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llvm-project/clang/lib/Basic/FileManager.cpp

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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 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/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 llvm::ErrorOr<const DirectoryEntry *>
getDirectoryFromFile(FileManager &FileMgr, StringRef Filename,
bool CacheFailure) {
if (Filename.empty())
return std::errc::no_such_file_or_directory;
if (llvm::sys::path::is_separator(Filename[Filename.size() - 1]))
return std::errc::is_a_directory;
StringRef DirName = llvm::sys::path::parent_path(Filename);
// Use the current directory if file has no path component.
if (DirName.empty())
DirName = ".";
return FileMgr.getDirectory(DirName, CacheFailure);
}
/// Add all ancestors of the given path (pointing to either a file or
/// a directory) as virtual directories.
void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
StringRef DirName = llvm::sys::path::parent_path(Path);
if (DirName.empty())
DirName = ".";
auto &NamedDirEnt = *SeenDirEntries.insert(
{DirName, std::errc::no_such_file_or_directory}).first;
// When caching a virtual directory, we always cache its ancestors
// at the same time. Therefore, if DirName is already in the cache,
// we don't need to recurse as its ancestors must also already be in
// the cache (or it's a known non-virtual directory).
if (NamedDirEnt.second)
return;
// Add the virtual directory to the cache.
auto UDE = std::make_unique<DirectoryEntry>();
UDE->Name = NamedDirEnt.first();
NamedDirEnt.second = *UDE.get();
VirtualDirectoryEntries.push_back(std::move(UDE));
// Recursively add the other ancestors.
addAncestorsAsVirtualDirs(DirName);
}
llvm::Expected<DirectoryEntryRef>
FileManager::getDirectoryRef(StringRef DirName, bool CacheFailure) {
// stat doesn't like trailing separators except for root directory.
// At least, on Win32 MSVCRT, stat() cannot strip trailing '/'.
// (though it can strip '\\')
if (DirName.size() > 1 &&
DirName != llvm::sys::path::root_path(DirName) &&
llvm::sys::path::is_separator(DirName.back()))
DirName = DirName.substr(0, DirName.size()-1);
#ifdef _WIN32
// Fixing a problem with "clang C:test.c" on Windows.
// Stat("C:") does not recognize "C:" as a valid directory
std::string DirNameStr;
if (DirName.size() > 1 && DirName.back() == ':' &&
DirName.equals_lower(llvm::sys::path::root_name(DirName))) {
DirNameStr = DirName.str() + '.';
DirName = DirNameStr;
}
#endif
++NumDirLookups;
// See if there was already an entry in the map. Note that the map
// contains both virtual and real directories.
auto SeenDirInsertResult =
SeenDirEntries.insert({DirName, std::errc::no_such_file_or_directory});
if (!SeenDirInsertResult.second) {
if (SeenDirInsertResult.first->second)
return DirectoryEntryRef(&*SeenDirInsertResult.first);
return llvm::errorCodeToError(SeenDirInsertResult.first->second.getError());
}
// We've not seen this before. Fill it in.
++NumDirCacheMisses;
auto &NamedDirEnt = *SeenDirInsertResult.first;
assert(!NamedDirEnt.second && "should be newly-created");
// Get the null-terminated directory name as stored as the key of the
// SeenDirEntries map.
StringRef InterndDirName = NamedDirEnt.first();
// Check to see if the directory exists.
llvm::vfs::Status Status;
auto statError = getStatValue(InterndDirName, Status, false,
nullptr /*directory lookup*/);
if (statError) {
// There's no real directory at the given path.
if (CacheFailure)
NamedDirEnt.second = statError;
else
SeenDirEntries.erase(DirName);
return llvm::errorCodeToError(statError);
}
// It exists. See if we have already opened a directory with the
// same inode (this occurs on Unix-like systems when one dir is
// symlinked to another, for example) or the same path (on
// Windows).
DirectoryEntry &UDE = UniqueRealDirs[Status.getUniqueID()];
NamedDirEnt.second = UDE;
if (UDE.getName().empty()) {
// We don't have this directory yet, add it. We use the string
// key from the SeenDirEntries map as the string.
UDE.Name = InterndDirName;
}
return DirectoryEntryRef(&NamedDirEnt);
}
llvm::ErrorOr<const DirectoryEntry *>
FileManager::getDirectory(StringRef DirName, bool CacheFailure) {
auto Result = getDirectoryRef(DirName, CacheFailure);
if (Result)
return &Result->getDirEntry();
return llvm::errorToErrorCode(Result.takeError());
}
llvm::ErrorOr<const FileEntry *>
FileManager::getFile(StringRef Filename, bool openFile, bool CacheFailure) {
auto Result = getFileRef(Filename, openFile, CacheFailure);
if (Result)
return &Result->getFileEntry();
return llvm::errorToErrorCode(Result.takeError());
}
llvm::Expected<FileEntryRef>
FileManager::getFileRef(StringRef Filename, bool openFile, bool CacheFailure) {
++NumFileLookups;
// See if there is already an entry in the map.
auto SeenFileInsertResult =
SeenFileEntries.insert({Filename, std::errc::no_such_file_or_directory});
if (!SeenFileInsertResult.second) {
if (!SeenFileInsertResult.first->second)
return llvm::errorCodeToError(
SeenFileInsertResult.first->second.getError());
// Construct and return and FileEntryRef, unless it's a redirect to another
// filename.
SeenFileEntryOrRedirect Value = *SeenFileInsertResult.first->second;
FileEntry *FE;
if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>()))
return FileEntryRef(SeenFileInsertResult.first->first(), *FE);
return getFileRef(*Value.get<const StringRef *>(), openFile, CacheFailure);
}
// We've not seen this before. Fill it in.
++NumFileCacheMisses;
auto &NamedFileEnt = *SeenFileInsertResult.first;
assert(!NamedFileEnt.second && "should be newly-created");
// Get the null-terminated file name as stored as the key of the
// SeenFileEntries map.
StringRef InterndFileName = NamedFileEnt.first();
// Look up the directory for the file. When looking up something like
// sys/foo.h we'll discover all of the search directories that have a 'sys'
// subdirectory. This will let us avoid having to waste time on known-to-fail
// searches when we go to find sys/bar.h, because all the search directories
// without a 'sys' subdir will get a cached failure result.
auto DirInfoOrErr = getDirectoryFromFile(*this, Filename, CacheFailure);
if (!DirInfoOrErr) { // Directory doesn't exist, file can't exist.
if (CacheFailure)
NamedFileEnt.second = DirInfoOrErr.getError();
else
SeenFileEntries.erase(Filename);
return llvm::errorCodeToError(DirInfoOrErr.getError());
}
const DirectoryEntry *DirInfo = *DirInfoOrErr;
// FIXME: Use the directory info to prune this, before doing the stat syscall.
// FIXME: This will reduce the # syscalls.
// Check to see if the file exists.
std::unique_ptr<llvm::vfs::File> F;
llvm::vfs::Status Status;
auto statError = getStatValue(InterndFileName, Status, true,
openFile ? &F : nullptr);
if (statError) {
// There's no real file at the given path.
if (CacheFailure)
NamedFileEnt.second = statError;
else
SeenFileEntries.erase(Filename);
return llvm::errorCodeToError(statError);
}
assert((openFile || !F) && "undesired open file");
// It exists. See if we have already opened a file with the same inode.
// This occurs when one dir is symlinked to another, for example.
FileEntry &UFE = UniqueRealFiles[Status.getUniqueID()];
NamedFileEnt.second = &UFE;
// If the name returned by getStatValue is different than Filename, re-intern
// the name.
if (Status.getName() != Filename) {
auto &NewNamedFileEnt =
*SeenFileEntries.insert({Status.getName(), &UFE}).first;
assert((*NewNamedFileEnt.second).get<FileEntry *>() == &UFE &&
"filename from getStatValue() refers to wrong file");
InterndFileName = NewNamedFileEnt.first().data();
// In addition to re-interning the name, construct a redirecting seen file
// entry, that will point to the name the filesystem actually wants to use.
StringRef *Redirect = new (CanonicalNameStorage) StringRef(InterndFileName);
NamedFileEnt.second = Redirect;
}
if (UFE.isValid()) { // Already have an entry with this inode, return it.
// FIXME: this hack ensures that if we look up a file by a virtual path in
// the VFS that the getDir() will have the virtual path, even if we found
// the file by a 'real' path first. This is required in order to find a
// module's structure when its headers/module map are mapped in the VFS.
// We should remove this as soon as we can properly support a file having
// multiple names.
if (DirInfo != UFE.Dir && Status.IsVFSMapped)
UFE.Dir = DirInfo;
// Always update the name to use the last name by which a file was accessed.
// FIXME: Neither this nor always using the first name is correct; we want
// to switch towards a design where we return a FileName object that
// encapsulates both the name by which the file was accessed and the
// corresponding FileEntry.
// FIXME: The Name should be removed from FileEntry once all clients
// adopt FileEntryRef.
UFE.Name = InterndFileName;
return FileEntryRef(InterndFileName, UFE);
}
// Otherwise, we don't have this file yet, add it.
UFE.Name = InterndFileName;
UFE.Size = Status.getSize();
UFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
UFE.Dir = DirInfo;
UFE.UID = NextFileUID++;
UFE.UniqueID = Status.getUniqueID();
UFE.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
UFE.File = std::move(F);
UFE.IsValid = true;
if (UFE.File) {
if (auto PathName = UFE.File->getName())
fillRealPathName(&UFE, *PathName);
} else if (!openFile) {
// We should still fill the path even if we aren't opening the file.
fillRealPathName(&UFE, InterndFileName);
}
return FileEntryRef(InterndFileName, UFE);
}
const FileEntry *
FileManager::getVirtualFile(StringRef Filename, off_t Size,
time_t ModificationTime) {
++NumFileLookups;
// See if there is already an entry in the map for an existing file.
auto &NamedFileEnt = *SeenFileEntries.insert(
{Filename, std::errc::no_such_file_or_directory}).first;
if (NamedFileEnt.second) {
SeenFileEntryOrRedirect Value = *NamedFileEnt.second;
FileEntry *FE;
if (LLVM_LIKELY(FE = Value.dyn_cast<FileEntry *>()))
return FE;
return getVirtualFile(*Value.get<const StringRef *>(), Size,
ModificationTime);
}
// We've not seen this before, or the file is cached as non-existent.
++NumFileCacheMisses;
addAncestorsAsVirtualDirs(Filename);
FileEntry *UFE = nullptr;
// Now that all ancestors of Filename are in the cache, the
// following call is guaranteed to find the DirectoryEntry from the
// cache.
auto DirInfo = getDirectoryFromFile(*this, Filename, /*CacheFailure=*/true);
assert(DirInfo &&
"The directory of a virtual file should already be in the cache.");
// Check to see if the file exists. If so, drop the virtual file
llvm::vfs::Status Status;
const char *InterndFileName = NamedFileEnt.first().data();
if (!getStatValue(InterndFileName, Status, true, nullptr)) {
UFE = &UniqueRealFiles[Status.getUniqueID()];
Status = llvm::vfs::Status(
Status.getName(), Status.getUniqueID(),
llvm::sys::toTimePoint(ModificationTime),
Status.getUser(), Status.getGroup(), Size,
Status.getType(), Status.getPermissions());
NamedFileEnt.second = UFE;
// If we had already opened this file, close it now so we don't
// leak the descriptor. We're not going to use the file
// descriptor anyway, since this is a virtual file.
if (UFE->File)
UFE->closeFile();
// If we already have an entry with this inode, return it.
if (UFE->isValid())
return UFE;
UFE->UniqueID = Status.getUniqueID();
UFE->IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
fillRealPathName(UFE, Status.getName());
} else {
VirtualFileEntries.push_back(std::make_unique<FileEntry>());
UFE = VirtualFileEntries.back().get();
NamedFileEnt.second = UFE;
}
UFE->Name = InterndFileName;
UFE->Size = Size;
UFE->ModTime = ModificationTime;
UFE->Dir = *DirInfo;
UFE->UID = NextFileUID++;
UFE->IsValid = true;
UFE->File.reset();
return UFE;
}
llvm::Optional<FileEntryRef> FileManager::getBypassFile(FileEntryRef VF) {
// Stat of the file and return nullptr if it doesn't exist.
llvm::vfs::Status Status;
if (getStatValue(VF.getName(), Status, /*isFile=*/true, /*F=*/nullptr))
return None;
// Fill it in from the stat.
BypassFileEntries.push_back(std::make_unique<FileEntry>());
const FileEntry &VFE = VF.getFileEntry();
FileEntry &BFE = *BypassFileEntries.back();
BFE.Name = VFE.getName();
BFE.Size = Status.getSize();
BFE.Dir = VFE.Dir;
BFE.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
BFE.UID = NextFileUID++;
BFE.IsValid = true;
return FileEntryRef(VF.getName(), BFE);
}
bool FileManager::FixupRelativePath(SmallVectorImpl<char> &path) const {
StringRef pathRef(path.data(), path.size());
if (FileSystemOpts.WorkingDir.empty()
|| llvm::sys::path::is_absolute(pathRef))
return false;
SmallString<128> NewPath(FileSystemOpts.WorkingDir);
llvm::sys::path::append(NewPath, pathRef);
path = NewPath;
return true;
}
bool FileManager::makeAbsolutePath(SmallVectorImpl<char> &Path) const {
bool Changed = FixupRelativePath(Path);
if (!llvm::sys::path::is_absolute(StringRef(Path.data(), Path.size()))) {
FS->makeAbsolute(Path);
Changed = true;
}
return Changed;
}
void FileManager::fillRealPathName(FileEntry *UFE, llvm::StringRef FileName) {
llvm::SmallString<128> AbsPath(FileName);
// This is not the same as `VFS::getRealPath()`, which resolves symlinks
// but can be very expensive on real file systems.
// FIXME: the semantic of RealPathName is unclear, and the name might be
// misleading. We need to clean up the interface here.
makeAbsolutePath(AbsPath);
llvm::sys::path::remove_dots(AbsPath, /*remove_dot_dot=*/true);
UFE->RealPathName = AbsPath.str();
}
llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile) {
uint64_t FileSize = Entry->getSize();
// If there's a high enough chance that the file have changed since we
// got its size, force a stat before opening it.
if (isVolatile)
FileSize = -1;
StringRef Filename = Entry->getName();
// If the file is already open, use the open file descriptor.
if (Entry->File) {
auto Result =
Entry->File->getBuffer(Filename, FileSize,
/*RequiresNullTerminator=*/true, isVolatile);
Entry->closeFile();
return Result;
}
// Otherwise, open the file.
return getBufferForFileImpl(Filename, FileSize, isVolatile);
}
llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
FileManager::getBufferForFileImpl(StringRef Filename, int64_t FileSize,
bool isVolatile) {
if (FileSystemOpts.WorkingDir.empty())
return FS->getBufferForFile(Filename, FileSize,
/*RequiresNullTerminator=*/true, isVolatile);
SmallString<128> FilePath(Filename);
FixupRelativePath(FilePath);
return FS->getBufferForFile(FilePath, FileSize,
/*RequiresNullTerminator=*/true, isVolatile);
}
/// getStatValue - Get the 'stat' information for the specified path,
/// using the cache to accelerate it if possible. This returns true
/// if the path points to a virtual file or does not exist, or returns
/// false if it's an existent real file. If FileDescriptor is NULL,
/// do directory look-up instead of file look-up.
std::error_code
FileManager::getStatValue(StringRef Path, llvm::vfs::Status &Status,
bool isFile, std::unique_ptr<llvm::vfs::File> *F) {
// FIXME: FileSystemOpts shouldn't be passed in here, all paths should be
// absolute!
if (FileSystemOpts.WorkingDir.empty())
return FileSystemStatCache::get(Path, Status, isFile, F,
StatCache.get(), *FS);
SmallString<128> FilePath(Path);
FixupRelativePath(FilePath);
return FileSystemStatCache::get(FilePath.c_str(), Status, isFile, F,
StatCache.get(), *FS);
}
std::error_code
FileManager::getNoncachedStatValue(StringRef Path,
llvm::vfs::Status &Result) {
SmallString<128> FilePath(Path);
FixupRelativePath(FilePath);
llvm::ErrorOr<llvm::vfs::Status> S = FS->status(FilePath.c_str());
if (!S)
return S.getError();
Result = *S;
return std::error_code();
}
void FileManager::GetUniqueIDMapping(
SmallVectorImpl<const FileEntry *> &UIDToFiles) const {
UIDToFiles.clear();
UIDToFiles.resize(NextFileUID);
// Map file entries
for (llvm::StringMap<llvm::ErrorOr<SeenFileEntryOrRedirect>,
llvm::BumpPtrAllocator>::const_iterator
FE = SeenFileEntries.begin(),
FEEnd = SeenFileEntries.end();
FE != FEEnd; ++FE)
if (llvm::ErrorOr<SeenFileEntryOrRedirect> Entry = FE->getValue()) {
if (const auto *FE = (*Entry).dyn_cast<FileEntry *>())
UIDToFiles[FE->getUID()] = FE;
}
// Map virtual file entries
for (const auto &VFE : VirtualFileEntries)
UIDToFiles[VFE->getUID()] = VFE.get();
}
StringRef FileManager::getCanonicalName(const DirectoryEntry *Dir) {
// FIXME: use llvm::sys::fs::canonical() when it gets implemented
llvm::DenseMap<const DirectoryEntry *, llvm::StringRef>::iterator Known
= CanonicalDirNames.find(Dir);
if (Known != CanonicalDirNames.end())
return Known->second;
StringRef CanonicalName(Dir->getName());
SmallString<4096> CanonicalNameBuf;
if (!FS->getRealPath(Dir->getName(), CanonicalNameBuf))
CanonicalName = StringRef(CanonicalNameBuf).copy(CanonicalNameStorage);
CanonicalDirNames.insert({Dir, CanonicalName});
return CanonicalName;
}
void FileManager::PrintStats() const {
llvm::errs() << "\n*** File Manager Stats:\n";
llvm::errs() << UniqueRealFiles.size() << " real files found, "
<< UniqueRealDirs.size() << " real dirs found.\n";
llvm::errs() << VirtualFileEntries.size() << " virtual files found, "
<< VirtualDirectoryEntries.size() << " virtual dirs found.\n";
llvm::errs() << NumDirLookups << " dir lookups, "
<< NumDirCacheMisses << " dir cache misses.\n";
llvm::errs() << NumFileLookups << " file lookups, "
<< NumFileCacheMisses << " file cache misses.\n";
//llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups;
}
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