DataSource.h revision b151194ce1cbf77cd9da87ce6fc895278977b0f4 
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#ifndef DATA_SOURCE_H_
18
19#define DATA_SOURCE_H_
20
21#include <sys/types.h>
22#include <media/stagefright/foundation/ADebug.h>
23#include <media/stagefright/MediaErrors.h>
24#include <utils/Errors.h>
25#include <utils/KeyedVector.h>
26#include <utils/List.h>
27#include <utils/RefBase.h>
28#include <utils/threads.h>
29#include <drm/DrmManagerClient.h>
30
31namespace android {
32
33struct AMessage;
34struct AString;
35class  IDataSource;
36struct IMediaHTTPService;
37class String8;
38struct HTTPBase;
39
40class DataSource : public RefBase {
41public:
42    enum Flags {
43        kWantsPrefetching      = 1,
44        kStreamedFromLocalHost = 2,
45        kIsCachingDataSource   = 4,
46        kIsHTTPBasedSource     = 8,
47    };
48
49    static sp<DataSource> CreateFromURI(
50            const sp<IMediaHTTPService> &httpService,
51            const char *uri,
52            const KeyedVector<String8, String8> *headers = NULL,
53            String8 *contentType = NULL,
54            HTTPBase *httpSource = NULL);
55
56    static sp<DataSource> CreateMediaHTTP(const sp<IMediaHTTPService> &httpService);
57    static sp<DataSource> CreateFromIDataSource(const sp<IDataSource> &source);
58
59    DataSource() {}
60
61    virtual status_t initCheck() const = 0;
62
63    // Returns the number of bytes read, or -1 on failure. It's not an error if
64    // this returns zero; it just means the given offset is equal to, or
65    // beyond, the end of the source.
66    virtual ssize_t readAt(off64_t offset, void *data, size_t size) = 0;
67
68    // Convenience methods:
69    bool getUInt16(off64_t offset, uint16_t *x);
70    bool getUInt24(off64_t offset, uint32_t *x); // 3 byte int, returned as a 32-bit int
71    bool getUInt32(off64_t offset, uint32_t *x);
72    bool getUInt64(off64_t offset, uint64_t *x);
73
74    // Reads in "count" entries of type T into vector *x.
75    // Returns true if "count" entries can be read.
76    // If fewer than "count" entries can be read, return false. In this case,
77    // the output vector *x will still have those entries that were read. Call
78    // x->size() to obtain the number of entries read.
79    // The optional parameter chunkSize specifies how many entries should be
80    // read from the data source at one time into a temporary buffer. Increasing
81    // chunkSize can improve the performance at the cost of extra memory usage.
82    // The default value for chunkSize is set to read at least 4k bytes at a
83    // time, depending on sizeof(T).
84    template <typename T>
85    bool getVector(off64_t offset, Vector<T>* x, size_t count,
86                   size_t chunkSize = (4095 / sizeof(T)) + 1);
87
88    // May return ERROR_UNSUPPORTED.
89    virtual status_t getSize(off64_t *size);
90
91    virtual uint32_t flags() {
92        return 0;
93    }
94
95    virtual String8 toString() {
96        return String8("<unspecified>");
97    }
98
99    virtual status_t reconnectAtOffset(off64_t offset) {
100        return ERROR_UNSUPPORTED;
101    }
102
103    ////////////////////////////////////////////////////////////////////////////
104
105    bool sniff(String8 *mimeType, float *confidence, sp<AMessage> *meta);
106
107    // The sniffer can optionally fill in "meta" with an AMessage containing
108    // a dictionary of values that helps the corresponding extractor initialize
109    // its state without duplicating effort already exerted by the sniffer.
110    typedef bool (*SnifferFunc)(
111            const sp<DataSource> &source, String8 *mimeType,
112            float *confidence, sp<AMessage> *meta);
113
114    static void RegisterDefaultSniffers();
115
116    // for DRM
117    virtual sp<DecryptHandle> DrmInitialization(const char *mime = NULL) {
118        return NULL;
119    }
120    virtual void getDrmInfo(sp<DecryptHandle> &handle, DrmManagerClient **client) {};
121
122    virtual String8 getUri() {
123        return String8();
124    }
125
126    virtual String8 getMIMEType() const;
127
128    virtual void close() {};
129
130protected:
131    virtual ~DataSource() {}
132
133private:
134    static Mutex gSnifferMutex;
135    static List<SnifferFunc> gSniffers;
136    static bool gSniffersRegistered;
137
138    static void RegisterSniffer_l(SnifferFunc func);
139
140    DataSource(const DataSource &);
141    DataSource &operator=(const DataSource &);
142};
143
144template <typename T>
145bool DataSource::getVector(off64_t offset, Vector<T>* x, size_t count,
146                           size_t chunkSize)
147{
148    x->clear();
149    if (chunkSize == 0) {
150        return false;
151    }
152    if (count == 0) {
153        return true;
154    }
155
156    T tmp[chunkSize];
157    ssize_t numBytesRead;
158    size_t numBytesPerChunk = chunkSize * sizeof(T);
159    size_t i;
160
161    for (i = 0; i + chunkSize < count; i += chunkSize) {
162        // This loops is executed when more than chunkSize records need to be
163        // read.
164        numBytesRead = this->readAt(offset, (void*)&tmp, numBytesPerChunk);
165        if (numBytesRead == -1) { // If readAt() returns -1, there is an error.
166            return false;
167        }
168        if (numBytesRead < numBytesPerChunk) {
169            // This case is triggered when the stream ends before the whole
170            // chunk is read.
171            x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
172            return false;
173        }
174        x->appendArray(tmp, chunkSize);
175        offset += numBytesPerChunk;
176    }
177
178    // There are (count - i) more records to read.
179    // Right now, (count - i) <= chunkSize.
180    // We do the same thing as above, but with chunkSize replaced by count - i.
181    numBytesRead = this->readAt(offset, (void*)&tmp, (count - i) * sizeof(T));
182    if (numBytesRead == -1) {
183        return false;
184    }
185    x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
186    return x->size() == count;
187}
188
189}  // namespace android
190
191#endif  // DATA_SOURCE_H_
192