xref: /freebsd/contrib/llvm-project/clang/lib/Basic/FileManager.cpp (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
1 //===--- FileManager.cpp - File System Probing and Caching ----------------===//
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 //  This file implements the FileManager interface.
10 //
11 //===----------------------------------------------------------------------===//
12 //
13 // TODO: This should index all interesting directories with dirent calls.
14 //  getdirentries ?
15 //  opendir/readdir_r/closedir ?
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "clang/Basic/FileManager.h"
20 #include "clang/Basic/FileSystemStatCache.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/Config/llvm-config.h"
25 #include "llvm/Support/FileSystem.h"
26 #include "llvm/Support/MemoryBuffer.h"
27 #include "llvm/Support/Path.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <climits>
32 #include <cstdint>
33 #include <cstdlib>
34 #include <string>
35 #include <utility>
36 
37 using namespace clang;
38 
39 #define DEBUG_TYPE "file-search"
40 
41 ALWAYS_ENABLED_STATISTIC(NumDirLookups, "Number of directory lookups.");
42 ALWAYS_ENABLED_STATISTIC(NumFileLookups, "Number of file lookups.");
43 ALWAYS_ENABLED_STATISTIC(NumDirCacheMisses,
44                          "Number of directory cache misses.");
45 ALWAYS_ENABLED_STATISTIC(NumFileCacheMisses, "Number of file cache misses.");
46 
47 //===----------------------------------------------------------------------===//
48 // Common logic.
49 //===----------------------------------------------------------------------===//
50 
51 FileManager::FileManager(const FileSystemOptions &FSO,
52                          IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
53     : FS(std::move(FS)), FileSystemOpts(FSO), SeenDirEntries(64),
54       SeenFileEntries(64), NextFileUID(0) {
55   // If the caller doesn't provide a virtual file system, just grab the real
56   // file system.
57   if (!this->FS)
58     this->FS = llvm::vfs::getRealFileSystem();
59 }
60 
61 FileManager::~FileManager() = default;
62 
63 void FileManager::setStatCache(std::unique_ptr<FileSystemStatCache> statCache) {
64   assert(statCache && "No stat cache provided?");
65   StatCache = std::move(statCache);
66 }
67 
68 void FileManager::clearStatCache() { StatCache.reset(); }
69 
70 /// Retrieve the directory that the given file name resides in.
71 /// Filename can point to either a real file or a virtual file.
72 static llvm::Expected<DirectoryEntryRef>
73 getDirectoryFromFile(FileManager &FileMgr, StringRef Filename,
74                      bool CacheFailure) {
75   if (Filename.empty())
76     return llvm::errorCodeToError(
77         make_error_code(std::errc::no_such_file_or_directory));
78 
79   if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
80     return llvm::errorCodeToError(make_error_code(std::errc::is_a_directory));
81 
82   StringRef DirName = llvm::sys::path::parent_path(Filename);
83   // Use the current directory if file has no path component.
84   if (DirName.empty())
85     DirName = ".";
86 
87   return FileMgr.getDirectoryRef(DirName, CacheFailure);
88 }
89 
90 /// Add all ancestors of the given path (pointing to either a file or
91 /// a directory) as virtual directories.
92 void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
93   StringRef DirName = llvm::sys::path::parent_path(Path);
94   if (DirName.empty())
95     DirName = ".";
96 
97   auto &NamedDirEnt = *SeenDirEntries.insert(
98         {DirName, std::errc::no_such_file_or_directory}).first;
99 
100   // When caching a virtual directory, we always cache its ancestors
101   // at the same time.  Therefore, if DirName is already in the cache,
102   // we don't need to recurse as its ancestors must also already be in
103   // the cache (or it's a known non-virtual directory).
104   if (NamedDirEnt.second)
105     return;
106 
107   // Add the virtual directory to the cache.
108   auto UDE = std::make_unique<DirectoryEntry>();
109   UDE->Name = NamedDirEnt.first();
110   NamedDirEnt.second = *UDE.get();
111   VirtualDirectoryEntries.push_back(std::move(UDE));
112 
113   // Recursively add the other ancestors.
114   addAncestorsAsVirtualDirs(DirName);
115 }
116 
117 llvm::Expected<DirectoryEntryRef>
118 FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) {
119   // stat doesn't like trailing separators except for root directory.
120   // At least, on Win32 MSVCRT, stat() cannot strip trailing '/'.
121   // (though it can strip '\\')
122   if (DirName.size() > 1 &&
123       DirName != llvm::sys::path::root_path(DirName) &&
124       llvm::sys::path::is_separator(DirName.back()))
125     DirName = DirName.substr(0, DirName.size()-1);
126 #ifdef _WIN32
127   // Fixing a problem with "clang C:test.c" on Windows.
128   // Stat("C:") does not recognize "C:" as a valid directory
129   std::string DirNameStr;
130   if (DirName.size() > 1 && DirName.back() == ':' &&
131       DirName.equals_insensitive(llvm::sys::path::root_name(DirName))) {
132     DirNameStr = DirName.str() + '.';
133     DirName = DirNameStr;
134   }
135 #endif
136 
137   ++NumDirLookups;
138 
139   // See if there was already an entry in the map.  Note that the map
140   // contains both virtual and real directories.
141   auto SeenDirInsertResult =
142       SeenDirEntries.insert({DirName, std::errc::no_such_file_or_directory});
143   if (!SeenDirInsertResult.second) {
144     if (SeenDirInsertResult.first->second)
145       return DirectoryEntryRef(*SeenDirInsertResult.first);
146     return llvm::errorCodeToError(SeenDirInsertResult.first->second.getError());
147   }
148 
149   // We've not seen this before. Fill it in.
150   ++NumDirCacheMisses;
151   auto &NamedDirEnt = *SeenDirInsertResult.first;
152   assert(!NamedDirEnt.second && "should be newly-created");
153 
154   // Get the null-terminated directory name as stored as the key of the
155   // SeenDirEntries map.
156   StringRef InterndDirName = NamedDirEnt.first();
157 
158   // Check to see if the directory exists.
159   llvm::vfs::Status Status;
160   auto statError = getStatValue(InterndDirName, Status, false,
161                                 nullptr /*directory lookup*/);
162   if (statError) {
163     // There's no real directory at the given path.
164     if (CacheFailure)
165       NamedDirEnt.second = statError;
166     else
167       SeenDirEntries.erase(DirName);
168     return llvm::errorCodeToError(statError);
169   }
170 
171   // It exists.  See if we have already opened a directory with the
172   // same inode (this occurs on Unix-like systems when one dir is
173   // symlinked to another, for example) or the same path (on
174   // Windows).
175   DirectoryEntry &UDE = UniqueRealDirs[Status.getUniqueID()];
176 
177   NamedDirEnt.second = UDE;
178   if (UDE.getName().empty()) {
179     // We don't have this directory yet, add it.  We use the string
180     // key from the SeenDirEntries map as the string.
181     UDE.Name  = InterndDirName;
182   }
183 
184   return DirectoryEntryRef(NamedDirEnt);
185 }
186 
187 llvm::ErrorOr<const DirectoryEntry *>
188 FileManager::getDirectory(StringRef DirName, bool CacheFailure) {
189   auto Result = getDirectoryRef(DirName, CacheFailure);
190   if (Result)
191     return &Result->getDirEntry();
192   return llvm::errorToErrorCode(Result.takeError());
193 }
194 
195 llvm::ErrorOr<const FileEntry *>
196 FileManager::getFile(StringRef Filename, bool openFile, bool CacheFailure) {
197   auto Result = getFileRef(Filename, openFile, CacheFailure);
198   if (Result)
199     return &Result->getFileEntry();
200   return llvm::errorToErrorCode(Result.takeError());
201 }
202 
203 llvm::Expected<FileEntryRef>
204 FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
205   ++NumFileLookups;
206 
207   // See if there is already an entry in the map.
208   auto SeenFileInsertResult =
209       SeenFileEntries.insert({Filename, std::errc::no_such_file_or_directory});
210   if (!SeenFileInsertResult.second) {
211     if (!SeenFileInsertResult.first->second)
212       return llvm::errorCodeToError(
213           SeenFileInsertResult.first->second.getError());
214     // Construct and return and FileEntryRef, unless it's a redirect to another
215     // filename.
216     FileEntryRef::MapValue Value = *SeenFileInsertResult.first->second;
217     if (LLVM_LIKELY(Value.V.is<FileEntry *>()))
218       return FileEntryRef(*SeenFileInsertResult.first);
219     return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
220         Value.V.get<const void *>()));
221   }
222 
223   // We've not seen this before. Fill it in.
224   ++NumFileCacheMisses;
225   auto *NamedFileEnt = &*SeenFileInsertResult.first;
226   assert(!NamedFileEnt->second && "should be newly-created");
227 
228   // Get the null-terminated file name as stored as the key of the
229   // SeenFileEntries map.
230   StringRef InterndFileName = NamedFileEnt->first();
231 
232   // Look up the directory for the file.  When looking up something like
233   // sys/foo.h we'll discover all of the search directories that have a 'sys'
234   // subdirectory.  This will let us avoid having to waste time on known-to-fail
235   // searches when we go to find sys/bar.h, because all the search directories
236   // without a 'sys' subdir will get a cached failure result.
237   auto DirInfoOrErr = getDirectoryFromFile(*this, Filename, CacheFailure);
238   if (!DirInfoOrErr) { // Directory doesn't exist, file can't exist.
239     std::error_code Err = errorToErrorCode(DirInfoOrErr.takeError());
240     if (CacheFailure)
241       NamedFileEnt->second = Err;
242     else
243       SeenFileEntries.erase(Filename);
244 
245     return llvm::errorCodeToError(Err);
246   }
247   DirectoryEntryRef DirInfo = *DirInfoOrErr;
248 
249   // FIXME: Use the directory info to prune this, before doing the stat syscall.
250   // FIXME: This will reduce the # syscalls.
251 
252   // Check to see if the file exists.
253   std::unique_ptr<llvm::vfs::File> F;
254   llvm::vfs::Status Status;
255   auto statError = getStatValue(InterndFileName, Status, true,
256                                 openFile ? &F : nullptr);
257   if (statError) {
258     // There's no real file at the given path.
259     if (CacheFailure)
260       NamedFileEnt->second = statError;
261     else
262       SeenFileEntries.erase(Filename);
263 
264     return llvm::errorCodeToError(statError);
265   }
266 
267   assert((openFile || !F) && "undesired open file");
268 
269   // It exists.  See if we have already opened a file with the same inode.
270   // This occurs when one dir is symlinked to another, for example.
271   FileEntry &UFE = UniqueRealFiles[Status.getUniqueID()];
272 
273   if (Status.getName() == Filename) {
274     // The name matches. Set the FileEntry.
275     NamedFileEnt->second = FileEntryRef::MapValue(UFE, DirInfo);
276   } else {
277     // Name mismatch. We need a redirect. First grab the actual entry we want
278     // to return.
279     auto &Redirection =
280         *SeenFileEntries
281              .insert({Status.getName(), FileEntryRef::MapValue(UFE, DirInfo)})
282              .first;
283     assert(Redirection.second->V.is<FileEntry *>() &&
284            "filename redirected to a non-canonical filename?");
285     assert(Redirection.second->V.get<FileEntry *>() == &UFE &&
286            "filename from getStatValue() refers to wrong file");
287 
288     // Cache the redirection in the previously-inserted entry, still available
289     // in the tentative return value.
290     NamedFileEnt->second = FileEntryRef::MapValue(Redirection);
291 
292     // Fix the tentative return value.
293     NamedFileEnt = &Redirection;
294   }
295 
296   FileEntryRef ReturnedRef(*NamedFileEnt);
297   if (UFE.isValid()) { // Already have an entry with this inode, return it.
298 
299     // FIXME: this hack ensures that if we look up a file by a virtual path in
300     // the VFS that the getDir() will have the virtual path, even if we found
301     // the file by a 'real' path first. This is required in order to find a
302     // module's structure when its headers/module map are mapped in the VFS.
303     // We should remove this as soon as we can properly support a file having
304     // multiple names.
305     if (&DirInfo.getDirEntry() != UFE.Dir && Status.IsVFSMapped)
306       UFE.Dir = &DirInfo.getDirEntry();
307 
308     // Always update LastRef to the last name by which a file was accessed.
309     // FIXME: Neither this nor always using the first reference is correct; we
310     // want to switch towards a design where we return a FileName object that
311     // encapsulates both the name by which the file was accessed and the
312     // corresponding FileEntry.
313     // FIXME: LastRef should be removed from FileEntry once all clients adopt
314     // FileEntryRef.
315     UFE.LastRef = ReturnedRef;
316 
317     return ReturnedRef;
318   }
319 
320   // Otherwise, we don't have this file yet, add it.
321   UFE.LastRef = ReturnedRef;
322   UFE.Size    = Status.getSize();
323   UFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
324   UFE.Dir     = &DirInfo.getDirEntry();
325   UFE.UID     = NextFileUID++;
326   UFE.UniqueID = Status.getUniqueID();
327   UFE.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
328   UFE.File = std::move(F);
329   UFE.IsValid = true;
330 
331   if (UFE.File) {
332     if (auto PathName = UFE.File->getName())
333       fillRealPathName(&UFE, *PathName);
334   } else if (!openFile) {
335     // We should still fill the path even if we aren't opening the file.
336     fillRealPathName(&UFE, InterndFileName);
337   }
338   return ReturnedRef;
339 }
340 
341 llvm::Expected<FileEntryRef> FileManager::getSTDIN() {
342   // Only read stdin once.
343   if (STDIN)
344     return *STDIN;
345 
346   std::unique_ptr<llvm::MemoryBuffer> Content;
347   if (auto ContentOrError = llvm::MemoryBuffer::getSTDIN())
348     Content = std::move(*ContentOrError);
349   else
350     return llvm::errorCodeToError(ContentOrError.getError());
351 
352   STDIN = getVirtualFileRef(Content->getBufferIdentifier(),
353                             Content->getBufferSize(), 0);
354   FileEntry &FE = const_cast<FileEntry &>(STDIN->getFileEntry());
355   FE.Content = std::move(Content);
356   FE.IsNamedPipe = true;
357   return *STDIN;
358 }
359 
360 const FileEntry *FileManager::getVirtualFile(StringRef Filename, off_t Size,
361                                              time_t ModificationTime) {
362   return &getVirtualFileRef(Filename, Size, ModificationTime).getFileEntry();
363 }
364 
365 FileEntryRef FileManager::getVirtualFileRef(StringRef Filename, off_t Size,
366                                             time_t ModificationTime) {
367   ++NumFileLookups;
368 
369   // See if there is already an entry in the map for an existing file.
370   auto &NamedFileEnt = *SeenFileEntries.insert(
371       {Filename, std::errc::no_such_file_or_directory}).first;
372   if (NamedFileEnt.second) {
373     FileEntryRef::MapValue Value = *NamedFileEnt.second;
374     if (LLVM_LIKELY(Value.V.is<FileEntry *>()))
375       return FileEntryRef(NamedFileEnt);
376     return FileEntryRef(*reinterpret_cast<const FileEntryRef::MapEntry *>(
377         Value.V.get<const void *>()));
378   }
379 
380   // We've not seen this before, or the file is cached as non-existent.
381   ++NumFileCacheMisses;
382   addAncestorsAsVirtualDirs(Filename);
383   FileEntry *UFE = nullptr;
384 
385   // Now that all ancestors of Filename are in the cache, the
386   // following call is guaranteed to find the DirectoryEntry from the
387   // cache. A virtual file can also have an empty filename, that could come
388   // from a source location preprocessor directive with an empty filename as
389   // an example, so we need to pretend it has a name to ensure a valid directory
390   // entry can be returned.
391   auto DirInfo = expectedToOptional(getDirectoryFromFile(
392       *this, Filename.empty() ? "." : Filename, /*CacheFailure=*/true));
393   assert(DirInfo &&
394          "The directory of a virtual file should already be in the cache.");
395 
396   // Check to see if the file exists. If so, drop the virtual file
397   llvm::vfs::Status Status;
398   const char *InterndFileName = NamedFileEnt.first().data();
399   if (!getStatValue(InterndFileName, Status, true, nullptr)) {
400     UFE = &UniqueRealFiles[Status.getUniqueID()];
401     Status = llvm::vfs::Status(
402       Status.getName(), Status.getUniqueID(),
403       llvm::sys::toTimePoint(ModificationTime),
404       Status.getUser(), Status.getGroup(), Size,
405       Status.getType(), Status.getPermissions());
406 
407     NamedFileEnt.second = FileEntryRef::MapValue(*UFE, *DirInfo);
408 
409     // If we had already opened this file, close it now so we don't
410     // leak the descriptor. We're not going to use the file
411     // descriptor anyway, since this is a virtual file.
412     if (UFE->File)
413       UFE->closeFile();
414 
415     // If we already have an entry with this inode, return it.
416     //
417     // FIXME: Surely this should add a reference by the new name, and return
418     // it instead...
419     if (UFE->isValid())
420       return FileEntryRef(NamedFileEnt);
421 
422     UFE->UniqueID = Status.getUniqueID();
423     UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
424     fillRealPathName(UFE, Status.getName());
425   } else {
426     VirtualFileEntries.push_back(std::make_unique<FileEntry>());
427     UFE = VirtualFileEntries.back().get();
428     NamedFileEnt.second = FileEntryRef::MapValue(*UFE, *DirInfo);
429   }
430 
431   UFE->LastRef = FileEntryRef(NamedFileEnt);
432   UFE->Size    = Size;
433   UFE->ModTime = ModificationTime;
434   UFE->Dir     = &DirInfo->getDirEntry();
435   UFE->UID     = NextFileUID++;
436   UFE->IsValid = true;
437   UFE->File.reset();
438   return FileEntryRef(NamedFileEnt);
439 }
440 
441 llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {
442   // Stat of the file and return nullptr if it doesn't exist.
443   llvm::vfs::Status Status;
444   if (getStatValue(VF.getName(), Status, /*isFile=*/true, /*F=*/nullptr))
445     return None;
446 
447   if (!SeenBypassFileEntries)
448     SeenBypassFileEntries = std::make_unique<
449         llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>>>();
450 
451   // If we've already bypassed just use the existing one.
452   auto Insertion = SeenBypassFileEntries->insert(
453       {VF.getName(), std::errc::no_such_file_or_directory});
454   if (!Insertion.second)
455     return FileEntryRef(*Insertion.first);
456 
457   // Fill in the new entry from the stat.
458   BypassFileEntries.push_back(std::make_unique<FileEntry>());
459   const FileEntry &VFE = VF.getFileEntry();
460   FileEntry &BFE = *BypassFileEntries.back();
461   Insertion.first->second = FileEntryRef::MapValue(BFE, VF.getDir());
462   BFE.LastRef = FileEntryRef(*Insertion.first);
463   BFE.Size = Status.getSize();
464   BFE.Dir = VFE.Dir;
465   BFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
466   BFE.UID = NextFileUID++;
467   BFE.IsValid = true;
468 
469   // Save the entry in the bypass table and return.
470   return FileEntryRef(*Insertion.first);
471 }
472 
473 bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
474   StringRef pathRef(path.data(), path.size());
475 
476   if (FileSystemOpts.WorkingDir.empty()
477       || llvm::sys::path::is_absolute(pathRef))
478     return false;
479 
480   SmallString<128> NewPath(FileSystemOpts.WorkingDir);
481   llvm::sys::path::append(NewPath, pathRef);
482   path = NewPath;
483   return true;
484 }
485 
486 bool FileManager::makeAbsolutePath(SmallVectorImpl<char> &Path) const {
487   bool Changed = FixupRelativePath(Path);
488 
489   if (!llvm::sys::path::is_absolute(StringRef(Path.data(), Path.size()))) {
490     FS->makeAbsolute(Path);
491     Changed = true;
492   }
493 
494   return Changed;
495 }
496 
497 void FileManager::fillRealPathName(FileEntry *UFE, llvm::StringRef FileName) {
498   llvm::SmallString<128> AbsPath(FileName);
499   // This is not the same as `VFS::getRealPath()`, which resolves symlinks
500   // but can be very expensive on real file systems.
501   // FIXME: the semantic of RealPathName is unclear, and the name might be
502   // misleading. We need to clean up the interface here.
503   makeAbsolutePath(AbsPath);
504   llvm::sys::path::remove_dots(AbsPath, /*remove_dot_dot=*/true);
505   UFE->RealPathName = std::string(AbsPath.str());
506 }
507 
508 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
509 FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile,
510                               bool RequiresNullTerminator) {
511   // If the content is living on the file entry, return a reference to it.
512   if (Entry->Content)
513     return llvm::MemoryBuffer::getMemBuffer(Entry->Content->getMemBufferRef());
514 
515   uint64_t FileSize = Entry->getSize();
516   // If there's a high enough chance that the file have changed since we
517   // got its size, force a stat before opening it.
518   if (isVolatile || Entry->isNamedPipe())
519     FileSize = -1;
520 
521   StringRef Filename = Entry->getName();
522   // If the file is already open, use the open file descriptor.
523   if (Entry->File) {
524     auto Result = Entry->File->getBuffer(Filename, FileSize,
525                                          RequiresNullTerminator, isVolatile);
526     Entry->closeFile();
527     return Result;
528   }
529 
530   // Otherwise, open the file.
531   return getBufferForFileImpl(Filename, FileSize, isVolatile,
532                               RequiresNullTerminator);
533 }
534 
535 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
536 FileManager::getBufferForFileImpl(StringRef Filename, int64_t FileSize,
537                                   bool isVolatile,
538                                   bool RequiresNullTerminator) {
539   if (FileSystemOpts.WorkingDir.empty())
540     return FS->getBufferForFile(Filename, FileSize, RequiresNullTerminator,
541                                 isVolatile);
542 
543   SmallString<128> FilePath(Filename);
544   FixupRelativePath(FilePath);
545   return FS->getBufferForFile(FilePath, FileSize, RequiresNullTerminator,
546                               isVolatile);
547 }
548 
549 /// getStatValue - Get the 'stat' information for the specified path,
550 /// using the cache to accelerate it if possible.  This returns true
551 /// if the path points to a virtual file or does not exist, or returns
552 /// false if it's an existent real file.  If FileDescriptor is NULL,
553 /// do directory look-up instead of file look-up.
554 std::error_code
555 FileManager::getStatValue(StringRef Path, llvm::vfs::Status &Status,
556                           bool isFile, std::unique_ptr<llvm::vfs::File> *F) {
557   // FIXME: FileSystemOpts shouldn't be passed in here, all paths should be
558   // absolute!
559   if (FileSystemOpts.WorkingDir.empty())
560     return FileSystemStatCache::get(Path, Status, isFile, F,
561                                     StatCache.get(), *FS);
562 
563   SmallString<128> FilePath(Path);
564   FixupRelativePath(FilePath);
565 
566   return FileSystemStatCache::get(FilePath.c_str(), Status, isFile, F,
567                                   StatCache.get(), *FS);
568 }
569 
570 std::error_code
571 FileManager::getNoncachedStatValue(StringRef Path,
572                                    llvm::vfs::Status &Result) {
573   SmallString<128> FilePath(Path);
574   FixupRelativePath(FilePath);
575 
576   llvm::ErrorOr<llvm::vfs::Status> S = FS->status(FilePath.c_str());
577   if (!S)
578     return S.getError();
579   Result = *S;
580   return std::error_code();
581 }
582 
583 void FileManager::GetUniqueIDMapping(
584                    SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
585   UIDToFiles.clear();
586   UIDToFiles.resize(NextFileUID);
587 
588   // Map file entries
589   for (llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>,
590                        llvm::BumpPtrAllocator>::const_iterator
591            FE = SeenFileEntries.begin(),
592            FEEnd = SeenFileEntries.end();
593        FE != FEEnd; ++FE)
594     if (llvm::ErrorOr<FileEntryRef::MapValue> Entry = FE->getValue()) {
595       if (const auto *FE = Entry->V.dyn_cast<FileEntry *>())
596         UIDToFiles[FE->getUID()] = FE;
597     }
598 
599   // Map virtual file entries
600   for (const auto &VFE : VirtualFileEntries)
601     UIDToFiles[VFE->getUID()] = VFE.get();
602 }
603 
604 StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) {
605   llvm::DenseMap<const void *, llvm::StringRef>::iterator Known
606     = CanonicalNames.find(Dir);
607   if (Known != CanonicalNames.end())
608     return Known->second;
609 
610   StringRef CanonicalName(Dir->getName());
611 
612   SmallString<4096> CanonicalNameBuf;
613   if (!FS->getRealPath(Dir->getName(), CanonicalNameBuf))
614     CanonicalName = CanonicalNameBuf.str().copy(CanonicalNameStorage);
615 
616   CanonicalNames.insert({Dir, CanonicalName});
617   return CanonicalName;
618 }
619 
620 StringRef FileManager::getCanonicalName(const FileEntry *File) {
621   llvm::DenseMap<const void *, llvm::StringRef>::iterator Known
622     = CanonicalNames.find(File);
623   if (Known != CanonicalNames.end())
624     return Known->second;
625 
626   StringRef CanonicalName(File->getName());
627 
628   SmallString<4096> CanonicalNameBuf;
629   if (!FS->getRealPath(File->getName(), CanonicalNameBuf))
630     CanonicalName = CanonicalNameBuf.str().copy(CanonicalNameStorage);
631 
632   CanonicalNames.insert({File, CanonicalName});
633   return CanonicalName;
634 }
635 
636 void FileManager::PrintStats() const {
637   llvm::errs() << "\n*** File Manager Stats:\n";
638   llvm::errs() << UniqueRealFiles.size() << " real files found, "
639                << UniqueRealDirs.size() << " real dirs found.\n";
640   llvm::errs() << VirtualFileEntries.size() << " virtual files found, "
641                << VirtualDirectoryEntries.size() << " virtual dirs found.\n";
642   llvm::errs() << NumDirLookups << " dir lookups, "
643                << NumDirCacheMisses << " dir cache misses.\n";
644   llvm::errs() << NumFileLookups << " file lookups, "
645                << NumFileCacheMisses << " file cache misses.\n";
646 
647   //llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups;
648 }
649