1 // Copyright (c) 2016 The WebM project authors. All Rights Reserved.
2 //
3 // Use of this source code is governed by a BSD-style license
4 // that can be found in the LICENSE file in the root of the source
5 // tree. An additional intellectual property rights grant can be found
6 // in the file PATENTS. All contributing project authors may
7 // be found in the AUTHORS file in the root of the source tree.
8 #include "src/date_parser.h"
9
10 #include <cassert>
11 #include <cstdint>
12 #include <limits>
13
14 #include "src/parser_utils.h"
15 #include "webm/element.h"
16 #include "webm/reader.h"
17 #include "webm/status.h"
18
19 namespace webm {
20
21 // Spec reference:
22 // http://matroska.org/technical/specs/index.html#EBML_ex
23 // https://github.com/Matroska-Org/ebml-specification/blob/master/specification.markdown#ebml-element-types
DateParser(std::int64_t default_value)24 DateParser::DateParser(std::int64_t default_value)
25 : default_value_(default_value) {}
26
Init(const ElementMetadata & metadata,std::uint64_t max_size)27 Status DateParser::Init(const ElementMetadata& metadata,
28 std::uint64_t max_size) {
29 assert(metadata.size == kUnknownElementSize || metadata.size <= max_size);
30
31 if (metadata.size != 0 && metadata.size != 8) {
32 return Status(Status::kInvalidElementSize);
33 }
34
35 num_bytes_remaining_ = static_cast<int>(metadata.size);
36
37 // The meaning of a 0-byte element is still being debated. EBML says the value
38 // is zero; Matroska says it's the default according to whatever the document
39 // spec says. Neither specifies what a 0-byte mandatory element means. I've
40 // asked about this on the Matroska mailing list. I'm going to assume a 0-byte
41 // mandatory element should be treated the same as a 0-byte optional element,
42 // meaning that they both get their default value (which may be some value
43 // other than zero). This applies to all non-master-elements (not just dates).
44 // This parser is an EBML-level parser, and so will default to a value of
45 // zero. The Matroska-level parser can reset this default value to something
46 // else after parsing (as needed).
47 // See:
48 // https://github.com/Matroska-Org/ebml-specification/pull/17
49 // http://lists.matroska.org/pipermail/matroska-devel/2015-October/004866.html
50 if (metadata.size == 0) {
51 value_ = default_value_;
52 } else {
53 value_ = 0;
54 }
55
56 return Status(Status::kOkCompleted);
57 }
58
Feed(Callback * callback,Reader * reader,std::uint64_t * num_bytes_read)59 Status DateParser::Feed(Callback* callback, Reader* reader,
60 std::uint64_t* num_bytes_read) {
61 assert(callback != nullptr);
62 assert(reader != nullptr);
63 assert(num_bytes_read != nullptr);
64
65 const Status status = AccumulateIntegerBytes(num_bytes_remaining_, reader,
66 &value_, num_bytes_read);
67 num_bytes_remaining_ -= static_cast<int>(*num_bytes_read);
68
69 return status;
70 }
71
72 } // namespace webm
73