Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 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 | #pragma once |
| 18 | |
| 19 | #include <sys/types.h> |
| 20 | |
| 21 | #include <memory> |
| 22 | |
| 23 | #include "android-base/macros.h" |
| 24 | #include "android-base/off64_t.h" |
| 25 | #include "android-base/unique_fd.h" |
| 26 | |
| 27 | #if defined(_WIN32) |
| 28 | #include <windows.h> |
| 29 | #define PROT_READ 1 |
| 30 | #define PROT_WRITE 2 |
| 31 | using os_handle = HANDLE; |
| 32 | #else |
| 33 | #include <sys/mman.h> |
| 34 | using os_handle = int; |
| 35 | #endif |
| 36 | |
| 37 | namespace android { |
| 38 | namespace base { |
| 39 | |
| 40 | /** |
| 41 | * A region of a file mapped into memory (for grepping: also known as MmapFile or file mapping). |
| 42 | */ |
| 43 | class MappedFile { |
| 44 | public: |
| 45 | /** |
| 46 | * Creates a new mapping of the file pointed to by `fd`. Unlike the underlying OS primitives, |
| 47 | * `offset` does not need to be page-aligned. If `PROT_WRITE` is set in `prot`, the mapping |
| 48 | * will be writable, otherwise it will be read-only. Mappings are always `MAP_SHARED`. |
| 49 | */ |
| 50 | static std::unique_ptr<MappedFile> FromFd(borrowed_fd fd, off64_t offset, size_t length, |
| 51 | int prot); |
| 52 | |
| 53 | /** |
| 54 | * Same thing, but using the raw OS file handle instead of a CRT wrapper. |
| 55 | */ |
| 56 | static std::unique_ptr<MappedFile> FromOsHandle(os_handle h, off64_t offset, size_t length, |
| 57 | int prot); |
| 58 | |
| 59 | /** |
| 60 | * Removes the mapping. |
| 61 | */ |
| 62 | ~MappedFile(); |
| 63 | |
| 64 | /** |
| 65 | * Not copyable but movable. |
| 66 | */ |
| 67 | MappedFile(MappedFile&& other); |
| 68 | MappedFile& operator=(MappedFile&& other); |
| 69 | |
| 70 | char* data() const { return base_ + offset_; } |
| 71 | size_t size() const { return size_; } |
| 72 | |
| 73 | private: |
| 74 | DISALLOW_IMPLICIT_CONSTRUCTORS(MappedFile); |
| 75 | |
| 76 | void Close(); |
| 77 | |
| 78 | char* base_; |
| 79 | size_t size_; |
| 80 | |
| 81 | size_t offset_; |
| 82 | |
| 83 | #if defined(_WIN32) |
| 84 | MappedFile(char* base, size_t size, size_t offset, HANDLE handle) |
| 85 | : base_(base), size_(size), offset_(offset), handle_(handle) {} |
| 86 | HANDLE handle_; |
| 87 | #else |
| 88 | MappedFile(char* base, size_t size, size_t offset) : base_(base), size_(size), offset_(offset) {} |
| 89 | #endif |
| 90 | }; |
| 91 | |
| 92 | } // namespace base |
| 93 | } // namespace android |