1 /*
2 * Copyright (C) 2009 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 //#define LOG_NDEBUG 0
18 #define LOG_TAG "Metadata"
19 #include <utils/Log.h>
20
21 #include <sys/types.h>
22 #include <media/Metadata.h>
23 #include <binder/Parcel.h>
24 #include <utils/Errors.h>
25 #include <utils/RefBase.h>
26
27 // This file contains code to serialize Metadata triples (key, type,
28 // value) into a parcel. The Parcel is destinated to be decoded by the
29 // Metadata.java class.
30
31 namespace {
32 // All these constants below must be kept in sync with Metadata.java.
33 enum MetadataId {
34 FIRST_SYSTEM_ID = 1,
35 LAST_SYSTEM_ID = 31,
36 FIRST_CUSTOM_ID = 8192
37 };
38
39 // Types
40 enum Types {
41 STRING_VAL = 1,
42 INTEGER_VAL,
43 BOOLEAN_VAL,
44 LONG_VAL,
45 DOUBLE_VAL,
46 DATE_VAL,
47 BYTE_ARRAY_VAL,
48 };
49
50 const size_t kRecordHeaderSize = 3 * sizeof(int32_t);
51 const int32_t kMetaMarker = 0x4d455441; // 'M' 'E' 'T' 'A'
52
53 } // anonymous namespace
54
55 namespace android {
56 namespace media {
57
Metadata(Parcel * p)58 Metadata::Metadata(Parcel *p)
59 :mData(p),
60 mBegin(p->dataPosition()) { }
61
~Metadata()62 Metadata::~Metadata() { }
63
resetParcel()64 void Metadata::resetParcel()
65 {
66 mData->setDataPosition(mBegin);
67 }
68
69 // Update the 4 bytes int at the beginning of the parcel which holds
70 // the number of bytes written so far.
updateLength()71 void Metadata::updateLength()
72 {
73 const size_t end = mData->dataPosition();
74
75 mData->setDataPosition(mBegin);
76 mData->writeInt32(end - mBegin);
77 mData->setDataPosition(end);
78 }
79
80 // Write the header. The java layer will look for the marker.
appendHeader()81 bool Metadata::appendHeader()
82 {
83 bool ok = true;
84
85 // Placeholder for the length of the metadata
86 ok = ok && mData->writeInt32(-1) == OK;
87 ok = ok && mData->writeInt32(kMetaMarker) == OK;
88 return ok;
89 }
90
appendBool(int key,bool val)91 bool Metadata::appendBool(int key, bool val)
92 {
93 if (!checkKey(key)) {
94 return false;
95 }
96
97 const size_t begin = mData->dataPosition();
98 bool ok = true;
99
100 // 4 int32s: size, key, type, value.
101 ok = ok && mData->writeInt32(4 * sizeof(int32_t)) == OK;
102 ok = ok && mData->writeInt32(key) == OK;
103 ok = ok && mData->writeInt32(BOOLEAN_VAL) == OK;
104 ok = ok && mData->writeInt32(val ? 1 : 0) == OK;
105 if (!ok) {
106 mData->setDataPosition(begin);
107 }
108 return ok;
109 }
110
appendInt32(int key,int32_t val)111 bool Metadata::appendInt32(int key, int32_t val)
112 {
113 if (!checkKey(key)) {
114 return false;
115 }
116
117 const size_t begin = mData->dataPosition();
118 bool ok = true;
119
120 // 4 int32s: size, key, type, value.
121 ok = ok && mData->writeInt32(4 * sizeof(int32_t)) == OK;
122 ok = ok && mData->writeInt32(key) == OK;
123 ok = ok && mData->writeInt32(INTEGER_VAL) == OK;
124 ok = ok && mData->writeInt32(val) == OK;
125 if (!ok) {
126 mData->setDataPosition(begin);
127 }
128 return ok;
129 }
130
131 // Check the key (i.e metadata id) is valid if it is a system one.
132 // Loop over all the exiting ones in the Parcel to check for duplicate
133 // (not allowed).
checkKey(int key)134 bool Metadata::checkKey(int key)
135 {
136 if (key < FIRST_SYSTEM_ID ||
137 (LAST_SYSTEM_ID < key && key < FIRST_CUSTOM_ID)) {
138 ALOGE("Bad key %d", key);
139 return false;
140 }
141 size_t curr = mData->dataPosition();
142 // Loop over the keys to check if it has been used already.
143 mData->setDataPosition(mBegin);
144
145 bool error = false;
146 size_t left = curr - mBegin;
147 while (left > 0) {
148 size_t pos = mData->dataPosition();
149 size_t size = mData->readInt32();
150 if (size < kRecordHeaderSize || size > left) {
151 error = true;
152 break;
153 }
154 if (mData->readInt32() == key) {
155 ALOGE("Key exists already %d", key);
156 error = true;
157 break;
158 }
159 mData->setDataPosition(pos + size);
160 left -= size;
161 }
162 mData->setDataPosition(curr);
163 return !error;
164 }
165
166 } // namespace android::media
167 } // namespace android
168