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      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_BASE_H_
     18 
     19 #define DATA_SOURCE_BASE_H_
     20 
     21 #include <sys/types.h>
     22 #include <utils/Errors.h>
     23 
     24 namespace android {
     25 
     26 class String8;
     27 
     28 class DataSourceBase {
     29 public:
     30     enum Flags {
     31         kWantsPrefetching      = 1,
     32         kStreamedFromLocalHost = 2,
     33         kIsCachingDataSource   = 4,
     34         kIsHTTPBasedSource     = 8,
     35         kIsLocalFileSource     = 16,
     36     };
     37 
     38     DataSourceBase() {}
     39 
     40     virtual status_t initCheck() const = 0;
     41 
     42     // Returns the number of bytes read, or -1 on failure. It's not an error if
     43     // this returns zero; it just means the given offset is equal to, or
     44     // beyond, the end of the source.
     45     virtual ssize_t readAt(off64_t offset, void *data, size_t size) = 0;
     46 
     47     // Convenience methods:
     48     bool getUInt16(off64_t offset, uint16_t *x);
     49     bool getUInt24(off64_t offset, uint32_t *x); // 3 byte int, returned as a 32-bit int
     50     bool getUInt32(off64_t offset, uint32_t *x);
     51     bool getUInt64(off64_t offset, uint64_t *x);
     52 
     53     // read either int<N> or int<2N> into a uint<2N>_t, size is the int size in bytes.
     54     bool getUInt16Var(off64_t offset, uint16_t *x, size_t size);
     55     bool getUInt32Var(off64_t offset, uint32_t *x, size_t size);
     56     bool getUInt64Var(off64_t offset, uint64_t *x, size_t size);
     57 
     58     // May return ERROR_UNSUPPORTED.
     59     virtual status_t getSize(off64_t *size);
     60 
     61     virtual bool getUri(char *uriString, size_t bufferSize);
     62 
     63     virtual uint32_t flags() {
     64         return 0;
     65     }
     66 
     67     virtual void close() {};
     68 
     69     virtual status_t getAvailableSize(off64_t /*offset*/, off64_t * /*size*/) {
     70         return -1;
     71     }
     72 
     73 protected:
     74     virtual ~DataSourceBase() {}
     75 
     76 private:
     77     DataSourceBase(const DataSourceBase &);
     78     DataSourceBase &operator=(const DataSourceBase &);
     79 };
     80 
     81 }  // namespace android
     82 
     83 #endif  // DATA_SOURCE_BASE_H_
     84