include/llvm/Support/VirtualFileSystem.h

   1 //===- VirtualFileSystem.h - Virtual File System Layer ----------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 /// \file
  10 /// Defines the virtual file system interface vfs::FileSystem.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_SUPPORT_VIRTUALFILESYSTEM_H
  15 #define LLVM_SUPPORT_VIRTUALFILESYSTEM_H
  16
  17 #include "llvm/ADT/IntrusiveRefCntPtr.h"
  18 #include "llvm/ADT/None.h"
  19 #include "llvm/ADT/Optional.h"
  20 #include "llvm/ADT/SmallVector.h"
  21 #include "llvm/ADT/StringRef.h"
  22 #include "llvm/ADT/Twine.h"
  23 #include "llvm/Support/Chrono.h"
  24 #include "llvm/Support/ErrorOr.h"
  25 #include "llvm/Support/FileSystem.h"
  26 #include "llvm/Support/Path.h"
  27 #include "llvm/Support/SourceMgr.h"
  28 #include <cassert>
  29 #include <cstdint>
  30 #include <ctime>
  31 #include <memory>
  32 #include <stack>
  33 #include <string>
  34 #include <system_error>
  35 #include <utility>
  36 #include <vector>
  37
  38 namespace llvm {
  39
  40 class MemoryBuffer;
  41
  42 namespace vfs {
  43
  44 /// The result of a \p status operation.
  45 class Status {
  46   std::string Name;
  47   llvm::sys::fs::UniqueID UID;
  48   llvm::sys::TimePoint<> MTime;
  49   uint32_t User;
  50   uint32_t Group;
  51   uint64_t Size;
  52   llvm::sys::fs::file_type Type = llvm::sys::fs::file_type::status_error;
  53   llvm::sys::fs::perms Perms;
  54
  55 public:
  56   // FIXME: remove when files support multiple names
  57   bool IsVFSMapped = false;
  58
  59   Status() = default;
  60   Status(const llvm::sys::fs::file_status &Status);
  61   Status(const Twine &Name, llvm::sys::fs::UniqueID UID,
  62          llvm::sys::TimePoint<> MTime, uint32_t User, uint32_t Group,
  63          uint64_t Size, llvm::sys::fs::file_type Type,
  64          llvm::sys::fs::perms Perms);
  65
  66   /// Get a copy of a Status with a different name.
  67   static Status copyWithNewName(const Status &In, const Twine &NewName);
  68   static Status copyWithNewName(const llvm::sys::fs::file_status &In,
  69                                 const Twine &NewName);
  70
  71   /// Returns the name that should be used for this file or directory.
  72   StringRef getName() const { return Name; }
  73
  74   /// @name Status interface from llvm::sys::fs
  75   /// @{
  76   llvm::sys::fs::file_type getType() const { return Type; }
  77   llvm::sys::fs::perms getPermissions() const { return Perms; }
  78   llvm::sys::TimePoint<> getLastModificationTime() const { return MTime; }
  79   llvm::sys::fs::UniqueID getUniqueID() const { return UID; }
  80   uint32_t getUser() const { return User; }
  81   uint32_t getGroup() const { return Group; }
  82   uint64_t getSize() const { return Size; }
  83   /// @}
  84   /// @name Status queries
  85   /// These are static queries in llvm::sys::fs.
  86   /// @{
  87   bool equivalent(const Status &Other) const;
  88   bool isDirectory() const;
  89   bool isRegularFile() const;
  90   bool isOther() const;
  91   bool isSymlink() const;
  92   bool isStatusKnown() const;
  93   bool exists() const;
  94   /// @}
  95 };
  96
  97 /// Represents an open file.
  98 class File {
  99 public:
 100   /// Destroy the file after closing it (if open).
 101   /// Sub-classes should generally call close() inside their destructors.  We
 102   /// cannot do that from the base class, since close is virtual.
 103   virtual ~File();
 104
 105   /// Get the status of the file.
 106   virtual llvm::ErrorOr<Status> status() = 0;
 107
 108   /// Get the name of the file
 109   virtual llvm::ErrorOr<std::string> getName() {
 110     if (auto Status = status())
 111       return Status->getName().str();
 112     else
 113       return Status.getError();
 114   }
 115
 116   /// Get the contents of the file as a \p MemoryBuffer.
 117   virtual llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
 118   getBuffer(const Twine &Name, int64_t FileSize = -1,
 119             bool RequiresNullTerminator = true, bool IsVolatile = false) = 0;
 120
 121   /// Closes the file.
 122   virtual std::error_code close() = 0;
 123 };
 124
 125 /// A member of a directory, yielded by a directory_iterator.
 126 /// Only information available on most platforms is included.
 127 class directory_entry {
 128   std::string Path;
 129   llvm::sys::fs::file_type Type;
 130
 131 public:
 132   directory_entry() = default;
 133   directory_entry(std::string Path, llvm::sys::fs::file_type Type)
 134       : Path(std::move(Path)), Type(Type) {}
 135
 136   llvm::StringRef path() const { return Path; }
 137   llvm::sys::fs::file_type type() const { return Type; }
 138 };
 139
 140 namespace detail {
 141
 142 /// An interface for virtual file systems to provide an iterator over the
 143 /// (non-recursive) contents of a directory.
 144 struct DirIterImpl {
 145   virtual ~DirIterImpl();
 146
 147   /// Sets \c CurrentEntry to the next entry in the directory on success,
 148   /// to directory_entry() at end,  or returns a system-defined \c error_code.
 149   virtual std::error_code increment() = 0;
 150
 151   directory_entry CurrentEntry;
 152 };
 153
 154 } // namespace detail
 155
 156 /// An input iterator over the entries in a virtual path, similar to
 157 /// llvm::sys::fs::directory_iterator.
 158 class directory_iterator {
 159   std::shared_ptr<detail::DirIterImpl> Impl; // Input iterator semantics on copy
 160
 161 public:
 162   directory_iterator(std::shared_ptr<detail::DirIterImpl> I)
 163       : Impl(std::move(I)) {
 164     assert(Impl.get() != nullptr && "requires non-null implementation");
 165     if (Impl->CurrentEntry.path().empty())
 166       Impl.reset(); // Normalize the end iterator to Impl == nullptr.
 167   }
 168
 169   /// Construct an 'end' iterator.
 170   directory_iterator() = default;
 171
 172   /// Equivalent to operator++, with an error code.
 173   directory_iterator &increment(std::error_code &EC) {
 174     assert(Impl && "attempting to increment past end");
 175     EC = Impl->increment();
 176     if (Impl->CurrentEntry.path().empty())
 177       Impl.reset(); // Normalize the end iterator to Impl == nullptr.
 178     return *this;
 179   }
 180
 181   const directory_entry &operator*() const { return Impl->CurrentEntry; }
 182   const directory_entry *operator->() const { return &Impl->CurrentEntry; }
 183
 184   bool operator==(const directory_iterator &RHS) const {
 185     if (Impl && RHS.Impl)
 186       return Impl->CurrentEntry.path() == RHS.Impl->CurrentEntry.path();
 187     return !Impl && !RHS.Impl;
 188   }
 189   bool operator!=(const directory_iterator &RHS) const {
 190     return !(*this == RHS);
 191   }
 192 };
 193
 194 class FileSystem;
 195
 196 namespace detail {
 197
 198 /// Keeps state for the recursive_directory_iterator.
 199 struct RecDirIterState {
 200   std::stack<directory_iterator, std::vector<directory_iterator>> Stack;
 201   bool HasNoPushRequest = false;
 202 };
 203
 204 } // end namespace detail
 205
 206 /// An input iterator over the recursive contents of a virtual path,
 207 /// similar to llvm::sys::fs::recursive_directory_iterator.
 208 class recursive_directory_iterator {
 209   FileSystem *FS;
 210   std::shared_ptr<detail::RecDirIterState>
 211       State; // Input iterator semantics on copy.
 212
 213 public:
 214   recursive_directory_iterator(FileSystem &FS, const Twine &Path,
 215                                std::error_code &EC);
 216
 217   /// Construct an 'end' iterator.
 218   recursive_directory_iterator() = default;
 219
 220   /// Equivalent to operator++, with an error code.
 221   recursive_directory_iterator &increment(std::error_code &EC);
 222
 223   const directory_entry &operator*() const { return *State->Stack.top(); }
 224   const directory_entry *operator->() const { return &*State->Stack.top(); }
 225
 226   bool operator==(const recursive_directory_iterator &Other) const {
 227     return State == Other.State; // identity
 228   }
 229   bool operator!=(const recursive_directory_iterator &RHS) const {
 230     return !(*this == RHS);
 231   }
 232
 233   /// Gets the current level. Starting path is at level 0.
 234   int level() const {
 235     assert(!State->Stack.empty() &&
 236            "Cannot get level without any iteration state");
 237     return State->Stack.size() - 1;
 238   }
 239
 240   void no_push() { State->HasNoPushRequest = true; }
 241 };
 242
 243 /// The virtual file system interface.
 244 class FileSystem : public llvm::ThreadSafeRefCountedBase<FileSystem> {
 245 public:
 246   virtual ~FileSystem();
 247
 248   /// Get the status of the entry at \p Path, if one exists.
 249   virtual llvm::ErrorOr<Status> status(const Twine &Path) = 0;
 250
 251   /// Get a \p File object for the file at \p Path, if one exists.
 252   virtual llvm::ErrorOr<std::unique_ptr<File>>
 253   openFileForRead(const Twine &Path) = 0;
 254
 255   /// This is a convenience method that opens a file, gets its content and then
 256   /// closes the file.
 257   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
 258   getBufferForFile(const Twine &Name, int64_t FileSize = -1,
 259                    bool RequiresNullTerminator = true, bool IsVolatile = false);
 260
 261   /// Get a directory_iterator for \p Dir.
 262   /// \note The 'end' iterator is directory_iterator().
 263   virtual directory_iterator dir_begin(const Twine &Dir,
 264                                        std::error_code &EC) = 0;
 265
 266   /// Set the working directory. This will affect all following operations on
 267   /// this file system and may propagate down for nested file systems.
 268   virtual std::error_code setCurrentWorkingDirectory(const Twine &Path) = 0;
 269
 270   /// Get the working directory of this file system.
 271   virtual llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const = 0;
 272
 273   /// Gets real path of \p Path e.g. collapse all . and .. patterns, resolve
 274   /// symlinks. For real file system, this uses `llvm::sys::fs::real_path`.
 275   /// This returns errc::operation_not_permitted if not implemented by subclass.
 276   virtual std::error_code getRealPath(const Twine &Path,
 277                                       SmallVectorImpl<char> &Output) const;
 278
 279   /// Check whether a file exists. Provided for convenience.
 280   bool exists(const Twine &Path);
 281
 282   /// Is the file mounted on a local filesystem?
 283   virtual std::error_code isLocal(const Twine &Path, bool &Result);
 284
 285   /// Make \a Path an absolute path.
 286   ///
 287   /// Makes \a Path absolute using the current directory if it is not already.
 288   /// An empty \a Path will result in the current directory.
 289   ///
 290   /// /absolute/path   => /absolute/path
 291   /// relative/../path => <current-directory>/relative/../path
 292   ///
 293   /// \param Path A path that is modified to be an absolute path.
 294   /// \returns success if \a path has been made absolute, otherwise a
 295   ///          platform-specific error_code.
 296   std::error_code makeAbsolute(SmallVectorImpl<char> &Path) const;
 297 };
 298
 299 /// Gets an \p vfs::FileSystem for the 'real' file system, as seen by
 300 /// the operating system.
 301 /// The working directory is linked to the process's working directory.
 302 /// (This is usually thread-hostile).
 303 IntrusiveRefCntPtr<FileSystem> getRealFileSystem();
 304
 305 /// Create an \p vfs::FileSystem for the 'real' file system, as seen by
 306 /// the operating system.
 307 /// It has its own working directory, independent of (but initially equal to)
 308 /// that of the process.
 309 std::unique_ptr<FileSystem> createPhysicalFileSystem();
 310
 311 /// A file system that allows overlaying one \p AbstractFileSystem on top
 312 /// of another.
 313 ///
 314 /// Consists of a stack of >=1 \p FileSystem objects, which are treated as being
 315 /// one merged file system. When there is a directory that exists in more than
 316 /// one file system, the \p OverlayFileSystem contains a directory containing
 317 /// the union of their contents.  The attributes (permissions, etc.) of the
 318 /// top-most (most recently added) directory are used.  When there is a file
 319 /// that exists in more than one file system, the file in the top-most file
 320 /// system overrides the other(s).
 321 class OverlayFileSystem : public FileSystem {
 322   using FileSystemList = SmallVector<IntrusiveRefCntPtr<FileSystem>, 1>;
 323
 324   /// The stack of file systems, implemented as a list in order of
 325   /// their addition.
 326   FileSystemList FSList;
 327
 328 public:
 329   OverlayFileSystem(IntrusiveRefCntPtr<FileSystem> Base);
 330
 331   /// Pushes a file system on top of the stack.
 332   void pushOverlay(IntrusiveRefCntPtr<FileSystem> FS);
 333
 334   llvm::ErrorOr<Status> status(const Twine &Path) override;
 335   llvm::ErrorOr<std::unique_ptr<File>>
 336   openFileForRead(const Twine &Path) override;
 337   directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
 338   llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override;
 339   std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
 340   std::error_code isLocal(const Twine &Path, bool &Result) override;
 341   std::error_code getRealPath(const Twine &Path,
 342                               SmallVectorImpl<char> &Output) const override;
 343
 344   using iterator = FileSystemList::reverse_iterator;
 345   using const_iterator = FileSystemList::const_reverse_iterator;
 346   using reverse_iterator = FileSystemList::iterator;
 347   using const_reverse_iterator = FileSystemList::const_iterator;
 348
 349   /// Get an iterator pointing to the most recently added file system.
 350   iterator overlays_begin() { return FSList.rbegin(); }
 351   const_iterator overlays_begin() const { return FSList.rbegin(); }
 352
 353   /// Get an iterator pointing one-past the least recently added file system.
 354   iterator overlays_end() { return FSList.rend(); }
 355   const_iterator overlays_end() const { return FSList.rend(); }
 356
 357   /// Get an iterator pointing to the least recently added file system.
 358   reverse_iterator overlays_rbegin() { return FSList.begin(); }
 359   const_reverse_iterator overlays_rbegin() const { return FSList.begin(); }
 360
 361   /// Get an iterator pointing one-past the most recently added file system.
 362   reverse_iterator overlays_rend() { return FSList.end(); }
 363   const_reverse_iterator overlays_rend() const { return FSList.end(); }
 364 };
 365
 366 /// By default, this delegates all calls to the underlying file system. This
 367 /// is useful when derived file systems want to override some calls and still
 368 /// proxy other calls.
 369 class ProxyFileSystem : public FileSystem {
 370 public:
 371   explicit ProxyFileSystem(IntrusiveRefCntPtr<FileSystem> FS)
 372       : FS(std::move(FS)) {}
 373
 374   llvm::ErrorOr<Status> status(const Twine &Path) override {
 375     return FS->status(Path);
 376   }
 377   llvm::ErrorOr<std::unique_ptr<File>>
 378   openFileForRead(const Twine &Path) override {
 379     return FS->openFileForRead(Path);
 380   }
 381   directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override {
 382     return FS->dir_begin(Dir, EC);
 383   }
 384   llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
 385     return FS->getCurrentWorkingDirectory();
 386   }
 387   std::error_code setCurrentWorkingDirectory(const Twine &Path) override {
 388     return FS->setCurrentWorkingDirectory(Path);
 389   }
 390   std::error_code getRealPath(const Twine &Path,
 391                               SmallVectorImpl<char> &Output) const override {
 392     return FS->getRealPath(Path, Output);
 393   }
 394   std::error_code isLocal(const Twine &Path, bool &Result) override {
 395     return FS->isLocal(Path, Result);
 396   }
 397
 398 protected:
 399   FileSystem &getUnderlyingFS() { return *FS; }
 400
 401 private:
 402   IntrusiveRefCntPtr<FileSystem> FS;
 403
 404   virtual void anchor();
 405 };
 406
 407 namespace detail {
 408
 409 class InMemoryDirectory;
 410 class InMemoryFile;
 411
 412 } // namespace detail
 413
 414 /// An in-memory file system.
 415 class InMemoryFileSystem : public FileSystem {
 416   std::unique_ptr<detail::InMemoryDirectory> Root;
 417   std::string WorkingDirectory;
 418   bool UseNormalizedPaths = true;
 419
 420   /// If HardLinkTarget is non-null, a hardlink is created to the To path which
 421   /// must be a file. If it is null then it adds the file as the public addFile.
 422   bool addFile(const Twine &Path, time_t ModificationTime,
 423                std::unique_ptr<llvm::MemoryBuffer> Buffer,
 424                Optional<uint32_t> User, Optional<uint32_t> Group,
 425                Optional<llvm::sys::fs::file_type> Type,
 426                Optional<llvm::sys::fs::perms> Perms,
 427                const detail::InMemoryFile *HardLinkTarget);
 428
 429 public:
 430   explicit InMemoryFileSystem(bool UseNormalizedPaths = true);
 431   ~InMemoryFileSystem() override;
 432
 433   /// Add a file containing a buffer or a directory to the VFS with a
 434   /// path. The VFS owns the buffer.  If present, User, Group, Type
 435   /// and Perms apply to the newly-created file or directory.
 436   /// \return true if the file or directory was successfully added,
 437   /// false if the file or directory already exists in the file system with
 438   /// different contents.
 439   bool addFile(const Twine &Path, time_t ModificationTime,
 440                std::unique_ptr<llvm::MemoryBuffer> Buffer,
 441                Optional<uint32_t> User = None, Optional<uint32_t> Group = None,
 442                Optional<llvm::sys::fs::file_type> Type = None,
 443                Optional<llvm::sys::fs::perms> Perms = None);
 444
 445   /// Add a hard link to a file.
 446   /// Here hard links are not intended to be fully equivalent to the classical
 447   /// filesystem. Both the hard link and the file share the same buffer and
 448   /// status (and thus have the same UniqueID). Because of this there is no way
 449   /// to distinguish between the link and the file after the link has been
 450   /// added.
 451   ///
 452   /// The To path must be an existing file or a hardlink. The From file must not
 453   /// have been added before. The To Path must not be a directory. The From Node
 454   /// is added as a hard link which points to the resolved file of To Node.
 455   /// \return true if the above condition is satisfied and hardlink was
 456   /// successfully created, false otherwise.
 457   bool addHardLink(const Twine &From, const Twine &To);
 458
 459   /// Add a buffer to the VFS with a path. The VFS does not own the buffer.
 460   /// If present, User, Group, Type and Perms apply to the newly-created file
 461   /// or directory.
 462   /// \return true if the file or directory was successfully added,
 463   /// false if the file or directory already exists in the file system with
 464   /// different contents.
 465   bool addFileNoOwn(const Twine &Path, time_t ModificationTime,
 466                     llvm::MemoryBuffer *Buffer, Optional<uint32_t> User = None,
 467                     Optional<uint32_t> Group = None,
 468                     Optional<llvm::sys::fs::file_type> Type = None,
 469                     Optional<llvm::sys::fs::perms> Perms = None);
 470
 471   std::string toString() const;
 472
 473   /// Return true if this file system normalizes . and .. in paths.
 474   bool useNormalizedPaths() const { return UseNormalizedPaths; }
 475
 476   llvm::ErrorOr<Status> status(const Twine &Path) override;
 477   llvm::ErrorOr<std::unique_ptr<File>>
 478   openFileForRead(const Twine &Path) override;
 479   directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
 480
 481   llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override {
 482     return WorkingDirectory;
 483   }
 484   /// Canonicalizes \p Path by combining with the current working
 485   /// directory and normalizing the path (e.g. remove dots). If the current
 486   /// working directory is not set, this returns errc::operation_not_permitted.
 487   ///
 488   /// This doesn't resolve symlinks as they are not supported in in-memory file
 489   /// system.
 490   std::error_code getRealPath(const Twine &Path,
 491                               SmallVectorImpl<char> &Output) const override;
 492   std::error_code isLocal(const Twine &Path, bool &Result) override;
 493   std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
 494 };
 495
 496 /// Get a globally unique ID for a virtual file or directory.
 497 llvm::sys::fs::UniqueID getNextVirtualUniqueID();
 498
 499 /// Gets a \p FileSystem for a virtual file system described in YAML
 500 /// format.
 501 IntrusiveRefCntPtr<FileSystem>
 502 getVFSFromYAML(std::unique_ptr<llvm::MemoryBuffer> Buffer,
 503                llvm::SourceMgr::DiagHandlerTy DiagHandler,
 504                StringRef YAMLFilePath, void *DiagContext = nullptr,
 505                IntrusiveRefCntPtr<FileSystem> ExternalFS = getRealFileSystem());
 506
 507 struct YAMLVFSEntry {
 508   template <typename T1, typename T2>
 509   YAMLVFSEntry(T1 &&VPath, T2 &&RPath)
 510       : VPath(std::forward<T1>(VPath)), RPath(std::forward<T2>(RPath)) {}
 511   std::string VPath;
 512   std::string RPath;
 513 };
 514
 515 class VFSFromYamlDirIterImpl;
 516 class RedirectingFileSystemParser;
 517
 518 /// A virtual file system parsed from a YAML file.
 519 ///
 520 /// Currently, this class allows creating virtual directories and mapping
 521 /// virtual file paths to existing external files, available in \c ExternalFS.
 522 ///
 523 /// The basic structure of the parsed file is:
 524 /// \verbatim
 525 /// {
 526 ///   'version': <version number>,
 527 ///   <optional configuration>
 528 ///   'roots': [
 529 ///              <directory entries>
 530 ///            ]
 531 /// }
 532 /// \endverbatim
 533 ///
 534 /// All configuration options are optional.
 535 ///   'case-sensitive': <boolean, default=true>
 536 ///   'use-external-names': <boolean, default=true>
 537 ///   'overlay-relative': <boolean, default=false>
 538 ///   'fallthrough': <boolean, default=true>
 539 ///
 540 /// Virtual directories are represented as
 541 /// \verbatim
 542 /// {
 543 ///   'type': 'directory',
 544 ///   'name': <string>,
 545 ///   'contents': [ <file or directory entries> ]
 546 /// }
 547 /// \endverbatim
 548 ///
 549 /// The default attributes for virtual directories are:
 550 /// \verbatim
 551 /// MTime = now() when created
 552 /// Perms = 0777
 553 /// User = Group = 0
 554 /// Size = 0
 555 /// UniqueID = unspecified unique value
 556 /// \endverbatim
 557 ///
 558 /// Re-mapped files are represented as
 559 /// \verbatim
 560 /// {
 561 ///   'type': 'file',
 562 ///   'name': <string>,
 563 ///   'use-external-name': <boolean> # Optional
 564 ///   'external-contents': <path to external file>
 565 /// }
 566 /// \endverbatim
 567 ///
 568 /// and inherit their attributes from the external contents.
 569 ///
 570 /// In both cases, the 'name' field may contain multiple path components (e.g.
 571 /// /path/to/file). However, any directory that contains more than one child
 572 /// must be uniquely represented by a directory entry.
 573 class RedirectingFileSystem : public vfs::FileSystem {
 574 public:
 575   enum EntryKind { EK_Directory, EK_File };
 576
 577   /// A single file or directory in the VFS.
 578   class Entry {
 579     EntryKind Kind;
 580     std::string Name;
 581
 582   public:
 583     Entry(EntryKind K, StringRef Name) : Kind(K), Name(Name) {}
 584     virtual ~Entry() = default;
 585
 586     StringRef getName() const { return Name; }
 587     EntryKind getKind() const { return Kind; }
 588   };
 589
 590   class RedirectingDirectoryEntry : public Entry {
 591     std::vector<std::unique_ptr<Entry>> Contents;
 592     Status S;
 593
 594   public:
 595     RedirectingDirectoryEntry(StringRef Name,
 596                               std::vector<std::unique_ptr<Entry>> Contents,
 597                               Status S)
 598         : Entry(EK_Directory, Name), Contents(std::move(Contents)),
 599           S(std::move(S)) {}
 600     RedirectingDirectoryEntry(StringRef Name, Status S)
 601         : Entry(EK_Directory, Name), S(std::move(S)) {}
 602
 603     Status getStatus() { return S; }
 604
 605     void addContent(std::unique_ptr<Entry> Content) {
 606       Contents.push_back(std::move(Content));
 607     }
 608
 609     Entry *getLastContent() const { return Contents.back().get(); }
 610
 611     using iterator = decltype(Contents)::iterator;
 612
 613     iterator contents_begin() { return Contents.begin(); }
 614     iterator contents_end() { return Contents.end(); }
 615
 616     static bool classof(const Entry *E) { return E->getKind() == EK_Directory; }
 617   };
 618
 619   class RedirectingFileEntry : public Entry {
 620   public:
 621     enum NameKind { NK_NotSet, NK_External, NK_Virtual };
 622
 623   private:
 624     std::string ExternalContentsPath;
 625     NameKind UseName;
 626
 627   public:
 628     RedirectingFileEntry(StringRef Name, StringRef ExternalContentsPath,
 629                          NameKind UseName)
 630         : Entry(EK_File, Name), ExternalContentsPath(ExternalContentsPath),
 631           UseName(UseName) {}
 632
 633     StringRef getExternalContentsPath() const { return ExternalContentsPath; }
 634
 635     /// whether to use the external path as the name for this file.
 636     bool useExternalName(bool GlobalUseExternalName) const {
 637       return UseName == NK_NotSet ? GlobalUseExternalName
 638                                   : (UseName == NK_External);
 639     }
 640
 641     NameKind getUseName() const { return UseName; }
 642
 643     static bool classof(const Entry *E) { return E->getKind() == EK_File; }
 644   };
 645
 646 private:
 647   friend class VFSFromYamlDirIterImpl;
 648   friend class RedirectingFileSystemParser;
 649
 650   /// The root(s) of the virtual file system.
 651   std::vector<std::unique_ptr<Entry>> Roots;
 652
 653   /// The file system to use for external references.
 654   IntrusiveRefCntPtr<FileSystem> ExternalFS;
 655
 656   /// If IsRelativeOverlay is set, this represents the directory
 657   /// path that should be prefixed to each 'external-contents' entry
 658   /// when reading from YAML files.
 659   std::string ExternalContentsPrefixDir;
 660
 661   /// @name Configuration
 662   /// @{
 663
 664   /// Whether to perform case-sensitive comparisons.
 665   ///
 666   /// Currently, case-insensitive matching only works correctly with ASCII.
 667   bool CaseSensitive = true;
 668
 669   /// IsRelativeOverlay marks whether a ExternalContentsPrefixDir path must
 670   /// be prefixed in every 'external-contents' when reading from YAML files.
 671   bool IsRelativeOverlay = false;
 672
 673   /// Whether to use to use the value of 'external-contents' for the
 674   /// names of files.  This global value is overridable on a per-file basis.
 675   bool UseExternalNames = true;
 676
 677   /// Whether to attempt a file lookup in external file system after it wasn't
 678   /// found in VFS.
 679   bool IsFallthrough = true;
 680   /// @}
 681
 682   /// Virtual file paths and external files could be canonicalized without "..",
 683   /// "." and "./" in their paths. FIXME: some unittests currently fail on
 684   /// win32 when using remove_dots and remove_leading_dotslash on paths.
 685   bool UseCanonicalizedPaths =
 686 #ifdef _WIN32
 687       false;
 688 #else
 689       true;
 690 #endif
 691
 692   RedirectingFileSystem(IntrusiveRefCntPtr<FileSystem> ExternalFS)
 693       : ExternalFS(std::move(ExternalFS)) {}
 694
 695   /// Looks up the path <tt>[Start, End)</tt> in \p From, possibly
 696   /// recursing into the contents of \p From if it is a directory.
 697   ErrorOr<Entry *> lookupPath(llvm::sys::path::const_iterator Start,
 698                               llvm::sys::path::const_iterator End,
 699                               Entry *From) const;
 700
 701   /// Get the status of a given an \c Entry.
 702   ErrorOr<Status> status(const Twine &Path, Entry *E);
 703
 704 public:
 705   /// Looks up \p Path in \c Roots.
 706   ErrorOr<Entry *> lookupPath(const Twine &Path) const;
 707
 708   /// Parses \p Buffer, which is expected to be in YAML format and
 709   /// returns a virtual file system representing its contents.
 710   static RedirectingFileSystem *
 711   create(std::unique_ptr<MemoryBuffer> Buffer,
 712          SourceMgr::DiagHandlerTy DiagHandler, StringRef YAMLFilePath,
 713          void *DiagContext, IntrusiveRefCntPtr<FileSystem> ExternalFS);
 714
 715   ErrorOr<Status> status(const Twine &Path) override;
 716   ErrorOr<std::unique_ptr<File>> openFileForRead(const Twine &Path) override;
 717
 718   std::error_code getRealPath(const Twine &Path,
 719                               SmallVectorImpl<char> &Output) const override;
 720
 721   llvm::ErrorOr<std::string> getCurrentWorkingDirectory() const override;
 722
 723   std::error_code setCurrentWorkingDirectory(const Twine &Path) override;
 724
 725   std::error_code isLocal(const Twine &Path, bool &Result) override;
 726
 727   directory_iterator dir_begin(const Twine &Dir, std::error_code &EC) override;
 728
 729   void setExternalContentsPrefixDir(StringRef PrefixDir);
 730
 731   StringRef getExternalContentsPrefixDir() const;
 732
 733   void dump(raw_ostream &OS) const;
 734   void dumpEntry(raw_ostream &OS, Entry *E, int NumSpaces = 0) const;
 735 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 736   LLVM_DUMP_METHOD void dump() const;
 737 #endif
 738 };
 739
 740 /// Collect all pairs of <virtual path, real path> entries from the
 741 /// \p YAMLFilePath. This is used by the module dependency collector to forward
 742 /// the entries into the reproducer output VFS YAML file.
 743 void collectVFSFromYAML(
 744     std::unique_ptr<llvm::MemoryBuffer> Buffer,
 745     llvm::SourceMgr::DiagHandlerTy DiagHandler, StringRef YAMLFilePath,
 746     SmallVectorImpl<YAMLVFSEntry> &CollectedEntries,
 747     void *DiagContext = nullptr,
 748     IntrusiveRefCntPtr<FileSystem> ExternalFS = getRealFileSystem());
 749
 750 class YAMLVFSWriter {
 751   std::vector<YAMLVFSEntry> Mappings;
 752   Optional<bool> IsCaseSensitive;
 753   Optional<bool> IsOverlayRelative;
 754   Optional<bool> UseExternalNames;
 755   std::string OverlayDir;
 756
 757 public:
 758   YAMLVFSWriter() = default;
 759
 760   void addFileMapping(StringRef VirtualPath, StringRef RealPath);
 761
 762   void setCaseSensitivity(bool CaseSensitive) {
 763     IsCaseSensitive = CaseSensitive;
 764   }
 765
 766   void setUseExternalNames(bool UseExtNames) { UseExternalNames = UseExtNames; }
 767
 768   void setOverlayDir(StringRef OverlayDirectory) {
 769     IsOverlayRelative = true;
 770     OverlayDir.assign(OverlayDirectory.str());
 771   }
 772
 773   const std::vector<YAMLVFSEntry> &getMappings() const { return Mappings; }
 774
 775   void write(llvm::raw_ostream &OS);
 776 };
 777
 778 } // namespace vfs
 779 } // namespace llvm
 780
 781 #endif // LLVM_SUPPORT_VIRTUALFILESYSTEM_H