include/clang/Basic/FileManager.h

   1 //===--- FileManager.h - File System Probing and Caching --------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 //  This file defines the FileManager interface.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_CLANG_FILEMANAGER_H
  15 #define LLVM_CLANG_FILEMANAGER_H
  16
  17 #include "llvm/ADT/SmallVector.h"
  18 #include "llvm/ADT/StringMap.h"
  19 #include "llvm/ADT/StringRef.h"
  20 #include "llvm/ADT/OwningPtr.h"
  21 #include "llvm/Support/Allocator.h"
  22 #include "llvm/Config/config.h" // for mode_t
  23 // FIXME: Enhance libsystem to support inode and other fields in stat.
  24 #include <sys/types.h>
  25 #include <sys/stat.h>
  26
  27 namespace llvm {
  28 class MemoryBuffer;
  29 namespace sys {
  30 class Path;
  31 }
  32 }
  33
  34 namespace clang {
  35 class FileManager;
  36 class FileSystemOptions;
  37
  38 /// DirectoryEntry - Cached information about one directory on the disk.
  39 ///
  40 class DirectoryEntry {
  41   const char *Name;   // Name of the directory.
  42   friend class FileManager;
  43 public:
  44   DirectoryEntry() : Name(0) {}
  45   const char *getName() const { return Name; }
  46 };
  47
  48 /// FileEntry - Cached information about one file on the disk.
  49 ///
  50 class FileEntry {
  51   const char *Name;           // Name of the file.
  52   off_t Size;                 // File size in bytes.
  53   time_t ModTime;             // Modification time of file.
  54   const DirectoryEntry *Dir;  // Directory file lives in.
  55   unsigned UID;               // A unique (small) ID for the file.
  56   dev_t Device;               // ID for the device containing the file.
  57   ino_t Inode;                // Inode number for the file.
  58   mode_t FileMode;            // The file mode as returned by 'stat'.
  59   friend class FileManager;
  60 public:
  61   FileEntry(dev_t device, ino_t inode, mode_t m)
  62     : Name(0), Device(device), Inode(inode), FileMode(m) {}
  63   // Add a default constructor for use with llvm::StringMap
  64   FileEntry() : Name(0), Device(0), Inode(0), FileMode(0) {}
  65
  66   const char *getName() const { return Name; }
  67   off_t getSize() const { return Size; }
  68   unsigned getUID() const { return UID; }
  69   ino_t getInode() const { return Inode; }
  70   dev_t getDevice() const { return Device; }
  71   time_t getModificationTime() const { return ModTime; }
  72   mode_t getFileMode() const { return FileMode; }
  73
  74   /// getDir - Return the directory the file lives in.
  75   ///
  76   const DirectoryEntry *getDir() const { return Dir; }
  77
  78   bool operator<(const FileEntry& RHS) const {
  79     return Device < RHS.Device || (Device == RHS.Device && Inode < RHS.Inode);
  80   }
  81 };
  82
  83 /// \brief Abstract interface for introducing a FileManager cache for 'stat'
  84 /// system calls, which is used by precompiled and pretokenized headers to
  85 /// improve performance.
  86 class StatSysCallCache {
  87 protected:
  88   llvm::OwningPtr<StatSysCallCache> NextStatCache;
  89
  90 public:
  91   virtual ~StatSysCallCache() {}
  92   virtual int stat(const char *path, struct stat *buf) {
  93     if (getNextStatCache())
  94       return getNextStatCache()->stat(path, buf);
  95
  96     return ::stat(path, buf);
  97   }
  98
  99   /// \brief Sets the next stat call cache in the chain of stat caches.
 100   /// Takes ownership of the given stat cache.
 101   void setNextStatCache(StatSysCallCache *Cache) {
 102     NextStatCache.reset(Cache);
 103   }
 104
 105   /// \brief Retrieve the next stat call cache in the chain.
 106   StatSysCallCache *getNextStatCache() { return NextStatCache.get(); }
 107
 108   /// \brief Retrieve the next stat call cache in the chain, transferring
 109   /// ownership of this cache (and, transitively, all of the remaining caches)
 110   /// to the caller.
 111   StatSysCallCache *takeNextStatCache() { return NextStatCache.take(); }
 112 };
 113
 114 /// \brief A stat "cache" that can be used by FileManager to keep
 115 /// track of the results of stat() calls that occur throughout the
 116 /// execution of the front end.
 117 class MemorizeStatCalls : public StatSysCallCache {
 118 public:
 119   /// \brief The result of a stat() call.
 120   ///
 121   /// The first member is the result of calling stat(). If stat()
 122   /// found something, the second member is a copy of the stat
 123   /// structure.
 124   typedef std::pair<int, struct stat> StatResult;
 125
 126   /// \brief The set of stat() calls that have been
 127   llvm::StringMap<StatResult, llvm::BumpPtrAllocator> StatCalls;
 128
 129   typedef llvm::StringMap<StatResult, llvm::BumpPtrAllocator>::const_iterator
 130     iterator;
 131
 132   iterator begin() const { return StatCalls.begin(); }
 133   iterator end() const { return StatCalls.end(); }
 134
 135   virtual int stat(const char *path, struct stat *buf);
 136 };
 137
 138 /// FileManager - Implements support for file system lookup, file system
 139 /// caching, and directory search management.  This also handles more advanced
 140 /// properties, such as uniquing files based on "inode", so that a file with two
 141 /// names (e.g. symlinked) will be treated as a single file.
 142 ///
 143 class FileManager {
 144   const FileSystemOptions &FileSystemOpts;
 145
 146   class UniqueDirContainer;
 147   class UniqueFileContainer;
 148
 149   /// UniqueDirs/UniqueFiles - Cache for existing directories/files.
 150   ///
 151   UniqueDirContainer &UniqueDirs;
 152   UniqueFileContainer &UniqueFiles;
 153
 154   /// DirEntries/FileEntries - This is a cache of directory/file entries we have
 155   /// looked up.  The actual Entry is owned by UniqueFiles/UniqueDirs above.
 156   ///
 157   llvm::StringMap<DirectoryEntry*, llvm::BumpPtrAllocator> DirEntries;
 158   llvm::StringMap<FileEntry*, llvm::BumpPtrAllocator> FileEntries;
 159
 160   /// NextFileUID - Each FileEntry we create is assigned a unique ID #.
 161   ///
 162   unsigned NextFileUID;
 163
 164   /// \brief The virtual files that we have allocated.
 165   llvm::SmallVector<FileEntry *, 4> VirtualFileEntries;
 166
 167   // Statistics.
 168   unsigned NumDirLookups, NumFileLookups;
 169   unsigned NumDirCacheMisses, NumFileCacheMisses;
 170
 171   // Caching.
 172   llvm::OwningPtr<StatSysCallCache> StatCache;
 173
 174   int stat_cached(const char* path, struct stat* buf);
 175
 176 public:
 177   FileManager(const FileSystemOptions &FileSystemOpts);
 178   ~FileManager();
 179
 180   /// \brief Installs the provided StatSysCallCache object within
 181   /// the FileManager.
 182   ///
 183   /// Ownership of this object is transferred to the FileManager.
 184   ///
 185   /// \param statCache the new stat cache to install. Ownership of this
 186   /// object is transferred to the FileManager.
 187   ///
 188   /// \param AtBeginning whether this new stat cache must be installed at the
 189   /// beginning of the chain of stat caches. Otherwise, it will be added to
 190   /// the end of the chain.
 191   void addStatCache(StatSysCallCache *statCache, bool AtBeginning = false);
 192
 193   /// \brief Removes the provided StatSysCallCache object from the file manager.
 194   void removeStatCache(StatSysCallCache *statCache);
 195
 196   /// getDirectory - Lookup, cache, and verify the specified directory.  This
 197   /// returns null if the directory doesn't exist.
 198   ///
 199   const DirectoryEntry *getDirectory(llvm::StringRef Filename,
 200                                      const FileSystemOptions &FileSystemOpts);
 201
 202   /// getFile - Lookup, cache, and verify the specified file.  This returns null
 203   /// if the file doesn't exist.
 204   ///
 205   const FileEntry *getFile(llvm::StringRef Filename,
 206                            const FileSystemOptions &FileSystemOpts);
 207
 208   /// \brief Retrieve a file entry for a "virtual" file that acts as
 209   /// if there were a file with the given name on disk. The file
 210   /// itself is not accessed.
 211   const FileEntry *getVirtualFile(llvm::StringRef Filename, off_t Size,
 212                                   time_t ModificationTime,
 213                                   const FileSystemOptions &FileSystemOpts);
 214
 215   /// \brief Open the specified file as a MemoryBuffer, returning a new
 216   /// MemoryBuffer if successful, otherwise returning null.
 217   llvm::MemoryBuffer *getBufferForFile(const FileEntry *Entry,
 218                                        const FileSystemOptions &FileSystemOpts,
 219                                        std::string *ErrorStr = 0) {
 220     return getBufferForFile(Entry->getName(), FileSystemOpts,
 221                             ErrorStr, Entry->getSize());
 222   }
 223   llvm::MemoryBuffer *getBufferForFile(llvm::StringRef Filename,
 224                                        const FileSystemOptions &FileSystemOpts,
 225                                        std::string *ErrorStr = 0,
 226                                        int64_t FileSize = -1);
 227
 228   /// \brief If path is not absolute and FileSystemOptions set the working
 229   /// directory, the path is modified to be relative to the given
 230   /// working directory.
 231   static void FixupRelativePath(llvm::sys::Path &path,
 232                                 const FileSystemOptions &FSOpts);
 233
 234   void PrintStats() const;
 235 };
 236
 237 }  // end namespace clang
 238
 239 #endif