DataSource.h revision ab7276351e41bc0d40d28c231993ba240b5f21a0 
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;
35struct IMediaHTTPService;
36class String8;
37struct HTTPBase;
38
39class DataSource : public RefBase {
40public:
41    enum Flags {
42        kWantsPrefetching      = 1,
43        kStreamedFromLocalHost = 2,
44        kIsCachingDataSource   = 4,
45        kIsHTTPBasedSource     = 8,
46    };
47
48    static sp<DataSource> CreateFromURI(
49            const sp<IMediaHTTPService> &httpService,
50            const char *uri,
51            const KeyedVector<String8, String8> *headers = NULL,
52            String8 *contentType = NULL,
53            HTTPBase *httpSource = NULL);
54
55    static sp<DataSource> CreateMediaHTTP(const sp<IMediaHTTPService> &httpService);
56
57    DataSource() {}
58
59    virtual status_t initCheck() const = 0;
60
61    virtual ssize_t readAt(off64_t offset, void *data, size_t size) = 0;
62
63    // Convenience methods:
64    bool getUInt16(off64_t offset, uint16_t *x);
65    bool getUInt24(off64_t offset, uint32_t *x); // 3 byte int, returned as a 32-bit int
66    bool getUInt32(off64_t offset, uint32_t *x);
67    bool getUInt64(off64_t offset, uint64_t *x);
68
69    // Reads in "count" entries of type T into vector *x.
70    // Returns true if "count" entries can be read.
71    // If fewer than "count" entries can be read, return false. In this case,
72    // the output vector *x will still have those entries that were read. Call
73    // x->size() to obtain the number of entries read.
74    // The optional parameter chunkSize specifies how many entries should be
75    // read from the data source at one time into a temporary buffer. Increasing
76    // chunkSize can improve the performance at the cost of extra memory usage.
77    // The default value for chunkSize is set to read at least 4k bytes at a
78    // time, depending on sizeof(T).
79    template <typename T>
80    bool getVector(off64_t offset, Vector<T>* x, size_t count,
81                   size_t chunkSize = (4095 / sizeof(T)) + 1);
82
83    // May return ERROR_UNSUPPORTED.
84    virtual status_t getSize(off64_t *size);
85
86    virtual uint32_t flags() {
87        return 0;
88    }
89
90    virtual status_t reconnectAtOffset(off64_t offset) {
91        return ERROR_UNSUPPORTED;
92    }
93
94    ////////////////////////////////////////////////////////////////////////////
95
96    bool sniff(String8 *mimeType, float *confidence, sp<AMessage> *meta);
97
98    // The sniffer can optionally fill in "meta" with an AMessage containing
99    // a dictionary of values that helps the corresponding extractor initialize
100    // its state without duplicating effort already exerted by the sniffer.
101    typedef bool (*SnifferFunc)(
102            const sp<DataSource> &source, String8 *mimeType,
103            float *confidence, sp<AMessage> *meta);
104
105    static void RegisterDefaultSniffers();
106
107    // for DRM
108    virtual sp<DecryptHandle> DrmInitialization(const char *mime = NULL) {
109        return NULL;
110    }
111    virtual void getDrmInfo(sp<DecryptHandle> &handle, DrmManagerClient **client) {};
112
113    virtual String8 getUri() {
114        return String8();
115    }
116
117    virtual String8 getMIMEType() const;
118
119protected:
120    virtual ~DataSource() {}
121
122private:
123    static Mutex gSnifferMutex;
124    static List<SnifferFunc> gSniffers;
125    static bool gSniffersRegistered;
126
127    static void RegisterSniffer_l(SnifferFunc func);
128
129    DataSource(const DataSource &);
130    DataSource &operator=(const DataSource &);
131};
132
133template <typename T>
134bool DataSource::getVector(off64_t offset, Vector<T>* x, size_t count,
135                           size_t chunkSize)
136{
137    x->clear();
138    if (chunkSize == 0) {
139        return false;
140    }
141    if (count == 0) {
142        return true;
143    }
144
145    T tmp[chunkSize];
146    ssize_t numBytesRead;
147    size_t numBytesPerChunk = chunkSize * sizeof(T);
148    size_t i;
149
150    for (i = 0; i + chunkSize < count; i += chunkSize) {
151        // This loops is executed when more than chunkSize records need to be
152        // read.
153        numBytesRead = this->readAt(offset, (void*)&tmp, numBytesPerChunk);
154        if (numBytesRead == -1) { // If readAt() returns -1, there is an error.
155            return false;
156        }
157        if (numBytesRead < numBytesPerChunk) {
158            // This case is triggered when the stream ends before the whole
159            // chunk is read.
160            x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
161            return false;
162        }
163        x->appendArray(tmp, chunkSize);
164        offset += numBytesPerChunk;
165    }
166
167    // There are (count - i) more records to read.
168    // Right now, (count - i) <= chunkSize.
169    // We do the same thing as above, but with chunkSize replaced by count - i.
170    numBytesRead = this->readAt(offset, (void*)&tmp, (count - i) * sizeof(T));
171    if (numBytesRead == -1) {
172        return false;
173    }
174    x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
175    return x->size() == count;
176}
177
178}  // namespace android
179
180#endif  // DATA_SOURCE_H_
181