1 //===--- FileManager.h - File System Probing and Caching --------*- C++ -*-===// 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 /// \file 10 /// Defines the clang::FileManager interface and associated types. 11 /// 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_BASIC_FILEMANAGER_H 15 #define LLVM_CLANG_BASIC_FILEMANAGER_H 16 17 #include "clang/Basic/DirectoryEntry.h" 18 #include "clang/Basic/FileEntry.h" 19 #include "clang/Basic/FileSystemOptions.h" 20 #include "clang/Basic/LLVM.h" 21 #include "llvm/ADT/DenseMap.h" 22 #include "llvm/ADT/IntrusiveRefCntPtr.h" 23 #include "llvm/ADT/PointerUnion.h" 24 #include "llvm/ADT/SmallVector.h" 25 #include "llvm/ADT/StringMap.h" 26 #include "llvm/ADT/StringRef.h" 27 #include "llvm/Support/Allocator.h" 28 #include "llvm/Support/ErrorOr.h" 29 #include "llvm/Support/FileSystem.h" 30 #include "llvm/Support/VirtualFileSystem.h" 31 #include <ctime> 32 #include <map> 33 #include <memory> 34 #include <string> 35 36 namespace llvm { 37 38 class MemoryBuffer; 39 40 } // end namespace llvm 41 42 namespace clang { 43 44 class FileSystemStatCache; 45 46 /// Implements support for file system lookup, file system caching, 47 /// and directory search management. 48 /// 49 /// This also handles more advanced properties, such as uniquing files based 50 /// on "inode", so that a file with two names (e.g. symlinked) will be treated 51 /// as a single file. 52 /// 53 class FileManager : public RefCountedBase<FileManager> { 54 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS; 55 FileSystemOptions FileSystemOpts; 56 llvm::SpecificBumpPtrAllocator<FileEntry> FilesAlloc; 57 llvm::SpecificBumpPtrAllocator<DirectoryEntry> DirsAlloc; 58 59 /// Cache for existing real directories. 60 llvm::DenseMap<llvm::sys::fs::UniqueID, DirectoryEntry *> UniqueRealDirs; 61 62 /// Cache for existing real files. 63 llvm::DenseMap<llvm::sys::fs::UniqueID, FileEntry *> UniqueRealFiles; 64 65 /// The virtual directories that we have allocated. 66 /// 67 /// For each virtual file (e.g. foo/bar/baz.cpp), we add all of its parent 68 /// directories (foo/ and foo/bar/) here. 69 SmallVector<DirectoryEntry *, 4> VirtualDirectoryEntries; 70 /// The virtual files that we have allocated. 71 SmallVector<FileEntry *, 4> VirtualFileEntries; 72 73 /// A set of files that bypass the maps and uniquing. They can have 74 /// conflicting filenames. 75 SmallVector<FileEntry *, 0> BypassFileEntries; 76 77 /// A cache that maps paths to directory entries (either real or 78 /// virtual) we have looked up, or an error that occurred when we looked up 79 /// the directory. 80 /// 81 /// The actual Entries for real directories/files are 82 /// owned by UniqueRealDirs/UniqueRealFiles above, while the Entries 83 /// for virtual directories/files are owned by 84 /// VirtualDirectoryEntries/VirtualFileEntries above. 85 /// 86 llvm::StringMap<llvm::ErrorOr<DirectoryEntry &>, llvm::BumpPtrAllocator> 87 SeenDirEntries; 88 89 /// A cache that maps paths to file entries (either real or 90 /// virtual) we have looked up, or an error that occurred when we looked up 91 /// the file. 92 /// 93 /// \see SeenDirEntries 94 llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>, llvm::BumpPtrAllocator> 95 SeenFileEntries; 96 97 /// A mirror of SeenFileEntries to give fake answers for getBypassFile(). 98 /// 99 /// Don't bother hooking up a BumpPtrAllocator. This should be rarely used, 100 /// and only on error paths. 101 std::unique_ptr<llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>>> 102 SeenBypassFileEntries; 103 104 /// The file entry for stdin, if it has been accessed through the FileManager. 105 OptionalFileEntryRef STDIN; 106 107 /// The canonical names of files and directories . 108 llvm::DenseMap<const void *, llvm::StringRef> CanonicalNames; 109 110 /// Storage for canonical names that we have computed. 111 llvm::BumpPtrAllocator CanonicalNameStorage; 112 113 /// Each FileEntry we create is assigned a unique ID #. 114 /// 115 unsigned NextFileUID; 116 117 /// Statistics gathered during the lifetime of the FileManager. 118 unsigned NumDirLookups = 0; 119 unsigned NumFileLookups = 0; 120 unsigned NumDirCacheMisses = 0; 121 unsigned NumFileCacheMisses = 0; 122 123 // Caching. 124 std::unique_ptr<FileSystemStatCache> StatCache; 125 126 std::error_code getStatValue(StringRef Path, llvm::vfs::Status &Status, 127 bool isFile, std::unique_ptr<llvm::vfs::File> *F, 128 bool IsText = true); 129 130 /// Add all ancestors of the given path (pointing to either a file 131 /// or a directory) as virtual directories. 132 void addAncestorsAsVirtualDirs(StringRef Path); 133 134 /// Fills the RealPathName in file entry. 135 void fillRealPathName(FileEntry *UFE, llvm::StringRef FileName); 136 137 public: 138 /// Construct a file manager, optionally with a custom VFS. 139 /// 140 /// \param FS if non-null, the VFS to use. Otherwise uses 141 /// llvm::vfs::getRealFileSystem(). 142 FileManager(const FileSystemOptions &FileSystemOpts, 143 IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS = nullptr); 144 ~FileManager(); 145 146 /// Installs the provided FileSystemStatCache object within 147 /// the FileManager. 148 /// 149 /// Ownership of this object is transferred to the FileManager. 150 /// 151 /// \param statCache the new stat cache to install. Ownership of this 152 /// object is transferred to the FileManager. 153 void setStatCache(std::unique_ptr<FileSystemStatCache> statCache); 154 155 /// Removes the FileSystemStatCache object from the manager. 156 void clearStatCache(); 157 158 /// Returns the number of unique real file entries cached by the file manager. getNumUniqueRealFiles()159 size_t getNumUniqueRealFiles() const { return UniqueRealFiles.size(); } 160 161 /// Lookup, cache, and verify the specified directory (real or 162 /// virtual). 163 /// 164 /// This returns a \c std::error_code if there was an error reading the 165 /// directory. On success, returns the reference to the directory entry 166 /// together with the exact path that was used to access a file by a 167 /// particular call to getDirectoryRef. 168 /// 169 /// \param CacheFailure If true and the file does not exist, we'll cache 170 /// the failure to find this file. 171 llvm::Expected<DirectoryEntryRef> getDirectoryRef(StringRef DirName, 172 bool CacheFailure = true); 173 174 /// Get a \c DirectoryEntryRef if it exists, without doing anything on error. 175 OptionalDirectoryEntryRef getOptionalDirectoryRef(StringRef DirName, 176 bool CacheFailure = true) { 177 return llvm::expectedToOptional(getDirectoryRef(DirName, CacheFailure)); 178 } 179 180 /// Lookup, cache, and verify the specified file (real or virtual). Return the 181 /// reference to the file entry together with the exact path that was used to 182 /// access a file by a particular call to getFileRef. If the underlying VFS is 183 /// a redirecting VFS that uses external file names, the returned FileEntryRef 184 /// will use the external name instead of the filename that was passed to this 185 /// method. 186 /// 187 /// This returns a \c std::error_code if there was an error loading the file, 188 /// or a \c FileEntryRef otherwise. 189 /// 190 /// \param OpenFile if true and the file exists, it will be opened. 191 /// 192 /// \param CacheFailure If true and the file does not exist, we'll cache 193 /// the failure to find this file. 194 llvm::Expected<FileEntryRef> getFileRef(StringRef Filename, 195 bool OpenFile = false, 196 bool CacheFailure = true, 197 bool IsText = true); 198 199 /// Get the FileEntryRef for stdin, returning an error if stdin cannot be 200 /// read. 201 /// 202 /// This reads and caches stdin before returning. Subsequent calls return the 203 /// same file entry, and a reference to the cached input is returned by calls 204 /// to getBufferForFile. 205 llvm::Expected<FileEntryRef> getSTDIN(); 206 207 /// Get a FileEntryRef if it exists, without doing anything on error. 208 OptionalFileEntryRef getOptionalFileRef(StringRef Filename, 209 bool OpenFile = false, 210 bool CacheFailure = true) { 211 return llvm::expectedToOptional( 212 getFileRef(Filename, OpenFile, CacheFailure)); 213 } 214 215 /// Returns the current file system options getFileSystemOpts()216 FileSystemOptions &getFileSystemOpts() { return FileSystemOpts; } getFileSystemOpts()217 const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; } 218 getVirtualFileSystem()219 llvm::vfs::FileSystem &getVirtualFileSystem() const { return *FS; } 220 llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> getVirtualFileSystemPtr()221 getVirtualFileSystemPtr() const { 222 return FS; 223 } 224 225 /// Enable or disable tracking of VFS usage. Used to not track full header 226 /// search and implicit modulemap lookup. 227 void trackVFSUsage(bool Active); 228 setVirtualFileSystem(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)229 void setVirtualFileSystem(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) { 230 this->FS = std::move(FS); 231 } 232 233 /// Retrieve a file entry for a "virtual" file that acts as 234 /// if there were a file with the given name on disk. 235 /// 236 /// The file itself is not accessed. 237 FileEntryRef getVirtualFileRef(StringRef Filename, off_t Size, 238 time_t ModificationTime); 239 240 LLVM_DEPRECATED("Functions returning FileEntry are deprecated.", 241 "getVirtualFileRef()") 242 const FileEntry *getVirtualFile(StringRef Filename, off_t Size, 243 time_t ModificationTime); 244 245 /// Retrieve a FileEntry that bypasses VFE, which is expected to be a virtual 246 /// file entry, to access the real file. The returned FileEntry will have 247 /// the same filename as FE but a different identity and its own stat. 248 /// 249 /// This should be used only for rare error recovery paths because it 250 /// bypasses all mapping and uniquing, blindly creating a new FileEntry. 251 /// There is no attempt to deduplicate these; if you bypass the same file 252 /// twice, you get two new file entries. 253 OptionalFileEntryRef getBypassFile(FileEntryRef VFE); 254 255 /// Open the specified file as a MemoryBuffer, returning a new 256 /// MemoryBuffer if successful, otherwise returning null. 257 /// The IsText parameter controls whether the file should be opened as a text 258 /// or binary file, and should be set to false if the file contents should be 259 /// treated as binary. 260 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> 261 getBufferForFile(FileEntryRef Entry, bool isVolatile = false, 262 bool RequiresNullTerminator = true, 263 std::optional<int64_t> MaybeLimit = std::nullopt, 264 bool IsText = true); 265 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> 266 getBufferForFile(StringRef Filename, bool isVolatile = false, 267 bool RequiresNullTerminator = true, 268 std::optional<int64_t> MaybeLimit = std::nullopt, 269 bool IsText = true) const { 270 return getBufferForFileImpl(Filename, 271 /*FileSize=*/MaybeLimit.value_or(-1), 272 isVolatile, RequiresNullTerminator, IsText); 273 } 274 275 private: 276 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> 277 getBufferForFileImpl(StringRef Filename, int64_t FileSize, bool isVolatile, 278 bool RequiresNullTerminator, bool IsText) const; 279 280 DirectoryEntry *&getRealDirEntry(const llvm::vfs::Status &Status); 281 282 public: 283 /// Get the 'stat' information for the given \p Path. 284 /// 285 /// If the path is relative, it will be resolved against the WorkingDir of the 286 /// FileManager's FileSystemOptions. 287 /// 288 /// \returns a \c std::error_code describing an error, if there was one 289 std::error_code getNoncachedStatValue(StringRef Path, 290 llvm::vfs::Status &Result); 291 292 /// If path is not absolute and FileSystemOptions set the working 293 /// directory, the path is modified to be relative to the given 294 /// working directory. 295 /// \returns true if \c path changed. 296 bool FixupRelativePath(SmallVectorImpl<char> &path) const; 297 298 /// Makes \c Path absolute taking into account FileSystemOptions and the 299 /// working directory option. 300 /// \returns true if \c Path changed to absolute. 301 bool makeAbsolutePath(SmallVectorImpl<char> &Path) const; 302 303 /// Produce an array mapping from the unique IDs assigned to each 304 /// file to the corresponding FileEntryRef. 305 void 306 GetUniqueIDMapping(SmallVectorImpl<OptionalFileEntryRef> &UIDToFiles) const; 307 308 /// Retrieve the canonical name for a given directory. 309 /// 310 /// This is a very expensive operation, despite its results being cached, 311 /// and should only be used when the physical layout of the file system is 312 /// required, which is (almost) never. 313 StringRef getCanonicalName(DirectoryEntryRef Dir); 314 315 /// Retrieve the canonical name for a given file. 316 /// 317 /// This is a very expensive operation, despite its results being cached, 318 /// and should only be used when the physical layout of the file system is 319 /// required, which is (almost) never. 320 StringRef getCanonicalName(FileEntryRef File); 321 322 private: 323 /// Retrieve the canonical name for a given file or directory. 324 /// 325 /// The first param is a key in the CanonicalNames array. 326 StringRef getCanonicalName(const void *Entry, StringRef Name); 327 328 public: 329 void PrintStats() const; 330 331 /// Import statistics from a child FileManager and add them to this current 332 /// FileManager. 333 void AddStats(const FileManager &Other); 334 }; 335 336 } // end namespace clang 337 338 #endif // LLVM_CLANG_BASIC_FILEMANAGER_H 339