1 // Copyright 2021 The Pigweed Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
5 // the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
13 // the License.
14 #pragma once
15
16 #include <cstddef>
17
18 #include "pw_preprocessor/compiler.h"
19
20 namespace pw::blob_store::internal {
21
22 enum MetadataVersion : uint32_t {
23 // Original metadata format does not include a version.
24 kVersion1 = 0,
25 kVersion2 = 0x1197851D,
26 kLatest = kVersion2
27 };
28
29 // Technically the original BlobMetadataV1 was not packed.
PW_PACKED(struct)30 PW_PACKED(struct) BlobMetadataV1 {
31 typedef uint32_t ChecksumValue;
32
33 // The checksum of the blob data stored in flash.
34 ChecksumValue checksum;
35
36 // Number of blob data bytes stored in flash.
37 // Technically this was originally size_t, but backwards compatibility for
38 // platform-specific sized types has been dropped.
39 uint32_t data_size_bytes;
40 };
41
42 // Changes to the metadata format should also get a different key signature to
43 // avoid new code improperly reading old format metadata.
PW_PACKED(struct)44 PW_PACKED(struct) BlobMetadataHeaderV2 {
45 BlobMetadataV1 v1_metadata;
46
47 // Metadata encoding version stored in flash.
48 MetadataVersion version;
49
50 // Length of the file name stored in the metadata entry.
51 uint8_t file_name_length;
52
53 // Following this struct is file_name_length chars of file name. Note that
54 // the string of characters is NOT null terminated.
55
56 constexpr void reset() {
57 *this = {
58 .v1_metadata =
59 {
60 .checksum = 0,
61 .data_size_bytes = 0,
62 },
63 .version = MetadataVersion::kLatest,
64 .file_name_length = 0,
65 };
66 }
67 };
68
69 using BlobMetadataHeader = BlobMetadataHeaderV2;
70 using ChecksumValue = BlobMetadataV1::ChecksumValue;
71
72 } // namespace pw::blob_store::internal
73