blob.h revision 42455ff2abfc7ed92a35287d1b3bc6049161adb9 
1/*
2 * Copyright (C) 2016 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 NVRAM_MESSAGES_BLOB_H_
18#define NVRAM_MESSAGES_BLOB_H_
19
20extern "C" {
21#include <stddef.h>
22#include <stdint.h>
23}
24
25#include <nvram/messages/compiler.h>
26
27namespace nvram {
28
29// A simple wrapper class holding binary data of fixed size.
30//
31// This is intended for use in restricted environments where there is no full
32// C++ standard library available and/or memory allocation failure must be
33// handled gracefully.
34class NVRAM_EXPORT Blob {
35 public:
36  Blob();
37  ~Blob();
38
39  // Blob is movable, but not copyable since the latter requires memory
40  // allocations, which can fail.
41  Blob(const Blob& other) = delete;
42  Blob& operator=(const Blob& other) = delete;
43  Blob(Blob&& other);
44  Blob& operator=(Blob&& other);
45  friend void swap(Blob& first, Blob& second);
46
47  uint8_t* data() { return data_; }
48  const uint8_t* data() const { return data_; }
49
50  size_t size() const { return size_; }
51
52  // Reallocate the underlying buffer to hold |size| bytes and copy in |data|.
53  // Returns true on success, false if memory allocation fails. Blob size and
54  // contents remain unchanged upon failure.
55  bool Assign(const void* data, size_t size) NVRAM_WARN_UNUSED_RESULT;
56
57  // Resize the blob to |size|. Existing data within the new |size| limit is
58  // retained. If |size| increases, new contents are unspecified. Returns true
59  // on success, false if memory allocation fails. Blob size and contents remain
60  // unchanged upon failure.
61  //
62  // Note that calling this function invalidates pointers to the memory block
63  // backing this |Blob|. You must call |data()| after |Resize()| returns to
64  // obtain fresh valid pointers.
65  bool Resize(size_t size) NVRAM_WARN_UNUSED_RESULT;
66
67 private:
68  uint8_t* data_ = nullptr;
69  size_t size_ = 0;
70};
71
72}  // namespace nvram
73
74#endif  // NVRAM_MESSAGES_BLOB_H_
75