//===--- 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 <optional>

#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::Expected<DirectoryEntryRef>

getDirectoryFromFile(FileManager &FileMgr, StringRef Filename,

                     bool CacheFailure) {

  if (Filename.empty())

    return llvm::errorCodeToError(

        make_error_code(std::errc::no_such_file_or_directory));

  if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))

    return llvm::errorCodeToError(make_error_code(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.getDirectoryRef(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 = new (DirsAlloc.Allocate()) DirectoryEntry();

  UDE->Name = NamedDirEnt.first();

  NamedDirEnt.second = *UDE;

  VirtualDirectoryEntries.push_back(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)10.4M
 &&

      
llvm::sys::path::is_separator(DirName.back())10.4M
)

    DirName = DirName.substr(0, DirName.size()-1);

  std::optional<std::string> DirNameStr;

  if (is_style_windows(llvm::sys::path::Style::native)) {

    // Fixing a problem with "clang C:test.c" on Windows.

    // Stat("C:") does not recognize "C:" as a valid directory

    if (DirName.size() > 1 && DirName.back() == ':' &&

        DirName.equals_insensitive(llvm::sys::path::root_name(DirName))) {

      DirNameStr = DirName.str() + '.';

      DirName = *DirNameStr;

    }

  }

  ++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()];

  if (!UDE) {

    // We don't have this directory yet, add it.  We use the string

    // key from the SeenDirEntries map as the string.

    UDE = new (DirsAlloc.Allocate()) DirectoryEntry();

    UDE->Name = InterndDirName;

  }

  NamedDirEnt.second = *UDE;

  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());

    return FileEntryRef(*SeenFileInsertResult.first);

  }

  // 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.

    std::error_code Err = errorToErrorCode(DirInfoOrErr.takeError());

    if (CacheFailure)

      NamedFileEnt->second = Err;

    else

      SeenFileEntries.erase(Filename);

    return llvm::errorCodeToError(Err);

  }

  DirectoryEntryRef 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 ? 
&F1.27M
 : 
nullptr800k
);

  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()];

  bool ReusingEntry = UFE != nullptr;

  if (!UFE)

    UFE = new (FilesAlloc.Allocate()) FileEntry();

  if (!Status.ExposesExternalVFSPath || 
Status.getName() == Filename189
) {

    // Use the requested name. Set the FileEntry.

    NamedFileEnt->second = FileEntryRef::MapValue(*UFE, DirInfo);

  } else {

    // Name mismatch. We need a redirect. First grab the actual entry we want

    // to return.

    //

    // This redirection logic intentionally leaks the external name of a

    // redirected file that uses 'use-external-name' in \a

    // vfs::RedirectionFileSystem. This allows clang to report the external

    // name to users (in diagnostics) and to tools that don't have access to

    // the VFS (in debug info and dependency '.d' files).

    //

    // FIXME: This is pretty complex and has some very complicated interactions

    // with the rest of clang. It's also inconsistent with how "real"

    // filesystems behave and confuses parts of clang expect to see the

    // name-as-accessed on the \a FileEntryRef.

    //

    // A potential plan to remove this is as follows -

    //   - Update callers such as `HeaderSearch::findUsableModuleForHeader()`

    //     to explicitly use the `getNameAsRequested()` rather than just using

    //     `getName()`.

    //   - Add a `FileManager::getExternalPath` API for explicitly getting the

    //     remapped external filename when there is one available. Adopt it in

    //     callers like diagnostics/deps reporting instead of calling

    //     `getName()` directly.

    //   - Switch the meaning of `FileEntryRef::getName()` to get the requested

    //     name, not the external name. Once that sticks, revert callers that

    //     want the requested name back to calling `getName()`.

    //   - Update the VFS to always return the requested name. This could also

    //     return the external name, or just have an API to request it

    //     lazily. The latter has the benefit of making accesses of the

    //     external path easily tracked, but may also require extra work than

    //     just returning up front.

    //   - (Optionally) Add an API to VFS to get the external filename lazily

    //     and update `FileManager::getExternalPath()` to use it instead. This

    //     has the benefit of making such accesses easily tracked, though isn't

    //     necessarily required (and could cause extra work than just adding to

    //     eg. `vfs::Status` up front).

    auto &Redirection =

        *SeenFileEntries

             .insert({Status.getName(), FileEntryRef::MapValue(*UFE, DirInfo)})

             .first;

    assert(Redirection.second->V.is<FileEntry *>() &&

           "filename redirected to a non-canonical filename?");

    assert(Redirection.second->V.get<FileEntry *>() == UFE &&

           "filename from getStatValue() refers to wrong file");

    // Cache the redirection in the previously-inserted entry, still available

    // in the tentative return value.

    NamedFileEnt->second = FileEntryRef::MapValue(Redirection, DirInfo);

  }

  FileEntryRef ReturnedRef(*NamedFileEnt);

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

    // FIXME: This hack ensures that `getDir()` will use the path that was

    // used to lookup this file, even if we found a file by different path

    // first. This is required in order to find a module's structure when its

    // headers/module map are mapped in the VFS.

    //

    // See above for how this will eventually be removed. `IsVFSMapped`

    // *cannot* be narrowed to `ExposesExternalVFSPath` as crash reproducers

    // also depend on this logic and they have `use-external-paths: false`.

    if (&DirInfo.getDirEntry() != UFE->Dir && 
Status.IsVFSMapped567
)

      UFE->Dir = &DirInfo.getDirEntry();

    // Always update LastRef to the last name by which a file was accessed.

    // FIXME: Neither this nor always using the first reference 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: LastRef should be removed from FileEntry once all clients adopt

    // FileEntryRef.

    UFE->LastRef = ReturnedRef;

    return ReturnedRef;

  }

  // Otherwise, we don't have this file yet, add it.

  UFE->LastRef = ReturnedRef;

  UFE->Size = Status.getSize();

  UFE->ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());

  UFE->Dir = &DirInfo.getDirEntry();

  UFE->UID = NextFileUID++;

  UFE->UniqueID = Status.getUniqueID();

  UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;

  UFE->File = std::move(F);

  if (UFE->File) {

    if (auto PathName = UFE->File->getName())

      fillRealPathName(UFE, *PathName);

  } else 
if (739k
!openFile739k
) {

    // We should still fill the path even if we aren't opening the file.

    fillRealPathName(UFE, InterndFileName);

  }

  return ReturnedRef;

}

llvm::Expected<FileEntryRef> FileManager::getSTDIN() {

  // Only read stdin once.

  if (STDIN)

    return *STDIN;

  std::unique_ptr<llvm::MemoryBuffer> Content;

  if (auto ContentOrError = llvm::MemoryBuffer::getSTDIN())

    Content = std::move(*ContentOrError);

  else

    return llvm::errorCodeToError(ContentOrError.getError());

  STDIN = getVirtualFileRef(Content->getBufferIdentifier(),

                            Content->getBufferSize(), 0);

  FileEntry &FE = const_cast<FileEntry &>(STDIN->getFileEntry());

  FE.Content = std::move(Content);

  FE.IsNamedPipe = true;

  return *STDIN;

}

const FileEntry *FileManager::getVirtualFile(StringRef Filename, off_t Size,

                                             time_t ModificationTime) {

  return &getVirtualFileRef(Filename, Size, ModificationTime).getFileEntry();

}

FileEntryRef FileManager::getVirtualFileRef(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) {

    FileEntryRef::MapValue Value = *NamedFileEnt.second;

    if (LLVM_LIKELY(Value.V.is<FileEntry *>()))

      return FileEntryRef(NamedFileEnt);

    return FileEntryRef(*Value.V.get<const FileEntryRef::MapEntry *>());

  }

  // 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. A virtual file can also have an empty filename, that could come

  // from a source location preprocessor directive with an empty filename as

  // an example, so we need to pretend it has a name to ensure a valid directory

  // entry can be returned.

  auto DirInfo = expectedToOptional(getDirectoryFromFile(

      *this, Filename.empty() ? 
"."1
 : 
Filename4.90k
, /*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)) {

    Status = llvm::vfs::Status(

      Status.getName(), Status.getUniqueID(),

      llvm::sys::toTimePoint(ModificationTime),

      Status.getUser(), Status.getGroup(), Size,

      Status.getType(), Status.getPermissions());

    auto &RealFE = UniqueRealFiles[Status.getUniqueID()];

    if (RealFE) {

      // 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 (RealFE->File)

        RealFE->closeFile();

      // If we already have an entry with this inode, return it.

      //

      // FIXME: Surely this should add a reference by the new name, and return

      // it instead...

      NamedFileEnt.second = FileEntryRef::MapValue(*RealFE, *DirInfo);

      return FileEntryRef(NamedFileEnt);

    }

    // File exists, but no entry - create it.

    RealFE = new (FilesAlloc.Allocate()) FileEntry();

    RealFE->UniqueID = Status.getUniqueID();

    RealFE->IsNamedPipe =

        Status.getType() == llvm::sys::fs::file_type::fifo_file;

    fillRealPathName(RealFE, Status.getName());

    UFE = RealFE;

  } else {

    // File does not exist, create a virtual entry.

    UFE = new (FilesAlloc.Allocate()) FileEntry();

    VirtualFileEntries.push_back(UFE);

  }

  NamedFileEnt.second = FileEntryRef::MapValue(*UFE, *DirInfo);

  UFE->LastRef = FileEntryRef(NamedFileEnt);

  UFE->Size    = Size;

  UFE->ModTime = ModificationTime;

  UFE->Dir     = &DirInfo->getDirEntry();

  UFE->UID     = NextFileUID++;

  UFE->File.reset();

  return FileEntryRef(NamedFileEnt);

}

OptionalFileEntryRef 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 std::nullopt;

  if (!SeenBypassFileEntries)

    SeenBypassFileEntries = std::make_unique<

        llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>>>();

  // If we've already bypassed just use the existing one.

  auto Insertion = SeenBypassFileEntries->insert(

      {VF.getName(), std::errc::no_such_file_or_directory});

  if (!Insertion.second)

    return FileEntryRef(*Insertion.first);

  // Fill in the new entry from the stat.

  FileEntry *BFE = new (FilesAlloc.Allocate()) FileEntry();

  BypassFileEntries.push_back(BFE);

  Insertion.first->second = FileEntryRef::MapValue(*BFE, VF.getDir());

  BFE->LastRef = FileEntryRef(*Insertion.first);

  BFE->Size = Status.getSize();

  BFE->Dir = VF.getFileEntry().Dir;

  BFE->ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());

  BFE->UID = NextFileUID++;

  // Save the entry in the bypass table and return.

  return FileEntryRef(*Insertion.first);

}

bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {

  StringRef pathRef(path.data(), path.size());

  if (FileSystemOpts.WorkingDir.empty()

      || 
llvm::sys::path::is_absolute(pathRef)7.88k
)

    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 = std::string(AbsPath.str());

}

llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>

FileManager::getBufferForFile(FileEntryRef FE, bool isVolatile,

                              bool RequiresNullTerminator) {

  const FileEntry *Entry = &FE.getFileEntry();

  // If the content is living on the file entry, return a reference to it.

  if (Entry->Content)

    return llvm::MemoryBuffer::getMemBuffer(Entry->Content->getMemBufferRef());

  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 || 
Entry->isNamedPipe()1.00M
)

    FileSize = -1;

  StringRef Filename = FE.getName();

  // If the file is already open, use the open file descriptor.

  if (Entry->File) {

    auto Result = Entry->File->getBuffer(Filename, FileSize,

                                         RequiresNullTerminator, isVolatile);

    Entry->closeFile();

    return Result;

  }

  // Otherwise, open the file.

  return getBufferForFileImpl(Filename, FileSize, isVolatile,

                              RequiresNullTerminator);

}

llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>

FileManager::getBufferForFileImpl(StringRef Filename, int64_t FileSize,

                                  bool isVolatile,

                                  bool RequiresNullTerminator) {

  if (FileSystemOpts.WorkingDir.empty())

    return FS->getBufferForFile(Filename, FileSize, RequiresNullTerminator,

                                isVolatile);

  SmallString<128> FilePath(Filename);

  FixupRelativePath(FilePath);

  return FS->getBufferForFile(FilePath, FileSize, RequiresNullTerminator,

                              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<OptionalFileEntryRef> &UIDToFiles) const {

  UIDToFiles.clear();

  UIDToFiles.resize(NextFileUID);

  for (const auto &Entry : SeenFileEntries) {

    // Only return files that exist and are not redirected.

    if (!Entry.getValue() || 
!Entry.getValue()->V.is<FileEntry *>()4.83M
)

      continue;

    FileEntryRef FE(Entry);

    // Add this file if it's the first one with the UID, or if its name is

    // better than the existing one.

    OptionalFileEntryRef &ExistingFE = UIDToFiles[FE.getUID()];

    if (!ExistingFE || 
FE.getName() < ExistingFE->getName()9.97k
)

      ExistingFE = FE;

  }

}

StringRef FileManager::getCanonicalName(DirectoryEntryRef Dir) {

  return getCanonicalName(Dir, Dir.getName());

}

StringRef FileManager::getCanonicalName(FileEntryRef File) {

  return getCanonicalName(File, File.getName());

}

StringRef FileManager::getCanonicalName(const void *Entry, StringRef Name) {

  llvm::DenseMap<const void *, llvm::StringRef>::iterator Known =

      CanonicalNames.find(Entry);

  if (Known != CanonicalNames.end())

    return Known->second;

  // Name comes from FileEntry/DirectoryEntry::getName(), so it is safe to

  // store it in the DenseMap below.

  StringRef CanonicalName(Name);

  SmallString<256> AbsPathBuf;

  SmallString<256> RealPathBuf;

  if (!FS->getRealPath(Name, RealPathBuf)) {

    if (is_style_windows(llvm::sys::path::Style::native)) {

      // For Windows paths, only use the real path if it doesn't resolve

      // a substitute drive, as those are used to avoid MAX_PATH issues.

      AbsPathBuf = Name;

      if (!FS->makeAbsolute(AbsPathBuf)) {

        if (llvm::sys::path::root_name(RealPathBuf) ==

            llvm::sys::path::root_name(AbsPathBuf)) {

          CanonicalName = RealPathBuf.str().copy(CanonicalNameStorage);

        } else {

          // Fallback to using the absolute path.

          // Simplifying /../ is semantically valid on Windows even in the

          // presence of symbolic links.

          llvm::sys::path::remove_dots(AbsPathBuf, /*remove_dot_dot=*/true);

          CanonicalName = AbsPathBuf.str().copy(CanonicalNameStorage);

        }

      }

    } else {

      CanonicalName = RealPathBuf.str().copy(CanonicalNameStorage);

    }

  }

  CanonicalNames.insert({Entry, 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;

}