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_FILEMANAGER_H
16#define LLVM_CLANG_FILEMANAGER_H
17
18#include "clang/Basic/FileSystemOptions.h"
19#include "clang/Basic/LLVM.h"
20#include "clang/Basic/VirtualFileSystem.h"
21#include "llvm/ADT/DenseMap.h"
22#include "llvm/ADT/IntrusiveRefCntPtr.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/StringMap.h"
25#include "llvm/ADT/StringRef.h"
26#include "llvm/Support/Allocator.h"
27#include <memory>
28// FIXME: Enhance libsystem to support inode and other fields in stat.
29#include <sys/types.h>
30#include <map>
31
32#ifdef _MSC_VER
33typedef unsigned short mode_t;
34#endif
35
36struct stat;
37
38namespace llvm {
39class MemoryBuffer;
40}
41
42namespace clang {
43class FileManager;
44class FileSystemStatCache;
45
46/// \brief Cached information about one directory (either on disk or in
47/// the virtual file system).
48class DirectoryEntry {
49  const char *Name;   // Name of the directory.
50  friend class FileManager;
51public:
52  DirectoryEntry() : Name(nullptr) {}
53  const char *getName() const { return Name; }
54};
55
56/// \brief Cached information about one file (either on disk
57/// or in the virtual file system).
58///
59/// If the 'File' member is valid, then this FileEntry has an open file
60/// descriptor for the file.
61class FileEntry {
62  std::string Name;           // Name of the file.
63  off_t Size;                 // File size in bytes.
64  time_t ModTime;             // Modification time of file.
65  const DirectoryEntry *Dir;  // Directory file lives in.
66  unsigned UID;               // A unique (small) ID for the file.
67  llvm::sys::fs::UniqueID UniqueID;
68  bool IsNamedPipe;
69  bool InPCH;
70  bool IsValid;               // Is this \c FileEntry initialized and valid?
71
72  /// \brief The open file, if it is owned by the \p FileEntry.
73  mutable std::unique_ptr<vfs::File> File;
74  friend class FileManager;
75
76  void closeFile() const {
77    File.reset(nullptr); // rely on destructor to close File
78  }
79
80  void operator=(const FileEntry &) LLVM_DELETED_FUNCTION;
81
82public:
83  FileEntry()
84      : UniqueID(0, 0), IsNamedPipe(false), InPCH(false), IsValid(false)
85  {}
86
87  // FIXME: this is here to allow putting FileEntry in std::map.  Once we have
88  // emplace, we shouldn't need a copy constructor anymore.
89  /// Intentionally does not copy fields that are not set in an uninitialized
90  /// \c FileEntry.
91  FileEntry(const FileEntry &FE) : UniqueID(FE.UniqueID),
92      IsNamedPipe(FE.IsNamedPipe), InPCH(FE.InPCH), IsValid(FE.IsValid) {
93    assert(!isValid() && "Cannot copy an initialized FileEntry");
94  }
95
96  const char *getName() const { return Name.c_str(); }
97  bool isValid() const { return IsValid; }
98  off_t getSize() const { return Size; }
99  unsigned getUID() const { return UID; }
100  const llvm::sys::fs::UniqueID &getUniqueID() const { return UniqueID; }
101  bool isInPCH() const { return InPCH; }
102  time_t getModificationTime() const { return ModTime; }
103
104  /// \brief Return the directory the file lives in.
105  const DirectoryEntry *getDir() const { return Dir; }
106
107  bool operator<(const FileEntry &RHS) const { return UniqueID < RHS.UniqueID; }
108
109  /// \brief Check whether the file is a named pipe (and thus can't be opened by
110  /// the native FileManager methods).
111  bool isNamedPipe() const { return IsNamedPipe; }
112};
113
114struct FileData;
115
116/// \brief Implements support for file system lookup, file system caching,
117/// and directory search management.
118///
119/// This also handles more advanced properties, such as uniquing files based
120/// on "inode", so that a file with two names (e.g. symlinked) will be treated
121/// as a single file.
122///
123class FileManager : public RefCountedBase<FileManager> {
124  IntrusiveRefCntPtr<vfs::FileSystem> FS;
125  FileSystemOptions FileSystemOpts;
126
127  /// \brief Cache for existing real directories.
128  std::map<llvm::sys::fs::UniqueID, DirectoryEntry> UniqueRealDirs;
129
130  /// \brief Cache for existing real files.
131  std::map<llvm::sys::fs::UniqueID, FileEntry> UniqueRealFiles;
132
133  /// \brief The virtual directories that we have allocated.
134  ///
135  /// For each virtual file (e.g. foo/bar/baz.cpp), we add all of its parent
136  /// directories (foo/ and foo/bar/) here.
137  SmallVector<DirectoryEntry*, 4> VirtualDirectoryEntries;
138  /// \brief The virtual files that we have allocated.
139  SmallVector<FileEntry*, 4> VirtualFileEntries;
140
141  /// \brief A cache that maps paths to directory entries (either real or
142  /// virtual) we have looked up
143  ///
144  /// The actual Entries for real directories/files are
145  /// owned by UniqueRealDirs/UniqueRealFiles above, while the Entries
146  /// for virtual directories/files are owned by
147  /// VirtualDirectoryEntries/VirtualFileEntries above.
148  ///
149  llvm::StringMap<DirectoryEntry*, llvm::BumpPtrAllocator> SeenDirEntries;
150
151  /// \brief A cache that maps paths to file entries (either real or
152  /// virtual) we have looked up.
153  ///
154  /// \see SeenDirEntries
155  llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator> SeenFileEntries;
156
157  /// \brief The canonical names of directories.
158  llvm::DenseMap<const DirectoryEntry *, llvm::StringRef> CanonicalDirNames;
159
160  /// \brief Storage for canonical names that we have computed.
161  llvm::BumpPtrAllocator CanonicalNameStorage;
162
163  /// \brief Each FileEntry we create is assigned a unique ID #.
164  ///
165  unsigned NextFileUID;
166
167  // Statistics.
168  unsigned NumDirLookups, NumFileLookups;
169  unsigned NumDirCacheMisses, NumFileCacheMisses;
170
171  // Caching.
172  std::unique_ptr<FileSystemStatCache> StatCache;
173
174  bool getStatValue(const char *Path, FileData &Data, bool isFile,
175                    std::unique_ptr<vfs::File> *F);
176
177  /// Add all ancestors of the given path (pointing to either a file
178  /// or a directory) as virtual directories.
179  void addAncestorsAsVirtualDirs(StringRef Path);
180
181public:
182  FileManager(const FileSystemOptions &FileSystemOpts,
183              IntrusiveRefCntPtr<vfs::FileSystem> FS = nullptr);
184  ~FileManager();
185
186  /// \brief 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  ///
194  /// \param AtBeginning whether this new stat cache must be installed at the
195  /// beginning of the chain of stat caches. Otherwise, it will be added to
196  /// the end of the chain.
197  void addStatCache(FileSystemStatCache *statCache, bool AtBeginning = false);
198
199  /// \brief Removes the specified FileSystemStatCache object from the manager.
200  void removeStatCache(FileSystemStatCache *statCache);
201
202  /// \brief Removes all FileSystemStatCache objects from the manager.
203  void clearStatCaches();
204
205  /// \brief Lookup, cache, and verify the specified directory (real or
206  /// virtual).
207  ///
208  /// This returns NULL if the directory doesn't exist.
209  ///
210  /// \param CacheFailure If true and the file does not exist, we'll cache
211  /// the failure to find this file.
212  const DirectoryEntry *getDirectory(StringRef DirName,
213                                     bool CacheFailure = true);
214
215  /// \brief Lookup, cache, and verify the specified file (real or
216  /// virtual).
217  ///
218  /// This returns NULL if the file doesn't exist.
219  ///
220  /// \param OpenFile if true and the file exists, it will be opened.
221  ///
222  /// \param CacheFailure If true and the file does not exist, we'll cache
223  /// the failure to find this file.
224  const FileEntry *getFile(StringRef Filename, bool OpenFile = false,
225                           bool CacheFailure = true);
226
227  /// \brief Returns the current file system options
228  const FileSystemOptions &getFileSystemOptions() { return FileSystemOpts; }
229
230  IntrusiveRefCntPtr<vfs::FileSystem> getVirtualFileSystem() const {
231    return FS;
232  }
233
234  /// \brief Retrieve a file entry for a "virtual" file that acts as
235  /// if there were a file with the given name on disk.
236  ///
237  /// The file itself is not accessed.
238  const FileEntry *getVirtualFile(StringRef Filename, off_t Size,
239                                  time_t ModificationTime);
240
241  /// \brief Open the specified file as a MemoryBuffer, returning a new
242  /// MemoryBuffer if successful, otherwise returning null.
243  llvm::MemoryBuffer *getBufferForFile(const FileEntry *Entry,
244                                       std::string *ErrorStr = nullptr,
245                                       bool isVolatile = false,
246                                       bool ShouldCloseOpenFile = true);
247  llvm::MemoryBuffer *getBufferForFile(StringRef Filename,
248                                       std::string *ErrorStr = nullptr);
249
250  /// \brief Get the 'stat' information for the given \p Path.
251  ///
252  /// If the path is relative, it will be resolved against the WorkingDir of the
253  /// FileManager's FileSystemOptions.
254  ///
255  /// \returns false on success, true on error.
256  bool getNoncachedStatValue(StringRef Path,
257                             vfs::Status &Result);
258
259  /// \brief Remove the real file \p Entry from the cache.
260  void invalidateCache(const FileEntry *Entry);
261
262  /// \brief If path is not absolute and FileSystemOptions set the working
263  /// directory, the path is modified to be relative to the given
264  /// working directory.
265  void FixupRelativePath(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
290