aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Basic/FileManager.cpp
blob: 88a7a12508375e01fc381781e6cdfd83a68b6888 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
//===--- FileManager.cpp - File System Probing and Caching ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file implements the FileManager interface.
//
//===----------------------------------------------------------------------===//
//
// TODO: This should index all interesting directories with dirent calls.
//  getdirentries ?
//  opendir/readdir_r/closedir ?
//
//===----------------------------------------------------------------------===//

#include "clang/Basic/FileManager.h"
#include "clang/Basic/FileSystemStatCache.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <climits>
#include <cstdint>
#include <cstdlib>
#include <string>
#include <utility>

using namespace clang;

#define DEBUG_TYPE "file-search"

ALWAYS_ENABLED_STATISTIC(NumDirLookups, "Number of directory lookups.");
ALWAYS_ENABLED_STATISTIC(NumFileLookups, "Number of file lookups.");
ALWAYS_ENABLED_STATISTIC(NumDirCacheMisses,
                         "Number of directory cache misses.");
ALWAYS_ENABLED_STATISTIC(NumFileCacheMisses, "Number of file cache misses.");

//===----------------------------------------------------------------------===//
// Common logic.
//===----------------------------------------------------------------------===//

FileManager::FileManager(const FileSystemOptions &FSO,
                         IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
    : FS(std::move(FS)), FileSystemOpts(FSO), SeenDirEntries(64),
      SeenFileEntries(64), NextFileUID(0) {
  // If the caller doesn't provide a virtual file system, just grab the real
  // file system.
  if (!this->FS)
    this->FS = llvm::vfs::getRealFileSystem();
}

FileManager::~FileManager() = default;

void FileManager::setStatCache(std::unique_ptr<FileSystemStatCache> statCache) {
  assert(statCache && "No stat cache provided?");
  StatCache = std::move(statCache);
}

void FileManager::clearStatCache() { StatCache.reset(); }

/// Retrieve the directory that the given file name resides in.
/// Filename can point to either a real file or a virtual file.
static llvm::ErrorOr<const DirectoryEntry *>
getDirectoryFromFile(FileManager &FileMgr, StringRef Filename,
                     bool CacheFailure) {
  if (Filename.empty())
    return std::errc::no_such_file_or_directory;

  if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
    return std::errc::is_a_directory;

  StringRef DirName = llvm::sys::path::parent_path(Filename);
  // Use the current directory if file has no path component.
  if (DirName.empty())
    DirName = ".";

  return FileMgr.getDirectory(DirName, CacheFailure);
}

/// Add all ancestors of the given path (pointing to either a file or
/// a directory) as virtual directories.
void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
  StringRef DirName = llvm::sys::path::parent_path(Path);
  if (DirName.empty())
    DirName = ".";

  auto &NamedDirEnt = *SeenDirEntries.insert(
        {DirName, std::errc::no_such_file_or_directory}).first;

  // When caching a virtual directory, we always cache its ancestors
  // at the same time.  Therefore, if DirName is already in the cache,
  // we don't need to recurse as its ancestors must also already be in
  // the cache (or it's a known non-virtual directory).
  if (NamedDirEnt.second)
    return;

  // Add the virtual directory to the cache.
  auto UDE = std::make_unique<DirectoryEntry>();
  UDE->Name = NamedDirEnt.first();
  NamedDirEnt.second = *UDE.get();
  VirtualDirectoryEntries.push_back(std::move(UDE));

  // Recursively add the other ancestors.
  addAncestorsAsVirtualDirs(DirName);
}

llvm::Expected<DirectoryEntryRef>
FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) {
  // stat doesn't like trailing separators except for root directory.
  // At least, on Win32 MSVCRT, stat() cannot strip trailing '/'.
  // (though it can strip '\\')
  if (DirName.size() > 1 &&
      DirName != llvm::sys::path::root_path(DirName) &&
      llvm::sys::path::is_separator(DirName.back()))
    DirName = DirName.substr(0, DirName.size()-1);
#ifdef _WIN32
  // Fixing a problem with "clang C:test.c" on Windows.
  // Stat("C:") does not recognize "C:" as a valid directory
  std::string DirNameStr;
  if (DirName.size() > 1 && DirName.back() == ':' &&
      DirName.equals_lower(llvm::sys::path::root_name(DirName))) {
    DirNameStr = DirName.str() + '.';
    DirName = DirNameStr;
  }
#endif

  ++NumDirLookups;

  // See if there was already an entry in the map.  Note that the map
  // contains both virtual and real directories.
  auto SeenDirInsertResult =
      SeenDirEntries.insert({DirName, std::errc::no_such_file_or_directory});
  if (!SeenDirInsertResult.second) {
    if (SeenDirInsertResult.first->second)
      return DirectoryEntryRef(&*SeenDirInsertResult.first);
    return llvm::errorCodeToError(SeenDirInsertResult.first->second.getError());
  }

  // We've not seen this before. Fill it in.
  ++NumDirCacheMisses;
  auto &NamedDirEnt = *SeenDirInsertResult.first;
  assert(!NamedDirEnt.second && "should be newly-created");

  // Get the null-terminated directory name as stored as the key of the
  // SeenDirEntries map.
  StringRef InterndDirName = NamedDirEnt.first();

  // Check to see if the directory exists.
  llvm::vfs::Status Status;
  auto statError = getStatValue(InterndDirName, Status, false,
                                nullptr /*directory lookup*/);
  if (statError) {
    // There's no real directory at the given path.
    if (CacheFailure)
      NamedDirEnt.second = statError;
    else
      SeenDirEntries.erase(DirName);
    return llvm::errorCodeToError(statError);
  }

  // It exists.  See if we have already opened a directory with the
  // same inode (this occurs on Unix-like systems when one dir is
  // symlinked to another, for example) or the same path (on
  // Windows).
  DirectoryEntry &UDE = UniqueRealDirs[Status.getUniqueID()];

  NamedDirEnt.second = UDE;
  if (UDE.getName().empty()) {
    // We don't have this directory yet, add it.  We use the string
    // key from the SeenDirEntries map as the string.
    UDE.Name  = InterndDirName;
  }

  return DirectoryEntryRef(&NamedDirEnt);
}

llvm::ErrorOr<const DirectoryEntry *>
FileManager::getDirectory(StringRef DirName, bool CacheFailure) {
  auto Result = getDirectoryRef(DirName, CacheFailure);
  if (Result)
    return &Result->getDirEntry();
  return llvm::errorToErrorCode(Result.takeError());
}

llvm::ErrorOr<const FileEntry *>
FileManager::getFile(StringRef Filename, bool openFile, bool CacheFailure) {
  auto Result = getFileRef(Filename, openFile, CacheFailure);
  if (Result)
    return &Result->getFileEntry();
  return llvm::errorToErrorCode(Result.takeError());
}

llvm::Expected<FileEntryRef>
FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
  ++NumFileLookups;

  // See if there is already an entry in the map.
  auto SeenFileInsertResult =
      SeenFileEntries.insert({Filename, std::errc::no_such_file_or_directory});
  if (!SeenFileInsertResult.second) {
    if (!SeenFileInsertResult.first->second)
      return llvm::errorCodeToError(
          SeenFileInsertResult.first->second.getError());
    // Construct and return and FileEntryRef, unless it's a redirect to another
    // filename.
    SeenFileEntryOrRedirect Value = *SeenFileInsertResult.first->second;
    FileEntry *FE;
    if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>()))
      return FileEntryRef(SeenFileInsertResult.first->first(), *FE);
    return getFileRef(*Value.get<const StringRef *>(), openFile, CacheFailure);
  }

  // We've not seen this before. Fill it in.
  ++NumFileCacheMisses;
  auto &NamedFileEnt = *SeenFileInsertResult.first;
  assert(!NamedFileEnt.second && "should be newly-created");

  // Get the null-terminated file name as stored as the key of the
  // SeenFileEntries map.
  StringRef InterndFileName = NamedFileEnt.first();

  // Look up the directory for the file.  When looking up something like
  // sys/foo.h we'll discover all of the search directories that have a 'sys'
  // subdirectory.  This will let us avoid having to waste time on known-to-fail
  // searches when we go to find sys/bar.h, because all the search directories
  // without a 'sys' subdir will get a cached failure result.
  auto DirInfoOrErr = getDirectoryFromFile(*this, Filename, CacheFailure);
  if (!DirInfoOrErr) { // Directory doesn't exist, file can't exist.
    if (CacheFailure)
      NamedFileEnt.second = DirInfoOrErr.getError();
    else
      SeenFileEntries.erase(Filename);

    return llvm::errorCodeToError(DirInfoOrErr.getError());
  }
  const DirectoryEntry *DirInfo = *DirInfoOrErr;

  // FIXME: Use the directory info to prune this, before doing the stat syscall.
  // FIXME: This will reduce the # syscalls.

  // Check to see if the file exists.
  std::unique_ptr<llvm::vfs::File> F;
  llvm::vfs::Status Status;
  auto statError = getStatValue(InterndFileName, Status, true,
                                openFile ? &F : nullptr);
  if (statError) {
    // There's no real file at the given path.
    if (CacheFailure)
      NamedFileEnt.second = statError;
    else
      SeenFileEntries.erase(Filename);

    return llvm::errorCodeToError(statError);
  }

  assert((openFile || !F) && "undesired open file");

  // It exists.  See if we have already opened a file with the same inode.
  // This occurs when one dir is symlinked to another, for example.
  FileEntry &UFE = UniqueRealFiles[Status.getUniqueID()];

  NamedFileEnt.second = &UFE;

  // If the name returned by getStatValue is different than Filename, re-intern
  // the name.
  if (Status.getName() != Filename) {
    auto &NewNamedFileEnt =
        *SeenFileEntries.insert({Status.getName(), &UFE}).first;
    assert((*NewNamedFileEnt.second).get<FileEntry *>() == &UFE &&
           "filename from getStatValue() refers to wrong file");
    InterndFileName = NewNamedFileEnt.first().data();
    // In addition to re-interning the name, construct a redirecting seen file
    // entry, that will point to the name the filesystem actually wants to use.
    StringRef *Redirect = new (CanonicalNameStorage) StringRef(InterndFileName);
    NamedFileEnt.second = Redirect;
  }

  if (UFE.isValid()) { // Already have an entry with this inode, return it.

    // FIXME: this hack ensures that if we look up a file by a virtual path in
    // the VFS that the getDir() will have the virtual path, even if we found
    // the file by a 'real' path first. This is required in order to find a
    // module's structure when its headers/module map are mapped in the VFS.
    // We should remove this as soon as we can properly support a file having
    // multiple names.
    if (DirInfo != UFE.Dir && Status.IsVFSMapped)
      UFE.Dir = DirInfo;

    // Always update the name to use the last name by which a file was accessed.
    // FIXME: Neither this nor always using the first name is correct; we want
    // to switch towards a design where we return a FileName object that
    // encapsulates both the name by which the file was accessed and the
    // corresponding FileEntry.
    // FIXME: The Name should be removed from FileEntry once all clients
    // adopt FileEntryRef.
    UFE.Name = InterndFileName;

    return FileEntryRef(InterndFileName, UFE);
  }

  // Otherwise, we don't have this file yet, add it.
  UFE.Name    = InterndFileName;
  UFE.Size    = Status.getSize();
  UFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
  UFE.Dir     = DirInfo;
  UFE.UID     = NextFileUID++;
  UFE.UniqueID = Status.getUniqueID();
  UFE.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
  UFE.File = std::move(F);
  UFE.IsValid = true;

  if (UFE.File) {
    if (auto PathName = UFE.File->getName())
      fillRealPathName(&UFE, *PathName);
  } else if (!openFile) {
    // We should still fill the path even if we aren't opening the file.
    fillRealPathName(&UFE, InterndFileName);
  }
  return FileEntryRef(InterndFileName, UFE);
}

const FileEntry *
FileManager::getVirtualFile(StringRef Filename, off_t Size,
                            time_t ModificationTime) {
  ++NumFileLookups;

  // See if there is already an entry in the map for an existing file.
  auto &NamedFileEnt = *SeenFileEntries.insert(
      {Filename, std::errc::no_such_file_or_directory}).first;
  if (NamedFileEnt.second) {
    SeenFileEntryOrRedirect Value = *NamedFileEnt.second;
    FileEntry *FE;
    if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>()))
      return FE;
    return getVirtualFile(*Value.get<const StringRef *>(), Size,
                          ModificationTime);
  }

  // We've not seen this before, or the file is cached as non-existent.
  ++NumFileCacheMisses;
  addAncestorsAsVirtualDirs(Filename);
  FileEntry *UFE = nullptr;

  // Now that all ancestors of Filename are in the cache, the
  // following call is guaranteed to find the DirectoryEntry from the
  // cache.
  auto DirInfo = getDirectoryFromFile(*this, Filename, /*CacheFailure=*/true);
  assert(DirInfo &&
         "The directory of a virtual file should already be in the cache.");

  // Check to see if the file exists. If so, drop the virtual file
  llvm::vfs::Status Status;
  const char *InterndFileName = NamedFileEnt.first().data();
  if (!getStatValue(InterndFileName, Status, true, nullptr)) {
    UFE = &UniqueRealFiles[Status.getUniqueID()];
    Status = llvm::vfs::Status(
      Status.getName(), Status.getUniqueID(),
      llvm::sys::toTimePoint(ModificationTime),
      Status.getUser(), Status.getGroup(), Size,
      Status.getType(), Status.getPermissions());

    NamedFileEnt.second = UFE;

    // If we had already opened this file, close it now so we don't
    // leak the descriptor. We're not going to use the file
    // descriptor anyway, since this is a virtual file.
    if (UFE->File)
      UFE->closeFile();

    // If we already have an entry with this inode, return it.
    if (UFE->isValid())
      return UFE;

    UFE->UniqueID = Status.getUniqueID();
    UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
    fillRealPathName(UFE, Status.getName());
  } else {
    VirtualFileEntries.push_back(std::make_unique<FileEntry>());
    UFE = VirtualFileEntries.back().get();
    NamedFileEnt.second = UFE;
  }

  UFE->Name    = InterndFileName;
  UFE->Size    = Size;
  UFE->ModTime = ModificationTime;
  UFE->Dir     = *DirInfo;
  UFE->UID     = NextFileUID++;
  UFE->IsValid = true;
  UFE->File.reset();
  return UFE;
}

llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {
  // Stat of the file and return nullptr if it doesn't exist.
  llvm::vfs::Status Status;
  if (getStatValue(VF.getName(), Status, /*isFile=*/true, /*F=*/nullptr))
    return None;

  // Fill it in from the stat.
  BypassFileEntries.push_back(std::make_unique<FileEntry>());
  const FileEntry &VFE = VF.getFileEntry();
  FileEntry &BFE = *BypassFileEntries.back();
  BFE.Name = VFE.getName();
  BFE.Size = Status.getSize();
  BFE.Dir = VFE.Dir;
  BFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
  BFE.UID = NextFileUID++;
  BFE.IsValid = true;
  return FileEntryRef(VF.getName(), BFE);
}

bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
  StringRef pathRef(path.data(), path.size());

  if (FileSystemOpts.WorkingDir.empty()
      || llvm::sys::path::is_absolute(pathRef))
    return false;

  SmallString<128> NewPath(FileSystemOpts.WorkingDir);
  llvm::sys::path::append(NewPath, pathRef);
  path = NewPath;
  return true;
}

bool FileManager::makeAbsolutePath(SmallVectorImpl<char> &Path) const {
  bool Changed = FixupRelativePath(Path);

  if (!llvm::sys::path::is_absolute(StringRef(Path.data(), Path.size()))) {
    FS->makeAbsolute(Path);
    Changed = true;
  }

  return Changed;
}

void FileManager::fillRealPathName(FileEntry *UFE, llvm::StringRef FileName) {
  llvm::SmallString<128> AbsPath(FileName);
  // This is not the same as `VFS::getRealPath()`, which resolves symlinks
  // but can be very expensive on real file systems.
  // FIXME: the semantic of RealPathName is unclear, and the name might be
  // misleading. We need to clean up the interface here.
  makeAbsolutePath(AbsPath);
  llvm::sys::path::remove_dots(AbsPath, /*remove_dot_dot=*/true);
  UFE->RealPathName = AbsPath.str();
}

llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile) {
  uint64_t FileSize = Entry->getSize();
  // If there's a high enough chance that the file have changed since we
  // got its size, force a stat before opening it.
  if (isVolatile)
    FileSize = -1;

  StringRef Filename = Entry->getName();
  // If the file is already open, use the open file descriptor.
  if (Entry->File) {
    auto Result =
        Entry->File->getBuffer(Filename, FileSize,
                               /*RequiresNullTerminator=*/true, isVolatile);
    Entry->closeFile();
    return Result;
  }

  // Otherwise, open the file.
  return getBufferForFileImpl(Filename, FileSize, isVolatile);
}

llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
FileManager::getBufferForFileImpl(StringRef Filename, int64_t FileSize,
                                  bool isVolatile) {
  if (FileSystemOpts.WorkingDir.empty())
    return FS->getBufferForFile(Filename, FileSize,
                                /*RequiresNullTerminator=*/true, isVolatile);

  SmallString<128> FilePath(Filename);
  FixupRelativePath(FilePath);
  return FS->getBufferForFile(FilePath, FileSize,
                              /*RequiresNullTerminator=*/true, isVolatile);
}

/// getStatValue - Get the 'stat' information for the specified path,
/// using the cache to accelerate it if possible.  This returns true
/// if the path points to a virtual file or does not exist, or returns
/// false if it's an existent real file.  If FileDescriptor is NULL,
/// do directory look-up instead of file look-up.
std::error_code
FileManager::getStatValue(StringRef Path, llvm::vfs::Status &Status,
                          bool isFile, std::unique_ptr<llvm::vfs::File> *F) {
  // FIXME: FileSystemOpts shouldn't be passed in here, all paths should be
  // absolute!
  if (FileSystemOpts.WorkingDir.empty())
    return FileSystemStatCache::get(Path, Status, isFile, F,
                                    StatCache.get(), *FS);

  SmallString<128> FilePath(Path);
  FixupRelativePath(FilePath);

  return FileSystemStatCache::get(FilePath.c_str(), Status, isFile, F,
                                  StatCache.get(), *FS);
}

std::error_code 
FileManager::getNoncachedStatValue(StringRef Path,
                                   llvm::vfs::Status &Result) {
  SmallString<128> FilePath(Path);
  FixupRelativePath(FilePath);

  llvm::ErrorOr<llvm::vfs::Status> S = FS->status(FilePath.c_str());
  if (!S)
    return S.getError();
  Result = *S;
  return std::error_code();
}

void FileManager::GetUniqueIDMapping(
                   SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
  UIDToFiles.clear();
  UIDToFiles.resize(NextFileUID);

  // Map file entries
  for (llvm::StringMap<llvm::ErrorOr<SeenFileEntryOrRedirect>,
                       llvm::BumpPtrAllocator>::const_iterator
           FE = SeenFileEntries.begin(),
           FEEnd = SeenFileEntries.end();
       FE != FEEnd; ++FE)
    if (llvm::ErrorOr<SeenFileEntryOrRedirect> Entry = FE->getValue()) {
      if (const auto *FE = (*Entry).dyn_cast<FileEntry *>())
        UIDToFiles[FE->getUID()] = FE;
    }

  // Map virtual file entries
  for (const auto &VFE : VirtualFileEntries)
    UIDToFiles[VFE->getUID()] = VFE.get();
}

StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) {
  // FIXME: use llvm::sys::fs::canonical() when it gets implemented
  llvm::DenseMap<const DirectoryEntry *, llvm::StringRef>::iterator Known
    = CanonicalDirNames.find(Dir);
  if (Known != CanonicalDirNames.end())
    return Known->second;

  StringRef CanonicalName(Dir->getName());

  SmallString<4096> CanonicalNameBuf;
  if (!FS->getRealPath(Dir->getName(), CanonicalNameBuf))
    CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);

  CanonicalDirNames.insert({Dir, CanonicalName});
  return CanonicalName;
}

void FileManager::PrintStats() const {
  llvm::errs() << "\n*** File Manager Stats:\n";
  llvm::errs() << UniqueRealFiles.size() << " real files found, "
               << UniqueRealDirs.size() << " real dirs found.\n";
  llvm::errs() << VirtualFileEntries.size() << " virtual files found, "
               << VirtualDirectoryEntries.size() << " virtual dirs found.\n";
  llvm::errs() << NumDirLookups << " dir lookups, "
               << NumDirCacheMisses << " dir cache misses.\n";
  llvm::errs() << NumFileLookups << " file lookups, "
               << NumFileCacheMisses << " file cache misses.\n";

  //llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups;
}