; 352 353 // Now that all ancestors of Filename are in the cache, the 354 // following call is guaranteed to find the DirectoryEntry from the 355 // cache. 356 auto DirInfo = getDirectoryFromFile(*this, Filename, /*CacheFailure=*/true); 357 assert(DirInfo && 358 "The directory of a virtual file should already be in the cache."); 359 360 // Check to see if the file exists. If so, drop the virtual file 361 llvm::vfs::Status Status; 362 const char *InterndFileName = NamedFileEnt.first().data(); 363 if (!getStatValue(InterndFileName, Status, true, nullptr)) { 364 UFE = &UniqueRealFiles[Status.getUniqueID()]; 365 Status = llvm::vfs::Status( 366 Status.getName(), Status.getUniqueID(), 367 llvm::sys::toTimePoint(ModificationTime), 368 Status.getUser(), Status.getGroup(), Size, 369 Status.getType(), Status.getPermissions()); 370 371 NamedFileEnt.second = UFE; 372 373 // If we had already opened this file, close it now so we don't 374 // leak the descriptor. We're not going to use the file 375 // descriptor anyway, since this is a virtual file. 376 if (UFE->File) 377 UFE->closeFile(); 378 379 // If we already have an entry with this inode, return it. 380 if (UFE->isValid()) 381 return UFE; 382 383 UFE->UniqueID = Status.getUniqueID(); 384 UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file; 385 fillRealPathName(UFE, Status.getName()); 386 } else { 387 VirtualFileEntries.push_back(std::make_unique<FileEntry>()); 388 UFE = VirtualFileEntries.back().get(); 389 NamedFileEnt.second = UFE; 390 } 391 392 UFE->Name = InterndFileName; 393 UFE->Size = Size; 394 UFE->ModTime = ModificationTime; 395 UFE->Dir = *DirInfo; 396 UFE->UID = NextFileUID++; 397 UFE->IsValid = true; 398 UFE->File.reset(); 399 return UFE; 400 } 401 402 llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) { 403 // Stat of the file and return nullptr if it doesn't exist. 404 llvm::vfs::Status Status; 405 if (getStatValue(VF.getName(), Status, /*isFile=*/true, /*F=*/nullptr)) 406 return None; 407 408 // Fill it in from the stat. 409 BypassFileEntries.push_back(std::make_unique<FileEntry>()); 410 const FileEntry &VFE = VF.getFileEntry(); 411 FileEntry &BFE = *BypassFileEntries.back(); 412 BFE.Name = VFE.getName(); 413 BFE.Size = Status.getSize(); 414 BFE.Dir = VFE.Dir; 415 BFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime()); 416 BFE.UID = NextFileUID++; 417 BFE.IsValid = true; 418 return FileEntryRef(VF.getName(), BFE); 419 } 420 421 bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const { 422 StringRef pathRef(path.data(), path.size()); 423 424 if (FileSystemOpts.WorkingDir.empty() 425 || llvm::sys::path::is_absolute(pathRef)) 426 return false; 427 428 SmallString<128> NewPath(FileSystemOpts.WorkingDir); 429 llvm::sys::path::append(NewPath, pathRef); 430 path = NewPath; 431 return true; 432 } 433 434 bool FileManager::makeAbsolutePath(SmallVectorImpl<char> &Path) const { 435 bool Changed = FixupRelativePath(Path); 436 437 if (!llvm::sys::path::is_absolute(StringRef(Path.data(), Path.size()))) { 438 FS->makeAbsolute(Path); 439 Changed = true; 440 } 441 442 return Changed; 443 } 444 445 void FileManager::fillRealPathName(FileEntry *UFE, llvm::StringRef FileName) { 446 llvm::SmallString<128> AbsPath(FileName); 447 // This is not the same as `VFS::getRealPath()`, which resolves symlinks 448 // but can be very expensive on real file systems. 449 // FIXME: the semantic of RealPathName is unclear, and the name might be 450 // misleading. We need to clean up the interface here. 451 makeAbsolutePath(AbsPath); 452 llvm::sys::path::remove_dots(AbsPath, /*remove_dot_dot=*/true); 453 UFE->RealPathName = AbsPath.str(); 454 } 455 456 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> 457 FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile) { 458 uint64_t FileSize = Entry->getSize(); 459 // If there's a high enough chance that the file have changed since we 460 // got its size, force a stat before opening it. 461 if (isVolatile) 462 FileSize = -1; 463 464 StringRef Filename = Entry->getName(); 465 // If the file is already open, use the open file descriptor. 466 if (Entry->File) { 467 auto Result = 468 Entry->File->getBuffer(Filename, FileSize, 469 /*RequiresNullTerminator=*/true, isVolatile); 470 Entry->closeFile(); 471 return Result; 472 } 473 474 // Otherwise, open the file. 475 return getBufferForFileImpl(Filename, FileSize, isVolatile); 476 } 477 478 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> 479 FileManager::getBufferForFileImpl(StringRef Filename, int64_t FileSize, 480 bool isVolatile) { 481 if (FileSystemOpts.WorkingDir.empty()) 482 return FS->getBufferForFile(Filename, FileSize, 483 /*RequiresNullTerminator=*/true, isVolatile); 484 485 SmallString<128> FilePath(Filename); 486 FixupRelativePath(FilePath); 487 return FS->getBufferForFile(FilePath, FileSize, 488 /*RequiresNullTerminator=*/true, isVolatile); 489 } 490 491 /// getStatValue - Get the 'stat' information for the specified path, 492 /// using the cache to accelerate it if possible. This returns true 493 /// if the path points to a virtual file or does not exist, or returns 494 /// false if it's an existent real file. If FileDescriptor is NULL, 495 /// do directory look-up instead of file look-up. 496 std::error_code 497 FileManager::getStatValue(StringRef Path, llvm::vfs::Status &Status, 498 bool isFile, std::unique_ptr<llvm::vfs::File> *F) { 499 // FIXME: FileSystemOpts shouldn't be passed in here, all paths should be 500 // absolute! 501 if (FileSystemOpts.WorkingDir.empty()) 502 return FileSystemStatCache::get(Path, Status, isFile, F, 503 StatCache.get(), *FS); 504 505 SmallString<128> FilePath(Path); 506 FixupRelativePath(FilePath); 507 508 return FileSystemStatCache::get(FilePath.c_str(), Status, isFile, F, 509 StatCache.get(), *FS); 510 } 511 512 std::error_code 513 FileManager::getNoncachedStatValue(StringRef Path, 514 llvm::vfs::Status &Result) { 515 SmallString<128> FilePath(Path); 516 FixupRelativePath(FilePath); 517 518 llvm::ErrorOr<llvm::vfs::Status> S = FS->status(FilePath.c_str()); 519 if (!S) 520 return S.getError(); 521 Result = *S; 522 return std::error_code(); 523 } 524 525 void FileManager::GetUniqueIDMapping( 526 SmallVectorImpl<const FileEntry *> &UIDToFiles) const { 527 UIDToFiles.clear(); 528 UIDToFiles.resize(NextFileUID); 529 530 // Map file entries 531 for (llvm::StringMap<llvm::ErrorOr<SeenFileEntryOrRedirect>, 532 llvm::BumpPtrAllocator>::const_iterator 533 FE = SeenFileEntries.begin(), 534 FEEnd = SeenFileEntries.end(); 535 FE != FEEnd; ++FE) 536 if (llvm::ErrorOr<SeenFileEntryOrRedirect> Entry = FE->getValue()) { 537 if (const auto *FE = (*Entry).dyn_cast<FileEntry *>()) 538 UIDToFiles[FE->getUID()] = FE; 539 } 540 541 // Map virtual file entries 542 for (const auto &VFE : VirtualFileEntries) 543 UIDToFiles[VFE->getUID()] = VFE.get(); 544 } 545 546 StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) { 547 // FIXME: use llvm::sys::fs::canonical() when it gets implemented 548 llvm::DenseMap<const DirectoryEntry *, llvm::StringRef>::iterator Known 549 = CanonicalDirNames.find(Dir); 550 if (Known != CanonicalDirNames.end()) 551 return Known->second; 552 553 StringRef CanonicalName(Dir->getName()); 554 555 SmallString<4096> CanonicalNameBuf; 556 if (!FS->getRealPath(Dir->getName(), CanonicalNameBuf)) 557 CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage); 558 559 CanonicalDirNames.insert({Dir, CanonicalName}); 560 return CanonicalName; 561 } 562 563 void FileManager::PrintStats() const { 564 llvm::errs() << "\n*** File Manager Stats:\n"; 565 llvm::errs() << UniqueRealFiles.size() << " real files found, " 566 << UniqueRealDirs.size() << " real dirs found.\n"; 567 llvm::errs() << VirtualFileEntries.size() << " virtual files found, " 568 << VirtualDirectoryEntries.size() << " virtual dirs found.\n"; 569 llvm::errs() << NumDirLookups << " dir lookups, " 570 << NumDirCacheMisses << " dir cache misses.\n"; 571 llvm::errs() << NumFileLookups << " file lookups, " 572 << NumFileCacheMisses << " file cache misses.\n"; 573 574 //llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups; 575 } 576