//===--- FileManager.h - File System Probing and Caching --------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Defines the clang::FileManager interface and associated types.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_BASIC_FILEMANAGER_H
#define LLVM_CLANG_BASIC_FILEMANAGER_H
#include "clang/Basic/FileSystemOptions.h"
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/IntrusiveRefCntPtr.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/VirtualFileSystem.h"
#include <ctime>
#include <map>
#include <memory>
#include <string>
namespace llvm {
class MemoryBuffer;
} // end namespace llvm
namespace clang {
class FileSystemStatCache;
/// Cached information about one directory (either on disk or in
/// the virtual file system).
class DirectoryEntry {
friend class FileManager;
StringRef Name; // Name of the directory.
public:
StringRef getName() const { return Name; }
};
/// Cached information about one file (either on disk
/// or in the virtual file system).
///
/// If the 'File' member is valid, then this FileEntry has an open file
/// descriptor for the file.
class FileEntry {
friend class FileManager;
StringRef Name; // Name of the file.
std::string RealPathName; // Real path to the file; could be empty.
off_t Size; // File size in bytes.
time_t ModTime; // Modification time of file.
const DirectoryEntry *Dir; // Directory file lives in.
unsigned UID; // A unique (small) ID for the file.
llvm::sys::fs::UniqueID UniqueID;
bool IsNamedPipe;
bool IsValid; // Is this \c FileEntry initialized and valid?
/// The open file, if it is owned by the \p FileEntry.
mutable std::unique_ptr<llvm::vfs::File> File;
public:
FileEntry()
: UniqueID(0, 0), IsNamedPipe(false), IsValid(false)
{}
FileEntry(const FileEntry &) = delete;
FileEntry &operator=(const FileEntry &) = delete;
StringRef getName() const { return Name; }
StringRef tryGetRealPathName() const { return RealPathName; }
bool isValid() const { return IsValid; }
off_t getSize() const { return Size; }
unsigned getUID() const { return UID; }
const llvm::sys::fs::UniqueID &getUniqueID() const { return UniqueID; }
time_t getModificationTime() const { return ModTime; }
/// Return the directory the file lives in.
const DirectoryEntry *getDir() const { return Dir; }
bool operator<(const FileEntry &RHS) const { return UniqueID < RHS.UniqueID; }
/// Check whether the file is a named pipe (and thus can't be opened by
/// the native FileManager methods).
bool isNamedPipe() const { return IsNamedPipe; }
void closeFile() const {
File.reset(); // rely on destructor to close File
}
// Only for use in tests to see if deferred opens are happening, rather than
// relying on RealPathName being empty.
bool isOpenForTests() const { return File != nullptr; }
};
/// Implements support for file system lookup, file system caching,
/// and directory search management.
///
/// This also handles more advanced properties, such as uniquing files based
/// on "inode", so that a file with two names (e.g. symlinked) will be treated
/// as a single file.
///
class FileManager : public RefCountedBase<FileManager> {
IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS;
FileSystemOptions FileSystemOpts;
/// Cache for existing real directories.
std::map<llvm::sys::fs::UniqueID, DirectoryEntry> UniqueRealDirs;
/// Cache for existing real files.
std::map<llvm::sys::fs::UniqueID, FileEntry> UniqueRealFiles;
/// The virtual directories that we have allocated.
///
/// For each virtual file (e.g. foo/bar/baz.cpp), we add all of its parent
/// directories (foo/ and foo/bar/) here.
SmallVector<std::unique_ptr<DirectoryEntry>, 4> VirtualDirectoryEntries;
/// The virtual files that we have allocated.
SmallVector<std::unique_ptr<FileEntry>, 4> VirtualFileEntries;
/// A cache that maps paths to directory entries (either real or
/// virtual) we have looked up
///
/// The actual Entries for real directories/files are
/// owned by UniqueRealDirs/UniqueRealFiles above, while the Entries
/// for virtual directories/files are owned by
/// VirtualDirectoryEntries/VirtualFileEntries above.
///
llvm::StringMap<DirectoryEntry*, llvm::BumpPtrAllocator> SeenDirEntries;
/// A cache that maps paths to file entries (either real or
/// virtual) we have looked up.
///
/// \see SeenDirEntries
llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator> SeenFileEntries;
/// The canonical names of directories.
llvm::DenseMap<const DirectoryEntry *, llvm::StringRef> CanonicalDirNames;
/// Storage for canonical names that we have computed.
llvm::BumpPtrAllocator CanonicalNameStorage;
/// Each FileEntry we create is assigned a unique ID #.
///
unsigned NextFileUID;
// Statistics.
unsigned NumDirLookups, NumFileLookups;
unsigned NumDirCacheMisses, NumFileCacheMisses;
// Caching.
std::unique_ptr<FileSystemStatCache> StatCache;
bool getStatValue(StringRef Path, llvm::vfs::Status &Status, bool isFile,
std::unique_ptr<llvm::vfs::File> *F);
/// Add all ancestors of the given path (pointing to either a file
/// or a directory) as virtual directories.
void addAncestorsAsVirtualDirs(StringRef Path);
/// Fills the RealPathName in file entry.
void fillRealPathName(FileEntry *UFE, llvm::StringRef FileName);
public:
/// Construct a file manager, optionally with a custom VFS.
///
/// \param FS if non-null, the VFS to use. Otherwise uses
/// llvm::vfs::getRealFileSystem().
FileManager(const FileSystemOptions &FileSystemOpts,
IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS = nullptr);
~FileManager();
/// Installs the provided FileSystemStatCache object within
/// the FileManager.
///
/// Ownership of this object is transferred to the FileManager.
///
/// \param statCache the new stat cache to install. Ownership of this
/// object is transferred to the FileManager.
void setStatCache(std::unique_ptr<FileSystemStatCache> statCache);
/// Removes the FileSystemStatCache object from the manager.
void clearStatCache();
/// Lookup, cache, and verify the specified directory (real or
/// virtual).
///
/// This returns NULL if the directory doesn't exist.
///
/// \param CacheFailure If true and the file does not exist, we'll cache
/// the failure to find this file.
const DirectoryEntry *getDirectory(StringRef DirName,
bool CacheFailure = true);
/// Lookup, cache, and verify the specified file (real or
/// virtual).
///
/// This returns NULL if the file doesn't exist.
///
/// \param OpenFile if true and the file exists, it will be opened.
///
/// \param CacheFailure If true and the file does not exist, we'll cache
/// the failure to find this file.
const FileEntry *getFile(StringRef Filename, bool OpenFile = false,
bool CacheFailure = true);
/// Returns the current file system options
FileSystemOptions &getFileSystemOpts() { return FileSystemOpts; }
const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
llvm::vfs::FileSystem &getVirtualFileSystem() const { return *FS; }
/// Retrieve a file entry for a "virtual" file that acts as
/// if there were a file with the given name on disk.
///
/// The file itself is not accessed.
const FileEntry *getVirtualFile(StringRef Filename, off_t Size,
time_t ModificationTime);
/// Open the specified file as a MemoryBuffer, returning a new
/// MemoryBuffer if successful, otherwise returning null.
llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
getBufferForFile(const FileEntry *Entry, bool isVolatile = false,
bool ShouldCloseOpenFile = true);
llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
getBufferForFile(StringRef Filename, bool isVolatile = false);
/// Get the 'stat' information for the given \p Path.
///
/// If the path is relative, it will be resolved against the WorkingDir of the
/// FileManager's FileSystemOptions.
///
/// \returns false on success, true on error.
bool getNoncachedStatValue(StringRef Path, llvm::vfs::Status &Result);
/// Remove the real file \p Entry from the cache.
void invalidateCache(const FileEntry *Entry);
/// If path is not absolute and FileSystemOptions set the working
/// directory, the path is modified to be relative to the given
/// working directory.
/// \returns true if \c path changed.
bool FixupRelativePath(SmallVectorImpl<char> &path) const;
/// Makes \c Path absolute taking into account FileSystemOptions and the
/// working directory option.
/// \returns true if \c Path changed to absolute.
bool makeAbsolutePath(SmallVectorImpl<char> &Path) const;
/// Produce an array mapping from the unique IDs assigned to each
/// file to the corresponding FileEntry pointer.
void GetUniqueIDMapping(
SmallVectorImpl<const FileEntry *> &UIDToFiles) const;
/// Modifies the size and modification time of a previously created
/// FileEntry. Use with caution.
static void modifyFileEntry(FileEntry *File, off_t Size,
time_t ModificationTime);
/// Retrieve the canonical name for a given directory.
///
/// This is a very expensive operation, despite its results being cached,
/// and should only be used when the physical layout of the file system is
/// required, which is (almost) never.
StringRef getCanonicalName(const DirectoryEntry *Dir);
void PrintStats() const;
};
} // end namespace clang
#endif // LLVM_CLANG_BASIC_FILEMANAGER_H
