DataSource.h revision 514674257ef6954a7479ac93a26a07061f54462d 
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    DataSource() {}
51
52    virtual status_t initCheck() const = 0;
53
54    // Returns the number of bytes read, or -1 on failure. It's not an error if
55    // this returns zero; it just means the given offset is equal to, or
56    // beyond, the end of the source.
57    virtual ssize_t readAt(off64_t offset, void *data, size_t size) = 0;
58
59    // Convenience methods:
60    bool getUInt16(off64_t offset, uint16_t *x);
61    bool getUInt24(off64_t offset, uint32_t *x); // 3 byte int, returned as a 32-bit int
62    bool getUInt32(off64_t offset, uint32_t *x);
63    bool getUInt64(off64_t offset, uint64_t *x);
64
65    // read either int<N> or int<2N> into a uint<2N>_t, size is the int size in bytes.
66    bool getUInt16Var(off64_t offset, uint16_t *x, size_t size);
67    bool getUInt32Var(off64_t offset, uint32_t *x, size_t size);
68    bool getUInt64Var(off64_t offset, uint64_t *x, size_t size);
69
70    // Reads in "count" entries of type T into vector *x.
71    // Returns true if "count" entries can be read.
72    // If fewer than "count" entries can be read, return false. In this case,
73    // the output vector *x will still have those entries that were read. Call
74    // x->size() to obtain the number of entries read.
75    // The optional parameter chunkSize specifies how many entries should be
76    // read from the data source at one time into a temporary buffer. Increasing
77    // chunkSize can improve the performance at the cost of extra memory usage.
78    // The default value for chunkSize is set to read at least 4k bytes at a
79    // time, depending on sizeof(T).
80    template <typename T>
81    bool getVector(off64_t offset, Vector<T>* x, size_t count,
82                   size_t chunkSize = (4095 / sizeof(T)) + 1);
83
84    // May return ERROR_UNSUPPORTED.
85    virtual status_t getSize(off64_t *size);
86
87    virtual uint32_t flags() {
88        return 0;
89    }
90
91    virtual String8 toString() {
92        return String8("<unspecified>");
93    }
94
95    virtual status_t reconnectAtOffset(off64_t /*offset*/) {
96        return ERROR_UNSUPPORTED;
97    }
98
99    ////////////////////////////////////////////////////////////////////////////
100
101    // for DRM
102    virtual sp<DecryptHandle> DrmInitialization(const char * /*mime*/ = NULL) {
103        return NULL;
104    }
105    virtual void getDrmInfo(sp<DecryptHandle> &/*handle*/, DrmManagerClient ** /*client*/) {};
106
107    virtual String8 getUri() {
108        return String8();
109    }
110
111    virtual String8 getMIMEType() const;
112
113    virtual void close() {};
114
115protected:
116    virtual ~DataSource() {}
117
118private:
119    DataSource(const DataSource &);
120    DataSource &operator=(const DataSource &);
121};
122
123template <typename T>
124bool DataSource::getVector(off64_t offset, Vector<T>* x, size_t count,
125                           size_t chunkSize)
126{
127    x->clear();
128    if (chunkSize == 0) {
129        return false;
130    }
131    if (count == 0) {
132        return true;
133    }
134
135    T tmp[chunkSize];
136    ssize_t numBytesRead;
137    size_t numBytesPerChunk = chunkSize * sizeof(T);
138    size_t i;
139
140    for (i = 0; i + chunkSize < count; i += chunkSize) {
141        // This loops is executed when more than chunkSize records need to be
142        // read.
143        numBytesRead = this->readAt(offset, (void*)&tmp, numBytesPerChunk);
144        if (numBytesRead == -1) { // If readAt() returns -1, there is an error.
145            return false;
146        }
147        if (static_cast<size_t>(numBytesRead) < numBytesPerChunk) {
148            // This case is triggered when the stream ends before the whole
149            // chunk is read.
150            x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
151            return false;
152        }
153        x->appendArray(tmp, chunkSize);
154        offset += numBytesPerChunk;
155    }
156
157    // There are (count - i) more records to read.
158    // Right now, (count - i) <= chunkSize.
159    // We do the same thing as above, but with chunkSize replaced by count - i.
160    numBytesRead = this->readAt(offset, (void*)&tmp, (count - i) * sizeof(T));
161    if (numBytesRead == -1) {
162        return false;
163    }
164    x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
165    return x->size() == count;
166}
167
168}  // namespace android
169
170#endif  // DATA_SOURCE_H_
171