clang  9.0.0svn
FileManager.h
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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 
18 #include "clang/Basic/LLVM.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/IntrusiveRefCntPtr.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringMap.h"
23 #include "llvm/ADT/StringRef.h"
24 #include "llvm/Support/Allocator.h"
25 #include "llvm/Support/ErrorOr.h"
26 #include "llvm/Support/FileSystem.h"
27 #include "llvm/Support/VirtualFileSystem.h"
28 #include <ctime>
29 #include <map>
30 #include <memory>
31 #include <string>
32 
33 namespace llvm {
34 
35 class MemoryBuffer;
36 
37 } // end namespace llvm
38 
39 namespace clang {
40 
41 class FileSystemStatCache;
42 
43 /// Cached information about one directory (either on disk or in
44 /// the virtual file system).
46  friend class FileManager;
47 
48  StringRef Name; // Name of the directory.
49 
50 public:
51  StringRef getName() const { return Name; }
52 };
53 
54 /// Cached information about one file (either on disk
55 /// or in the virtual file system).
56 ///
57 /// If the 'File' member is valid, then this FileEntry has an open file
58 /// descriptor for the file.
59 class FileEntry {
60  friend class FileManager;
61 
62  StringRef Name; // Name of the file.
63  std::string RealPathName; // Real path to the file; could be empty.
64  off_t Size; // File size in bytes.
65  time_t ModTime; // Modification time of file.
66  const DirectoryEntry *Dir; // Directory file lives in.
67  unsigned UID; // A unique (small) ID for the file.
68  llvm::sys::fs::UniqueID UniqueID;
69  bool IsNamedPipe;
70  bool InPCH;
71  bool IsValid; // Is this \c FileEntry initialized and valid?
72 
73  /// The open file, if it is owned by the \p FileEntry.
74  mutable std::unique_ptr<llvm::vfs::File> File;
75 
76 public:
78  : UniqueID(0, 0), IsNamedPipe(false), InPCH(false), IsValid(false)
79  {}
80 
81  FileEntry(const FileEntry &) = delete;
82  FileEntry &operator=(const FileEntry &) = delete;
83 
84  StringRef getName() const { return Name; }
85  StringRef tryGetRealPathName() const { return RealPathName; }
86  bool isValid() const { return IsValid; }
87  off_t getSize() const { return Size; }
88  unsigned getUID() const { return UID; }
89  const llvm::sys::fs::UniqueID &getUniqueID() const { return UniqueID; }
90  bool isInPCH() const { return InPCH; }
91  time_t getModificationTime() const { return ModTime; }
92 
93  /// Return the directory the file lives in.
94  const DirectoryEntry *getDir() const { return Dir; }
95 
96  bool operator<(const FileEntry &RHS) const { return UniqueID < RHS.UniqueID; }
97 
98  /// Check whether the file is a named pipe (and thus can't be opened by
99  /// the native FileManager methods).
100  bool isNamedPipe() const { return IsNamedPipe; }
101 
102  void closeFile() const {
103  File.reset(); // rely on destructor to close File
104  }
105 
106  // Only for use in tests to see if deferred opens are happening, rather than
107  // relying on RealPathName being empty.
108  bool isOpenForTests() const { return File != nullptr; }
109 };
110 
111 struct FileData;
112 
113 /// Implements support for file system lookup, file system caching,
114 /// and directory search management.
115 ///
116 /// This also handles more advanced properties, such as uniquing files based
117 /// on "inode", so that a file with two names (e.g. symlinked) will be treated
118 /// as a single file.
119 ///
120 class FileManager : public RefCountedBase<FileManager> {
122  FileSystemOptions FileSystemOpts;
123 
124  /// Cache for existing real directories.
125  std::map<llvm::sys::fs::UniqueID, DirectoryEntry> UniqueRealDirs;
126 
127  /// Cache for existing real files.
128  std::map<llvm::sys::fs::UniqueID, FileEntry> UniqueRealFiles;
129 
130  /// The virtual directories that we have allocated.
131  ///
132  /// For each virtual file (e.g. foo/bar/baz.cpp), we add all of its parent
133  /// directories (foo/ and foo/bar/) here.
134  SmallVector<std::unique_ptr<DirectoryEntry>, 4> VirtualDirectoryEntries;
135  /// The virtual files that we have allocated.
136  SmallVector<std::unique_ptr<FileEntry>, 4> VirtualFileEntries;
137 
138  /// A cache that maps paths to directory entries (either real or
139  /// virtual) we have looked up
140  ///
141  /// The actual Entries for real directories/files are
142  /// owned by UniqueRealDirs/UniqueRealFiles above, while the Entries
143  /// for virtual directories/files are owned by
144  /// VirtualDirectoryEntries/VirtualFileEntries above.
145  ///
146  llvm::StringMap<DirectoryEntry*, llvm::BumpPtrAllocator> SeenDirEntries;
147 
148  /// A cache that maps paths to file entries (either real or
149  /// virtual) we have looked up.
150  ///
151  /// \see SeenDirEntries
152  llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator> SeenFileEntries;
153 
154  /// The canonical names of directories.
155  llvm::DenseMap<const DirectoryEntry *, llvm::StringRef> CanonicalDirNames;
156 
157  /// Storage for canonical names that we have computed.
158  llvm::BumpPtrAllocator CanonicalNameStorage;
159 
160  /// Each FileEntry we create is assigned a unique ID #.
161  ///
162  unsigned NextFileUID;
163 
164  // Statistics.
165  unsigned NumDirLookups, NumFileLookups;
166  unsigned NumDirCacheMisses, NumFileCacheMisses;
167 
168  // Caching.
169  std::unique_ptr<FileSystemStatCache> StatCache;
170 
171  bool getStatValue(StringRef Path, FileData &Data, bool isFile,
172  std::unique_ptr<llvm::vfs::File> *F);
173 
174  /// Add all ancestors of the given path (pointing to either a file
175  /// or a directory) as virtual directories.
176  void addAncestorsAsVirtualDirs(StringRef Path);
177 
178  /// Fills the RealPathName in file entry.
179  void fillRealPathName(FileEntry *UFE, llvm::StringRef FileName);
180 
181 public:
182  FileManager(const FileSystemOptions &FileSystemOpts,
184  ~FileManager();
185 
186  /// Installs the provided FileSystemStatCache object within
187  /// the FileManager.
188  ///
189  /// Ownership of this object is transferred to the FileManager.
190  ///
191  /// \param statCache the new stat cache to install. Ownership of this
192  /// object is transferred to the FileManager.
193  void setStatCache(std::unique_ptr<FileSystemStatCache> statCache);
194 
195  /// Removes the FileSystemStatCache object from the manager.
196  void clearStatCache();
197 
198  /// Lookup, cache, and verify the specified directory (real or
199  /// virtual).
200  ///
201  /// This returns NULL if the directory doesn't exist.
202  ///
203  /// \param CacheFailure If true and the file does not exist, we'll cache
204  /// the failure to find this file.
205  const DirectoryEntry *getDirectory(StringRef DirName,
206  bool CacheFailure = true);
207 
208  /// Lookup, cache, and verify the specified file (real or
209  /// virtual).
210  ///
211  /// This returns NULL if the file doesn't exist.
212  ///
213  /// \param OpenFile if true and the file exists, it will be opened.
214  ///
215  /// \param CacheFailure If true and the file does not exist, we'll cache
216  /// the failure to find this file.
217  const FileEntry *getFile(StringRef Filename, bool OpenFile = false,
218  bool CacheFailure = true);
219 
220  /// Returns the current file system options
221  FileSystemOptions &getFileSystemOpts() { return FileSystemOpts; }
222  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
223 
225  return FS;
226  }
227 
228  /// Retrieve a file entry for a "virtual" file that acts as
229  /// if there were a file with the given name on disk.
230  ///
231  /// The file itself is not accessed.
232  const FileEntry *getVirtualFile(StringRef Filename, off_t Size,
233  time_t ModificationTime);
234 
235  /// Open the specified file as a MemoryBuffer, returning a new
236  /// MemoryBuffer if successful, otherwise returning null.
237  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
238  getBufferForFile(const FileEntry *Entry, bool isVolatile = false,
239  bool ShouldCloseOpenFile = true);
240  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
241  getBufferForFile(StringRef Filename, bool isVolatile = false);
242 
243  /// Get the 'stat' information for the given \p Path.
244  ///
245  /// If the path is relative, it will be resolved against the WorkingDir of the
246  /// FileManager's FileSystemOptions.
247  ///
248  /// \returns false on success, true on error.
249  bool getNoncachedStatValue(StringRef Path, llvm::vfs::Status &Result);
250 
251  /// Remove the real file \p Entry from the cache.
252  void invalidateCache(const FileEntry *Entry);
253 
254  /// If path is not absolute and FileSystemOptions set the working
255  /// directory, the path is modified to be relative to the given
256  /// working directory.
257  /// \returns true if \c path changed.
258  bool FixupRelativePath(SmallVectorImpl<char> &path) const;
259 
260  /// Makes \c Path absolute taking into account FileSystemOptions and the
261  /// working directory option.
262  /// \returns true if \c Path changed to absolute.
263  bool makeAbsolutePath(SmallVectorImpl<char> &Path) const;
264 
265  /// Produce an array mapping from the unique IDs assigned to each
266  /// file to the corresponding FileEntry pointer.
267  void GetUniqueIDMapping(
268  SmallVectorImpl<const FileEntry *> &UIDToFiles) const;
269 
270  /// Modifies the size and modification time of a previously created
271  /// FileEntry. Use with caution.
272  static void modifyFileEntry(FileEntry *File, off_t Size,
273  time_t ModificationTime);
274 
275  /// Retrieve the canonical name for a given directory.
276  ///
277  /// This is a very expensive operation, despite its results being cached,
278  /// and should only be used when the physical layout of the file system is
279  /// required, which is (almost) never.
280  StringRef getCanonicalName(const DirectoryEntry *Dir);
281 
282  void PrintStats() const;
283 };
284 
285 } // end namespace clang
286 
287 #endif // LLVM_CLANG_BASIC_FILEMANAGER_H
StringRef tryGetRealPathName() const
Definition: FileManager.h:85
Implements support for file system lookup, file system caching, and directory search management...
Definition: FileManager.h:120
time_t getModificationTime() const
Definition: FileManager.h:91
DominatorTree GraphTraits specialization so the DominatorTree can be iterable by generic graph iterat...
Definition: Dominators.h:29
void closeFile() const
Definition: FileManager.h:102
const llvm::sys::fs::UniqueID & getUniqueID() const
Definition: FileManager.h:89
unsigned getUID() const
Definition: FileManager.h:88
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
StringRef Filename
Definition: Format.cpp:1628
const DirectoryEntry * getDir() const
Return the directory the file lives in.
Definition: FileManager.h:94
#define false
Definition: stdbool.h:33
StringRef getName() const
Definition: FileManager.h:84
FileSystemOptions & getFileSystemOpts()
Returns the current file system options.
Definition: FileManager.h:221
bool isNamedPipe() const
Check whether the file is a named pipe (and thus can&#39;t be opened by the native FileManager methods)...
Definition: FileManager.h:100
bool operator<(const FileEntry &RHS) const
Definition: FileManager.h:96
Cached information about one file (either on disk or in the virtual file system). ...
Definition: FileManager.h:59
const FileSystemOptions & getFileSystemOpts() const
Definition: FileManager.h:222
bool isValid() const
Definition: FileManager.h:86
Dataflow Directional Tag Classes.
bool isInPCH() const
Definition: FileManager.h:90
off_t getSize() const
Definition: FileManager.h:87
bool isOpenForTests() const
Definition: FileManager.h:108
Defines the clang::FileSystemOptions interface.
Cached information about one directory (either on disk or in the virtual file system).
Definition: FileManager.h:45
Keeps track of options that affect how file operations are performed.
IntrusiveRefCntPtr< llvm::vfs::FileSystem > getVirtualFileSystem() const
Definition: FileManager.h:224
StringRef getName() const
Definition: FileManager.h:51