//===- VirtualFileSystem.h - Virtual File System Layer ----------*- 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 virtual file system interface vfs::FileSystem.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_VIRTUALFILESYSTEM_H
#define LLVM_SUPPORT_VIRTUALFILESYSTEM_H
#include "llvm/ADT/IntrusiveRefCntPtr.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/STLFunctionalExtras.h"
#include "llvm/Support/Chrono.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SourceMgr.h"
#include <cassert>
#include <cstdint>
#include <ctime>
#include <memory>
#include <optional>
#include <stack>
#include <string>
#include <system_error>
#include <utility>
#include <vector>
namespace llvm {
class MemoryBuffer;
class MemoryBufferRef;
class Twine;
namespace vfs {
/// The result of a \p status operation.
class Status {
std::string Name;
llvm::sys::fs::UniqueID UID;
llvm::sys::TimePoint<> MTime;
uint32_t User;
uint32_t Group;
uint64_t Size;
llvm::sys::fs::file_type Type = llvm::sys::fs::file_type::status_error;
llvm::sys::fs::perms Perms;
public:
// FIXME: remove when files support multiple names
bool IsVFSMapped = false;
/// Whether this entity has an external path different from the virtual path,
/// and the external path is exposed by leaking it through the abstraction.
/// For example, a RedirectingFileSystem will set this for paths where
/// UseExternalName is true.
///
/// FIXME: Currently the external path is exposed by replacing the virtual
/// path in this Status object. Instead, we should leave the path in the
/// Status intact (matching the requested virtual path) - see
/// FileManager::getFileRef for how how we plan to fix this.
bool ExposesExternalVFSPath = false;
Status() = default;
Status(const llvm::sys::fs::file_status &Status);
Status(const Twine &Name, llvm::sys::fs::UniqueID UID,
llvm::sys::TimePoint<> MTime, uint32_t User, uint32_t Group,
uint64_t Size, llvm::sys::fs::file_type Type,
llvm::sys::fs::perms Perms);
/// Get a copy of a Status with a different size.
static Status copyWithNewSize(const Status &In, uint64_t NewSize);
/// Get a copy of a Status with a different name.
static Status copyWithNewName(const Status &In, const Twine &NewName);
static Status copyWithNewName(const llvm::sys::fs::file_status &In,
const Twine &NewName);
/// Returns the name that should be used for this file or directory.
StringRef getName() const { return Name; }
/// @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::TimePoint<> 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; }
/// @}
/// @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;
/// @}
};
/// Represents an open file.
class File {
public:
/// 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();
/// Get the status of the file.
virtual llvm::ErrorOr<Status> status() = 0;
/// Get the name of the file
virtual llvm::ErrorOr<std::string> getName() {
if (auto Status = status())
return Status->getName().str();
else
return Status.getError();
}
/// Get the contents of the file as a \p MemoryBuffer.
virtual llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
getBuffer(const Twine &Name, int64_t FileSize = -1,
bool RequiresNullTerminator = true, bool IsVolatile = false) = 0;
/// Closes the file.
virtual std::error_code close() = 0;
// Get the same file with a different path.
static ErrorOr<std::unique_ptr<File>>
getWithPath(ErrorOr<std::unique_ptr<File>> Result, const Twine &P);
protected:
// Set the file's underlying path.
virtual void setPath(const Twine &Path) {}
};
/// A member of a directory, yielded by a directory_iterator.
/// Only information available on most platforms is included.
class directory_entry {
std::string Path;
llvm::sys::fs::file_type Type = llvm::sys::fs::file_type::type_unknown;
public:
directory_entry() = default;
directory_entry(std::string Path, llvm::sys::fs::file_type Type)
: Path(std::move(Path)), Type(Type) {}
llvm::StringRef path() const { return Path; }
llvm::sys::fs::file_type type() const { return Type; }
};
namespace detail {
/// An interface for virtual file systems to provide an iterator over the
/// (non-recursive) contents of a directory.
struct DirIterImpl {
virtual ~DirIterImpl();
/// Sets \c CurrentEntry to the next entry in the directory on success,
/// to directory_entry() at end, or returns a system-defined \c error_code.
virtual std::error_code increment() = 0;
directory_entry CurrentEntry;
};
} // namespace detail
/// 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
public:
directory_iterator(std::shared_ptr<detail::DirIterImpl> I)
: Impl(std::move(I)) {
assert(Impl.get() != nullptr && "requires non-null implementation");
if (Impl->CurrentEntry.path().empty())
Impl.reset(); // Normalize the end iterator to Impl == nullptr.
}
/// Construct an 'end' iterator.
directory_iterator() = default;
/// 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 (Impl->CurrentEntry.path().empty())
Impl.reset(); // Normalize the end iterator to Impl == nullptr.
return *this;
}
const directory_entry &operator*() const { return Impl->CurrentEntry; }
const directory_entry *operator->() const { return &Impl->CurrentEntry; }
bool operator==(const directory_iterator &RHS) const {
if (Impl && RHS.Impl)
return Impl->CurrentEntry.path() == RHS.Impl->CurrentEntry.path();
return !Impl && !RHS.Impl;
}
bool operator!=(const directory_iterator &RHS) const {
return !(*this == RHS);
}
};
class FileSystem;
namespace detail {
/// Keeps state for the recursive_directory_iterator.
struct RecDirIterState {
std::stack<directory_iterator, std::vector<directory_iterator>> Stack;
bool HasNoPushRequest = false;
};
} // end namespace detail
/// An input iterator over the recursive contents of a virtual path,
/// similar to llvm::sys::fs::recursive_directory_iterator.
class recursive_directory_iterator {
FileSystem *FS;
std::shared_ptr<detail::RecDirIterState>
State; // Input iterator semantics on copy.
public:
recursive_directory_iterator(FileSystem &FS, const Twine &Path,
std::error_code &EC);
/// Construct an 'end' iterator.
recursive_directory_iterator() = default;
/// Equivalent to operator++, with an error code.
recursive_directory_iterator &increment(std::error_code &EC);
const directory_entry &operator*() const { return *State->Stack.top(); }
const directory_entry *operator->() const { return &*State->Stack.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);
}
/// Gets the current level. Starting path is at level 0.
int level() const {
assert(!State->Stack.empty() &&
"Cannot get level without any iteration state");
return State->Stack.size() - 1;
}
void no_push() { State->HasNoPushRequest = true; }
};
/// The virtual file system interface.
class FileSystem : public llvm::ThreadSafeRefCountedBase<FileSystem> {
public:
virtual ~FileSystem();
/// Get the status of the entry at \p Path, if one exists.
virtual llvm::ErrorOr<Status> status(const Twine &Path) = 0;
/// Get a \p File object for the file at \p Path, if one exists.
virtual llvm::ErrorOr<std::unique_ptr<File>>
openFileForRead(const Twine &Path) = 0;
/// This is a convenience method that opens a file, gets its content and then
/// closes the file.
llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
getBufferForFile(const Twine &Name, int64_t FileSize = -1,
bool RequiresNullTerminator = true, bool IsVolatile = false);
/// 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;
/// Set the working directory. This will affect all following operations on
/// this file system and may propagate down for nested file systems.
virtual std::error_code setCurrentWorkingDirectory(const Twine &Path) = 0;
/// Get the working directory of this file system.
virtual llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const = 0;
/// Gets real path of \p Path e.g. collapse all . and .. patterns, resolve
/// symlinks. For real file system, this uses `llvm::sys::fs::real_path`.
/// This returns errc::operation_not_permitted if not implemented by subclass.
virtual std::error_code getRealPath(const Twine &Path,
SmallVectorImpl<char> &Output) const;
/// Check whether a file exists. Provided for convenience.
bool exists(const Twine &Path);
/// Is the file mounted on a local filesystem?
virtual std::error_code isLocal(const Twine &Path, bool &Result);
/// Make \a Path an absolute path.
///
/// Makes \a Path absolute using the current directory if it is not already.
/// An empty \a Path will result in the current directory.
///
/// /absolute/path => /absolute/path
/// relative/../path => <current-directory>/relative/../path
///
/// \param Path A path that is modified to be an absolute path.
/// \returns success if \a path has been made absolute, otherwise a
/// platform-specific error_code.
virtual std::error_code makeAbsolute(SmallVectorImpl<char> &Path) const;
enum class PrintType { Summary, Contents, RecursiveContents };
void print(raw_ostream &OS, PrintType Type = PrintType::Contents,
unsigned IndentLevel = 0) const {
printImpl(OS, Type, IndentLevel);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void dump() const;
#endif
protected:
virtual void printImpl(raw_ostream &OS, PrintType Type,
unsigned IndentLevel) const {
printIndent(OS, IndentLevel);
OS << "FileSystem\n";
}
void printIndent(raw_ostream &OS, unsigned IndentLevel) const {
for (unsigned i = 0; i < IndentLevel; ++i)
OS << " ";
}
};
/// Gets an \p vfs::FileSystem for the 'real' file system, as seen by
/// the operating system.
/// The working directory is linked to the process's working directory.
/// (This is usually thread-hostile).
IntrusiveRefCntPtr<FileSystem> getRealFileSystem();
/// Create an \p vfs::FileSystem for the 'real' file system, as seen by
/// the operating system.
/// It has its own working directory, independent of (but initially equal to)
/// that of the process.
std::unique_ptr<FileSystem> createPhysicalFileSystem();
/// 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 {
using FileSystemList = SmallVector<IntrusiveRefCntPtr<FileSystem>, 1>;
/// The stack of file systems, implemented as a list in order of
/// their addition.
FileSystemList FSList;
public:
OverlayFileSystem(IntrusiveRefCntPtr<FileSystem> Base);
/// Pushes a file system on top of the stack.
void pushOverlay(IntrusiveRefCntPtr<FileSystem> FS);
llvm::ErrorOr<Status> status(const Twine &Path) override;
llvm::ErrorOr<std::unique_ptr<File>>
openFileForRead(const Twine &Path) override;
directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override;
std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
std::error_code isLocal(const Twine &Path, bool &Result) override;
std::error_code getRealPath(const Twine &Path,
SmallVectorImpl<char> &Output) const override;
using iterator = FileSystemList::reverse_iterator;
using const_iterator = FileSystemList::const_reverse_iterator;
using reverse_iterator = FileSystemList::iterator;
using const_reverse_iterator = FileSystemList::const_iterator;
using range = iterator_range<iterator>;
using const_range = iterator_range<const_iterator>;
/// Get an iterator pointing to the most recently added file system.
iterator overlays_begin() { return FSList.rbegin(); }
const_iterator overlays_begin() const { return FSList.rbegin(); }
/// Get an iterator pointing one-past the least recently added file system.
iterator overlays_end() { return FSList.rend(); }
const_iterator overlays_end() const { return FSList.rend(); }
/// Get an iterator pointing to the least recently added file system.
reverse_iterator overlays_rbegin() { return FSList.begin(); }
const_reverse_iterator overlays_rbegin() const { return FSList.begin(); }
/// Get an iterator pointing one-past the most recently added file system.
reverse_iterator overlays_rend() { return FSList.end(); }
const_reverse_iterator overlays_rend() const { return FSList.end(); }
range overlays_range() { return llvm::reverse(FSList); }
const_range overlays_range() const { return llvm::reverse(FSList); }
protected:
void printImpl(raw_ostream &OS, PrintType Type,
unsigned IndentLevel) const override;
};
/// By default, this delegates all calls to the underlying file system. This
/// is useful when derived file systems want to override some calls and still
/// proxy other calls.
class ProxyFileSystem : public FileSystem {
public:
explicit ProxyFileSystem(IntrusiveRefCntPtr<FileSystem> FS)
: FS(std::move(FS)) {}
llvm::ErrorOr<Status> status(const Twine &Path) override {
return FS->status(Path);
}
llvm::ErrorOr<std::unique_ptr<File>>
openFileForRead(const Twine &Path) override {
return FS->openFileForRead(Path);
}
directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override {
return FS->dir_begin(Dir, EC);
}
llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
return FS->getCurrentWorkingDirectory();
}
std::error_code setCurrentWorkingDirectory(const Twine &Path) override {
return FS->setCurrentWorkingDirectory(Path);
}
std::error_code getRealPath(const Twine &Path,
SmallVectorImpl<char> &Output) const override {
return FS->getRealPath(Path, Output);
}
std::error_code isLocal(const Twine &Path, bool &Result) override {
return FS->isLocal(Path, Result);
}
protected:
FileSystem &getUnderlyingFS() const { return *FS; }
private:
IntrusiveRefCntPtr<FileSystem> FS;
virtual void anchor();
};
namespace detail {
class InMemoryDirectory;
class InMemoryNode;
struct NewInMemoryNodeInfo {
llvm::sys::fs::UniqueID DirUID;
StringRef Path;
StringRef Name;
time_t ModificationTime;
std::unique_ptr<llvm::MemoryBuffer> Buffer;
uint32_t User;
uint32_t Group;
llvm::sys::fs::file_type Type;
llvm::sys::fs::perms Perms;
Status makeStatus() const;
};
class NamedNodeOrError {
ErrorOr<std::pair<llvm::SmallString<128>, const detail::InMemoryNode *>>
Value;
public:
NamedNodeOrError(llvm::SmallString<128> Name,
const detail::InMemoryNode *Node)
: Value(std::make_pair(Name, Node)) {}
NamedNodeOrError(std::error_code EC) : Value(EC) {}
NamedNodeOrError(llvm::errc EC) : Value(EC) {}
StringRef getName() const { return (*Value).first; }
explicit operator bool() const { return static_cast<bool>(Value); }
operator std::error_code() const { return Value.getError(); }
std::error_code getError() const { return Value.getError(); }
const detail::InMemoryNode *operator*() const { return (*Value).second; }
};
} // namespace detail
/// An in-memory file system.
class InMemoryFileSystem : public FileSystem {
std::unique_ptr<detail::InMemoryDirectory> Root;
std::string WorkingDirectory;
bool UseNormalizedPaths = true;
using MakeNodeFn = llvm::function_ref<std::unique_ptr<detail::InMemoryNode>(
detail::NewInMemoryNodeInfo)>;
/// Create node with \p MakeNode and add it into this filesystem at \p Path.
bool addFile(const Twine &Path, time_t ModificationTime,
std::unique_ptr<llvm::MemoryBuffer> Buffer,
std::optional<uint32_t> User, std::optional<uint32_t> Group,
std::optional<llvm::sys::fs::file_type> Type,
std::optional<llvm::sys::fs::perms> Perms, MakeNodeFn MakeNode);
/// Looks up the in-memory node for the path \p P.
/// If \p FollowFinalSymlink is true, the returned node is guaranteed to
/// not be a symlink and its path may differ from \p P.
detail::NamedNodeOrError lookupNode(const Twine &P, bool FollowFinalSymlink,
size_t SymlinkDepth = 0) const;
class DirIterator;
public:
explicit InMemoryFileSystem(bool UseNormalizedPaths = true);
~InMemoryFileSystem() override;
/// Add a file containing a buffer or a directory to the VFS with a
/// path. The VFS owns the buffer. If present, User, Group, Type
/// and Perms apply to the newly-created file or directory.
/// \return true if the file or directory was successfully added,
/// false if the file or directory already exists in the file system with
/// different contents.
bool addFile(const Twine &Path, time_t ModificationTime,
std::unique_ptr<llvm::MemoryBuffer> Buffer,
std::optional<uint32_t> User = std::nullopt,
std::optional<uint32_t> Group = std::nullopt,
std::optional<llvm::sys::fs::file_type> Type = std::nullopt,
std::optional<llvm::sys::fs::perms> Perms = std::nullopt);
/// Add a hard link to a file.
///
/// Here hard links are not intended to be fully equivalent to the classical
/// filesystem. Both the hard link and the file share the same buffer and
/// status (and thus have the same UniqueID). Because of this there is no way
/// to distinguish between the link and the file after the link has been
/// added.
///
/// The \p Target path must be an existing file or a hardlink. The
/// \p NewLink file must not have been added before. The \p Target
/// path must not be a directory. The \p NewLink node is added as a hard
/// link which points to the resolved file of \p Target node.
/// \return true if the above condition is satisfied and hardlink was
/// successfully created, false otherwise.
bool addHardLink(const Twine &NewLink, const Twine &Target);
/// Arbitrary max depth to search through symlinks. We can get into problems
/// if a link links to a link that links back to the link, for example.
static constexpr size_t MaxSymlinkDepth = 16;
/// Add a symbolic link. Unlike a HardLink, because \p Target doesn't need
/// to refer to a file (or refer to anything, as it happens). Also, an
/// in-memory directory for \p Target isn't automatically created.
bool
addSymbolicLink(const Twine &NewLink, const Twine &Target,
time_t ModificationTime,
std::optional<uint32_t> User = std::nullopt,
std::optional<uint32_t> Group = std::nullopt,
std::optional<llvm::sys::fs::perms> Perms = std::nullopt);
/// Add a buffer to the VFS with a path. The VFS does not own the buffer.
/// If present, User, Group, Type and Perms apply to the newly-created file
/// or directory.
/// \return true if the file or directory was successfully added,
/// false if the file or directory already exists in the file system with
/// different contents.
bool addFileNoOwn(const Twine &Path, time_t ModificationTime,
const llvm::MemoryBufferRef &Buffer,
std::optional<uint32_t> User = std::nullopt,
std::optional<uint32_t> Group = std::nullopt,
std::optional<llvm::sys::fs::file_type> Type = std::nullopt,
std::optional<llvm::sys::fs::perms> Perms = std::nullopt);
std::string toString() const;
/// Return true if this file system normalizes . and .. in paths.
bool useNormalizedPaths() const { return UseNormalizedPaths; }
llvm::ErrorOr<Status> status(const Twine &Path) override;
llvm::ErrorOr<std::unique_ptr<File>>
openFileForRead(const Twine &Path) override;
directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
return WorkingDirectory;
}
/// Canonicalizes \p Path by combining with the current working
/// directory and normalizing the path (e.g. remove dots). If the current
/// working directory is not set, this returns errc::operation_not_permitted.
///
/// This doesn't resolve symlinks as they are not supported in in-memory file
/// system.
std::error_code getRealPath(const Twine &Path,
SmallVectorImpl<char> &Output) const override;
std::error_code isLocal(const Twine &Path, bool &Result) override;
std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
protected:
void printImpl(raw_ostream &OS, PrintType Type,
unsigned IndentLevel) const override;
};
/// Get a globally unique ID for a virtual file or directory.
llvm::sys::fs::UniqueID getNextVirtualUniqueID();
/// Gets a \p FileSystem for a virtual file system described in YAML
/// format.
std::unique_ptr<FileSystem>
getVFSFromYAML(std::unique_ptr<llvm::MemoryBuffer> Buffer,
llvm::SourceMgr::DiagHandlerTy DiagHandler,
StringRef YAMLFilePath, void *DiagContext = nullptr,
IntrusiveRefCntPtr<FileSystem> ExternalFS = getRealFileSystem());
struct YAMLVFSEntry {
template <typename T1, typename T2>
YAMLVFSEntry(T1 &&VPath, T2 &&RPath, bool IsDirectory = false)
: VPath(std::forward<T1>(VPath)), RPath(std::forward<T2>(RPath)),
IsDirectory(IsDirectory) {}
std::string VPath;
std::string RPath;
bool IsDirectory = false;
};
class RedirectingFSDirIterImpl;
class RedirectingFileSystemParser;
/// A virtual file system parsed from a YAML file.
///
/// Currently, this class allows creating virtual files and directories. Virtual
/// files map to existing external files in \c ExternalFS, and virtual
/// directories may either map to existing directories in \c ExternalFS or list
/// their contents in the form of other virtual directories and/or files.
///
/// The basic structure of the parsed file is:
/// \verbatim
/// {
/// 'version': <version number>,
/// <optional configuration>
/// 'roots': [
/// <directory entries>
/// ]
/// }
/// \endverbatim
///
/// The roots may be absolute or relative. If relative they will be made
/// absolute against either current working directory or the directory where
/// the Overlay YAML file is located, depending on the 'root-relative'
/// configuration.
///
/// All configuration options are optional.
/// 'case-sensitive': <boolean, default=(true for Posix, false for Windows)>
/// 'use-external-names': <boolean, default=true>
/// 'root-relative': <string, one of 'cwd' or 'overlay-dir', default='cwd'>
/// 'overlay-relative': <boolean, default=false>
/// 'fallthrough': <boolean, default=true, deprecated - use 'redirecting-with'
/// instead>
/// 'redirecting-with': <string, one of 'fallthrough', 'fallback', or
/// 'redirect-only', default='fallthrough'>
///
/// To clarify, 'root-relative' option will prepend the current working
/// directory, or the overlay directory to the 'roots->name' field only if
/// 'roots->name' is a relative path. On the other hand, when 'overlay-relative'
/// is set to 'true', external paths will always be prepended with the overlay
/// directory, even if external paths are not relative paths. The
/// 'root-relative' option has no interaction with the 'overlay-relative'
/// option.
///
/// Virtual directories that list their contents are represented as
/// \verbatim
/// {
/// 'type': 'directory',
/// 'name': <string>,
/// 'contents': [ <file or directory entries> ]
/// }
/// \endverbatim
///
/// The default attributes for such virtual directories are:
/// \verbatim
/// MTime = now() when created
/// Perms = 0777
/// User = Group = 0
/// Size = 0
/// UniqueID = unspecified unique value
/// \endverbatim
///
/// When a path prefix matches such a directory, the next component in the path
/// is matched against the entries in the 'contents' array.
///
/// Re-mapped directories, on the other hand, are represented as
/// /// \verbatim
/// {
/// 'type': 'directory-remap',
/// 'name': <string>,
/// 'use-external-name': <boolean>, # Optional
/// 'external-contents': <path to external directory>
/// }
/// \endverbatim
///
/// and inherit their attributes from the external directory. When a path
/// prefix matches such an entry, the unmatched components are appended to the
/// 'external-contents' path, and the resulting path is looked up in the
/// external file system instead.
///
/// Re-mapped files are represented as
/// \verbatim
/// {
/// 'type': 'file',
/// 'name': <string>,
/// 'use-external-name': <boolean>, # Optional
/// 'external-contents': <path to external file>
/// }
/// \endverbatim
///
/// Their attributes and file contents are determined by looking up the file at
/// their 'external-contents' path in the external file system.
///
/// For 'file', 'directory' and 'directory-remap' entries the 'name' field may
/// contain multiple path components (e.g. /path/to/file). However, any
/// directory in such a path that contains more than one child must be uniquely
/// represented by a 'directory' entry.
///
/// When the 'use-external-name' field is set, calls to \a vfs::File::status()
/// give the external (remapped) filesystem name instead of the name the file
/// was accessed by. This is an intentional leak through the \a
/// RedirectingFileSystem abstraction layer. It enables clients to discover
/// (and use) the external file location when communicating with users or tools
/// that don't use the same VFS overlay.
///
/// FIXME: 'use-external-name' causes behaviour that's inconsistent with how
/// "real" filesystems behave. Maybe there should be a separate channel for
/// this information.
class RedirectingFileSystem : public vfs::FileSystem {
public:
enum EntryKind { EK_Directory, EK_DirectoryRemap, EK_File };
enum NameKind { NK_NotSet, NK_External, NK_Virtual };
/// The type of redirection to perform.
enum class RedirectKind {
/// Lookup the redirected path first (ie. the one specified in
/// 'external-contents') and if that fails "fallthrough" to a lookup of the
/// originally provided path.
Fallthrough,
/// Lookup the provided path first and if that fails, "fallback" to a
/// lookup of the redirected path.
Fallback,
/// Only lookup the redirected path, do not lookup the originally provided
/// path.
RedirectOnly
};
/// The type of relative path used by Roots.
enum class RootRelativeKind {
/// The roots are relative to the current working directory.
CWD,
/// The roots are relative to the directory where the Overlay YAML file
// locates.
OverlayDir
};
/// A single file or directory in the VFS.
class Entry {
EntryKind Kind;
std::string Name;
public:
Entry(EntryKind K, StringRef Name) : Kind(K), Name(Name) {}
virtual ~Entry() = default;
StringRef getName() const { return Name; }
EntryKind getKind() const { return Kind; }
};
/// A directory in the vfs with explicitly specified contents.
class DirectoryEntry : public Entry {
std::vector<std::unique_ptr<Entry>> Contents;
Status S;
public:
/// Constructs a directory entry with explicitly specified contents.
DirectoryEntry(StringRef Name, std::vector<std::unique_ptr<Entry>> Contents,
Status S)
: Entry(EK_Directory, Name), Contents(std::move(Contents)),
S(std::move(S)) {}
/// Constructs an empty directory entry.
DirectoryEntry(StringRef Name, Status S)
: Entry(EK_Directory, Name), S(std::move(S)) {}
Status getStatus() { return S; }
void addContent(std::unique_ptr<Entry> Content) {
Contents.push_back(std::move(Content));
}
Entry *getLastContent() const { return Contents.back().get(); }
using iterator = decltype(Contents)::iterator;
iterator contents_begin() { return Contents.begin(); }
iterator contents_end() { return Contents.end(); }
static bool classof(const Entry *E) { return E->getKind() == EK_Directory; }
};
/// A file or directory in the vfs that is mapped to a file or directory in
/// the external filesystem.
class RemapEntry : public Entry {
std::string ExternalContentsPath;
NameKind UseName;
protected:
RemapEntry(EntryKind K, StringRef Name, StringRef ExternalContentsPath,
NameKind UseName)
: Entry(K, Name), ExternalContentsPath(ExternalContentsPath),
UseName(UseName) {}
public:
StringRef getExternalContentsPath() const { return ExternalContentsPath; }
/// Whether to use the external path as the name for this file or directory.
bool useExternalName(bool GlobalUseExternalName) const {
return UseName == NK_NotSet ? GlobalUseExternalName
: (UseName == NK_External);
}
NameKind getUseName() const { return UseName; }
static bool classof(const Entry *E) {
switch (E->getKind()) {
case EK_DirectoryRemap:
[[fallthrough]];
case EK_File:
return true;
case EK_Directory:
return false;
}
llvm_unreachable("invalid entry kind");
}
};
/// A directory in the vfs that maps to a directory in the external file
/// system.
class DirectoryRemapEntry : public RemapEntry {
public:
DirectoryRemapEntry(StringRef Name, StringRef ExternalContentsPath,
NameKind UseName)
: RemapEntry(EK_DirectoryRemap, Name, ExternalContentsPath, UseName) {}
static bool classof(const Entry *E) {
return E->getKind() == EK_DirectoryRemap;
}
};
/// A file in the vfs that maps to a file in the external file system.
class FileEntry : public RemapEntry {
public:
FileEntry(StringRef Name, StringRef ExternalContentsPath, NameKind UseName)
: RemapEntry(EK_File, Name, ExternalContentsPath, UseName) {}
static bool classof(const Entry *E) { return E->getKind() == EK_File; }
};
/// Represents the result of a path lookup into the RedirectingFileSystem.
struct LookupResult {
/// The entry the looked-up path corresponds to.
Entry *E;
private:
/// When the found Entry is a DirectoryRemapEntry, stores the path in the
/// external file system that the looked-up path in the virtual file system
// corresponds to.
std::optional<std::string> ExternalRedirect;
public:
LookupResult(Entry *E, sys::path::const_iterator Start,
sys::path::const_iterator End);
/// If the found Entry maps the the input path to a path in the external
/// file system (i.e. it is a FileEntry or DirectoryRemapEntry), returns
/// that path.
std::optional<StringRef> getExternalRedirect() const {
if (isa<DirectoryRemapEntry>(E))
return StringRef(*ExternalRedirect);
if (auto *FE = dyn_cast<FileEntry>(E))
return FE->getExternalContentsPath();
return std::nullopt;
}
};
private:
friend class RedirectingFSDirIterImpl;
friend class RedirectingFileSystemParser;
/// Canonicalize path by removing ".", "..", "./", components. This is
/// a VFS request, do not bother about symlinks in the path components
/// but canonicalize in order to perform the correct entry search.
std::error_code makeCanonical(SmallVectorImpl<char> &Path) const;
/// Get the File status, or error, from the underlying external file system.
/// This returns the status with the originally requested name, while looking
/// up the entry using the canonical path.
ErrorOr<Status> getExternalStatus(const Twine &CanonicalPath,
const Twine &OriginalPath) const;
/// Make \a Path an absolute path.
///
/// Makes \a Path absolute using the \a WorkingDir if it is not already.
///
/// /absolute/path => /absolute/path
/// relative/../path => <WorkingDir>/relative/../path
///
/// \param WorkingDir A path that will be used as the base Dir if \a Path
/// is not already absolute.
/// \param Path A path that is modified to be an absolute path.
/// \returns success if \a path has been made absolute, otherwise a
/// platform-specific error_code.
std::error_code makeAbsolute(StringRef WorkingDir,
SmallVectorImpl<char> &Path) const;
// In a RedirectingFileSystem, keys can be specified in Posix or Windows
// style (or even a mixture of both), so this comparison helper allows
// slashes (representing a root) to match backslashes (and vice versa). Note
// that, other than the root, path components should not contain slashes or
// backslashes.
bool pathComponentMatches(llvm::StringRef lhs, llvm::StringRef rhs) const {
if ((CaseSensitive ? lhs.equals(rhs) : lhs.equals_insensitive(rhs)))
return true;
return (lhs == "/" && rhs == "\\") || (lhs == "\\" && rhs == "/");
}
/// The root(s) of the virtual file system.
std::vector<std::unique_ptr<Entry>> Roots;
/// The current working directory of the file system.
std::string WorkingDirectory;
/// The file system to use for external references.
IntrusiveRefCntPtr<FileSystem> ExternalFS;
/// This represents the directory path that the YAML file is located.
/// This will be prefixed to each 'external-contents' if IsRelativeOverlay
/// is set. This will also be prefixed to each 'roots->name' if RootRelative
/// is set to RootRelativeKind::OverlayDir and the path is relative.
std::string OverlayFileDir;
/// @name Configuration
/// @{
/// Whether to perform case-sensitive comparisons.
///
/// Currently, case-insensitive matching only works correctly with ASCII.
bool CaseSensitive = is_style_posix(sys::path::Style::native);
/// IsRelativeOverlay marks whether a OverlayFileDir path must
/// be prefixed in every 'external-contents' when reading from YAML files.
bool IsRelativeOverlay = false;
/// Whether to use to use the value of 'external-contents' for the
/// names of files. This global value is overridable on a per-file basis.
bool UseExternalNames = true;
/// Determines the lookups to perform, as well as their order. See
/// \c RedirectKind for details.
RedirectKind Redirection = RedirectKind::Fallthrough;
/// Determine the prefix directory if the roots are relative paths. See
/// \c RootRelativeKind for details.
RootRelativeKind RootRelative = RootRelativeKind::CWD;
/// @}
RedirectingFileSystem(IntrusiveRefCntPtr<FileSystem> ExternalFS);
/// Looks up the path <tt>[Start, End)</tt> in \p From, possibly recursing
/// into the contents of \p From if it is a directory. Returns a LookupResult
/// giving the matched entry and, if that entry is a FileEntry or
/// DirectoryRemapEntry, the path it redirects to in the external file system.
ErrorOr<LookupResult> lookupPathImpl(llvm::sys::path::const_iterator Start,
llvm::sys::path::const_iterator End,
Entry *From) const;
/// Get the status for a path with the provided \c LookupResult.
ErrorOr<Status> status(const Twine &CanonicalPath, const Twine &OriginalPath,
const LookupResult &Result);
public:
/// Looks up \p Path in \c Roots and returns a LookupResult giving the
/// matched entry and, if the entry was a FileEntry or DirectoryRemapEntry,
/// the path it redirects to in the external file system.
ErrorOr<LookupResult> lookupPath(StringRef Path) const;
/// Parses \p Buffer, which is expected to be in YAML format and
/// returns a virtual file system representing its contents.
static std::unique_ptr<RedirectingFileSystem>
create(std::unique_ptr<MemoryBuffer> Buffer,
SourceMgr::DiagHandlerTy DiagHandler, StringRef YAMLFilePath,
void *DiagContext, IntrusiveRefCntPtr<FileSystem> ExternalFS);
/// Redirect each of the remapped files from first to second.
static std::unique_ptr<RedirectingFileSystem>
create(ArrayRef<std::pair<std::string, std::string>> RemappedFiles,
bool UseExternalNames, FileSystem &ExternalFS);
ErrorOr<Status> status(const Twine &Path) override;
ErrorOr<std::unique_ptr<File>> openFileForRead(const Twine &Path) override;
std::error_code getRealPath(const Twine &Path,
SmallVectorImpl<char> &Output) const override;
llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override;
std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
std::error_code isLocal(const Twine &Path, bool &Result) override;
std::error_code makeAbsolute(SmallVectorImpl<char> &Path) const override;
directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
void setOverlayFileDir(StringRef PrefixDir);
StringRef getOverlayFileDir() const;
/// Sets the redirection kind to \c Fallthrough if true or \c RedirectOnly
/// otherwise. Will removed in the future, use \c setRedirection instead.
void setFallthrough(bool Fallthrough);
void setRedirection(RedirectingFileSystem::RedirectKind Kind);
std::vector<llvm::StringRef> getRoots() const;
void printEntry(raw_ostream &OS, Entry *E, unsigned IndentLevel = 0) const;
protected:
void printImpl(raw_ostream &OS, PrintType Type,
unsigned IndentLevel) const override;
};
/// Collect all pairs of <virtual path, real path> entries from the
/// \p YAMLFilePath. This is used by the module dependency collector to forward
/// the entries into the reproducer output VFS YAML file.
void collectVFSFromYAML(
std::unique_ptr<llvm::MemoryBuffer> Buffer,
llvm::SourceMgr::DiagHandlerTy DiagHandler, StringRef YAMLFilePath,
SmallVectorImpl<YAMLVFSEntry> &CollectedEntries,
void *DiagContext = nullptr,
IntrusiveRefCntPtr<FileSystem> ExternalFS = getRealFileSystem());
class YAMLVFSWriter {
std::vector<YAMLVFSEntry> Mappings;
std::optional<bool> IsCaseSensitive;
std::optional<bool> IsOverlayRelative;
std::optional<bool> UseExternalNames;
std::string OverlayDir;
void addEntry(StringRef VirtualPath, StringRef RealPath, bool IsDirectory);
public:
YAMLVFSWriter() = default;
void addFileMapping(StringRef VirtualPath, StringRef RealPath);
void addDirectoryMapping(StringRef VirtualPath, StringRef RealPath);
void setCaseSensitivity(bool CaseSensitive) {
IsCaseSensitive = CaseSensitive;
}
void setUseExternalNames(bool UseExtNames) { UseExternalNames = UseExtNames; }
void setOverlayDir(StringRef OverlayDirectory) {
IsOverlayRelative = true;
OverlayDir.assign(OverlayDirectory.str());
}
const std::vector<YAMLVFSEntry> &getMappings() const { return Mappings; }
void write(llvm::raw_ostream &OS);
};
} // namespace vfs
} // namespace llvm
#endif // LLVM_SUPPORT_VIRTUALFILESYSTEM_H