summaryrefslogtreecommitdiffstats
path: root/media/libmedia/Metadata.cpp
blob: 8eeebbb57dce5d9a987d0b60e130ffdd23cd6652 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//#define LOG_NDEBUG 0
#define LOG_TAG "Metadata"
#include <utils/Log.h>

#include <sys/types.h>
#include <media/Metadata.h>
#include <binder/Parcel.h>
#include <utils/Errors.h>
#include <utils/RefBase.h>

// This file contains code to serialize Metadata triples (key, type,
// value) into a parcel. The Parcel is destinated to be decoded by the
// Metadata.java class.

namespace {
// All these constants below must be kept in sync with Metadata.java.
enum MetadataId {
    FIRST_SYSTEM_ID = 1,
    LAST_SYSTEM_ID = 31,
    FIRST_CUSTOM_ID = 8192
};

// Types
enum Types {
    STRING_VAL = 1,
    INTEGER_VAL,
    BOOLEAN_VAL,
    LONG_VAL,
    DOUBLE_VAL,
    DATE_VAL,
    BYTE_ARRAY_VAL,
};

const size_t kRecordHeaderSize = 3 * sizeof(int32_t);
const int32_t kMetaMarker = 0x4d455441;  // 'M' 'E' 'T' 'A'

}  // anonymous namespace

namespace android {
namespace media {

Metadata::Metadata(Parcel *p)
    :mData(p),
     mBegin(p->dataPosition()) { }

Metadata::~Metadata() { }

void Metadata::resetParcel()
{
    mData->setDataPosition(mBegin);
}

// Update the 4 bytes int at the beginning of the parcel which holds
// the number of bytes written so far.
void Metadata::updateLength()
{
    const size_t end = mData->dataPosition();

    mData->setDataPosition(mBegin);
    mData->writeInt32(end - mBegin);
    mData->setDataPosition(end);
}

// Write the header. The java layer will look for the marker.
bool Metadata::appendHeader()
{
    bool ok = true;

    // Placeholder for the length of the metadata
    ok = ok && mData->writeInt32(-1) == OK;
    ok = ok && mData->writeInt32(kMetaMarker) == OK;
    return ok;
}

bool Metadata::appendBool(int key, bool val)
{
    if (!checkKey(key)) {
        return false;
    }

    const size_t begin = mData->dataPosition();
    bool ok = true;

    // 4 int32s: size, key, type, value.
    ok = ok && mData->writeInt32(4 * sizeof(int32_t)) == OK;
    ok = ok && mData->writeInt32(key) == OK;
    ok = ok && mData->writeInt32(BOOLEAN_VAL) == OK;
    ok = ok && mData->writeInt32(val ? 1 : 0) == OK;
    if (!ok) {
        mData->setDataPosition(begin);
    }
    return ok;
}

bool Metadata::appendInt32(int key, int32_t val)
{
    if (!checkKey(key)) {
        return false;
    }

    const size_t begin = mData->dataPosition();
    bool ok = true;

    // 4 int32s: size, key, type, value.
    ok = ok && mData->writeInt32(4 * sizeof(int32_t)) == OK;
    ok = ok && mData->writeInt32(key) == OK;
    ok = ok && mData->writeInt32(INTEGER_VAL) == OK;
    ok = ok && mData->writeInt32(val) == OK;
    if (!ok) {
        mData->setDataPosition(begin);
    }
    return ok;
}

// Check the key (i.e metadata id) is valid if it is a system one.
// Loop over all the exiting ones in the Parcel to check for duplicate
// (not allowed).
bool Metadata::checkKey(int key)
{
    if (key < FIRST_SYSTEM_ID ||
        (LAST_SYSTEM_ID < key && key < FIRST_CUSTOM_ID)) {
        LOGE("Bad key %d", key);
        return false;
    }
    size_t curr = mData->dataPosition();
    // Loop over the keys to check if it has been used already.
    mData->setDataPosition(mBegin);

    bool error = false;
    size_t left = curr - mBegin;
    while (left > 0) {
        size_t pos = mData->dataPosition();
        size_t size = mData->readInt32();
        if (size < kRecordHeaderSize || size > left) {
            error = true;
            break;
        }
        if (mData->readInt32() == key) {
            LOGE("Key exists already %d", key);
            error = true;
            break;
        }
        mData->setDataPosition(pos + size);
        left -= size;
    }
    mData->setDataPosition(curr);
    return !error;
}

}  // namespace android::media
}  // namespace android