FileManager.h source code [clang_source_code/include/clang/Basic/FileManager.h]

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/FileSystemOptions.h"
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).
45	class DirectoryEntry {
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 IsValid; // Is this \c FileEntry initialized and valid?
71
72	/// The open file, if it is owned by the \p FileEntry.
73	mutable std::unique_ptr<llvm::vfs::File> File;
74
75	public:
76	FileEntry()
77	: UniqueID(0, 0), IsNamedPipe(false), IsValid(false)
78	{}
79
80	FileEntry(const FileEntry &) = delete;
81	FileEntry &operator=(const FileEntry &) = delete;
82
83	StringRef getName() const { return Name; }
84	StringRef tryGetRealPathName() const { return RealPathName; }
85	bool isValid() const { return IsValid; }
86	off_t getSize() const { return Size; }
87	unsigned getUID() const { return UID; }
88	const llvm::sys::fs::UniqueID &getUniqueID() const { return UniqueID; }
89	time_t getModificationTime() const { return ModTime; }
90
91	/// Return the directory the file lives in.
92	const DirectoryEntry *getDir() const { return Dir; }
93
94	bool operator<(const FileEntry &RHS) const { return UniqueID < RHS.UniqueID; }
95
96	/// Check whether the file is a named pipe (and thus can't be opened by
97	/// the native FileManager methods).
98	bool isNamedPipe() const { return IsNamedPipe; }
99
100	void closeFile() const {
101	File.reset(); // rely on destructor to close File
102	}
103
104	// Only for use in tests to see if deferred opens are happening, rather than
105	// relying on RealPathName being empty.
106	bool isOpenForTests() const { return File != nullptr; }
107	};
108
109	/// 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	///
116	class FileManager : public RefCountedBase<FileManager> {
117	IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS;
118	FileSystemOptions FileSystemOpts;
119
120	/// Cache for existing real directories.
121	std::map<llvm::sys::fs::UniqueID, DirectoryEntry> UniqueRealDirs;
122
123	/// Cache for existing real files.
124	std::map<llvm::sys::fs::UniqueID, FileEntry> UniqueRealFiles;
125
126	/// 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	/// The virtual files that we have allocated.
132	SmallVector<std::unique_ptr<FileEntry>, 4> VirtualFileEntries;
133
134	/// 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	/// 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	/// The canonical names of directories.
151	llvm::DenseMap<const DirectoryEntry *, llvm::StringRef> CanonicalDirNames;
152
153	/// Storage for canonical names that we have computed.
154	llvm::BumpPtrAllocator CanonicalNameStorage;
155
156	/// 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, llvm::vfs::Status &Status, bool isFile,
168	std::unique_ptr<llvm::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
174	/// Fills the RealPathName in file entry.
175	void fillRealPathName(FileEntry *UFE, llvm::StringRef FileName);
176
177	public:
178	/// Construct a file manager, optionally with a custom VFS.
179	///
180	/// \param FS if non-null, the VFS to use. Otherwise uses
181	/// llvm::vfs::getRealFileSystem().
182	FileManager(const FileSystemOptions &FileSystemOpts,
183	IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS = nullptr);
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
224	llvm::vfs::FileSystem &getVirtualFileSystem() const { return *FS; }
225
226	/// Retrieve a file entry for a "virtual" file that acts as
227	/// if there were a file with the given name on disk.
228	///
229	/// The file itself is not accessed.
230	const FileEntry *getVirtualFile(StringRef Filename, off_t Size,
231	time_t ModificationTime);
232
233	/// Open the specified file as a MemoryBuffer, returning a new
234	/// MemoryBuffer if successful, otherwise returning null.
235	llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
236	getBufferForFile(const FileEntry *Entry, bool isVolatile = false,
237	bool ShouldCloseOpenFile = true);
238	llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
239	getBufferForFile(StringRef Filename, bool isVolatile = false);
240
241	/// Get the 'stat' information for the given \p Path.
242	///
243	/// If the path is relative, it will be resolved against the WorkingDir of the
244	/// FileManager's FileSystemOptions.
245	///
246	/// \returns false on success, true on error.
247	bool getNoncachedStatValue(StringRef Path, llvm::vfs::Status &Result);
248
249	/// Remove the real file \p Entry from the cache.
250	void invalidateCache(const FileEntry *Entry);
251
252	/// If path is not absolute and FileSystemOptions set the working
253	/// directory, the path is modified to be relative to the given
254	/// working directory.
255	/// \returns true if \c path changed.
256	bool FixupRelativePath(SmallVectorImpl<char> &path) const;
257
258	/// Makes \c Path absolute taking into account FileSystemOptions and the
259	/// working directory option.
260	/// \returns true if \c Path changed to absolute.
261	bool makeAbsolutePath(SmallVectorImpl<char> &Path) const;
262
263	/// Produce an array mapping from the unique IDs assigned to each
264	/// file to the corresponding FileEntry pointer.
265	void GetUniqueIDMapping(
266	SmallVectorImpl<const FileEntry *> &UIDToFiles) const;
267
268	/// Modifies the size and modification time of a previously created
269	/// FileEntry. Use with caution.
270	static void modifyFileEntry(FileEntry *File, off_t Size,
271	time_t ModificationTime);
272
273	/// Retrieve the canonical name for a given directory.
274	///
275	/// This is a very expensive operation, despite its results being cached,
276	/// and should only be used when the physical layout of the file system is
277	/// required, which is (almost) never.
278	StringRef getCanonicalName(const DirectoryEntry *Dir);
279
280	void PrintStats() const;
281	};
282
283	} // end namespace clang
284
285	#endif // LLVM_CLANG_BASIC_FILEMANAGER_H
286