DataSource.h revision 44a1dc40b0c66ca2f66c4be4debdcc908a3c5f8b 
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 status_t reconnectAtOffset(off64_t offset) {
96        return ERROR_UNSUPPORTED;
97    }
98
99    ////////////////////////////////////////////////////////////////////////////
100
101    bool sniff(String8 *mimeType, float *confidence, sp<AMessage> *meta);
102
103    // The sniffer can optionally fill in "meta" with an AMessage containing
104    // a dictionary of values that helps the corresponding extractor initialize
105    // its state without duplicating effort already exerted by the sniffer.
106    typedef bool (*SnifferFunc)(
107            const sp<DataSource> &source, String8 *mimeType,
108            float *confidence, sp<AMessage> *meta);
109
110    static void RegisterDefaultSniffers();
111
112    // for DRM
113    virtual sp<DecryptHandle> DrmInitialization(const char *mime = NULL) {
114        return NULL;
115    }
116    virtual void getDrmInfo(sp<DecryptHandle> &handle, DrmManagerClient **client) {};
117
118    virtual String8 getUri() {
119        return String8();
120    }
121
122    virtual String8 getMIMEType() const;
123
124protected:
125    virtual ~DataSource() {}
126
127private:
128    static Mutex gSnifferMutex;
129    static List<SnifferFunc> gSniffers;
130    static bool gSniffersRegistered;
131
132    static void RegisterSniffer_l(SnifferFunc func);
133
134    DataSource(const DataSource &);
135    DataSource &operator=(const DataSource &);
136};
137
138template <typename T>
139bool DataSource::getVector(off64_t offset, Vector<T>* x, size_t count,
140                           size_t chunkSize)
141{
142    x->clear();
143    if (chunkSize == 0) {
144        return false;
145    }
146    if (count == 0) {
147        return true;
148    }
149
150    T tmp[chunkSize];
151    ssize_t numBytesRead;
152    size_t numBytesPerChunk = chunkSize * sizeof(T);
153    size_t i;
154
155    for (i = 0; i + chunkSize < count; i += chunkSize) {
156        // This loops is executed when more than chunkSize records need to be
157        // read.
158        numBytesRead = this->readAt(offset, (void*)&tmp, numBytesPerChunk);
159        if (numBytesRead == -1) { // If readAt() returns -1, there is an error.
160            return false;
161        }
162        if (numBytesRead < numBytesPerChunk) {
163            // This case is triggered when the stream ends before the whole
164            // chunk is read.
165            x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
166            return false;
167        }
168        x->appendArray(tmp, chunkSize);
169        offset += numBytesPerChunk;
170    }
171
172    // There are (count - i) more records to read.
173    // Right now, (count - i) <= chunkSize.
174    // We do the same thing as above, but with chunkSize replaced by count - i.
175    numBytesRead = this->readAt(offset, (void*)&tmp, (count - i) * sizeof(T));
176    if (numBytesRead == -1) {
177        return false;
178    }
179    x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
180    return x->size() == count;
181}
182
183}  // namespace android
184
185#endif  // DATA_SOURCE_H_
186