DataSource.h revision e2b43843fd12783188edd2c54188ea8d26864788 
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        kIsLocalFileSource     = 16,
48    };
49
50    static sp<DataSource> CreateFromURI(
51            const sp<IMediaHTTPService> &httpService,
52            const char *uri,
53            const KeyedVector<String8, String8> *headers = NULL,
54            String8 *contentType = NULL,
55            HTTPBase *httpSource = NULL);
56
57    static sp<DataSource> CreateMediaHTTP(const sp<IMediaHTTPService> &httpService);
58    static sp<DataSource> CreateFromIDataSource(const sp<IDataSource> &source);
59
60    DataSource() {}
61
62    virtual status_t initCheck() const = 0;
63
64    // Returns the number of bytes read, or -1 on failure. It's not an error if
65    // this returns zero; it just means the given offset is equal to, or
66    // beyond, the end of the source.
67    virtual ssize_t readAt(off64_t offset, void *data, size_t size) = 0;
68
69    // Convenience methods:
70    bool getUInt16(off64_t offset, uint16_t *x);
71    bool getUInt24(off64_t offset, uint32_t *x); // 3 byte int, returned as a 32-bit int
72    bool getUInt32(off64_t offset, uint32_t *x);
73    bool getUInt64(off64_t offset, uint64_t *x);
74
75    // Reads in "count" entries of type T into vector *x.
76    // Returns true if "count" entries can be read.
77    // If fewer than "count" entries can be read, return false. In this case,
78    // the output vector *x will still have those entries that were read. Call
79    // x->size() to obtain the number of entries read.
80    // The optional parameter chunkSize specifies how many entries should be
81    // read from the data source at one time into a temporary buffer. Increasing
82    // chunkSize can improve the performance at the cost of extra memory usage.
83    // The default value for chunkSize is set to read at least 4k bytes at a
84    // time, depending on sizeof(T).
85    template <typename T>
86    bool getVector(off64_t offset, Vector<T>* x, size_t count,
87                   size_t chunkSize = (4095 / sizeof(T)) + 1);
88
89    // May return ERROR_UNSUPPORTED.
90    virtual status_t getSize(off64_t *size);
91
92    virtual uint32_t flags() {
93        return 0;
94    }
95
96    virtual String8 toString() {
97        return String8("<unspecified>");
98    }
99
100    virtual status_t reconnectAtOffset(off64_t /*offset*/) {
101        return ERROR_UNSUPPORTED;
102    }
103
104    ////////////////////////////////////////////////////////////////////////////
105
106    // for DRM
107    virtual sp<DecryptHandle> DrmInitialization(const char * /*mime*/ = NULL) {
108        return NULL;
109    }
110    virtual void getDrmInfo(sp<DecryptHandle> &/*handle*/, DrmManagerClient ** /*client*/) {};
111
112    virtual String8 getUri() {
113        return String8();
114    }
115
116    virtual String8 getMIMEType() const;
117
118    virtual void close() {};
119
120protected:
121    virtual ~DataSource() {}
122
123private:
124    DataSource(const DataSource &);
125    DataSource &operator=(const DataSource &);
126};
127
128template <typename T>
129bool DataSource::getVector(off64_t offset, Vector<T>* x, size_t count,
130                           size_t chunkSize)
131{
132    x->clear();
133    if (chunkSize == 0) {
134        return false;
135    }
136    if (count == 0) {
137        return true;
138    }
139
140    T tmp[chunkSize];
141    ssize_t numBytesRead;
142    size_t numBytesPerChunk = chunkSize * sizeof(T);
143    size_t i;
144
145    for (i = 0; i + chunkSize < count; i += chunkSize) {
146        // This loops is executed when more than chunkSize records need to be
147        // read.
148        numBytesRead = this->readAt(offset, (void*)&tmp, numBytesPerChunk);
149        if (numBytesRead == -1) { // If readAt() returns -1, there is an error.
150            return false;
151        }
152        if (numBytesRead < numBytesPerChunk) {
153            // This case is triggered when the stream ends before the whole
154            // chunk is read.
155            x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
156            return false;
157        }
158        x->appendArray(tmp, chunkSize);
159        offset += numBytesPerChunk;
160    }
161
162    // There are (count - i) more records to read.
163    // Right now, (count - i) <= chunkSize.
164    // We do the same thing as above, but with chunkSize replaced by count - i.
165    numBytesRead = this->readAt(offset, (void*)&tmp, (count - i) * sizeof(T));
166    if (numBytesRead == -1) {
167        return false;
168    }
169    x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
170    return x->size() == count;
171}
172
173}  // namespace android
174
175#endif  // DATA_SOURCE_H_
176