//===--- 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/DirectoryEntry.h"

#include "clang/Basic/FileEntry.h"

#include "clang/Basic/FileSystemOptions.h"

#include "clang/Basic/LLVM.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/IntrusiveRefCntPtr.h"

#include "llvm/ADT/PointerUnion.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;

/// 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;

  llvm::SpecificBumpPtrAllocator<FileEntry> FilesAlloc;

  llvm::SpecificBumpPtrAllocator<DirectoryEntry> DirsAlloc;

  /// Cache for existing real directories.

  llvm::DenseMap<llvm::sys::fs::UniqueID, DirectoryEntry *> UniqueRealDirs;

  /// Cache for existing real files.

  llvm::DenseMap<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<DirectoryEntry *, 4> VirtualDirectoryEntries;

  /// The virtual files that we have allocated.

  SmallVector<FileEntry *, 4> VirtualFileEntries;

  /// A set of files that bypass the maps and uniquing.  They can have

  /// conflicting filenames.

  SmallVector<FileEntry *, 0> BypassFileEntries;

  /// A cache that maps paths to directory entries (either real or

  /// virtual) we have looked up, or an error that occurred when we looked up

  /// the directory.

  ///

  /// 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<llvm::ErrorOr<DirectoryEntry &>, llvm::BumpPtrAllocator>

  SeenDirEntries;

  /// A cache that maps paths to file entries (either real or

  /// virtual) we have looked up, or an error that occurred when we looked up

  /// the file.

  ///

  /// \see SeenDirEntries

  llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>, llvm::BumpPtrAllocator>

      SeenFileEntries;

  /// A mirror of SeenFileEntries to give fake answers for getBypassFile().

  ///

  /// Don't bother hooking up a BumpPtrAllocator. This should be rarely used,

  /// and only on error paths.

  std::unique_ptr<llvm::StringMap<llvm::ErrorOr<FileEntryRef::MapValue>>>

      SeenBypassFileEntries;

  /// The file entry for stdin, if it has been accessed through the FileManager.

  Optional<FileEntryRef> STDIN;

  /// The canonical names of files and directories .

  llvm::DenseMap<const void *, llvm::StringRef> CanonicalNames;

  /// Storage for canonical names that we have computed.

  llvm::BumpPtrAllocator CanonicalNameStorage;

  /// Each FileEntry we create is assigned a unique ID #.

  ///

  unsigned NextFileUID;

  // Caching.

  std::unique_ptr<FileSystemStatCache> StatCache;

  std::error_code 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();

  /// Returns the number of unique real file entries cached by the file manager.

  size_t getNumUniqueRealFiles() const { return UniqueRealFiles.size(); }

  /// Lookup, cache, and verify the specified directory (real or

  /// virtual).

  ///

  /// This returns a \c std::error_code if there was an error reading the

  /// directory. On success, returns the reference to the directory entry

  /// together with the exact path that was used to access a file by a

  /// particular call to getDirectoryRef.

  ///

  /// \param CacheFailure If true and the file does not exist, we'll cache

  /// the failure to find this file.

  llvm::Expected<DirectoryEntryRef> getDirectoryRef(StringRef DirName,

                                                    bool CacheFailure = true);

  /// Get a \c DirectoryEntryRef if it exists, without doing anything on error.

  llvm::Optional<DirectoryEntryRef>

  getOptionalDirectoryRef(StringRef DirName, bool CacheFailure = true) {

    return llvm::expectedToOptional(getDirectoryRef(DirName, CacheFailure));

  }

  /// Lookup, cache, and verify the specified directory (real or

  /// virtual).

  ///

  /// This function is deprecated and will be removed at some point in the

  /// future, new clients should use

  ///  \c getDirectoryRef.

  ///

  /// This returns a \c std::error_code if there was an error reading the

  /// directory. If there is no error, the DirectoryEntry is guaranteed to be

  /// non-NULL.

  ///

  /// \param CacheFailure If true and the file does not exist, we'll cache

  /// the failure to find this file.

  llvm::ErrorOr<const DirectoryEntry *>

  getDirectory(StringRef DirName, bool CacheFailure = true);

  /// Lookup, cache, and verify the specified file (real or

  /// virtual).

  ///

  /// This function is deprecated and will be removed at some point in the

  /// future, new clients should use

  ///  \c getFileRef.

  ///

  /// This returns a \c std::error_code if there was an error loading the file.

  /// If there is no error, the FileEntry is guaranteed to be non-NULL.

  ///

  /// \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.

  llvm::ErrorOr<const FileEntry *>

  getFile(StringRef Filename, bool OpenFile = false, bool CacheFailure = true);

  /// Lookup, cache, and verify the specified file (real or virtual). Return the

  /// reference to the file entry together with the exact path that was used to

  /// access a file by a particular call to getFileRef. If the underlying VFS is

  /// a redirecting VFS that uses external file names, the returned FileEntryRef

  /// will use the external name instead of the filename that was passed to this

  /// method.

  ///

  /// This returns a \c std::error_code if there was an error loading the file,

  /// or a \c FileEntryRef otherwise.

  ///

  /// \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.

  llvm::Expected<FileEntryRef> getFileRef(StringRef Filename,

                                          bool OpenFile = false,

                                          bool CacheFailure = true);

  /// Get the FileEntryRef for stdin, returning an error if stdin cannot be

  /// read.

  ///

  /// This reads and caches stdin before returning. Subsequent calls return the

  /// same file entry, and a reference to the cached input is returned by calls

  /// to getBufferForFile.

  llvm::Expected<FileEntryRef> getSTDIN();

  /// Get a FileEntryRef if it exists, without doing anything on error.

  llvm::Optional<FileEntryRef> getOptionalFileRef(StringRef Filename,

                                                  bool OpenFile = false,

                                                  bool CacheFailure = true) {

    return llvm::expectedToOptional(

        getFileRef(Filename, OpenFile, CacheFailure));

  }

  /// Returns the current file system options

  FileSystemOptions &getFileSystemOpts() { return FileSystemOpts; }

  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }

  llvm::vfs::FileSystem &getVirtualFileSystem() const { return *FS; }

  void setVirtualFileSystem(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) {

    this->FS = std::move(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.

  FileEntryRef getVirtualFileRef(StringRef Filename, off_t Size,

                                 time_t ModificationTime);

  const FileEntry *getVirtualFile(StringRef Filename, off_t Size,

                                  time_t ModificationTime);

  /// Retrieve a FileEntry that bypasses VFE, which is expected to be a virtual

  /// file entry, to access the real file.  The returned FileEntry will have

  /// the same filename as FE but a different identity and its own stat.

  ///

  /// This should be used only for rare error recovery paths because it

  /// bypasses all mapping and uniquing, blindly creating a new FileEntry.

  /// There is no attempt to deduplicate these; if you bypass the same file

  /// twice, you get two new file entries.

  llvm::Optional<FileEntryRef> getBypassFile(FileEntryRef VFE);

  /// 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 RequiresNullTerminator = true);

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

  getBufferForFile(StringRef Filename, bool isVolatile = false,

                   bool RequiresNullTerminator = true) {

    return getBufferForFileImpl(Filename, /*FileSize=*/-1, isVolatile,

                                RequiresNullTerminator);

  }

private:

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

  getBufferForFileImpl(StringRef Filename, int64_t FileSize, bool isVolatile,

                       bool RequiresNullTerminator);

public:

  /// 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 a \c std::error_code describing an error, if there was one

  std::error_code getNoncachedStatValue(StringRef Path,

                                        llvm::vfs::Status &Result);

  /// 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;

  /// 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);

  /// Retrieve the canonical name for a given file.

  ///

  /// 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 FileEntry *File);

  void PrintStats() const;

};

} // end namespace clang

#endif // LLVM_CLANG_BASIC_FILEMANAGER_H