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//===--- FileManager.cpp - File System Probing and Caching ----------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See 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/SmallString.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/ADT/STLExtras.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;
// Common logic.
FileManager::FileManager(const FileSystemOptions &FSO,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
: FS(std::move(FS)), FileSystemOpts(FSO), SeenDirEntries(64),
SeenFileEntries(64), NextFileUID(0) {
NumDirLookups = NumFileLookups = 0;
NumDirCacheMisses = NumFileCacheMisses = 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 const DirectoryEntry *getDirectoryFromFile(FileManager &FileMgr,
StringRef Filename,
bool CacheFailure) {
if (Filename.empty())
return nullptr;
if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
return nullptr; // If Filename 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, nullptr}).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)
// Add the virtual directory to the cache.
auto UDE = llvm::make_unique<DirectoryEntry>();
UDE->Name = NamedDirEnt.first();
NamedDirEnt.second = UDE.get();
// Recursively add the other ancestors.
const DirectoryEntry *FileManager::getDirectory(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) &&
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;
// 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, nullptr});
if (!SeenDirInsertResult.second)
return SeenDirInsertResult.first->second;
// We've not seen this before. Fill it in.
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;
if (getStatValue(InterndDirName, Status, false, nullptr /*directory lookup*/)) {
// There's no real directory at the given path.
if (!CacheFailure)
return nullptr;
// 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 &UDE;
const FileEntry *FileManager::getFile(StringRef Filename, bool openFile,
bool CacheFailure) {
// See if there is already an entry in the map.
auto SeenFileInsertResult = SeenFileEntries.insert({Filename, nullptr});
if (!SeenFileInsertResult.second)
return SeenFileInsertResult.first->second;
// We've not seen this before. Fill it in.
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.
const DirectoryEntry *DirInfo = getDirectoryFromFile(*this, Filename,
if (DirInfo == nullptr) { // Directory doesn't exist, file can't exist.
if (!CacheFailure)
return nullptr;
// 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;
if (getStatValue(InterndFileName, Status, true, openFile ? &F : nullptr)) {
// There's no real file at the given path.
if (!CacheFailure)
return nullptr;
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 &NamedFileEnt =
*SeenFileEntries.insert({Status.getName(), &UFE}).first;
assert(NamedFileEnt.second == &UFE &&
"filename from getStatValue() refers to wrong file");
InterndFileName = NamedFileEnt.first().data();
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.
UFE.Name = InterndFileName;
return &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 &UFE;
const FileEntry *
FileManager::getVirtualFile(StringRef Filename, off_t Size,
time_t ModificationTime) {
// See if there is already an entry in the map for an existing file.
auto &NamedFileEnt = *SeenFileEntries.insert({Filename, nullptr}).first;
if (NamedFileEnt.second)
return NamedFileEnt.second;
// We've not seen this before, or the file is cached as non-existent.
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.
const DirectoryEntry *DirInfo = getDirectoryFromFile(*this, Filename,
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) == 0) {
UFE = &UniqueRealFiles[Status.getUniqueID()];
Status = llvm::vfs::Status(
Status.getName(), Status.getUniqueID(),
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)
// 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 {
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;
return UFE;
bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
StringRef pathRef(, 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.size()))) {
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.
llvm::sys::path::remove_dots(AbsPath, /*remove_dot_dot=*/true);
UFE->RealPathName = AbsPath.str();
FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile,
bool ShouldCloseOpenFile) {
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);
// FIXME: we need a set of APIs that can make guarantees about whether a
// FileEntry is open or not.
if (ShouldCloseOpenFile)
return Result;
// Otherwise, open the file.
if (FileSystemOpts.WorkingDir.empty())
return FS->getBufferForFile(Filename, FileSize,
/*RequiresNullTerminator=*/true, isVolatile);
SmallString<128> FilePath(Entry->getName());
return FS->getBufferForFile(FilePath, FileSize,
/*RequiresNullTerminator=*/true, isVolatile);
FileManager::getBufferForFile(StringRef Filename, bool isVolatile) {
if (FileSystemOpts.WorkingDir.empty())
return FS->getBufferForFile(Filename, -1, true, isVolatile);
SmallString<128> FilePath(Filename);
return FS->getBufferForFile(FilePath.c_str(), -1, 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.
bool 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 bool(FileSystemStatCache::get(Path, Status, isFile, F,
StatCache.get(), *FS));
SmallString<128> FilePath(Path);
return bool(FileSystemStatCache::get(FilePath.c_str(), Status, isFile, F,
StatCache.get(), *FS));
bool FileManager::getNoncachedStatValue(StringRef Path,
llvm::vfs::Status &Result) {
SmallString<128> FilePath(Path);
llvm::ErrorOr<llvm::vfs::Status> S = FS->status(FilePath.c_str());
if (!S)
return true;
Result = *S;
return false;
void FileManager::invalidateCache(const FileEntry *Entry) {
assert(Entry && "Cannot invalidate a NULL FileEntry");
// FileEntry invalidation should not block future optimizations in the file
// caches. Possible alternatives are cache truncation (invalidate last N) or
// invalidation of the whole cache.
// FIXME: This is broken. We sometimes have the same FileEntry* shared
// betweeen multiple SeenFileEntries, so this can leave dangling pointers.
void FileManager::GetUniqueIDMapping(
SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
// Map file entries
for (llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator>::const_iterator
FE = SeenFileEntries.begin(), FEEnd = SeenFileEntries.end();
FE != FEEnd; ++FE)
if (FE->getValue())
UIDToFiles[FE->getValue()->getUID()] = FE->getValue();
// Map virtual file entries
for (const auto &VFE : VirtualFileEntries)
UIDToFiles[VFE->getUID()] = VFE.get();
void FileManager::modifyFileEntry(FileEntry *File,
off_t Size, time_t ModificationTime) {
File->Size = Size;
File->ModTime = ModificationTime;
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;