DataSource.h revision 04ce1be860b40e18ca7f5fdf64ecb82567d7fe24 
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    static sp<DataSource> CreateFromFd(int fd, int64_t offset, int64_t length);
60
61    DataSource() {}
62
63    virtual status_t initCheck() const = 0;
64
65    // Returns the number of bytes read, or -1 on failure. It's not an error if
66    // this returns zero; it just means the given offset is equal to, or
67    // beyond, the end of the source.
68    virtual ssize_t readAt(off64_t offset, void *data, size_t size) = 0;
69
70    // Convenience methods:
71    bool getUInt16(off64_t offset, uint16_t *x);
72    bool getUInt24(off64_t offset, uint32_t *x); // 3 byte int, returned as a 32-bit int
73    bool getUInt32(off64_t offset, uint32_t *x);
74    bool getUInt64(off64_t offset, uint64_t *x);
75
76    // read either int<N> or int<2N> into a uint<2N>_t, size is the int size in bytes.
77    bool getUInt16Var(off64_t offset, uint16_t *x, size_t size);
78    bool getUInt32Var(off64_t offset, uint32_t *x, size_t size);
79    bool getUInt64Var(off64_t offset, uint64_t *x, size_t size);
80
81    // Reads in "count" entries of type T into vector *x.
82    // Returns true if "count" entries can be read.
83    // If fewer than "count" entries can be read, return false. In this case,
84    // the output vector *x will still have those entries that were read. Call
85    // x->size() to obtain the number of entries read.
86    // The optional parameter chunkSize specifies how many entries should be
87    // read from the data source at one time into a temporary buffer. Increasing
88    // chunkSize can improve the performance at the cost of extra memory usage.
89    // The default value for chunkSize is set to read at least 4k bytes at a
90    // time, depending on sizeof(T).
91    template <typename T>
92    bool getVector(off64_t offset, Vector<T>* x, size_t count,
93                   size_t chunkSize = (4095 / sizeof(T)) + 1);
94
95    // May return ERROR_UNSUPPORTED.
96    virtual status_t getSize(off64_t *size);
97
98    virtual uint32_t flags() {
99        return 0;
100    }
101
102    virtual String8 toString() {
103        return String8("<unspecified>");
104    }
105
106    virtual status_t reconnectAtOffset(off64_t /*offset*/) {
107        return ERROR_UNSUPPORTED;
108    }
109
110    ////////////////////////////////////////////////////////////////////////////
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
124    virtual void close() {};
125
126    // creates an IDataSource wrapper to the DataSource.
127    virtual sp<IDataSource> asIDataSource();
128
129    // returns a pointer to IDataSource if it is wrapped.
130    virtual sp<IDataSource> getIDataSource() const;
131
132protected:
133    virtual ~DataSource() {}
134
135private:
136    DataSource(const DataSource &);
137    DataSource &operator=(const DataSource &);
138};
139
140template <typename T>
141bool DataSource::getVector(off64_t offset, Vector<T>* x, size_t count,
142                           size_t chunkSize)
143{
144    x->clear();
145    if (chunkSize == 0) {
146        return false;
147    }
148    if (count == 0) {
149        return true;
150    }
151
152    T tmp[chunkSize];
153    ssize_t numBytesRead;
154    size_t numBytesPerChunk = chunkSize * sizeof(T);
155    size_t i;
156
157    for (i = 0; i + chunkSize < count; i += chunkSize) {
158        // This loops is executed when more than chunkSize records need to be
159        // read.
160        numBytesRead = this->readAt(offset, (void*)&tmp, numBytesPerChunk);
161        if (numBytesRead == -1) { // If readAt() returns -1, there is an error.
162            return false;
163        }
164        if (static_cast<size_t>(numBytesRead) < numBytesPerChunk) {
165            // This case is triggered when the stream ends before the whole
166            // chunk is read.
167            x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
168            return false;
169        }
170        x->appendArray(tmp, chunkSize);
171        offset += numBytesPerChunk;
172    }
173
174    // There are (count - i) more records to read.
175    // Right now, (count - i) <= chunkSize.
176    // We do the same thing as above, but with chunkSize replaced by count - i.
177    numBytesRead = this->readAt(offset, (void*)&tmp, (count - i) * sizeof(T));
178    if (numBytesRead == -1) {
179        return false;
180    }
181    x->appendArray(tmp, (size_t)numBytesRead / sizeof(T));
182    return x->size() == count;
183}
184
185}  // namespace android
186
187#endif  // DATA_SOURCE_H_
188