A virtual file system parsed from a YAML file. More...

#include "llvm/Support/VirtualFileSystem.h"

Inheritance diagram for llvm::vfs::RedirectingFileSystem:

[legend]

Classes
class	DirectoryEntry
	A directory in the vfs with explicitly specified contents. More...

class	DirectoryRemapEntry
	A directory in the vfs that maps to a directory in the external file system. More...

class	Entry
	A single file or directory in the VFS. More...

class	FileEntry
	A file in the vfs that maps to a file in the external file system. More...

struct	LookupResult
	Represents the result of a path lookup into the RedirectingFileSystem. More...

class	RemapEntry
	A file or directory in the vfs that is mapped to a file or directory in the external filesystem. More...

Public Types
enum	EntryKind { EK_Directory , EK_DirectoryRemap , EK_File }

enum	NameKind { NK_NotSet , NK_External , NK_Virtual }

enum class	RedirectKind { Fallthrough , Fallback , RedirectOnly }
	The type of redirection to perform. More...

enum class	RootRelativeKind { CWD , OverlayDir }
	The type of relative path used by Roots. More...

Public Types inherited from llvm::vfs::FileSystem
enum class	PrintType { Summary , Contents , RecursiveContents }

Public Member Functions
ErrorOr< LookupResult >	lookupPath (StringRef Path) const
	Looks up `Path` in `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< Status >	status (const Twine &Path) override
	Get the status of the entry at `Path`, if one exists.

ErrorOr< std::unique_ptr< File > >	openFileForRead (const Twine &Path) override
	Get a `File` object for the file at `Path`, if one exists.

std::error_code	getRealPath (const Twine &Path, SmallVectorImpl< char > &Output) const override
	Gets real path of `Path` e.g.

llvm::ErrorOr< std::string >	getCurrentWorkingDirectory () const override
	Get the working directory of this file system.

std::error_code	setCurrentWorkingDirectory (const Twine &Path) override
	Set the working directory.

std::error_code	isLocal (const Twine &Path, bool &Result) override
	Is the file mounted on a local filesystem?

std::error_code	makeAbsolute (SmallVectorImpl< char > &Path) const override
	Make Path an absolute path.

directory_iterator	dir_begin (const Twine &Dir, std::error_code &EC) override
	Get a directory_iterator for `Dir`.

void	setOverlayFileDir (StringRef PrefixDir)

StringRef	getOverlayFileDir () const

void	setFallthrough (bool Fallthrough)
	Sets the redirection kind to `Fallthrough` if true or `RedirectOnly` otherwise.

void	setRedirection (RedirectingFileSystem::RedirectKind Kind)

std::vector< llvm::StringRef >	getRoots () const

void	printEntry (raw_ostream &OS, Entry *E, unsigned IndentLevel=0) const

Public Member Functions inherited from llvm::vfs::FileSystem
virtual	~FileSystem ()

virtual llvm::ErrorOr< Status >	status (const Twine &Path)=0
	Get the status of the entry at `Path`, if one exists.

virtual llvm::ErrorOr< std::unique_ptr< File > >	openFileForRead (const Twine &Path)=0
	Get a `File` object for the file at `Path`, if one exists.

llvm::ErrorOr< std::unique_ptr< llvm::MemoryBuffer > >	getBufferForFile (const Twine &Name, int64_t FileSize=-1, bool RequiresNullTerminator=true, bool IsVolatile=false)
	This is a convenience method that opens a file, gets its content and then closes the file.

virtual directory_iterator	dir_begin (const Twine &Dir, std::error_code &EC)=0
	Get a directory_iterator for `Dir`.

virtual std::error_code	setCurrentWorkingDirectory (const Twine &Path)=0
	Set the working directory.

virtual llvm::ErrorOr< std::string >	getCurrentWorkingDirectory () const =0
	Get the working directory of this file system.

virtual std::error_code	getRealPath (const Twine &Path, SmallVectorImpl< char > &Output) const
	Gets real path of `Path` e.g.

bool	exists (const Twine &Path)
	Check whether a file exists. Provided for convenience.

virtual std::error_code	isLocal (const Twine &Path, bool &Result)
	Is the file mounted on a local filesystem?

virtual std::error_code	makeAbsolute (SmallVectorImpl< char > &Path) const
	Make Path an absolute path.

void	print (raw_ostream &OS, PrintType Type=PrintType::Contents, unsigned IndentLevel=0) const

LLVM_DUMP_METHOD void	dump () const

Public Member Functions inherited from llvm::ThreadSafeRefCountedBase< FileSystem >
unsigned	UseCount () const

void	Retain () const

void	Release () const

Static Public Member Functions
static std::unique_ptr< RedirectingFileSystem >	create (std::unique_ptr< MemoryBuffer > Buffer, SourceMgr::DiagHandlerTy DiagHandler, StringRef YAMLFilePath, void *DiagContext, IntrusiveRefCntPtr< FileSystem > ExternalFS)
	Parses `Buffer`, which is expected to be in YAML format and returns a virtual file system representing its contents.

static std::unique_ptr< RedirectingFileSystem >	create (ArrayRef< std::pair< std::string, std::string > > RemappedFiles, bool UseExternalNames, FileSystem &ExternalFS)
	Redirect each of the remapped files from first to second.

Protected Member Functions
void	printImpl (raw_ostream &OS, PrintType Type, unsigned IndentLevel) const override

Protected Member Functions inherited from llvm::vfs::FileSystem
virtual void	printImpl (raw_ostream &OS, PrintType Type, unsigned IndentLevel) const

void	printIndent (raw_ostream &OS, unsigned IndentLevel) const

Protected Member Functions inherited from llvm::ThreadSafeRefCountedBase< FileSystem >
	ThreadSafeRefCountedBase ()=default

	ThreadSafeRefCountedBase (const ThreadSafeRefCountedBase &)

ThreadSafeRefCountedBase &	operator= (const ThreadSafeRefCountedBase &)=delete

	~ThreadSafeRefCountedBase ()

Friends
class	RedirectingFSDirIterImpl

class	RedirectingFileSystemParser

Detailed Description

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 ExternalFS, and virtual directories may either map to existing directories in ExternalFS or list their contents in the form of other virtual directories and/or files.

The basic structure of the parsed file is:

/// {
///   'version': <version number>,
///   <optional configuration>
///   'roots': [
///              <directory entries>
///            ]
/// }
///

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> ] /// } ///

The default attributes for such virtual directories are:
\verbatim

/// MTime = now() when created /// Perms = 0777 /// User = Group = 0 /// Size = 0 /// UniqueID = unspecified unique value ///

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> /// } ///

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> /// } ///

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.

Definition at line 742 of file VirtualFileSystem.h.

Member Enumeration Documentation

◆ EntryKind

enum llvm::vfs::RedirectingFileSystem::EntryKind

Enumerator
EK_Directory
EK_DirectoryRemap
EK_File

Definition at line 744 of file VirtualFileSystem.h.

◆ NameKind

enum llvm::vfs::RedirectingFileSystem::NameKind

Enumerator
NK_NotSet
NK_External
NK_Virtual

Definition at line 745 of file VirtualFileSystem.h.

◆ RedirectKind

enum class llvm::vfs::RedirectingFileSystem::RedirectKind

strong

The type of redirection to perform.

Enumerator

Fallthrough

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.

Fallback

Lookup the provided path first and if that fails, "fallback" to a lookup of the redirected path.

RedirectOnly

Only lookup the redirected path, do not lookup the originally provided path.

Definition at line 748 of file VirtualFileSystem.h.

◆ RootRelativeKind

enum class llvm::vfs::RedirectingFileSystem::RootRelativeKind

strong

The type of relative path used by Roots.

Enumerator
CWD	The roots are relative to the current working directory.
OverlayDir	The roots are relative to the directory where the Overlay YAML file.

Definition at line 762 of file VirtualFileSystem.h.

Member Function Documentation

◆ create() [1/2]

std::unique_ptr< RedirectingFileSystem > RedirectingFileSystem::create	(	ArrayRef< std::pair< std::string, std::string > >	RemappedFiles,
		bool	UseExternalNames,
		FileSystem &	ExternalFS
	)

static

Redirect each of the remapped files from first to second.

Definition at line 2174 of file VirtualFileSystem.cpp.

References assert(), llvm::sys::path::begin(), E, llvm::sys::path::end(), llvm::sys::path::filename(), From, I, llvm::vfs::RedirectingFileSystemParser::lookupOrCreateEntry(), llvm::vfs::FileSystem::makeAbsolute(), NK_External, NK_Virtual, llvm::sys::path::parent_path(), and llvm::reverse().

◆ create() [2/2]

std::unique_ptr< RedirectingFileSystem > RedirectingFileSystem::create	(	std::unique_ptr< MemoryBuffer >	Buffer,
		SourceMgr::DiagHandlerTy	DiagHandler,
		StringRef	YAMLFilePath,
		void *	DiagContext,
		IntrusiveRefCntPtr< FileSystem >	ExternalFS
	)

static

Parses Buffer, which is expected to be in YAML format and returns a virtual file system representing its contents.

Definition at line 2132 of file VirtualFileSystem.cpp.

References assert(), llvm::yaml::Stream::begin(), DiagHandler(), llvm::SourceMgr::DK_Error, llvm::StringRef::empty(), llvm::yaml::Stream::end(), llvm::sys::fs::make_absolute(), P, llvm::sys::path::parent_path(), llvm::SourceMgr::PrintMessage(), and llvm::SourceMgr::setDiagHandler().

◆ dir_begin()

directory_iterator RedirectingFileSystem::dir_begin	(	const Twine &	Dir,
		std::error_code &	EC
	)

overridevirtual

Get a directory_iterator for Dir.

Note: The 'end' iterator is directory_iterator().

Implements llvm::vfs::FileSystem.

Definition at line 1402 of file VirtualFileSystem.cpp.

References Fallback, Fallthrough, llvm::ErrorOr< T >::getError(), llvm_unreachable, lookupPath(), llvm::no_such_file_or_directory, llvm::not_a_directory, llvm::SmallVectorTemplateBase< T, bool >::push_back(), RedirectOnly, and llvm::Twine::toVector().

◆ getCurrentWorkingDirectory()

llvm::ErrorOr< std::string > RedirectingFileSystem::getCurrentWorkingDirectory ( ) const

overridevirtual

Get the working directory of this file system.

Implements llvm::vfs::FileSystem.

Definition at line 1317 of file VirtualFileSystem.cpp.

Referenced by makeAbsolute().

◆ getOverlayFileDir()

StringRef RedirectingFileSystem::getOverlayFileDir ( ) const

Definition at line 1506 of file VirtualFileSystem.cpp.

◆ getRealPath()

std::error_code RedirectingFileSystem::getRealPath	(	const Twine &	Path,
		SmallVectorImpl< char > &	Output
	)		const

overridevirtual

Gets real path of 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.

Reimplemented from llvm::vfs::FileSystem.

Definition at line 2519 of file VirtualFileSystem.cpp.

References Fallback, Fallthrough, llvm::invalid_argument, lookupPath(), P, and llvm::Twine::toVector().

◆ getRoots()

std::vector< StringRef > RedirectingFileSystem::getRoots ( ) const

Definition at line 1523 of file VirtualFileSystem.cpp.

◆ isLocal()

std::error_code RedirectingFileSystem::isLocal	(	const Twine &	Path,
		bool &	Result
	)

overridevirtual

Is the file mounted on a local filesystem?

Reimplemented from llvm::vfs::FileSystem.

Definition at line 1335 of file VirtualFileSystem.cpp.

References llvm::Twine::toVector().

◆ lookupPath()

ErrorOr< RedirectingFileSystem::LookupResult > RedirectingFileSystem::lookupPath ( StringRef Path ) const

Looks up Path in 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.

Definition at line 2265 of file VirtualFileSystem.cpp.

References llvm::sys::path::begin(), End, llvm::sys::path::end(), llvm::make_error_code(), and llvm::no_such_file_or_directory.

Referenced by dir_begin(), getRealPath(), openFileForRead(), and status().