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1 //===--- FileManager.cpp - File System Probing and Caching ----------------===//
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 //  This file implements the FileManager interface.
11 //
12 //===----------------------------------------------------------------------===//
13 //
14 // TODO: This should index all interesting directories with dirent calls.
15 //  getdirentries ?
16 //  opendir/readdir_r/closedir ?
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "clang/Basic/FileManager.h"
21 #include "clang/Basic/FileSystemStatCache.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/Config/llvm-config.h"
24 #include "llvm/ADT/STLExtras.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 <map>
30 #include <set>
31 #include <string>
32 #include <system_error>
33 
34 using namespace clang;
35 
36 /// NON_EXISTENT_DIR - A special value distinct from null that is used to
37 /// represent a dir name that doesn't exist on the disk.
38 #define NON_EXISTENT_DIR reinterpret_cast<DirectoryEntry*>((intptr_t)-1)
39 
40 /// NON_EXISTENT_FILE - A special value distinct from null that is used to
41 /// represent a filename that doesn't exist on the disk.
42 #define NON_EXISTENT_FILE reinterpret_cast<FileEntry*>((intptr_t)-1)
43 
44 //===----------------------------------------------------------------------===//
45 // Common logic.
46 //===----------------------------------------------------------------------===//
47 
FileManager(const FileSystemOptions & FSO,IntrusiveRefCntPtr<vfs::FileSystem> FS)48 FileManager::FileManager(const FileSystemOptions &FSO,
49                          IntrusiveRefCntPtr<vfs::FileSystem> FS)
50   : FS(FS), FileSystemOpts(FSO),
51     SeenDirEntries(64), SeenFileEntries(64), NextFileUID(0) {
52   NumDirLookups = NumFileLookups = 0;
53   NumDirCacheMisses = NumFileCacheMisses = 0;
54 
55   // If the caller doesn't provide a virtual file system, just grab the real
56   // file system.
57   if (!FS)
58     this->FS = vfs::getRealFileSystem();
59 }
60 
61 FileManager::~FileManager() = default;
62 
addStatCache(std::unique_ptr<FileSystemStatCache> statCache,bool AtBeginning)63 void FileManager::addStatCache(std::unique_ptr<FileSystemStatCache> statCache,
64                                bool AtBeginning) {
65   assert(statCache && "No stat cache provided?");
66   if (AtBeginning || !StatCache.get()) {
67     statCache->setNextStatCache(std::move(StatCache));
68     StatCache = std::move(statCache);
69     return;
70   }
71 
72   FileSystemStatCache *LastCache = StatCache.get();
73   while (LastCache->getNextStatCache())
74     LastCache = LastCache->getNextStatCache();
75 
76   LastCache->setNextStatCache(std::move(statCache));
77 }
78 
removeStatCache(FileSystemStatCache * statCache)79 void FileManager::removeStatCache(FileSystemStatCache *statCache) {
80   if (!statCache)
81     return;
82 
83   if (StatCache.get() == statCache) {
84     // This is the first stat cache.
85     StatCache = StatCache->takeNextStatCache();
86     return;
87   }
88 
89   // Find the stat cache in the list.
90   FileSystemStatCache *PrevCache = StatCache.get();
91   while (PrevCache && PrevCache->getNextStatCache() != statCache)
92     PrevCache = PrevCache->getNextStatCache();
93 
94   assert(PrevCache && "Stat cache not found for removal");
95   PrevCache->setNextStatCache(statCache->takeNextStatCache());
96 }
97 
clearStatCaches()98 void FileManager::clearStatCaches() {
99   StatCache.reset();
100 }
101 
102 /// \brief Retrieve the directory that the given file name resides in.
103 /// Filename can point to either a real file or a virtual file.
getDirectoryFromFile(FileManager & FileMgr,StringRef Filename,bool CacheFailure)104 static const DirectoryEntry *getDirectoryFromFile(FileManager &FileMgr,
105                                                   StringRef Filename,
106                                                   bool CacheFailure) {
107   if (Filename.empty())
108     return nullptr;
109 
110   if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
111     return nullptr; // If Filename is a directory.
112 
113   StringRef DirName = llvm::sys::path::parent_path(Filename);
114   // Use the current directory if file has no path component.
115   if (DirName.empty())
116     DirName = ".";
117 
118   return FileMgr.getDirectory(DirName, CacheFailure);
119 }
120 
121 /// Add all ancestors of the given path (pointing to either a file or
122 /// a directory) as virtual directories.
addAncestorsAsVirtualDirs(StringRef Path)123 void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
124   StringRef DirName = llvm::sys::path::parent_path(Path);
125   if (DirName.empty())
126     DirName = ".";
127 
128   auto &NamedDirEnt =
129       *SeenDirEntries.insert(std::make_pair(DirName, nullptr)).first;
130 
131   // When caching a virtual directory, we always cache its ancestors
132   // at the same time.  Therefore, if DirName is already in the cache,
133   // we don't need to recurse as its ancestors must also already be in
134   // the cache.
135   if (NamedDirEnt.second && NamedDirEnt.second != NON_EXISTENT_DIR)
136     return;
137 
138   // Add the virtual directory to the cache.
139   auto UDE = llvm::make_unique<DirectoryEntry>();
140   UDE->Name = NamedDirEnt.first().data();
141   NamedDirEnt.second = UDE.get();
142   VirtualDirectoryEntries.push_back(std::move(UDE));
143 
144   // Recursively add the other ancestors.
145   addAncestorsAsVirtualDirs(DirName);
146 }
147 
getDirectory(StringRef DirName,bool CacheFailure)148 const DirectoryEntry *FileManager::getDirectory(StringRef DirName,
149                                                 bool CacheFailure) {
150   // stat doesn't like trailing separators except for root directory.
151   // At least, on Win32 MSVCRT, stat() cannot strip trailing '/'.
152   // (though it can strip '\\')
153   if (DirName.size() > 1 &&
154       DirName != llvm::sys::path::root_path(DirName) &&
155       llvm::sys::path::is_separator(DirName.back()))
156     DirName = DirName.substr(0, DirName.size()-1);
157 #ifdef LLVM_ON_WIN32
158   // Fixing a problem with "clang C:test.c" on Windows.
159   // Stat("C:") does not recognize "C:" as a valid directory
160   std::string DirNameStr;
161   if (DirName.size() > 1 && DirName.back() == ':' &&
162       DirName.equals_lower(llvm::sys::path::root_name(DirName))) {
163     DirNameStr = DirName.str() + '.';
164     DirName = DirNameStr;
165   }
166 #endif
167 
168   ++NumDirLookups;
169   auto &NamedDirEnt =
170       *SeenDirEntries.insert(std::make_pair(DirName, nullptr)).first;
171 
172   // See if there was already an entry in the map.  Note that the map
173   // contains both virtual and real directories.
174   if (NamedDirEnt.second)
175     return NamedDirEnt.second == NON_EXISTENT_DIR ? nullptr
176                                                   : NamedDirEnt.second;
177 
178   ++NumDirCacheMisses;
179 
180   // By default, initialize it to invalid.
181   NamedDirEnt.second = NON_EXISTENT_DIR;
182 
183   // Get the null-terminated directory name as stored as the key of the
184   // SeenDirEntries map.
185   const char *InterndDirName = NamedDirEnt.first().data();
186 
187   // Check to see if the directory exists.
188   FileData Data;
189   if (getStatValue(InterndDirName, Data, false, nullptr /*directory lookup*/)) {
190     // There's no real directory at the given path.
191     if (!CacheFailure)
192       SeenDirEntries.erase(DirName);
193     return nullptr;
194   }
195 
196   // It exists.  See if we have already opened a directory with the
197   // same inode (this occurs on Unix-like systems when one dir is
198   // symlinked to another, for example) or the same path (on
199   // Windows).
200   DirectoryEntry &UDE = UniqueRealDirs[Data.UniqueID];
201 
202   NamedDirEnt.second = &UDE;
203   if (!UDE.getName()) {
204     // We don't have this directory yet, add it.  We use the string
205     // key from the SeenDirEntries map as the string.
206     UDE.Name  = InterndDirName;
207   }
208 
209   return &UDE;
210 }
211 
getFile(StringRef Filename,bool openFile,bool CacheFailure)212 const FileEntry *FileManager::getFile(StringRef Filename, bool openFile,
213                                       bool CacheFailure) {
214   ++NumFileLookups;
215 
216   // See if there is already an entry in the map.
217   auto &NamedFileEnt =
218       *SeenFileEntries.insert(std::make_pair(Filename, nullptr)).first;
219 
220   // See if there is already an entry in the map.
221   if (NamedFileEnt.second)
222     return NamedFileEnt.second == NON_EXISTENT_FILE ? nullptr
223                                                     : NamedFileEnt.second;
224 
225   ++NumFileCacheMisses;
226 
227   // By default, initialize it to invalid.
228   NamedFileEnt.second = NON_EXISTENT_FILE;
229 
230   // Get the null-terminated file name as stored as the key of the
231   // SeenFileEntries map.
232   const char *InterndFileName = NamedFileEnt.first().data();
233 
234   // Look up the directory for the file.  When looking up something like
235   // sys/foo.h we'll discover all of the search directories that have a 'sys'
236   // subdirectory.  This will let us avoid having to waste time on known-to-fail
237   // searches when we go to find sys/bar.h, because all the search directories
238   // without a 'sys' subdir will get a cached failure result.
239   const DirectoryEntry *DirInfo = getDirectoryFromFile(*this, Filename,
240                                                        CacheFailure);
241   if (DirInfo == nullptr) { // Directory doesn't exist, file can't exist.
242     if (!CacheFailure)
243       SeenFileEntries.erase(Filename);
244 
245     return nullptr;
246   }
247 
248   // FIXME: Use the directory info to prune this, before doing the stat syscall.
249   // FIXME: This will reduce the # syscalls.
250 
251   // Nope, there isn't.  Check to see if the file exists.
252   std::unique_ptr<vfs::File> F;
253   FileData Data;
254   if (getStatValue(InterndFileName, Data, true, openFile ? &F : nullptr)) {
255     // There's no real file at the given path.
256     if (!CacheFailure)
257       SeenFileEntries.erase(Filename);
258 
259     return nullptr;
260   }
261 
262   assert((openFile || !F) && "undesired open file");
263 
264   // It exists.  See if we have already opened a file with the same inode.
265   // This occurs when one dir is symlinked to another, for example.
266   FileEntry &UFE = UniqueRealFiles[Data.UniqueID];
267 
268   NamedFileEnt.second = &UFE;
269 
270   // If the name returned by getStatValue is different than Filename, re-intern
271   // the name.
272   if (Data.Name != Filename) {
273     auto &NamedFileEnt =
274         *SeenFileEntries.insert(std::make_pair(Data.Name, nullptr)).first;
275     if (!NamedFileEnt.second)
276       NamedFileEnt.second = &UFE;
277     else
278       assert(NamedFileEnt.second == &UFE &&
279              "filename from getStatValue() refers to wrong file");
280     InterndFileName = NamedFileEnt.first().data();
281   }
282 
283   if (UFE.isValid()) { // Already have an entry with this inode, return it.
284 
285     // FIXME: this hack ensures that if we look up a file by a virtual path in
286     // the VFS that the getDir() will have the virtual path, even if we found
287     // the file by a 'real' path first. This is required in order to find a
288     // module's structure when its headers/module map are mapped in the VFS.
289     // We should remove this as soon as we can properly support a file having
290     // multiple names.
291     if (DirInfo != UFE.Dir && Data.IsVFSMapped)
292       UFE.Dir = DirInfo;
293 
294     // Always update the name to use the last name by which a file was accessed.
295     // FIXME: Neither this nor always using the first name is correct; we want
296     // to switch towards a design where we return a FileName object that
297     // encapsulates both the name by which the file was accessed and the
298     // corresponding FileEntry.
299     UFE.Name = InterndFileName;
300 
301     return &UFE;
302   }
303 
304   // Otherwise, we don't have this file yet, add it.
305   UFE.Name    = InterndFileName;
306   UFE.Size = Data.Size;
307   UFE.ModTime = Data.ModTime;
308   UFE.Dir     = DirInfo;
309   UFE.UID     = NextFileUID++;
310   UFE.UniqueID = Data.UniqueID;
311   UFE.IsNamedPipe = Data.IsNamedPipe;
312   UFE.InPCH = Data.InPCH;
313   UFE.File = std::move(F);
314   UFE.IsValid = true;
315   if (UFE.File)
316     if (auto RealPathName = UFE.File->getName())
317       UFE.RealPathName = *RealPathName;
318   return &UFE;
319 }
320 
321 const FileEntry *
getVirtualFile(StringRef Filename,off_t Size,time_t ModificationTime)322 FileManager::getVirtualFile(StringRef Filename, off_t Size,
323                             time_t ModificationTime) {
324   ++NumFileLookups;
325 
326   // See if there is already an entry in the map.
327   auto &NamedFileEnt =
328       *SeenFileEntries.insert(std::make_pair(Filename, nullptr)).first;
329 
330   // See if there is already an entry in the map.
331   if (NamedFileEnt.second && NamedFileEnt.second != NON_EXISTENT_FILE)
332     return NamedFileEnt.second;
333 
334   ++NumFileCacheMisses;
335 
336   // By default, initialize it to invalid.
337   NamedFileEnt.second = NON_EXISTENT_FILE;
338 
339   addAncestorsAsVirtualDirs(Filename);
340   FileEntry *UFE = nullptr;
341 
342   // Now that all ancestors of Filename are in the cache, the
343   // following call is guaranteed to find the DirectoryEntry from the
344   // cache.
345   const DirectoryEntry *DirInfo = getDirectoryFromFile(*this, Filename,
346                                                        /*CacheFailure=*/true);
347   assert(DirInfo &&
348          "The directory of a virtual file should already be in the cache.");
349 
350   // Check to see if the file exists. If so, drop the virtual file
351   FileData Data;
352   const char *InterndFileName = NamedFileEnt.first().data();
353   if (getStatValue(InterndFileName, Data, true, nullptr) == 0) {
354     Data.Size = Size;
355     Data.ModTime = ModificationTime;
356     UFE = &UniqueRealFiles[Data.UniqueID];
357 
358     NamedFileEnt.second = UFE;
359 
360     // If we had already opened this file, close it now so we don't
361     // leak the descriptor. We're not going to use the file
362     // descriptor anyway, since this is a virtual file.
363     if (UFE->File)
364       UFE->closeFile();
365 
366     // If we already have an entry with this inode, return it.
367     if (UFE->isValid())
368       return UFE;
369 
370     UFE->UniqueID = Data.UniqueID;
371     UFE->IsNamedPipe = Data.IsNamedPipe;
372     UFE->InPCH = Data.InPCH;
373   }
374 
375   if (!UFE) {
376     VirtualFileEntries.push_back(llvm::make_unique<FileEntry>());
377     UFE = VirtualFileEntries.back().get();
378     NamedFileEnt.second = UFE;
379   }
380 
381   UFE->Name    = InterndFileName;
382   UFE->Size    = Size;
383   UFE->ModTime = ModificationTime;
384   UFE->Dir     = DirInfo;
385   UFE->UID     = NextFileUID++;
386   UFE->File.reset();
387   return UFE;
388 }
389 
FixupRelativePath(SmallVectorImpl<char> & path) const390 bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
391   StringRef pathRef(path.data(), path.size());
392 
393   if (FileSystemOpts.WorkingDir.empty()
394       || llvm::sys::path::is_absolute(pathRef))
395     return false;
396 
397   SmallString<128> NewPath(FileSystemOpts.WorkingDir);
398   llvm::sys::path::append(NewPath, pathRef);
399   path = NewPath;
400   return true;
401 }
402 
makeAbsolutePath(SmallVectorImpl<char> & Path) const403 bool FileManager::makeAbsolutePath(SmallVectorImpl<char> &Path) const {
404   bool Changed = FixupRelativePath(Path);
405 
406   if (!llvm::sys::path::is_absolute(StringRef(Path.data(), Path.size()))) {
407     llvm::sys::fs::make_absolute(Path);
408     Changed = true;
409   }
410 
411   return Changed;
412 }
413 
414 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
getBufferForFile(const FileEntry * Entry,bool isVolatile,bool ShouldCloseOpenFile)415 FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile,
416                               bool ShouldCloseOpenFile) {
417   uint64_t FileSize = Entry->getSize();
418   // If there's a high enough chance that the file have changed since we
419   // got its size, force a stat before opening it.
420   if (isVolatile)
421     FileSize = -1;
422 
423   const char *Filename = Entry->getName();
424   // If the file is already open, use the open file descriptor.
425   if (Entry->File) {
426     auto Result =
427         Entry->File->getBuffer(Filename, FileSize,
428                                /*RequiresNullTerminator=*/true, isVolatile);
429     // FIXME: we need a set of APIs that can make guarantees about whether a
430     // FileEntry is open or not.
431     if (ShouldCloseOpenFile)
432       Entry->closeFile();
433     return Result;
434   }
435 
436   // Otherwise, open the file.
437 
438   if (FileSystemOpts.WorkingDir.empty())
439     return FS->getBufferForFile(Filename, FileSize,
440                                 /*RequiresNullTerminator=*/true, isVolatile);
441 
442   SmallString<128> FilePath(Entry->getName());
443   FixupRelativePath(FilePath);
444   return FS->getBufferForFile(FilePath, FileSize,
445                               /*RequiresNullTerminator=*/true, isVolatile);
446 }
447 
448 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
getBufferForFile(StringRef Filename)449 FileManager::getBufferForFile(StringRef Filename) {
450   if (FileSystemOpts.WorkingDir.empty())
451     return FS->getBufferForFile(Filename);
452 
453   SmallString<128> FilePath(Filename);
454   FixupRelativePath(FilePath);
455   return FS->getBufferForFile(FilePath.c_str());
456 }
457 
458 /// getStatValue - Get the 'stat' information for the specified path,
459 /// using the cache to accelerate it if possible.  This returns true
460 /// if the path points to a virtual file or does not exist, or returns
461 /// false if it's an existent real file.  If FileDescriptor is NULL,
462 /// do directory look-up instead of file look-up.
getStatValue(const char * Path,FileData & Data,bool isFile,std::unique_ptr<vfs::File> * F)463 bool FileManager::getStatValue(const char *Path, FileData &Data, bool isFile,
464                                std::unique_ptr<vfs::File> *F) {
465   // FIXME: FileSystemOpts shouldn't be passed in here, all paths should be
466   // absolute!
467   if (FileSystemOpts.WorkingDir.empty())
468     return FileSystemStatCache::get(Path, Data, isFile, F,StatCache.get(), *FS);
469 
470   SmallString<128> FilePath(Path);
471   FixupRelativePath(FilePath);
472 
473   return FileSystemStatCache::get(FilePath.c_str(), Data, isFile, F,
474                                   StatCache.get(), *FS);
475 }
476 
getNoncachedStatValue(StringRef Path,vfs::Status & Result)477 bool FileManager::getNoncachedStatValue(StringRef Path,
478                                         vfs::Status &Result) {
479   SmallString<128> FilePath(Path);
480   FixupRelativePath(FilePath);
481 
482   llvm::ErrorOr<vfs::Status> S = FS->status(FilePath.c_str());
483   if (!S)
484     return true;
485   Result = *S;
486   return false;
487 }
488 
invalidateCache(const FileEntry * Entry)489 void FileManager::invalidateCache(const FileEntry *Entry) {
490   assert(Entry && "Cannot invalidate a NULL FileEntry");
491 
492   SeenFileEntries.erase(Entry->getName());
493 
494   // FileEntry invalidation should not block future optimizations in the file
495   // caches. Possible alternatives are cache truncation (invalidate last N) or
496   // invalidation of the whole cache.
497   UniqueRealFiles.erase(Entry->getUniqueID());
498 }
499 
500 
GetUniqueIDMapping(SmallVectorImpl<const FileEntry * > & UIDToFiles) const501 void FileManager::GetUniqueIDMapping(
502                    SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
503   UIDToFiles.clear();
504   UIDToFiles.resize(NextFileUID);
505 
506   // Map file entries
507   for (llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator>::const_iterator
508          FE = SeenFileEntries.begin(), FEEnd = SeenFileEntries.end();
509        FE != FEEnd; ++FE)
510     if (FE->getValue() && FE->getValue() != NON_EXISTENT_FILE)
511       UIDToFiles[FE->getValue()->getUID()] = FE->getValue();
512 
513   // Map virtual file entries
514   for (const auto &VFE : VirtualFileEntries)
515     if (VFE && VFE.get() != NON_EXISTENT_FILE)
516       UIDToFiles[VFE->getUID()] = VFE.get();
517 }
518 
modifyFileEntry(FileEntry * File,off_t Size,time_t ModificationTime)519 void FileManager::modifyFileEntry(FileEntry *File,
520                                   off_t Size, time_t ModificationTime) {
521   File->Size = Size;
522   File->ModTime = ModificationTime;
523 }
524 
getCanonicalName(const DirectoryEntry * Dir)525 StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) {
526   // FIXME: use llvm::sys::fs::canonical() when it gets implemented
527   llvm::DenseMap<const DirectoryEntry *, llvm::StringRef>::iterator Known
528     = CanonicalDirNames.find(Dir);
529   if (Known != CanonicalDirNames.end())
530     return Known->second;
531 
532   StringRef CanonicalName(Dir->getName());
533 
534 #ifdef LLVM_ON_UNIX
535   char CanonicalNameBuf[PATH_MAX];
536   if (realpath(Dir->getName(), CanonicalNameBuf))
537     CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
538 #else
539   SmallString<256> CanonicalNameBuf(CanonicalName);
540   llvm::sys::fs::make_absolute(CanonicalNameBuf);
541   llvm::sys::path::native(CanonicalNameBuf);
542   // We've run into needing to remove '..' here in the wild though, so
543   // remove it.
544   // On Windows, symlinks are significantly less prevalent, so removing
545   // '..' is pretty safe.
546   // Ideally we'd have an equivalent of `realpath` and could implement
547   // sys::fs::canonical across all the platforms.
548   llvm::sys::path::remove_dots(CanonicalNameBuf, /* remove_dot_dot */ true);
549   CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
550 #endif
551 
552   CanonicalDirNames.insert(std::make_pair(Dir, CanonicalName));
553   return CanonicalName;
554 }
555 
PrintStats() const556 void FileManager::PrintStats() const {
557   llvm::errs() << "\n*** File Manager Stats:\n";
558   llvm::errs() << UniqueRealFiles.size() << " real files found, "
559                << UniqueRealDirs.size() << " real dirs found.\n";
560   llvm::errs() << VirtualFileEntries.size() << " virtual files found, "
561                << VirtualDirectoryEntries.size() << " virtual dirs found.\n";
562   llvm::errs() << NumDirLookups << " dir lookups, "
563                << NumDirCacheMisses << " dir cache misses.\n";
564   llvm::errs() << NumFileLookups << " file lookups, "
565                << NumFileCacheMisses << " file cache misses.\n";
566 
567   //llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups;
568 }
569