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//===- VirtualFileSystem.h - Virtual File System Layer ----------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
/// \file
/// \brief Defines the virtual file system interface vfs::FileSystem.
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/IntrusiveRefCntPtr.h"
#include "llvm/ADT/Optional.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/SourceMgr.h"
namespace llvm {
class MemoryBuffer;
namespace clang {
namespace vfs {
/// \brief The result of a \p status operation.
class Status {
std::string Name;
llvm::sys::fs::UniqueID UID;
llvm::sys::TimeValue MTime;
uint32_t User;
uint32_t Group;
uint64_t Size;
llvm::sys::fs::file_type Type;
llvm::sys::fs::perms Perms;
bool IsVFSMapped; // FIXME: remove when files support multiple names
Status() : Type(llvm::sys::fs::file_type::status_error) {}
Status(const llvm::sys::fs::file_status &Status);
Status(StringRef Name, StringRef RealName, llvm::sys::fs::UniqueID UID,
llvm::sys::TimeValue MTime, uint32_t User, uint32_t Group,
uint64_t Size, llvm::sys::fs::file_type Type,
llvm::sys::fs::perms Perms);
/// \brief Returns the name that should be used for this file or directory.
StringRef getName() const { return Name; }
void setName(StringRef N) { Name = N; }
/// @name Status interface from llvm::sys::fs
/// @{
llvm::sys::fs::file_type getType() const { return Type; }
llvm::sys::fs::perms getPermissions() const { return Perms; }
llvm::sys::TimeValue getLastModificationTime() const { return MTime; }
llvm::sys::fs::UniqueID getUniqueID() const { return UID; }
uint32_t getUser() const { return User; }
uint32_t getGroup() const { return Group; }
uint64_t getSize() const { return Size; }
void setType(llvm::sys::fs::file_type v) { Type = v; }
void setPermissions(llvm::sys::fs::perms p) { Perms = p; }
/// @}
/// @name Status queries
/// These are static queries in llvm::sys::fs.
/// @{
bool equivalent(const Status &Other) const;
bool isDirectory() const;
bool isRegularFile() const;
bool isOther() const;
bool isSymlink() const;
bool isStatusKnown() const;
bool exists() const;
/// @}
/// \brief Represents an open file.
class File {
/// \brief Destroy the file after closing it (if open).
/// Sub-classes should generally call close() inside their destructors. We
/// cannot do that from the base class, since close is virtual.
virtual ~File();
/// \brief Get the status of the file.
virtual llvm::ErrorOr<Status> status() = 0;
/// \brief Get the contents of the file as a \p MemoryBuffer.
virtual std::error_code getBuffer(const Twine &Name,
std::unique_ptr<llvm::MemoryBuffer> &Result,
int64_t FileSize = -1,
bool RequiresNullTerminator = true,
bool IsVolatile = false) = 0;
/// \brief Closes the file.
virtual std::error_code close() = 0;
/// \brief Sets the name to use for this file.
virtual void setName(StringRef Name) = 0;
namespace detail {
/// \brief An interface for virtual file systems to provide an iterator over the
/// (non-recursive) contents of a directory.
struct DirIterImpl {
virtual ~DirIterImpl();
/// \brief Sets \c CurrentEntry to the next entry in the directory on success,
/// or returns a system-defined \c error_code.
virtual std::error_code increment() = 0;
Status CurrentEntry;
} // end namespace detail
/// \brief An input iterator over the entries in a virtual path, similar to
/// llvm::sys::fs::directory_iterator.
class directory_iterator {
std::shared_ptr<detail::DirIterImpl> Impl; // Input iterator semantics on copy
directory_iterator(std::shared_ptr<detail::DirIterImpl> I) : Impl(I) {
assert(Impl.get() != nullptr && "requires non-null implementation");
if (!Impl->CurrentEntry.isStatusKnown())
Impl.reset(); // Normalize the end iterator to Impl == nullptr.
/// \brief Construct an 'end' iterator.
directory_iterator() { }
/// \brief Equivalent to operator++, with an error code.
directory_iterator &increment(std::error_code &EC) {
assert(Impl && "attempting to increment past end");
EC = Impl->increment();
if (EC || !Impl->CurrentEntry.isStatusKnown())
Impl.reset(); // Normalize the end iterator to Impl == nullptr.
return *this;
const Status &operator*() const { return Impl->CurrentEntry; }
const Status *operator->() const { return &Impl->CurrentEntry; }
bool operator==(const directory_iterator &RHS) const {
if (Impl && RHS.Impl)
return Impl->CurrentEntry.equivalent(RHS.Impl->CurrentEntry);
return !Impl && !RHS.Impl;
bool operator!=(const directory_iterator &RHS) const {
return !(*this == RHS);
class FileSystem;
/// \brief An input iterator over the recursive contents of a virtual path,
/// similar to llvm::sys::fs::recursive_directory_iterator.
class recursive_directory_iterator {
typedef std::stack<directory_iterator, std::vector<directory_iterator>>
FileSystem *FS;
std::shared_ptr<IterState> State; // Input iterator semantics on copy.
recursive_directory_iterator(FileSystem &FS, const Twine &Path,
std::error_code &EC);
/// \brief Construct an 'end' iterator.
recursive_directory_iterator() { }
/// \brief Equivalent to operator++, with an error code.
recursive_directory_iterator &increment(std::error_code &EC);
const Status &operator*() const { return *State->top(); }
const Status *operator->() const { return &*State->top(); }
bool operator==(const recursive_directory_iterator &Other) const {
return State == Other.State; // identity
bool operator!=(const recursive_directory_iterator &RHS) const {
return !(*this == RHS);
/// \brief The virtual file system interface.
class FileSystem : public llvm::ThreadSafeRefCountedBase<FileSystem> {
virtual ~FileSystem();
/// \brief Get the status of the entry at \p Path, if one exists.
virtual llvm::ErrorOr<Status> status(const Twine &Path) = 0;
/// \brief Get a \p File object for the file at \p Path, if one exists.
virtual std::error_code openFileForRead(const Twine &Path,
std::unique_ptr<File> &Result) = 0;
/// This is a convenience method that opens a file, gets its content and then
/// closes the file.
std::error_code getBufferForFile(const Twine &Name,
std::unique_ptr<llvm::MemoryBuffer> &Result,
int64_t FileSize = -1,
bool RequiresNullTerminator = true,
bool IsVolatile = false);
/// \brief Get a directory_iterator for \p Dir.
/// \note The 'end' iterator is directory_iterator().
virtual directory_iterator dir_begin(const Twine &Dir,
std::error_code &EC) = 0;
/// \brief Gets an \p vfs::FileSystem for the 'real' file system, as seen by
/// the operating system.
IntrusiveRefCntPtr<FileSystem> getRealFileSystem();
/// \brief A file system that allows overlaying one \p AbstractFileSystem on top
/// of another.
/// Consists of a stack of >=1 \p FileSystem objects, which are treated as being
/// one merged file system. When there is a directory that exists in more than
/// one file system, the \p OverlayFileSystem contains a directory containing
/// the union of their contents. The attributes (permissions, etc.) of the
/// top-most (most recently added) directory are used. When there is a file
/// that exists in more than one file system, the file in the top-most file
/// system overrides the other(s).
class OverlayFileSystem : public FileSystem {
typedef SmallVector<IntrusiveRefCntPtr<FileSystem>, 1> FileSystemList;
/// \brief The stack of file systems, implemented as a list in order of
/// their addition.
FileSystemList FSList;
OverlayFileSystem(IntrusiveRefCntPtr<FileSystem> Base);
/// \brief Pushes a file system on top of the stack.
void pushOverlay(IntrusiveRefCntPtr<FileSystem> FS);
llvm::ErrorOr<Status> status(const Twine &Path) override;
std::error_code openFileForRead(const Twine &Path,
std::unique_ptr<File> &Result) override;
directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
typedef FileSystemList::reverse_iterator iterator;
/// \brief Get an iterator pointing to the most recently added file system.
iterator overlays_begin() { return FSList.rbegin(); }
/// \brief Get an iterator pointing one-past the least recently added file
/// system.
iterator overlays_end() { return FSList.rend(); }
/// \brief Get a globally unique ID for a virtual file or directory.
llvm::sys::fs::UniqueID getNextVirtualUniqueID();
/// \brief Gets a \p FileSystem for a virtual file system described in YAML
/// format.
/// Takes ownership of \p Buffer.
getVFSFromYAML(llvm::MemoryBuffer *Buffer,
llvm::SourceMgr::DiagHandlerTy DiagHandler,
void *DiagContext = nullptr,
IntrusiveRefCntPtr<FileSystem> ExternalFS = getRealFileSystem());
struct YAMLVFSEntry {
template <typename T1, typename T2> YAMLVFSEntry(T1 &&VPath, T2 &&RPath)
: VPath(std::forward<T1>(VPath)), RPath(std::forward<T2>(RPath)) {}
std::string VPath;
std::string RPath;
class YAMLVFSWriter {
std::vector<YAMLVFSEntry> Mappings;
Optional<bool> IsCaseSensitive;
YAMLVFSWriter() {}
void addFileMapping(StringRef VirtualPath, StringRef RealPath);
void setCaseSensitivity(bool CaseSensitive) {
IsCaseSensitive = CaseSensitive;
void write(llvm::raw_ostream &OS);
} // end namespace vfs
} // end namespace clang