1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ART_RUNTIME_BASE_UNIX_FILE_MAPPED_FILE_H_ 18 #define ART_RUNTIME_BASE_UNIX_FILE_MAPPED_FILE_H_ 19 20 #include <fcntl.h> 21 #include <string> 22 #include "base/unix_file/fd_file.h" 23 24 namespace unix_file { 25 26 // Random access file which handles an mmap(2), munmap(2) pair in C++ 27 // RAII style. When a file is mmapped, the random access file 28 // interface accesses the mmapped memory directly; otherwise, the 29 // standard file I/O is used. Whenever a function fails, it returns 30 // false and errno is set to the corresponding error code. 31 class MappedFile : public FdFile { 32 public: 33 // File modes used in Open(). 34 enum FileMode { 35 #ifdef __linux__ 36 kReadOnlyMode = O_RDONLY | O_LARGEFILE, 37 kReadWriteMode = O_CREAT | O_RDWR | O_LARGEFILE, 38 #else 39 kReadOnlyMode = O_RDONLY, 40 kReadWriteMode = O_CREAT | O_RDWR, 41 #endif 42 }; 43 44 MappedFile() : FdFile(), file_size_(-1), mapped_file_(NULL) { 45 } 46 // Creates a MappedFile using the given file descriptor. Takes ownership of 47 // the file descriptor. 48 explicit MappedFile(int fd) : FdFile(fd), file_size_(-1), mapped_file_(NULL) { 49 } 50 51 // Unmaps and closes the file if needed. 52 virtual ~MappedFile(); 53 54 // Maps an opened file to memory in the read-only mode. 55 bool MapReadOnly(); 56 57 // Maps an opened file to memory in the read-write mode. Before the 58 // file is mapped, it is truncated to 'file_size' bytes. 59 bool MapReadWrite(int64_t file_size); 60 61 // Unmaps a mapped file so that, e.g., SetLength() may be invoked. 62 bool Unmap(); 63 64 // RandomAccessFile API. 65 // The functions below require that the file is open, but it doesn't 66 // have to be mapped. 67 virtual int Close(); 68 virtual int64_t Read(char* buf, int64_t byte_count, int64_t offset) const; 69 // SetLength() requires that the file is not mmapped. 70 virtual int SetLength(int64_t new_length); 71 virtual int64_t GetLength() const; 72 virtual int Flush(); 73 // Write() requires that, if the file is mmapped, it is mmapped in 74 // the read-write mode. Writes past the end of file are discarded. 75 virtual int64_t Write(const char* buf, int64_t byte_count, int64_t offset); 76 77 // A convenience method equivalent to GetLength(). 78 int64_t size() const; 79 80 // Returns true if the file has been mmapped. 81 bool IsMapped() const; 82 83 // Returns a pointer to the start of the memory mapping once the 84 // file is successfully mapped; crashes otherwise. 85 char* data() const; 86 87 private: 88 enum MapMode { 89 kMapReadOnly = 1, 90 kMapReadWrite = 2, 91 }; 92 93 mutable int64_t file_size_; // May be updated in GetLength(). 94 void* mapped_file_; 95 MapMode map_mode_; 96 97 DISALLOW_COPY_AND_ASSIGN(MappedFile); 98 }; 99 100 } // namespace unix_file 101 102 #endif // ART_RUNTIME_BASE_UNIX_FILE_MAPPED_FILE_H_ 103
