1//===--- FileManager.h - File System Probing and Caching --------*- 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/// \file
11/// \brief Defines the clang::FileManager interface and associated types.
12///
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CLANG_BASIC_FILEMANAGER_H
16#define LLVM_CLANG_BASIC_FILEMANAGER_H
17
18#include "clang/Basic/FileSystemOptions.h"
19#include "clang/Basic/VirtualFileSystem.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/IntrusiveRefCntPtr.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/StringMap.h"
24#include "llvm/ADT/StringRef.h"
25#include "llvm/Support/Allocator.h"
26#include "llvm/Support/ErrorOr.h"
27#include "llvm/Support/FileSystem.h"
28#include <ctime>
29#include <memory>
30#include <map>
31#include <string>
32
33namespace llvm {
34
35class MemoryBuffer;
36
37} // end namespace llvm
38
39namespace clang {
40
41class FileSystemStatCache;
42
43/// \brief Cached information about one directory (either on disk or in
44/// the virtual file system).
45class DirectoryEntry {
46  friend class FileManager;
47
48  StringRef Name; // Name of the directory.
49
50public:
51  StringRef getName() const { return Name; }
52};
53
54/// \brief 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.
59class 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  /// \brief The open file, if it is owned by the \p FileEntry.
74  mutable std::unique_ptr<vfs::File> File;
75
76public:
77  FileEntry()
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  /// \brief 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  /// \brief 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
107struct FileData;
108
109/// \brief Implements support for file system lookup, file system caching,
110/// and directory search management.
111///
112/// This also handles more advanced properties, such as uniquing files based
113/// on "inode", so that a file with two names (e.g. symlinked) will be treated
114/// as a single file.
115///
116class FileManager : public RefCountedBase<FileManager> {
117  IntrusiveRefCntPtr<vfs::FileSystem> FS;
118  FileSystemOptions FileSystemOpts;
119
120  /// \brief Cache for existing real directories.
121  std::map<llvm::sys::fs::UniqueID, DirectoryEntry> UniqueRealDirs;
122
123  /// \brief Cache for existing real files.
124  std::map<llvm::sys::fs::UniqueID, FileEntry> UniqueRealFiles;
125
126  /// \brief The virtual directories that we have allocated.
127  ///
128  /// For each virtual file (e.g. foo/bar/baz.cpp), we add all of its parent
129  /// directories (foo/ and foo/bar/) here.
130  SmallVector<std::unique_ptr<DirectoryEntry>, 4> VirtualDirectoryEntries;
131  /// \brief The virtual files that we have allocated.
132  SmallVector<std::unique_ptr<FileEntry>, 4> VirtualFileEntries;
133
134  /// \brief A cache that maps paths to directory entries (either real or
135  /// virtual) we have looked up
136  ///
137  /// The actual Entries for real directories/files are
138  /// owned by UniqueRealDirs/UniqueRealFiles above, while the Entries
139  /// for virtual directories/files are owned by
140  /// VirtualDirectoryEntries/VirtualFileEntries above.
141  ///
142  llvm::StringMap<DirectoryEntry*, llvm::BumpPtrAllocator> SeenDirEntries;
143
144  /// \brief A cache that maps paths to file entries (either real or
145  /// virtual) we have looked up.
146  ///
147  /// \see SeenDirEntries
148  llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator> SeenFileEntries;
149
150  /// \brief The canonical names of directories.
151  llvm::DenseMap<const DirectoryEntry *, llvm::StringRef> CanonicalDirNames;
152
153  /// \brief Storage for canonical names that we have computed.
154  llvm::BumpPtrAllocator CanonicalNameStorage;
155
156  /// \brief Each FileEntry we create is assigned a unique ID #.
157  ///
158  unsigned NextFileUID;
159
160  // Statistics.
161  unsigned NumDirLookups, NumFileLookups;
162  unsigned NumDirCacheMisses, NumFileCacheMisses;
163
164  // Caching.
165  std::unique_ptr<FileSystemStatCache> StatCache;
166
167  bool getStatValue(StringRef Path, FileData &Data, bool isFile,
168                    std::unique_ptr<vfs::File> *F);
169
170  /// Add all ancestors of the given path (pointing to either a file
171  /// or a directory) as virtual directories.
172  void addAncestorsAsVirtualDirs(StringRef Path);
173
174public:
175  FileManager(const FileSystemOptions &FileSystemOpts,
176              IntrusiveRefCntPtr<vfs::FileSystem> FS = nullptr);
177  ~FileManager();
178
179  /// \brief Installs the provided FileSystemStatCache object within
180  /// the FileManager.
181  ///
182  /// Ownership of this object is transferred to the FileManager.
183  ///
184  /// \param statCache the new stat cache to install. Ownership of this
185  /// object is transferred to the FileManager.
186  ///
187  /// \param AtBeginning whether this new stat cache must be installed at the
188  /// beginning of the chain of stat caches. Otherwise, it will be added to
189  /// the end of the chain.
190  void addStatCache(std::unique_ptr<FileSystemStatCache> statCache,
191                    bool AtBeginning = false);
192
193  /// \brief Removes the specified FileSystemStatCache object from the manager.
194  void removeStatCache(FileSystemStatCache *statCache);
195
196  /// \brief Removes all FileSystemStatCache objects from the manager.
197  void clearStatCaches();
198
199  /// \brief Lookup, cache, and verify the specified directory (real or
200  /// virtual).
201  ///
202  /// This returns NULL if the directory doesn't exist.
203  ///
204  /// \param CacheFailure If true and the file does not exist, we'll cache
205  /// the failure to find this file.
206  const DirectoryEntry *getDirectory(StringRef DirName,
207                                     bool CacheFailure = true);
208
209  /// \brief Lookup, cache, and verify the specified file (real or
210  /// virtual).
211  ///
212  /// This returns NULL if the file doesn't exist.
213  ///
214  /// \param OpenFile if true and the file exists, it will be opened.
215  ///
216  /// \param CacheFailure If true and the file does not exist, we'll cache
217  /// the failure to find this file.
218  const FileEntry *getFile(StringRef Filename, bool OpenFile = false,
219                           bool CacheFailure = true);
220
221  /// \brief Returns the current file system options
222  FileSystemOptions &getFileSystemOpts() { return FileSystemOpts; }
223  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
224
225  IntrusiveRefCntPtr<vfs::FileSystem> getVirtualFileSystem() const {
226    return FS;
227  }
228
229  /// \brief Retrieve a file entry for a "virtual" file that acts as
230  /// if there were a file with the given name on disk.
231  ///
232  /// The file itself is not accessed.
233  const FileEntry *getVirtualFile(StringRef Filename, off_t Size,
234                                  time_t ModificationTime);
235
236  /// \brief Open the specified file as a MemoryBuffer, returning a new
237  /// MemoryBuffer if successful, otherwise returning null.
238  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
239  getBufferForFile(const FileEntry *Entry, bool isVolatile = false,
240                   bool ShouldCloseOpenFile = true);
241  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
242  getBufferForFile(StringRef Filename);
243
244  /// \brief Get the 'stat' information for the given \p Path.
245  ///
246  /// If the path is relative, it will be resolved against the WorkingDir of the
247  /// FileManager's FileSystemOptions.
248  ///
249  /// \returns false on success, true on error.
250  bool getNoncachedStatValue(StringRef Path,
251                             vfs::Status &Result);
252
253  /// \brief Remove the real file \p Entry from the cache.
254  void invalidateCache(const FileEntry *Entry);
255
256  /// \brief If path is not absolute and FileSystemOptions set the working
257  /// directory, the path is modified to be relative to the given
258  /// working directory.
259  /// \returns true if \c path changed.
260  bool FixupRelativePath(SmallVectorImpl<char> &path) const;
261
262  /// Makes \c Path absolute taking into account FileSystemOptions and the
263  /// working directory option.
264  /// \returns true if \c Path changed to absolute.
265  bool makeAbsolutePath(SmallVectorImpl<char> &Path) const;
266
267  /// \brief Produce an array mapping from the unique IDs assigned to each
268  /// file to the corresponding FileEntry pointer.
269  void GetUniqueIDMapping(
270                    SmallVectorImpl<const FileEntry *> &UIDToFiles) const;
271
272  /// \brief Modifies the size and modification time of a previously created
273  /// FileEntry. Use with caution.
274  static void modifyFileEntry(FileEntry *File, off_t Size,
275                              time_t ModificationTime);
276
277  /// \brief Retrieve the canonical name for a given directory.
278  ///
279  /// This is a very expensive operation, despite its results being cached,
280  /// and should only be used when the physical layout of the file system is
281  /// required, which is (almost) never.
282  StringRef getCanonicalName(const DirectoryEntry *Dir);
283
284  void PrintStats() const;
285};
286
287} // end namespace clang
288
289#endif // LLVM_CLANG_BASIC_FILEMANAGER_H
290