Implement -working-directory.

When -working-directory is passed in command line, file paths are resolved relative to the specified directory.
This helps both when using libclang (where we can't require the user to actually change the working directory)
and to help reproduce test cases when the reproduction work comes along.

--FileSystemOptions is introduced which controls how file system operations are performed (currently it just contains
 the working directory value if set).
--FileSystemOptions are passed around to various interfaces that perform file operations.
--Opening & reading the content of files should be done only through FileManager. This is useful in general since
 file operations will be abstracted in the future for the reproduction mechanism.

FileSystemOptions is independent of FileManager so that we can have multiple translation units sharing the same
FileManager but with different FileSystemOptions.

Addresses rdar://8583824.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@118203 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/ASTImporter.h

@@ -28,6 +28,7 @@ namespace clang {
   class Diagnostic;
   class Expr;
   class FileManager;
+  class FileSystemOptions;
   class IdentifierInfo;
   class NestedNameSpecifier;
   class Stmt;
@@ -45,6 +46,8 @@ namespace clang {
     
     /// \brief The file managers we're importing to and from.
     FileManager &ToFileManager, &FromFileManager;
+
+    const FileSystemOptions &ToFileSystemOpts, &FromFileSystemOpts;
     
     /// \brief The diagnostics object that we should use to emit diagnostics.
     Diagnostic &Diags;
@@ -76,7 +79,9 @@ namespace clang {
   public:
     ASTImporter(Diagnostic &Diags,
                 ASTContext &ToContext, FileManager &ToFileManager,
-                ASTContext &FromContext, FileManager &FromFileManager);
+                const FileSystemOptions &ToFileSystemOpts,
+                ASTContext &FromContext, FileManager &FromFileManager,
+                const FileSystemOptions &FromFileSystemOpts);
     
     virtual ~ASTImporter();
     

include/clang/Basic/FileManager.h

@@ -24,8 +24,16 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 
+namespace llvm {
+class MemoryBuffer;
+namespace sys {
+class Path;
+}
+}
+
 namespace clang {
 class FileManager;
+class FileSystemOptions;
 
 /// DirectoryEntry - Cached information about one directory on the disk.
 ///
@@ -162,9 +170,8 @@ class FileManager {
   // Caching.
   llvm::OwningPtr<StatSysCallCache> StatCache;
 
-  int stat_cached(const char* path, struct stat* buf) {
-    return StatCache.get() ? StatCache->stat(path, buf) : stat(path, buf);
-  }
+  int stat_cached(const char* path, struct stat* buf,
+                  const FileSystemOptions &FileSystemOpts);
 
 public:
   FileManager();
@@ -189,25 +196,61 @@ public:
   /// getDirectory - Lookup, cache, and verify the specified directory.  This
   /// returns null if the directory doesn't exist.
   ///
-  const DirectoryEntry *getDirectory(llvm::StringRef Filename) {
-    return getDirectory(Filename.begin(), Filename.end());
+  const DirectoryEntry *getDirectory(llvm::StringRef Filename,
+                                     const FileSystemOptions &FileSystemOpts) {
+    return getDirectory(Filename.begin(), Filename.end(), FileSystemOpts);
   }
-  const DirectoryEntry *getDirectory(const char *FileStart,const char *FileEnd);
+  const DirectoryEntry *getDirectory(const char *FileStart,const char *FileEnd,
+                                     const FileSystemOptions &FileSystemOpts);
 
   /// getFile - Lookup, cache, and verify the specified file.  This returns null
   /// if the file doesn't exist.
   ///
-  const FileEntry *getFile(llvm::StringRef Filename) {
-    return getFile(Filename.begin(), Filename.end());
+  const FileEntry *getFile(llvm::StringRef Filename,
+                           const FileSystemOptions &FileSystemOpts) {
+    return getFile(Filename.begin(), Filename.end(), FileSystemOpts);
   }
   const FileEntry *getFile(const char *FilenameStart,
-                           const char *FilenameEnd);
+                           const char *FilenameEnd,
+                           const FileSystemOptions &FileSystemOpts);
 
   /// \brief Retrieve a file entry for a "virtual" file that acts as
   /// if there were a file with the given name on disk. The file
   /// itself is not accessed.
   const FileEntry *getVirtualFile(llvm::StringRef Filename, off_t Size,
-                                  time_t ModificationTime);
+                                  time_t ModificationTime,
+                                  const FileSystemOptions &FileSystemOpts);
+
+  /// \brief Open the specified file as a MemoryBuffer, returning a new
+  /// MemoryBuffer if successful, otherwise returning null.
+  llvm::MemoryBuffer *getBufferForFile(const FileEntry *Entry,
+                                       const FileSystemOptions &FileSystemOpts,
+                                       std::string *ErrorStr = 0,
+                                       struct stat *FileInfo = 0) {
+    return getBufferForFile(Entry->getName(), FileSystemOpts,
+                            ErrorStr, Entry->getSize(), FileInfo);
+  }
+  llvm::MemoryBuffer *getBufferForFile(llvm::StringRef Filename,
+                                       const FileSystemOptions &FileSystemOpts,
+                                       std::string *ErrorStr = 0,
+                                       int64_t FileSize = -1,
+                                       struct stat *FileInfo = 0) {
+    return getBufferForFile(Filename.begin(), Filename.end(), FileSystemOpts,
+                            ErrorStr, FileSize, FileInfo);
+  }
+  llvm::MemoryBuffer *getBufferForFile(const char *FilenameStart,
+                                       const char *FilenameEnd,
+                                       const FileSystemOptions &FileSystemOpts,
+                                       std::string *ErrorStr = 0,
+                                       int64_t FileSize = -1,
+                                       struct stat *FileInfo = 0);
+
+  /// \brief If path is not absolute and FileSystemOptions set the working
+  /// directory, the path is modified to be relative to the given
+  /// working directory.
+  static void FixupRelativePath(llvm::sys::Path &path,
+                                const FileSystemOptions &FSOpts);
+
   void PrintStats() const;
 };
 

include/clang/Basic/FileSystemOptions.h

@@ -0,0 +1,29 @@
+//===--- FileSystemOptions.h - File System Options --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the FileSystemOptions interface.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_BASIC_FILESYSTEMOPTIONS_H
+#define LLVM_CLANG_BASIC_FILESYSTEMOPTIONS_H
+
+namespace clang {
+
+/// \brief Keeps track of options that affect how file operations are performed.
+class FileSystemOptions {
+public:
+  /// \brief If set, paths are resolved as if the working directory was
+  /// set to the value of WorkingDir.
+  std::string WorkingDir;
+};
+
+} // end namespace clang
+
+#endif

include/clang/Basic/SourceManager.h

@@ -33,6 +33,7 @@ namespace clang {
 class Diagnostic;
 class SourceManager;
 class FileManager;
+class FileSystemOptions;
 class FileEntry;
 class LineTableInfo;
   
@@ -369,7 +370,10 @@ public:
 class SourceManager {
   /// \brief Diagnostic object.
   Diagnostic &Diag;
-  
+
+  FileManager &FileMgr;
+  const FileSystemOptions &FileSystemOpts;
+
   mutable llvm::BumpPtrAllocator ContentCacheAlloc;
 
   /// FileInfos - Memoized information about all of the files tracked by this
@@ -427,8 +431,10 @@ class SourceManager {
   explicit SourceManager(const SourceManager&);
   void operator=(const SourceManager&);
 public:
-  SourceManager(Diagnostic &Diag)
-    : Diag(Diag), ExternalSLocEntries(0), LineTable(0), NumLinearScans(0),
+  SourceManager(Diagnostic &Diag, FileManager &FileMgr,
+                const FileSystemOptions &FSOpts)
+    : Diag(Diag), FileMgr(FileMgr), FileSystemOpts(FSOpts),
+      ExternalSLocEntries(0), LineTable(0), NumLinearScans(0),
       NumBinaryProbes(0) {
     clearIDTables();
   }
@@ -438,6 +444,9 @@ public:
 
   Diagnostic &getDiagnostics() const { return Diag; }
 
+  FileManager &getFileManager() const { return FileMgr; }
+  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
+
   //===--------------------------------------------------------------------===//
   // MainFileID creation and querying methods.
   //===--------------------------------------------------------------------===//

include/clang/Driver/CC1Options.td

@@ -366,6 +366,11 @@ def create_module : Flag<"-create-module">,
 def import_module : Separate<"-import-module">,
   HelpText<"Import a module definition file">;
 
+def working_directory : JoinedOrSeparate<"-working-directory">,
+  HelpText<"Resolve file paths relative to the specified directory">;
+def working_directory_EQ : Joined<"-working-directory=">,
+  Alias<working_directory>;
+
 def relocatable_pch : Flag<"-relocatable-pch">,
   HelpText<"Whether to build a relocatable precompiled header">;
 def chained_pch : Flag<"-chained-pch">,

include/clang/Driver/Options.td

@@ -624,6 +624,11 @@ def x : JoinedOrSeparate<"-x">, Flags<[DriverOption]>,
   MetaVarName<"<language>">;
 def y : Joined<"-y">;
 
+def working_directory : Separate<"-working-directory">,
+  HelpText<"Resolve file paths relative to the specified directory">;
+def working_directory_EQ : Joined<"-working-directory=">,
+  Alias<working_directory>;
+
 // Double dash options, which are usually an alias for one of the previous
 // options.
 

include/clang/Frontend/ASTUnit.h

@@ -21,6 +21,7 @@
 #include "clang/Lex/PreprocessingRecord.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/FileManager.h"
+#include "clang/Basic/FileSystemOptions.h"
 #include "clang-c/Index.h"
 #include "llvm/ADT/IntrusiveRefCntPtr.h"
 #include "llvm/ADT/OwningPtr.h"
@@ -68,7 +69,9 @@ private:
   llvm::OwningPtr<TargetInfo>       Target;
   llvm::OwningPtr<Preprocessor>     PP;
   llvm::OwningPtr<ASTContext>       Ctx;
-  
+
+  FileSystemOptions FileSystemOpts;
+
   /// \brief The AST consumer that received information about the translation
   /// unit as it was parsed or loaded.
   llvm::OwningPtr<ASTConsumer> Consumer;
@@ -359,6 +362,8 @@ public:
   const FileManager &getFileManager() const { return *FileMgr; }
         FileManager &getFileManager()       { return *FileMgr; }
 
+  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
+
   const std::string &getOriginalSourceFileName();
   const std::string &getASTFileName();
 
@@ -452,7 +457,12 @@ public:
   unsigned cached_completion_size() const { 
     return CachedCompletionResults.size(); 
   }
-  
+
+  llvm::MemoryBuffer *getBufferForFile(llvm::StringRef Filename,
+                                       std::string *ErrorStr = 0,
+                                       int64_t FileSize = -1,
+                                       struct stat *FileInfo = 0);
+
   /// \brief Whether this AST represents a complete translation unit.
   ///
   /// If false, this AST is only a partial translation unit, e.g., one
@@ -473,6 +483,7 @@ public:
   /// \returns - The initialized ASTUnit or null if the AST failed to load.
   static ASTUnit *LoadFromASTFile(const std::string &Filename,
                                   llvm::IntrusiveRefCntPtr<Diagnostic> Diags,
+                                  const FileSystemOptions &FileSystemOpts,
                                   bool OnlyLocalDecls = false,
                                   RemappedFile *RemappedFiles = 0,
                                   unsigned NumRemappedFiles = 0,

include/clang/Frontend/CompilerInstance.h

@@ -220,6 +220,10 @@ public:
     return Invocation->getDiagnosticOpts();
   }
 
+  const FileSystemOptions &getFileSystemOpts() const {
+    return Invocation->getFileSystemOpts();
+  }
+
   FrontendOptions &getFrontendOpts() {
     return Invocation->getFrontendOpts();
   }
@@ -499,7 +503,8 @@ public:
   void createFileManager();
 
   /// Create the source manager and replace any existing one with it.
-  void createSourceManager();
+  void createSourceManager(FileManager &FileMgr,
+                           const FileSystemOptions &FSOpts);
 
   /// Create the preprocessor, using the invocation, file, and source managers,
   /// and replace any existing one with it.
@@ -517,6 +522,7 @@ public:
                                           const DependencyOutputOptions &,
                                           const TargetInfo &,
                                           const FrontendOptions &,
+                                          const FileSystemOptions &,
                                           SourceManager &, FileManager &);
 
   /// Create the AST context.
@@ -617,6 +623,7 @@ public:
   static bool InitializeSourceManager(llvm::StringRef InputFile,
                                       Diagnostic &Diags,
                                       FileManager &FileMgr,
+                                      const FileSystemOptions &FSOpts,
                                       SourceManager &SourceMgr,
                                       const FrontendOptions &Opts);
 

include/clang/Frontend/CompilerInvocation.h

@@ -12,6 +12,7 @@
 
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/TargetOptions.h"
+#include "clang/Basic/FileSystemOptions.h"
 #include "clang/Frontend/AnalyzerOptions.h"
 #include "clang/Frontend/CodeGenOptions.h"
 #include "clang/Frontend/DependencyOutputOptions.h"
@@ -52,6 +53,9 @@ class CompilerInvocation {
   /// Options controlling the diagnostic engine.
   DiagnosticOptions DiagnosticOpts;
 
+  /// Options controlling file system operations.
+  FileSystemOptions FileSystemOpts;
+
   /// Options controlling the frontend itself.
   FrontendOptions FrontendOpts;
 
@@ -126,6 +130,11 @@ public:
   DiagnosticOptions &getDiagnosticOpts() { return DiagnosticOpts; }
   const DiagnosticOptions &getDiagnosticOpts() const { return DiagnosticOpts; }
 
+  FileSystemOptions &getFileSystemOpts() { return FileSystemOpts; }
+  const FileSystemOptions &getFileSystemOpts() const {
+    return FileSystemOpts;
+  }
+
   HeaderSearchOptions &getHeaderSearchOpts() { return HeaderSearchOpts; }
   const HeaderSearchOptions &getHeaderSearchOpts() const {
     return HeaderSearchOpts;

include/clang/Frontend/Utils.h

@@ -39,6 +39,7 @@ class SourceManager;
 class Stmt;
 class TargetInfo;
 class FrontendOptions;
+class FileSystemOptions;
 
 /// Normalize \arg File for use in a user defined #include directive (in the
 /// predefines buffer).
@@ -53,6 +54,7 @@ void ApplyHeaderSearchOptions(HeaderSearch &HS,
 /// InitializePreprocessor - Initialize the preprocessor getting it and the
 /// environment ready to process a single file.
 void InitializePreprocessor(Preprocessor &PP,
+                            const FileSystemOptions &FSOpts,
                             const PreprocessorOptions &PPOpts,
                             const HeaderSearchOptions &HSOpts,
                             const FrontendOptions &FEOpts);

include/clang/Lex/HeaderMap.h

@@ -21,6 +21,7 @@ namespace llvm {
 namespace clang {
   class FileEntry;
   class FileManager;
+  class FileSystemOptions;
   struct HMapBucket;
   struct HMapHeader;
 
@@ -43,11 +44,13 @@ public:
 
   /// HeaderMap::Create - This attempts to load the specified file as a header
   /// map.  If it doesn't look like a HeaderMap, it gives up and returns null.
-  static const HeaderMap *Create(const FileEntry *FE);
+  static const HeaderMap *Create(const FileEntry *FE, FileManager &FM,
+                                 const FileSystemOptions &FSOpts);
 
   /// LookupFile - Check to see if the specified relative filename is located in
   /// this HeaderMap.  If so, open it and return its FileEntry.
-  const FileEntry *LookupFile(llvm::StringRef Filename, FileManager &FM) const;
+  const FileEntry *LookupFile(llvm::StringRef Filename, FileManager &FM,
+                              const FileSystemOptions &FileSystemOpts) const;
 
   /// getFileName - Return the filename of the headermap.
   const char *getFileName() const;

include/clang/Lex/HeaderSearch.h

@@ -23,6 +23,7 @@ namespace clang {
 class ExternalIdentifierLookup;
 class FileEntry;
 class FileManager;
+class FileSystemOptions;
 class IdentifierInfo;
 
 /// HeaderFileInfo - The preprocessor keeps track of this information for each
@@ -71,6 +72,7 @@ struct HeaderFileInfo {
 /// file referenced by a #include or #include_next, (sub-)framework lookup, etc.
 class HeaderSearch {
   FileManager &FileMgr;
+  const FileSystemOptions &FileSystemOpts;
 
   /// #include search path information.  Requests for #include "x" search the
   /// directory of the #including file first, then each directory in SearchDirs
@@ -118,10 +120,11 @@ class HeaderSearch {
   explicit HeaderSearch(const HeaderSearch&);
   void operator=(const HeaderSearch&);
 public:
-  HeaderSearch(FileManager &FM);
+  HeaderSearch(FileManager &FM, const FileSystemOptions &FSOpts);
   ~HeaderSearch();
 
   FileManager &getFileMgr() const { return FileMgr; }
+  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
 
   /// SetSearchPaths - Interface for setting the file search paths.
   ///

include/clang/Lex/PTHManager.h

@@ -119,7 +119,9 @@ public:
 
   /// Create - This method creates PTHManager objects.  The 'file' argument
   ///  is the name of the PTH file.  This method returns NULL upon failure.
-  static PTHManager *Create(const std::string& file, Diagnostic &Diags);
+  static PTHManager *Create(const std::string& file, FileManager &FileMgr,
+                            const FileSystemOptions &FSOpts,
+                            Diagnostic &Diags);
 
   void setPreprocessor(Preprocessor *pp) { PP = pp; }
 

include/clang/Lex/Preprocessor.h

@@ -35,6 +35,7 @@ namespace clang {
 class SourceManager;
 class ExternalPreprocessorSource;
 class FileManager;
+class FileSystemOptions;
 class FileEntry;
 class HeaderSearch;
 class PragmaNamespace;
@@ -57,6 +58,7 @@ class Preprocessor {
   LangOptions        Features;
   const TargetInfo  &Target;
   FileManager       &FileMgr;
+  const FileSystemOptions &FileSystemOpts;
   SourceManager     &SourceMgr;
   ScratchBuffer     *ScratchBuf;
   HeaderSearch      &HeaderInfo;
@@ -279,6 +281,7 @@ public:
   const LangOptions &getLangOptions() const { return Features; }
   const TargetInfo &getTargetInfo() const { return Target; }
   FileManager &getFileManager() const { return FileMgr; }
+  const FileSystemOptions &getFileSystemOpts() const { return FileSystemOpts; }
   SourceManager &getSourceManager() const { return SourceMgr; }
   HeaderSearch &getHeaderSearchInfo() const { return HeaderInfo; }
 

include/clang/Serialization/ASTReader.h

@@ -67,6 +67,7 @@ class ASTDeclReader;
 class ASTStmtReader;
 class ASTIdentifierLookupTrait;
 class TypeLocReader;
+class FileSystemOptions;
 struct HeaderFileInfo;
 
 struct PCHPredefinesBlock {
@@ -193,6 +194,7 @@ private:
 
   SourceManager &SourceMgr;
   FileManager &FileMgr;
+  const FileSystemOptions &FileSystemOpts;
   Diagnostic &Diags;
 
   /// \brief The semantic analysis object that will be processing the
@@ -802,7 +804,8 @@ public:
   /// \param DisableValidation If true, the AST reader will suppress most
   /// of its regular consistency checking, allowing the use of precompiled
   /// headers that cannot be determined to be compatible.
-      ASTReader(SourceManager &SourceMgr, FileManager &FileMgr,
+  ASTReader(SourceManager &SourceMgr, FileManager &FileMgr,
+            const FileSystemOptions &FileSystemOpts,
             Diagnostic &Diags, const char *isysroot = 0,
             bool DisableValidation = false);
   ~ASTReader();
@@ -834,6 +837,8 @@ public:
   /// \brief Retrieve the name of the original source file name directly from
   /// the AST file, without actually loading the AST file.
   static std::string getOriginalSourceFile(const std::string &ASTFileName,
+                                           FileManager &FileMgr,
+                                           const FileSystemOptions &FSOpts,
                                            Diagnostic &Diags);
 
   /// \brief Returns the suggested contents of the predefines buffer,

lib/AST/ASTImporter.cpp

@@ -2980,9 +2980,12 @@ Expr *ASTNodeImporter::VisitCStyleCastExpr(CStyleCastExpr *E) {
 
 ASTImporter::ASTImporter(Diagnostic &Diags,
                          ASTContext &ToContext, FileManager &ToFileManager,
-                         ASTContext &FromContext, FileManager &FromFileManager)
+                         const FileSystemOptions &ToFileSystemOpts,
+                         ASTContext &FromContext, FileManager &FromFileManager,
+                         const FileSystemOptions &FromFileSystemOpts)
   : ToContext(ToContext), FromContext(FromContext),
     ToFileManager(ToFileManager), FromFileManager(FromFileManager),
+    ToFileSystemOpts(ToFileSystemOpts), FromFileSystemOpts(FromFileSystemOpts),
     Diags(Diags) {
   ImportedDecls[FromContext.getTranslationUnitDecl()]
     = ToContext.getTranslationUnitDecl();
@@ -3153,7 +3156,8 @@ FileID ASTImporter::Import(FileID FromID) {
     // disk again
     // FIXME: We definitely want to re-use the existing MemoryBuffer, rather
     // than mmap the files several times.
-    const FileEntry *Entry = ToFileManager.getFile(Cache->Entry->getName());
+    const FileEntry *Entry = ToFileManager.getFile(Cache->Entry->getName(),
+                                                   ToFileSystemOpts);
     ToID = ToSM.createFileID(Entry, ToIncludeLoc, 
                              FromSLoc.getFile().getFileCharacteristic());
   } else {

lib/Basic/FileManager.cpp

@@ -18,8 +18,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Basic/FileManager.h"
+#include "clang/Basic/FileSystemOptions.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/System/Path.h"
 #include "llvm/Config/config.h"
@@ -197,7 +199,8 @@ void FileManager::removeStatCache(StatSysCallCache *statCache) {
 /// \brief Retrieve the directory that the given file name resides in.
 static const DirectoryEntry *getDirectoryFromFile(FileManager &FileMgr,
                                                   const char *NameStart,
-                                                  const char *NameEnd) {
+                                                  const char *NameEnd,
+                                      const FileSystemOptions &FileSystemOpts) {
   // Figure out what directory it is in.   If the string contains a / in it,
   // strip off everything after it.
   // FIXME: this logic should be in sys::Path.
@@ -211,18 +214,19 @@ static const DirectoryEntry *getDirectoryFromFile(FileManager &FileMgr,
   if (SlashPos < NameStart) {
     // Use the current directory if file has no path component.
     const char *Name = ".";
-    return FileMgr.getDirectory(Name, Name+1);
+    return FileMgr.getDirectory(Name, Name+1, FileSystemOpts);
   } else if (SlashPos == NameEnd-1)
     return 0;       // If filename ends with a /, it's a directory.
   else
-    return FileMgr.getDirectory(NameStart, SlashPos);
+    return FileMgr.getDirectory(NameStart, SlashPos, FileSystemOpts);
 }
 
 /// getDirectory - Lookup, cache, and verify the specified directory.  This
 /// returns null if the directory doesn't exist.
 ///
 const DirectoryEntry *FileManager::getDirectory(const char *NameStart,
-                                                const char *NameEnd) {
+                                                const char *NameEnd,
+                                      const FileSystemOptions &FileSystemOpts) {
   // stat doesn't like trailing separators (at least on Windows).
   if (((NameEnd - NameStart) > 1) &&
       ((*(NameEnd - 1) == '/') || (*(NameEnd - 1) == '\\')))
@@ -248,7 +252,7 @@ const DirectoryEntry *FileManager::getDirectory(const char *NameStart,
 
   // Check to see if the directory exists.
   struct stat StatBuf;
-  if (stat_cached(InterndDirName, &StatBuf) ||   // Error stat'ing.
+  if (stat_cached(InterndDirName, &StatBuf, FileSystemOpts) ||   // Error stat'ing.
       !S_ISDIR(StatBuf.st_mode))          // Not a directory?
     return 0;
 
@@ -274,7 +278,8 @@ const DirectoryEntry *FileManager::getDirectory(const char *NameStart,
 /// if the file doesn't exist.
 ///
 const FileEntry *FileManager::getFile(const char *NameStart,
-                                      const char *NameEnd) {
+                                      const char *NameEnd,
+                                      const FileSystemOptions &FileSystemOpts) {
   ++NumFileLookups;
 
   // See if there is already an entry in the map.
@@ -297,7 +302,7 @@ const FileEntry *FileManager::getFile(const char *NameStart,
   const char *InterndFileName = NamedFileEnt.getKeyData();
 
   const DirectoryEntry *DirInfo
-    = getDirectoryFromFile(*this, NameStart, NameEnd);
+    = getDirectoryFromFile(*this, NameStart, NameEnd, FileSystemOpts);
   if (DirInfo == 0)  // Directory doesn't exist, file can't exist.
     return 0;
 
@@ -307,7 +312,7 @@ const FileEntry *FileManager::getFile(const char *NameStart,
   // Nope, there isn't.  Check to see if the file exists.
   struct stat StatBuf;
   //llvm::errs() << "STATING: " << Filename;
-  if (stat_cached(InterndFileName, &StatBuf) ||   // Error stat'ing.
+  if (stat_cached(InterndFileName, &StatBuf, FileSystemOpts) ||   // Error stat'ing.
         S_ISDIR(StatBuf.st_mode)) {           // A directory?
     // If this file doesn't exist, we leave a null in FileEntries for this path.
     //llvm::errs() << ": Not existing\n";
@@ -336,7 +341,8 @@ const FileEntry *FileManager::getFile(const char *NameStart,
 
 const FileEntry *
 FileManager::getVirtualFile(llvm::StringRef Filename, off_t Size,
-                            time_t ModificationTime) {
+                            time_t ModificationTime,
+                            const FileSystemOptions &FileSystemOpts) {
   const char *NameStart = Filename.begin(), *NameEnd = Filename.end();
 
   ++NumFileLookups;
@@ -356,7 +362,7 @@ FileManager::getVirtualFile(llvm::StringRef Filename, off_t Size,
   NamedFileEnt.setValue(NON_EXISTENT_FILE);
 
   const DirectoryEntry *DirInfo
-    = getDirectoryFromFile(*this, NameStart, NameEnd);
+    = getDirectoryFromFile(*this, NameStart, NameEnd, FileSystemOpts);
   if (DirInfo == 0)  // Directory doesn't exist, file can't exist.
     return 0;
 
@@ -374,7 +380,7 @@ FileManager::getVirtualFile(llvm::StringRef Filename, off_t Size,
   // newly-created file entry.
   const char *InterndFileName = NamedFileEnt.getKeyData();
   struct stat StatBuf;
-  if (!stat_cached(InterndFileName, &StatBuf) &&
+  if (!stat_cached(InterndFileName, &StatBuf, FileSystemOpts) &&
       !S_ISDIR(StatBuf.st_mode)) {
     llvm::sys::Path FilePath(InterndFileName);
     FilePath.makeAbsolute();
@@ -384,6 +390,38 @@ FileManager::getVirtualFile(llvm::StringRef Filename, off_t Size,
   return UFE;
 }
 
+llvm::MemoryBuffer *FileManager::getBufferForFile(const char *FilenameStart,
+                                     const char *FilenameEnd,
+                                     const FileSystemOptions &FileSystemOpts,
+                                     std::string *ErrorStr,
+                                     int64_t FileSize,
+                                     struct stat *FileInfo) {
+  llvm::sys::Path FilePath(llvm::StringRef(FilenameStart,
+                                           FilenameEnd-FilenameStart));
+  FixupRelativePath(FilePath, FileSystemOpts);
+
+  return llvm::MemoryBuffer::getFile(FilePath.c_str(), ErrorStr,
+                                     FileSize, FileInfo);
+}
+
+int FileManager::stat_cached(const char* path, struct stat* buf,
+                             const FileSystemOptions &FileSystemOpts) {
+  llvm::sys::Path FilePath(path);
+  FixupRelativePath(FilePath, FileSystemOpts);
+
+  return StatCache.get() ? StatCache->stat(FilePath.c_str(), buf)
+                         : stat(FilePath.c_str(), buf);
+}
+
+void FileManager::FixupRelativePath(llvm::sys::Path &path,
+                                    const FileSystemOptions &FSOpts) {
+  if (!FSOpts.WorkingDir.empty() && !path.isAbsolute()) {
+    llvm::sys::Path NewPath(FSOpts.WorkingDir);
+    NewPath.appendComponent(path.str());
+    path = NewPath;
+  }
+}
+
 void FileManager::PrintStats() const {
   llvm::errs() << "\n*** File Manager Stats:\n";
   llvm::errs() << UniqueFiles.size() << " files found, "

lib/Basic/SourceManager.cpp

@@ -73,9 +73,10 @@ const llvm::MemoryBuffer *ContentCache::getBuffer(Diagnostic &Diag,
   if (!Buffer.getPointer() && Entry) {
     std::string ErrorStr;
     struct stat FileInfo;
-    Buffer.setPointer(MemoryBuffer::getFile(Entry->getName(), &ErrorStr,
-                                            Entry->getSize(), &FileInfo));
-    
+    Buffer.setPointer(SM.getFileManager().getBufferForFile(Entry,
+                                                         SM.getFileSystemOpts(),
+                                                         &ErrorStr, &FileInfo));
+
     // If we were unable to open the file, then we are in an inconsistent
     // situation where the content cache referenced a file which no longer
     // exists. Most likely, we were using a stat cache with an invalid entry but

lib/Driver/Driver.cpp

@@ -753,10 +753,19 @@ void Driver::BuildActions(const ToolChain &TC, const ArgList &Args,
       }
 
       // Check that the file exists, if enabled.
-      if (CheckInputsExist && memcmp(Value, "-", 2) != 0 &&
-          !llvm::sys::Path(Value).exists())
-        Diag(clang::diag::err_drv_no_such_file) << A->getValue(Args);
-      else
+      if (CheckInputsExist && memcmp(Value, "-", 2) != 0) {
+        llvm::sys::Path Path(Value);
+        if (Arg *WorkDir = Args.getLastArg(options::OPT_working_directory))
+          if (!Path.isAbsolute()) {
+            Path = WorkDir->getValue(Args);
+            Path.appendComponent(Value);
+          }
+
+        if (!Path.exists())
+          Diag(clang::diag::err_drv_no_such_file) << Path.str();
+        else
+          Inputs.push_back(std::make_pair(Ty, A));
+      } else
         Inputs.push_back(std::make_pair(Ty, A));
 
     } else if (A->getOption().isLinkerInput()) {

lib/Driver/Tools.cpp

@@ -1073,6 +1073,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   CmdArgs.push_back("-resource-dir");
   CmdArgs.push_back(D.ResourceDir.c_str());
 
+  Args.AddLastArg(CmdArgs, options::OPT_working_directory);
+
   // Add preprocessing options like -I, -D, etc. if we are using the
   // preprocessor.
   //

lib/Frontend/ASTMerge.cpp

@@ -40,7 +40,8 @@ void ASTMergeAction::ExecuteAction() {
                                        &CI.getASTContext());
   llvm::IntrusiveRefCntPtr<Diagnostic> Diags(&CI.getDiagnostics());
   for (unsigned I = 0, N = ASTFiles.size(); I != N; ++I) {
-    ASTUnit *Unit = ASTUnit::LoadFromASTFile(ASTFiles[I], Diags, false);
+    ASTUnit *Unit = ASTUnit::LoadFromASTFile(ASTFiles[I], Diags,
+                                             CI.getFileSystemOpts(), false);
     if (!Unit)
       continue;
 
@@ -53,8 +54,10 @@ void ASTMergeAction::ExecuteAction() {
     ASTImporter Importer(CI.getDiagnostics(),
                          CI.getASTContext(), 
                          CI.getFileManager(),
+                         CI.getFileSystemOpts(),
                          Unit->getASTContext(), 
-                         Unit->getFileManager());
+                         Unit->getFileManager(),
+                         Unit->getFileSystemOpts());
 
     TranslationUnitDecl *TU = Unit->getASTContext().getTranslationUnitDecl();
     for (DeclContext::decl_iterator D = TU->decls_begin(), 

lib/Frontend/ASTUnit.cpp

@@ -449,8 +449,17 @@ const std::string &ASTUnit::getASTFileName() {
   return static_cast<ASTReader *>(Ctx->getExternalSource())->getFileName();
 }
 
+llvm::MemoryBuffer *ASTUnit::getBufferForFile(llvm::StringRef Filename,
+                                              std::string *ErrorStr,
+                                              int64_t FileSize,
+                                              struct stat *FileInfo) {
+  return FileMgr->getBufferForFile(Filename, FileSystemOpts,
+                                   ErrorStr, FileSize, FileInfo);
+}
+
 ASTUnit *ASTUnit::LoadFromASTFile(const std::string &Filename,
                                   llvm::IntrusiveRefCntPtr<Diagnostic> Diags,
+                                  const FileSystemOptions &FileSystemOpts,
                                   bool OnlyLocalDecls,
                                   RemappedFile *RemappedFiles,
                                   unsigned NumRemappedFiles,
@@ -467,9 +476,13 @@ ASTUnit *ASTUnit::LoadFromASTFile(const std::string &Filename,
   AST->CaptureDiagnostics = CaptureDiagnostics;
   AST->OnlyLocalDecls = OnlyLocalDecls;
   AST->Diagnostics = Diags;
+  AST->FileSystemOpts = FileSystemOpts;
   AST->FileMgr.reset(new FileManager);
-  AST->SourceMgr.reset(new SourceManager(AST->getDiagnostics()));
-  AST->HeaderInfo.reset(new HeaderSearch(AST->getFileManager()));
+  AST->SourceMgr.reset(new SourceManager(AST->getDiagnostics(),
+                                         AST->getFileManager(),
+                                         AST->getFileSystemOpts()));
+  AST->HeaderInfo.reset(new HeaderSearch(AST->getFileManager(),
+                                         AST->getFileSystemOpts()));
   
   // If requested, capture diagnostics in the ASTUnit.
   CaptureDroppedDiagnostics Capture(CaptureDiagnostics, AST->getDiagnostics(),
@@ -480,7 +493,8 @@ ASTUnit *ASTUnit::LoadFromASTFile(const std::string &Filename,
     const FileEntry *FromFile
       = AST->getFileManager().getVirtualFile(RemappedFiles[I].first,
                                     RemappedFiles[I].second->getBufferSize(),
-                                             0);
+                                             0,
+                                             AST->getFileSystemOpts());
     if (!FromFile) {
       AST->getDiagnostics().Report(diag::err_fe_remap_missing_from_file)
         << RemappedFiles[I].first;
@@ -505,7 +519,7 @@ ASTUnit *ASTUnit::LoadFromASTFile(const std::string &Filename,
   llvm::OwningPtr<ASTReader> Reader;
 
   Reader.reset(new ASTReader(AST->getSourceManager(), AST->getFileManager(),
-                             AST->getDiagnostics()));
+                             AST->getFileSystemOpts(), AST->getDiagnostics()));
   Reader->setListener(new ASTInfoCollector(LangInfo, HeaderInfo, TargetTriple,
                                            Predefines, Counter));
 
@@ -732,7 +746,8 @@ bool ASTUnit::Parse(llvm::MemoryBuffer *OverrideMainBuffer) {
   // Configure the various subsystems.
   // FIXME: Should we retain the previous file manager?
   FileMgr.reset(new FileManager);
-  SourceMgr.reset(new SourceManager(getDiagnostics()));
+  FileSystemOpts = Clang.getFileSystemOpts();
+  SourceMgr.reset(new SourceManager(getDiagnostics(), *FileMgr, FileSystemOpts));
   TheSema.reset();
   Ctx.reset();
   PP.reset();
@@ -908,7 +923,7 @@ ASTUnit::ComputePreamble(CompilerInvocation &Invocation,
             CreatedBuffer = false;
           }
           
-          Buffer = llvm::MemoryBuffer::getFile(M->second);
+          Buffer = getBufferForFile(M->second);
           if (!Buffer)
             return std::make_pair((llvm::MemoryBuffer*)0, 
                                   std::make_pair(0, true));
@@ -941,7 +956,7 @@ ASTUnit::ComputePreamble(CompilerInvocation &Invocation,
   
   // If the main source file was not remapped, load it now.
   if (!Buffer) {
-    Buffer = llvm::MemoryBuffer::getFile(FrontendOpts.Inputs[0].second);
+    Buffer = getBufferForFile(FrontendOpts.Inputs[0].second);
     if (!Buffer)
       return std::make_pair((llvm::MemoryBuffer*)0, std::make_pair(0, true));    
     
@@ -1240,7 +1255,9 @@ llvm::MemoryBuffer *ASTUnit::getMainBufferWithPrecompiledPreamble(
   Clang.setFileManager(new FileManager);
   
   // Create the source manager.
-  Clang.setSourceManager(new SourceManager(getDiagnostics()));
+  Clang.setSourceManager(new SourceManager(getDiagnostics(),
+                                           Clang.getFileManager(),
+                                           Clang.getFileSystemOpts()));
   
   llvm::OwningPtr<PrecompilePreambleAction> Act;
   Act.reset(new PrecompilePreambleAction(*this));

lib/Frontend/CompilerInstance.cpp

@@ -148,8 +148,9 @@ void CompilerInstance::createFileManager() {
 
 // Source Manager
 
-void CompilerInstance::createSourceManager() {
-  SourceMgr.reset(new SourceManager(getDiagnostics()));
+void CompilerInstance::createSourceManager(FileManager &FileMgr,
+                                           const FileSystemOptions &FSOpts) {
+  SourceMgr.reset(new SourceManager(getDiagnostics(), FileMgr, FSOpts));
 }
 
 // Preprocessor
@@ -158,8 +159,8 @@ void CompilerInstance::createPreprocessor() {
   PP.reset(createPreprocessor(getDiagnostics(), getLangOpts(),
                               getPreprocessorOpts(), getHeaderSearchOpts(),
                               getDependencyOutputOpts(), getTarget(),
-                              getFrontendOpts(), getSourceManager(),
-                              getFileManager()));
+                              getFrontendOpts(), getFileSystemOpts(),
+                              getSourceManager(), getFileManager()));
 }
 
 Preprocessor *
@@ -170,15 +171,16 @@ CompilerInstance::createPreprocessor(Diagnostic &Diags,
                                      const DependencyOutputOptions &DepOpts,
                                      const TargetInfo &Target,
                                      const FrontendOptions &FEOpts,
+                                     const FileSystemOptions &FSOpts,
                                      SourceManager &SourceMgr,
                                      FileManager &FileMgr) {
   // Create a PTH manager if we are using some form of a token cache.
   PTHManager *PTHMgr = 0;
   if (!PPOpts.TokenCache.empty())
-    PTHMgr = PTHManager::Create(PPOpts.TokenCache, Diags);
+    PTHMgr = PTHManager::Create(PPOpts.TokenCache, FileMgr, FSOpts, Diags);
 
   // Create the Preprocessor.
-  HeaderSearch *HeaderInfo = new HeaderSearch(FileMgr);
+  HeaderSearch *HeaderInfo = new HeaderSearch(FileMgr, FSOpts);
   Preprocessor *PP = new Preprocessor(Diags, LangInfo, Target,
                                       SourceMgr, *HeaderInfo, PTHMgr,
                                       /*OwnsHeaderSearch=*/true);
@@ -194,7 +196,7 @@ CompilerInstance::createPreprocessor(Diagnostic &Diags,
   if (PPOpts.DetailedRecord)
     PP->createPreprocessingRecord();
   
-  InitializePreprocessor(*PP, PPOpts, HSOpts, FEOpts);
+  InitializePreprocessor(*PP, FSOpts, PPOpts, HSOpts, FEOpts);
 
   // Handle generating dependencies, if requested.
   if (!DepOpts.OutputFile.empty())
@@ -271,7 +273,8 @@ static bool EnableCodeCompletion(Preprocessor &PP,
                                  unsigned Column) {
   // Tell the source manager to chop off the given file at a specific
   // line and column.
-  const FileEntry *Entry = PP.getFileManager().getFile(Filename);
+  const FileEntry *Entry = PP.getFileManager().getFile(Filename,
+                                                       PP.getFileSystemOpts());
   if (!Entry) {
     PP.getDiagnostics().Report(diag::err_fe_invalid_code_complete_file)
       << Filename;
@@ -352,7 +355,11 @@ void CompilerInstance::clearOutputFiles(bool EraseFiles) {
         TempPath.eraseFromDisk();
       else {
         std::string Error;
-        if (TempPath.renamePathOnDisk(llvm::sys::Path(it->Filename), &Error)) {
+        llvm::sys::Path NewOutFile(it->Filename);
+        // If '-working-directory' was passed, the output filename should be
+        // relative to that.
+        FileManager::FixupRelativePath(NewOutFile, getFileSystemOpts());
+        if (TempPath.renamePathOnDisk(NewOutFile, &Error)) {
           getDiagnostics().Report(diag::err_fe_unable_to_rename_temp)
             << it->TempFilename << it->Filename << Error;
           TempPath.eraseFromDisk();
@@ -457,17 +464,19 @@ CompilerInstance::createOutputFile(llvm::StringRef OutputPath,
 
 bool CompilerInstance::InitializeSourceManager(llvm::StringRef InputFile) {
   return InitializeSourceManager(InputFile, getDiagnostics(), getFileManager(),
+                                 getFileSystemOpts(),
                                  getSourceManager(), getFrontendOpts());
 }
 
 bool CompilerInstance::InitializeSourceManager(llvm::StringRef InputFile,
                                                Diagnostic &Diags,
                                                FileManager &FileMgr,
+                                               const FileSystemOptions &FSOpts,
                                                SourceManager &SourceMgr,
                                                const FrontendOptions &Opts) {
   // Figure out where to get and map in the main file.
   if (InputFile != "-") {
-    const FileEntry *File = FileMgr.getFile(InputFile);
+    const FileEntry *File = FileMgr.getFile(InputFile, FSOpts);
     if (!File) {
       Diags.Report(diag::err_fe_error_reading) << InputFile;
       return false;
@@ -480,7 +489,8 @@ bool CompilerInstance::InitializeSourceManager(llvm::StringRef InputFile,
       return false;
     }
     const FileEntry *File = FileMgr.getVirtualFile(SB->getBufferIdentifier(),
-                                                   SB->getBufferSize(), 0);
+                                                   SB->getBufferSize(), 0,
+                                                   FSOpts);
     SourceMgr.createMainFileID(File);
     SourceMgr.overrideFileContents(File, SB);
   }

lib/Frontend/CompilerInvocation.cpp

@@ -10,6 +10,7 @@
 #include "clang/Frontend/CompilerInvocation.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/Version.h"
+#include "clang/Basic/FileManager.h"
 #include "clang/Driver/Arg.h"
 #include "clang/Driver/ArgList.h"
 #include "clang/Driver/CC1Options.h"
@@ -351,6 +352,14 @@ static const char *getActionName(frontend::ActionKind Kind) {
   return 0;
 }
 
+static void FileSystemOptsToArgs(const FileSystemOptions &Opts,
+                                 std::vector<std::string> &Res) {
+  if (!Opts.WorkingDir.empty()) {
+    Res.push_back("-working-directory");
+    Res.push_back(Opts.WorkingDir);
+  }
+}
+
 static void FrontendOptsToArgs(const FrontendOptions &Opts,
                                std::vector<std::string> &Res) {
   if (Opts.DisableFree)
@@ -743,6 +752,7 @@ void CompilerInvocation::toArgs(std::vector<std::string> &Res) {
   CodeGenOptsToArgs(getCodeGenOpts(), Res);
   DependencyOutputOptsToArgs(getDependencyOutputOpts(), Res);
   DiagnosticOptsToArgs(getDiagnosticOpts(), Res);
+  FileSystemOptsToArgs(getFileSystemOpts(), Res);
   FrontendOptsToArgs(getFrontendOpts(), Res);
   HeaderSearchOptsToArgs(getHeaderSearchOpts(), Res);
   LangOptsToArgs(getLangOpts(), Res);
@@ -979,6 +989,10 @@ static void ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
   Opts.Warnings = Args.getAllArgValues(OPT_W);
 }
 
+static void ParseFileSystemArgs(FileSystemOptions &Opts, ArgList &Args) {
+  Opts.WorkingDir = Args.getLastArgValue(OPT_working_directory);
+}
+
 static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
                                    Diagnostic &Diags) {
   using namespace cc1options;
@@ -1402,6 +1416,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
 }
 
 static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
+                                  FileManager &FileMgr,
+                                  const FileSystemOptions &FSOpts,
                                   Diagnostic &Diags) {
   using namespace cc1options;
   Opts.ImplicitPCHInclude = Args.getLastArgValue(OPT_include_pch);
@@ -1456,7 +1472,8 @@ static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
     // PCH is handled specially, we need to extra the original include path.
     if (A->getOption().matches(OPT_include_pch)) {
       std::string OriginalFile =
-        ASTReader::getOriginalSourceFile(A->getValue(Args), Diags);
+        ASTReader::getOriginalSourceFile(A->getValue(Args), FileMgr, FSOpts,
+                                         Diags);
       if (OriginalFile.empty())
         continue;
 
@@ -1535,11 +1552,18 @@ void CompilerInvocation::CreateFromArgs(CompilerInvocation &Res,
   ParseCodeGenArgs(Res.getCodeGenOpts(), *Args, Diags);
   ParseDependencyOutputArgs(Res.getDependencyOutputOpts(), *Args);
   ParseDiagnosticArgs(Res.getDiagnosticOpts(), *Args, Diags);
+  ParseFileSystemArgs(Res.getFileSystemOpts(), *Args);
   InputKind DashX = ParseFrontendArgs(Res.getFrontendOpts(), *Args, Diags);
   ParseHeaderSearchArgs(Res.getHeaderSearchOpts(), *Args);
   if (DashX != IK_AST && DashX != IK_LLVM_IR)
     ParseLangArgs(Res.getLangOpts(), *Args, DashX, Diags);
-  ParsePreprocessorArgs(Res.getPreprocessorOpts(), *Args, Diags);
+  // FIXME: ParsePreprocessorArgs uses the FileManager to read the contents of
+  // PCH file and find the original header name. Remove the need to do that in
+  // ParsePreprocessorArgs and remove the FileManager & FileSystemOptions
+  // parameters from the function and the "FileManager.h" #include.
+  FileManager FileMgr;
+  ParsePreprocessorArgs(Res.getPreprocessorOpts(), *Args,
+                        FileMgr, Res.getFileSystemOpts(), Diags);
   ParsePreprocessorOutputArgs(Res.getPreprocessorOutputOpts(), *Args);
   ParseTargetArgs(Res.getTargetOpts(), *Args);
 }

lib/Frontend/FrontendAction.cpp

@@ -103,7 +103,8 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
 
     llvm::IntrusiveRefCntPtr<Diagnostic> Diags(&CI.getDiagnostics());
     std::string Error;
-    ASTUnit *AST = ASTUnit::LoadFromASTFile(Filename, Diags);
+    ASTUnit *AST = ASTUnit::LoadFromASTFile(Filename, Diags,
+                                            CI.getFileSystemOpts());
     if (!AST)
       goto failure;
 
@@ -132,7 +133,7 @@ bool FrontendAction::BeginSourceFile(CompilerInstance &CI,
   if (!CI.hasFileManager())
     CI.createFileManager();
   if (!CI.hasSourceManager())
-    CI.createSourceManager();
+    CI.createSourceManager(CI.getFileManager(), CI.getFileSystemOpts());
 
   // IR files bypass the rest of initialization.
   if (InputKind == IK_LLVM_IR) {

lib/Frontend/FrontendActions.cpp

@@ -207,7 +207,10 @@ void PrintPreambleAction::ExecuteAction() {
     return;
   }
   
-  llvm::MemoryBuffer *Buffer = llvm::MemoryBuffer::getFile(getCurrentFile());
+  CompilerInstance &CI = getCompilerInstance();
+  llvm::MemoryBuffer *Buffer
+      = CI.getFileManager().getBufferForFile(getCurrentFile(),
+                                             CI.getFileSystemOpts());
   if (Buffer) {
     unsigned Preamble = Lexer::ComputePreamble(Buffer).first;
     llvm::outs().write(Buffer->getBufferStart(), Preamble);

lib/Frontend/InitHeaderSearch.cpp

@@ -99,6 +99,7 @@ void InitHeaderSearch::AddPath(const llvm::Twine &Path,
                                bool IgnoreSysRoot) {
   assert(!Path.isTriviallyEmpty() && "can't handle empty path here");
   FileManager &FM = Headers.getFileMgr();
+  const FileSystemOptions &FSOpts = Headers.getFileSystemOpts();
 
   // Compute the actual path, taking into consideration -isysroot.
   llvm::SmallString<256> MappedPathStr;
@@ -125,7 +126,7 @@ void InitHeaderSearch::AddPath(const llvm::Twine &Path,
 
 
   // If the directory exists, add it.
-  if (const DirectoryEntry *DE = FM.getDirectory(MappedPath.str())) {
+  if (const DirectoryEntry *DE = FM.getDirectory(MappedPath.str(), FSOpts)) {
     IncludeGroup[Group].push_back(DirectoryLookup(DE, Type, isUserSupplied,
                                                   isFramework));
     return;
@@ -134,7 +135,7 @@ void InitHeaderSearch::AddPath(const llvm::Twine &Path,
   // Check to see if this is an apple-style headermap (which are not allowed to
   // be frameworks).
   if (!isFramework) {
-    if (const FileEntry *FE = FM.getFile(MappedPath.str())) {
+    if (const FileEntry *FE = FM.getFile(MappedPath.str(), FSOpts)) {
       if (const HeaderMap *HM = Headers.CreateHeaderMap(FE)) {
         // It is a headermap, add it to the search path.
         IncludeGroup[Group].push_back(DirectoryLookup(HM, Type,isUserSupplied));

lib/Frontend/InitPreprocessor.cpp

@@ -478,6 +478,7 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
 static void InitializeFileRemapping(Diagnostic &Diags,
                                     SourceManager &SourceMgr,
                                     FileManager &FileMgr,
+                                    const FileSystemOptions &FSOpts,
                                     const PreprocessorOptions &InitOpts) {
   // Remap files in the source manager (with buffers).
   for (PreprocessorOptions::const_remapped_file_buffer_iterator
@@ -488,7 +489,7 @@ static void InitializeFileRemapping(Diagnostic &Diags,
     // Create the file entry for the file that we're mapping from.
     const FileEntry *FromFile = FileMgr.getVirtualFile(Remap->first,
                                                 Remap->second->getBufferSize(),
-                                                       0);
+                                                       0, FSOpts);
     if (!FromFile) {
       Diags.Report(diag::err_fe_remap_missing_from_file)
         << Remap->first;
@@ -510,7 +511,7 @@ static void InitializeFileRemapping(Diagnostic &Diags,
        Remap != RemapEnd;
        ++Remap) {
     // Find the file that we're mapping to.
-    const FileEntry *ToFile = FileMgr.getFile(Remap->second);
+    const FileEntry *ToFile = FileMgr.getFile(Remap->second, FSOpts);
     if (!ToFile) {
       Diags.Report(diag::err_fe_remap_missing_to_file)
       << Remap->first << Remap->second;
@@ -520,7 +521,7 @@ static void InitializeFileRemapping(Diagnostic &Diags,
     // Create the file entry for the file that we're mapping from.
     const FileEntry *FromFile = FileMgr.getVirtualFile(Remap->first,
                                                        ToFile->getSize(),
-                                                       0);
+                                                       0, FSOpts);
     if (!FromFile) {
       Diags.Report(diag::err_fe_remap_missing_from_file)
       << Remap->first;
@@ -530,7 +531,7 @@ static void InitializeFileRemapping(Diagnostic &Diags,
     // Load the contents of the file we're mapping to.
     std::string ErrorStr;
     const llvm::MemoryBuffer *Buffer
-    = llvm::MemoryBuffer::getFile(ToFile->getName(), &ErrorStr);
+    = FileMgr.getBufferForFile(ToFile->getName(), FSOpts, &ErrorStr);
     if (!Buffer) {
       Diags.Report(diag::err_fe_error_opening)
         << Remap->second << ErrorStr;
@@ -547,6 +548,7 @@ static void InitializeFileRemapping(Diagnostic &Diags,
 /// environment ready to process a single file. This returns true on error.
 ///
 void clang::InitializePreprocessor(Preprocessor &PP,
+                                   const FileSystemOptions &FSOpts,
                                    const PreprocessorOptions &InitOpts,
                                    const HeaderSearchOptions &HSOpts,
                                    const FrontendOptions &FEOpts) {
@@ -556,7 +558,7 @@ void clang::InitializePreprocessor(Preprocessor &PP,
   MacroBuilder Builder(Predefines);
 
   InitializeFileRemapping(PP.getDiagnostics(), PP.getSourceManager(),
-                          PP.getFileManager(), InitOpts);
+                          PP.getFileManager(), FSOpts, InitOpts);
 
   // Emit line markers for various builtin sections of the file.  We don't do
   // this in asm preprocessor mode, because "# 4" is not a line marker directive

lib/Lex/HeaderMap.cpp

@@ -75,13 +75,14 @@ static inline unsigned HashHMapKey(llvm::StringRef Str) {
 /// map.  If it doesn't look like a HeaderMap, it gives up and returns null.
 /// If it looks like a HeaderMap but is obviously corrupted, it puts a reason
 /// into the string error argument and returns null.
-const HeaderMap *HeaderMap::Create(const FileEntry *FE) {
+const HeaderMap *HeaderMap::Create(const FileEntry *FE, FileManager &FM,
+                                   const FileSystemOptions &FSOpts) {
   // If the file is too small to be a header map, ignore it.
   unsigned FileSize = FE->getSize();
   if (FileSize <= sizeof(HMapHeader)) return 0;
 
   llvm::OwningPtr<const llvm::MemoryBuffer> FileBuffer(
-    llvm::MemoryBuffer::getFile(FE->getName(), 0, FE->getSize()));
+    FM.getBufferForFile(FE, FSOpts));
   if (FileBuffer == 0) return 0;  // Unreadable file?
   const char *FileStart = FileBuffer->getBufferStart();
 
@@ -200,7 +201,8 @@ void HeaderMap::dump() const {
 /// LookupFile - Check to see if the specified relative filename is located in
 /// this HeaderMap.  If so, open it and return its FileEntry.
 const FileEntry *HeaderMap::LookupFile(llvm::StringRef Filename,
-                                       FileManager &FM) const {
+                                       FileManager &FM,
+                                const FileSystemOptions &FileSystemOpts) const {
   const HMapHeader &Hdr = getHeader();
   unsigned NumBuckets = getEndianAdjustedWord(Hdr.NumBuckets);
 
@@ -223,6 +225,6 @@ const FileEntry *HeaderMap::LookupFile(llvm::StringRef Filename,
     llvm::SmallString<1024> DestPath;
     DestPath += getString(B.Prefix);
     DestPath += getString(B.Suffix);
-    return FM.getFile(DestPath.begin(), DestPath.end());
+    return FM.getFile(DestPath.begin(), DestPath.end(), FileSystemOpts);
   }
 }

lib/Lex/HeaderSearch.cpp

@@ -32,7 +32,8 @@ HeaderFileInfo::getControllingMacro(ExternalIdentifierLookup *External) {
   return ControllingMacro;
 }
 
-HeaderSearch::HeaderSearch(FileManager &FM) : FileMgr(FM), FrameworkMap(64) {
+HeaderSearch::HeaderSearch(FileManager &FM, const FileSystemOptions &FSOpts)
+    : FileMgr(FM), FileSystemOpts(FSOpts), FrameworkMap(64) {
   SystemDirIdx = 0;
   NoCurDirSearch = false;
 
@@ -83,7 +84,7 @@ const HeaderMap *HeaderSearch::CreateHeaderMap(const FileEntry *FE) {
         return HeaderMaps[i].second;
   }
 
-  if (const HeaderMap *HM = HeaderMap::Create(FE)) {
+  if (const HeaderMap *HM = HeaderMap::Create(FE, FileMgr, FileSystemOpts)) {
     HeaderMaps.push_back(std::make_pair(FE, HM));
     return HM;
   }
@@ -118,14 +119,16 @@ const FileEntry *DirectoryLookup::LookupFile(llvm::StringRef Filename,
     TmpDir += getDir()->getName();
     TmpDir.push_back('/');
     TmpDir.append(Filename.begin(), Filename.end());
-    return HS.getFileMgr().getFile(TmpDir.begin(), TmpDir.end());
+    return HS.getFileMgr().getFile(TmpDir.begin(), TmpDir.end(),
+                                   HS.getFileSystemOpts());
   }
 
   if (isFramework())
     return DoFrameworkLookup(Filename, HS);
 
   assert(isHeaderMap() && "Unknown directory lookup");
-  return getHeaderMap()->LookupFile(Filename, HS.getFileMgr());
+  return getHeaderMap()->LookupFile(Filename, HS.getFileMgr(),
+                                    HS.getFileSystemOpts());
 }
 
 
@@ -134,6 +137,7 @@ const FileEntry *DirectoryLookup::LookupFile(llvm::StringRef Filename,
 const FileEntry *DirectoryLookup::DoFrameworkLookup(llvm::StringRef Filename,
                                                     HeaderSearch &HS) const {
   FileManager &FileMgr = HS.getFileMgr();
+  const FileSystemOptions &FileSystemOpts = HS.getFileSystemOpts();
 
   // Framework names must have a '/' in the filename.
   size_t SlashPos = Filename.find('/');
@@ -184,7 +188,8 @@ const FileEntry *DirectoryLookup::DoFrameworkLookup(llvm::StringRef Filename,
   FrameworkName += "Headers/";
   FrameworkName.append(Filename.begin()+SlashPos+1, Filename.end());
   if (const FileEntry *FE = FileMgr.getFile(FrameworkName.begin(),
-                                            FrameworkName.end())) {
+                                            FrameworkName.end(),
+                                            FileSystemOpts)) {
     return FE;
   }
 
@@ -192,7 +197,8 @@ const FileEntry *DirectoryLookup::DoFrameworkLookup(llvm::StringRef Filename,
   const char *Private = "Private";
   FrameworkName.insert(FrameworkName.begin()+OrigSize, Private,
                        Private+strlen(Private));
-  return FileMgr.getFile(FrameworkName.begin(), FrameworkName.end());
+  return FileMgr.getFile(FrameworkName.begin(), FrameworkName.end(),
+                         FileSystemOpts);
 }
 
 
@@ -219,7 +225,7 @@ const FileEntry *HeaderSearch::LookupFile(llvm::StringRef Filename,
     if (FromDir) return 0;
 
     // Otherwise, just return the file.
-    return FileMgr.getFile(Filename);
+    return FileMgr.getFile(Filename, FileSystemOpts);
   }
 
   // Step #0, unless disabled, check to see if the file is in the #includer's
@@ -234,7 +240,7 @@ const FileEntry *HeaderSearch::LookupFile(llvm::StringRef Filename,
     TmpDir += CurFileEnt->getDir()->getName();
     TmpDir.push_back('/');
     TmpDir.append(Filename.begin(), Filename.end());
-    if (const FileEntry *FE = FileMgr.getFile(TmpDir.str())) {
+    if (const FileEntry *FE = FileMgr.getFile(TmpDir.str(), FileSystemOpts)) {
       // Leave CurDir unset.
       // This file is a system header or C++ unfriendly if the old file is.
       //
@@ -344,7 +350,8 @@ LookupSubframeworkHeader(llvm::StringRef Filename,
 
     // If the framework dir doesn't exist, we fail.
     const DirectoryEntry *Dir = FileMgr.getDirectory(FrameworkName.begin(),
-                                                     FrameworkName.end());
+                                                     FrameworkName.end(),
+                                                     FileSystemOpts);
     if (Dir == 0) return 0;
 
     // Otherwise, if it does, remember that this is the right direntry for this
@@ -359,13 +366,14 @@ LookupSubframeworkHeader(llvm::StringRef Filename,
   HeadersFilename += "Headers/";
   HeadersFilename.append(Filename.begin()+SlashPos+1, Filename.end());
   if (!(FE = FileMgr.getFile(HeadersFilename.begin(),
-                             HeadersFilename.end()))) {
+                             HeadersFilename.end(), FileSystemOpts))) {
 
     // Check ".../Frameworks/HIToolbox.framework/PrivateHeaders/HIToolbox.h"
     HeadersFilename = FrameworkName;
     HeadersFilename += "PrivateHeaders/";
     HeadersFilename.append(Filename.begin()+SlashPos+1, Filename.end());
-    if (!(FE = FileMgr.getFile(HeadersFilename.begin(), HeadersFilename.end())))
+    if (!(FE = FileMgr.getFile(HeadersFilename.begin(), HeadersFilename.end(),
+                               FileSystemOpts)))
       return 0;
   }
 

lib/Lex/PTHLexer.cpp

@@ -434,10 +434,12 @@ static void InvalidPTH(Diagnostic &Diags, const char *Msg) {
   Diags.Report(Diags.getCustomDiagID(Diagnostic::Error, Msg));
 }
 
-PTHManager* PTHManager::Create(const std::string& file, Diagnostic &Diags) {
+PTHManager* PTHManager::Create(const std::string& file, FileManager &FileMgr,
+                               const FileSystemOptions &FSOpts,
+                               Diagnostic &Diags) {
   // Memory map the PTH file.
   llvm::OwningPtr<llvm::MemoryBuffer>
-  File(llvm::MemoryBuffer::getFile(file.c_str()));
+  File(FileMgr.getBufferForFile(file, FSOpts));
 
   if (!File) {
     Diags.Report(diag::err_invalid_pth_file) << file;

lib/Lex/Preprocessor.cpp

@@ -53,7 +53,8 @@ Preprocessor::Preprocessor(Diagnostic &diags, const LangOptions &opts,
                            IdentifierInfoLookup* IILookup,
                            bool OwnsHeaders)
   : Diags(&diags), Features(opts), Target(target),FileMgr(Headers.getFileMgr()),
-    SourceMgr(SM), HeaderInfo(Headers), ExternalSource(0),
+    FileSystemOpts(Headers.getFileSystemOpts()), SourceMgr(SM),
+    HeaderInfo(Headers), ExternalSource(0),
     Identifiers(opts, IILookup), BuiltinInfo(Target), CodeComplete(0),
     CodeCompletionFile(0), SkipMainFilePreamble(0, true), CurPPLexer(0), 
     CurDirLookup(0), Callbacks(0), MacroArgCache(0), Record(0), MIChainHead(0),

lib/Serialization/ASTReader.cpp

@@ -1234,7 +1234,7 @@ ASTReader::ASTReadResult ASTReader::ReadSLocEntryRecord(unsigned ID) {
   case SM_SLOC_FILE_ENTRY: {
     std::string Filename(BlobStart, BlobStart + BlobLen);
     MaybeAddSystemRootToFilename(Filename);
-    const FileEntry *File = FileMgr.getFile(Filename);
+    const FileEntry *File = FileMgr.getFile(Filename, FileSystemOpts);
     if (File == 0) {
       std::string ErrorStr = "could not find file '";
       ErrorStr += Filename;
@@ -1549,7 +1549,8 @@ void ASTReader::ReadMacroRecord(PerFileData &F, uint64_t Offset) {
       const char *FullFileNameStart = BlobStart + Record[3];
       const FileEntry *File
         = PP->getFileManager().getFile(FullFileNameStart,
-                                     FullFileNameStart + (BlobLen - Record[3]));
+                                     FullFileNameStart + (BlobLen - Record[3]),
+                                     FileSystemOpts);
 
       // FIXME: Stable encoding
       InclusionDirective::InclusionKind Kind
@@ -2257,7 +2258,10 @@ ASTReader::ASTReadResult ASTReader::ReadASTCore(llvm::StringRef FileName,
   //
   // FIXME: This shouldn't be here, we should just take a raw_ostream.
   std::string ErrStr;
-  F.Buffer.reset(llvm::MemoryBuffer::getFileOrSTDIN(FileName, &ErrStr));
+  if (FileName == "-")
+    F.Buffer.reset(llvm::MemoryBuffer::getSTDIN(&ErrStr));
+  else
+    F.Buffer.reset(FileMgr.getBufferForFile(FileName, FileSystemOpts, &ErrStr));
   if (!F.Buffer) {
     Error(ErrStr.c_str());
     return IgnorePCH;
@@ -2459,11 +2463,13 @@ void ASTReader::InitializeContext(ASTContext &Ctx) {
 /// directly from the AST file, without actually loading the AST
 /// file.
 std::string ASTReader::getOriginalSourceFile(const std::string &ASTFileName,
+                                             FileManager &FileMgr,
+                                             const FileSystemOptions &FSOpts,
                                              Diagnostic &Diags) {
   // Open the AST file.
   std::string ErrStr;
   llvm::OwningPtr<llvm::MemoryBuffer> Buffer;
-  Buffer.reset(llvm::MemoryBuffer::getFile(ASTFileName.c_str(), &ErrStr));
+  Buffer.reset(FileMgr.getBufferForFile(ASTFileName, FSOpts, &ErrStr));
   if (!Buffer) {
     Diags.Report(diag::err_fe_unable_to_read_pch_file) << ErrStr;
     return std::string();
@@ -4477,6 +4483,7 @@ ASTReader::ASTReader(Preprocessor &PP, ASTContext *Context,
                      const char *isysroot, bool DisableValidation)
   : Listener(new PCHValidator(PP, *this)), DeserializationListener(0),
     SourceMgr(PP.getSourceManager()), FileMgr(PP.getFileManager()),
+    FileSystemOpts(PP.getFileSystemOpts()),
     Diags(PP.getDiagnostics()), SemaObj(0), PP(&PP), Context(Context),
     Consumer(0), isysroot(isysroot), DisableValidation(DisableValidation),
     NumStatHits(0), NumStatMisses(0), NumSLocEntriesRead(0),
@@ -4490,9 +4497,11 @@ ASTReader::ASTReader(Preprocessor &PP, ASTContext *Context,
 }
 
 ASTReader::ASTReader(SourceManager &SourceMgr, FileManager &FileMgr,
+                     const FileSystemOptions &FileSystemOpts,
                      Diagnostic &Diags, const char *isysroot,
                      bool DisableValidation)
   : DeserializationListener(0), SourceMgr(SourceMgr), FileMgr(FileMgr),
+    FileSystemOpts(FileSystemOpts),
     Diags(Diags), SemaObj(0), PP(0), Context(0), Consumer(0),
     isysroot(isysroot), DisableValidation(DisableValidation), NumStatHits(0),
     NumStatMisses(0), NumSLocEntriesRead(0), TotalNumSLocEntries(0),

test/Misc/Inputs/working-directory.h

@@ -0,0 +1 @@
+typedef int Foo;

test/Misc/working-directory.c

@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -working-directory %S working-directory.c -IInputs -fsyntax-only
+
+#include "working-directory.h"
+
+Foo bar;

tools/libclang/CIndex.cpp

@@ -1977,9 +1977,11 @@ CXTranslationUnit clang_createTranslationUnit(CXIndex CIdx,
     return 0;
 
   CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);
+  FileSystemOptions FileSystemOpts;
+  FileSystemOpts.WorkingDir = CXXIdx->getWorkingDirectory();
 
   llvm::IntrusiveRefCntPtr<Diagnostic> Diags;
-  return ASTUnit::LoadFromASTFile(ast_filename, Diags,
+  return ASTUnit::LoadFromASTFile(ast_filename, Diags, FileSystemOpts,
                                   CXXIdx->getOnlyLocalDecls(),
                                   0, 0, true);
 }
@@ -2405,7 +2407,8 @@ CXFile clang_getFile(CXTranslationUnit tu, const char *file_name) {
   ASTUnit *CXXUnit = static_cast<ASTUnit *>(tu);
 
   FileManager &FMgr = CXXUnit->getFileManager();
-  const FileEntry *File = FMgr.getFile(file_name, file_name+strlen(file_name));
+  const FileEntry *File = FMgr.getFile(file_name, file_name+strlen(file_name),
+                                       CXXUnit->getFileSystemOpts());
   return const_cast<FileEntry *>(File);
 }
 

tools/libclang/CIndexCodeCompletion.cpp

@@ -232,12 +232,14 @@ struct AllocatedCXCodeCompleteResults : public CXCodeCompleteResults {
   
   /// \brief Language options used to adjust source locations.
   LangOptions LangOpts;
-
-  /// \brief Source manager, used for diagnostics.
-  SourceManager SourceMgr;
   
   /// \brief File manager, used for diagnostics.
   FileManager FileMgr;
+
+  FileSystemOptions FileSystemOpts;
+
+  /// \brief Source manager, used for diagnostics.
+  SourceManager SourceMgr;
   
   /// \brief Temporary files that should be removed once we have finished
   /// with the code-completion results.
@@ -248,7 +250,8 @@ struct AllocatedCXCodeCompleteResults : public CXCodeCompleteResults {
 };
 
 AllocatedCXCodeCompleteResults::AllocatedCXCodeCompleteResults() 
-  : CXCodeCompleteResults(), Diag(new Diagnostic), SourceMgr(*Diag) { }
+  : CXCodeCompleteResults(), Diag(new Diagnostic),
+    SourceMgr(*Diag, FileMgr, FileSystemOpts) { }
   
 AllocatedCXCodeCompleteResults::~AllocatedCXCodeCompleteResults() {
   for (unsigned I = 0, N = NumResults; I != N; ++I)

tools/libclang/CIndexer.h

@@ -32,7 +32,8 @@ class CIndexer {
   bool DisplayDiagnostics;
 
   llvm::sys::Path ResourcesPath;
-  
+  std::string WorkingDir;
+
 public:
  CIndexer() : OnlyLocalDecls(false), DisplayDiagnostics(false) { }
   
@@ -49,6 +50,9 @@ public:
 
   /// \brief Get the path of the clang resource files.
   std::string getClangResourcesPath();
+
+  const std::string &getWorkingDirectory() const { return WorkingDir; }
+  void setWorkingDirectory(const std::string &Dir) { WorkingDir = Dir; }
 };
 
 namespace clang {