LLVM 17.0.0git
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llvm::vfs::RedirectingFileSystem Class Reference

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

#include "llvm/Support/VirtualFileSystem.h"

Inheritance diagram for llvm::vfs::RedirectingFileSystem:
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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< LookupResultlookupPath (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< Statusstatus (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::StringRefgetRoots () 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< Statusstatus (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 >
void Retain () const
 
void Release () const
 

Static Public Member Functions

static std::unique_ptr< RedirectingFileSystemcreate (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< RedirectingFileSystemcreate (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 &)
 
ThreadSafeRefCountedBaseoperator= (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

Enumerator
EK_Directory 
EK_DirectoryRemap 
EK_File 

Definition at line 744 of file VirtualFileSystem.h.

◆ NameKind

Enumerator
NK_NotSet 
NK_External 
NK_Virtual 

Definition at line 745 of file VirtualFileSystem.h.

◆ RedirectKind

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

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

◆ 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 2130 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

◆ getCurrentWorkingDirectory()

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

Get the working directory of this file system.

Implements llvm::vfs::FileSystem.

Definition at line 1315 of file VirtualFileSystem.cpp.

Referenced by makeAbsolute().

◆ getOverlayFileDir()

StringRef RedirectingFileSystem::getOverlayFileDir ( ) const

Definition at line 1504 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 2503 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 1521 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 1333 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 2255 of file VirtualFileSystem.cpp.

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

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

◆ makeAbsolute()

std::error_code RedirectingFileSystem::makeAbsolute ( SmallVectorImpl< char > &  Path) const
overridevirtual

Make Path an absolute path.

Makes Path absolute using the current directory if it is not already. An empty Path will result in the current directory.

/absolute/path => /absolute/path relative/../path => <current-directory>/relative/../path

Parameters
PathA path that is modified to be an absolute path.
Returns
success if path has been made absolute, otherwise a platform-specific error_code.

Reimplemented from llvm::vfs::FileSystem.

Definition at line 1344 of file VirtualFileSystem.cpp.

References getCurrentWorkingDirectory(), llvm::sys::path::is_absolute(), llvm::sys::path::posix, and llvm::sys::path::windows_backslash.

◆ openFileForRead()

ErrorOr< std::unique_ptr< File > > RedirectingFileSystem::openFileForRead ( const Twine Path)
overridevirtual

◆ printEntry()

void RedirectingFileSystem::printEntry ( raw_ostream OS,
RedirectingFileSystem::Entry E,
unsigned  IndentLevel = 0 
) const

◆ printImpl()

void RedirectingFileSystem::printImpl ( raw_ostream OS,
PrintType  Type,
unsigned  IndentLevel 
) const
overrideprotectedvirtual

◆ setCurrentWorkingDirectory()

std::error_code RedirectingFileSystem::setCurrentWorkingDirectory ( const Twine Path)
overridevirtual

Set the working directory.

This will affect all following operations on this file system and may propagate down for nested file systems.

Implements llvm::vfs::FileSystem.

Definition at line 1320 of file VirtualFileSystem.cpp.

References llvm::vfs::FileSystem::exists(), llvm::no_such_file_or_directory, and llvm::SmallString< InternalLen >::str().

◆ setFallthrough()

void RedirectingFileSystem::setFallthrough ( bool  Fallthrough)

Sets the redirection kind to Fallthrough if true or RedirectOnly otherwise.

Will removed in the future, use setRedirection instead.

Definition at line 1508 of file VirtualFileSystem.cpp.

References Fallthrough, and RedirectOnly.

◆ setOverlayFileDir()

void RedirectingFileSystem::setOverlayFileDir ( StringRef  PrefixDir)

Definition at line 1500 of file VirtualFileSystem.cpp.

References llvm::StringRef::str().

◆ setRedirection()

void RedirectingFileSystem::setRedirection ( RedirectingFileSystem::RedirectKind  Kind)

Definition at line 1516 of file VirtualFileSystem.cpp.

◆ status()

ErrorOr< Status > RedirectingFileSystem::status ( const Twine Path)
overridevirtual

Get the status of the entry at Path, if one exists.

Implements llvm::vfs::FileSystem.

Definition at line 2358 of file VirtualFileSystem.cpp.

References Fallback, Fallthrough, llvm::ErrorOr< T >::getError(), lookupPath(), and llvm::Twine::toVector().

Friends And Related Function Documentation

◆ RedirectingFileSystemParser

friend class RedirectingFileSystemParser
friend

Definition at line 902 of file VirtualFileSystem.h.

◆ RedirectingFSDirIterImpl

friend class RedirectingFSDirIterImpl
friend

Definition at line 901 of file VirtualFileSystem.h.


The documentation for this class was generated from the following files: