49   virtual Status NewSequentialFile(const std::string& fname,
59   virtual Status NewRandomAccessFile(const std::string& fname,
69   virtual Status NewWritableFile(const std::string& fname,
84   virtual Status NewAppendableFile(const std::string& fname,
93   virtual Status GetChildren(const std::string& dir,
97   virtual Status DeleteFile(const std::string& fname) = 0;
100   virtual Status CreateDir(const std::string& dirname) = 0;
103   virtual Status DeleteDir(const std::string& dirname) = 0;
106   virtual Status GetFileSize(const std::string& fname, uint64_t* file_size) = 0;
109   virtual Status RenameFile(const std::string& src,
126   virtual Status LockFile(const std::string& fname, FileLock** lock) = 0;
131   virtual Status UnlockFile(FileLock* lock) = 0;
151   virtual Status GetTestDirectory(std::string* path) = 0;
154   virtual Status NewLogger(const std::string& fname, Logger** result) = 0;
183   virtual Status Read(size_t n, Slice* result, char* scratch) = 0;
192   virtual Status Skip(uint64_t n) = 0;
215   virtual Status Read(uint64_t offset, size_t n, Slice* result,
232   virtual Status Append(const Slice& data) = 0;
233   virtual Status Close() = 0;
234   virtual Status Flush() = 0;
235   virtual Status Sync() = 0;
278 extern Status WriteStringToFile(Env* env, const Slice& data,
282 extern Status ReadFileToString(Env* env, const std::string& fname,
298   Status NewSequentialFile(const std::string& f, SequentialFile** r) {  in NewSequentialFile()
301   Status NewRandomAccessFile(const std::string& f, RandomAccessFile** r) {  in NewRandomAccessFile()
304   Status NewWritableFile(const std::string& f, WritableFile** r) {  in NewWritableFile()
307   Status NewAppendableFile(const std::string& f, WritableFile** r) {  in NewAppendableFile()
311   Status GetChildren(const std::string& dir, std::vector<std::string>* r) {  in GetChildren()
314   Status DeleteFile(const std::string& f) { return target_->DeleteFile(f); }  in DeleteFile()
315   Status CreateDir(const std::string& d) { return target_->CreateDir(d); }  in CreateDir()
316   Status DeleteDir(const std::string& d) { return target_->DeleteDir(d); }  in DeleteDir()
317   Status GetFileSize(const std::string& f, uint64_t* s) {  in GetFileSize()
320   Status RenameFile(const std::string& s, const std::string& t) {  in RenameFile()
323   Status LockFile(const std::string& f, FileLock** l) {  in LockFile()
326   Status UnlockFile(FileLock* l) { return target_->UnlockFile(l); }  in UnlockFile()
333   virtual Status GetTestDirectory(std::string* path) {  in GetTestDirectory()
336   virtual Status NewLogger(const std::string& fname, Logger** result) {  in NewLogger()