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#include <nvram/core/storage.h>
18
19namespace nvram {
20namespace storage {
21namespace {
22
23// Maximum number of space blobs supported.
24const int kMaxSpaces = 32;
25
26class StorageSlot {
27 public:
28  bool present() const { return blob_.size() != 0; }
29
30  Status Load(Blob* blob) const {
31    if (blob_.size() == 0) {
32      return Status::kNotFound;
33    }
34
35    if (!blob->Assign(blob_.data(), blob_.size())) {
36      return Status::kStorageError;
37    }
38
39    return Status::kSuccess;
40  }
41
42  Status Store(const Blob& blob) {
43    if (!blob_.Assign(blob.data(), blob.size())) {
44      return Status::kStorageError;
45    }
46
47    return Status::kSuccess;
48  }
49
50  Status Delete() {
51    return blob_.Resize(0) ? Status::kSuccess : Status::kStorageError;
52  }
53
54 private:
55  Blob blob_;
56};
57
58// Stores the header blob.
59StorageSlot g_header;
60
61// Stores the space blobs.
62struct {
63  uint32_t index;
64  StorageSlot slot;
65} g_spaces[kMaxSpaces];
66
67// Find the storage slot in |g_spaces| that corresponds to |index|. Returns
68// |nullptr| if no matching slot exists.
69StorageSlot* FindSpaceSlot(uint32_t index) {
70  for (size_t i = 0; i < kMaxSpaces; ++i) {
71    if (g_spaces[i].slot.present() && g_spaces[i].index == index) {
72      return &g_spaces[i].slot;
73    }
74  }
75
76  return nullptr;
77}
78
79}  // namespace
80
81Status LoadHeader(Blob* blob) {
82  return g_header.Load(blob);
83}
84
85Status StoreHeader(const Blob& blob) {
86  return g_header.Store(blob);
87}
88
89Status LoadSpace(uint32_t index, Blob* blob) {
90  StorageSlot* slot = FindSpaceSlot(index);
91  return slot ? slot->Load(blob) : Status::kNotFound;
92}
93
94Status StoreSpace(uint32_t index, const Blob& blob) {
95  StorageSlot* slot = FindSpaceSlot(index);
96  if (slot) {
97    return slot->Store(blob);
98  }
99
100  // Allocate a new slot.
101  for (size_t i = 0; i < kMaxSpaces; ++i) {
102    if (!g_spaces[i].slot.present()) {
103      g_spaces[i].index = index;
104      return g_spaces[i].slot.Store(blob);
105    }
106  }
107
108  return Status::kStorageError;
109}
110
111Status DeleteSpace(uint32_t index) {
112  StorageSlot* slot = FindSpaceSlot(index);
113  if (slot) {
114    slot->Delete();
115  }
116
117  return Status::kSuccess;
118}
119
120}  // namespace storage
121}  // namespace nvram
122