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      1 /*
      2  * Copyright (C) 2015 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 AAPT_IO_FILE_H
     18 #define AAPT_IO_FILE_H
     19 
     20 #include <list>
     21 #include <memory>
     22 #include <vector>
     23 
     24 #include "android-base/macros.h"
     25 
     26 #include "Source.h"
     27 #include "io/Data.h"
     28 #include "util/Util.h"
     29 
     30 namespace aapt {
     31 namespace io {
     32 
     33 // Interface for a file, which could be a real file on the file system, or a
     34 // file inside a ZIP archive.
     35 class IFile {
     36  public:
     37   virtual ~IFile() = default;
     38 
     39   // Open the file and return it as a block of contiguous memory. How this
     40   // occurs is implementation dependent. For example, if this is a file on the file
     41   // system, it may simply mmap the contents. If this file represents a compressed file in a
     42   // ZIP archive, it may need to inflate it to memory, incurring a copy.
     43   // Returns nullptr on failure.
     44   virtual std::unique_ptr<IData> OpenAsData() = 0;
     45 
     46   virtual std::unique_ptr<io::InputStream> OpenInputStream() = 0;
     47 
     48   // Returns the source of this file. This is for presentation to the user and
     49   // may not be a valid file system path (for example, it may contain a '@' sign to separate
     50   // the files within a ZIP archive from the path to the containing ZIP archive.
     51   virtual const Source& GetSource() const = 0;
     52 
     53   IFile* CreateFileSegment(size_t offset, size_t len);
     54 
     55   // Returns whether the file was compressed before it was stored in memory.
     56   virtual bool WasCompressed() {
     57     return false;
     58   }
     59 
     60  private:
     61   // Any segments created from this IFile need to be owned by this IFile, so
     62   // keep them
     63   // in a list. This will never be read, so we prefer better insertion
     64   // performance
     65   // than cache locality, hence the list.
     66   std::list<std::unique_ptr<IFile>> segments_;
     67 };
     68 
     69 // An IFile that wraps an underlying IFile but limits it to a subsection of that file.
     70 class FileSegment : public IFile {
     71  public:
     72   explicit FileSegment(IFile* file, size_t offset, size_t len)
     73       : file_(file), offset_(offset), len_(len) {}
     74 
     75   std::unique_ptr<IData> OpenAsData() override;
     76   std::unique_ptr<io::InputStream> OpenInputStream() override;
     77 
     78   const Source& GetSource() const override {
     79     return file_->GetSource();
     80   }
     81 
     82  private:
     83   DISALLOW_COPY_AND_ASSIGN(FileSegment);
     84 
     85   IFile* file_;
     86   size_t offset_;
     87   size_t len_;
     88 };
     89 
     90 class IFileCollectionIterator {
     91  public:
     92   virtual ~IFileCollectionIterator() = default;
     93 
     94   virtual bool HasNext() = 0;
     95   virtual IFile* Next() = 0;
     96 };
     97 
     98 // Interface for a collection of files, all of which share a common source. That source may
     99 // simply be the filesystem, or a ZIP archive.
    100 class IFileCollection {
    101  public:
    102   virtual ~IFileCollection() = default;
    103 
    104   virtual IFile* FindFile(const android::StringPiece& path) = 0;
    105   virtual std::unique_ptr<IFileCollectionIterator> Iterator() = 0;
    106 };
    107 
    108 }  // namespace io
    109 }  // namespace aapt
    110 
    111 #endif /* AAPT_IO_FILE_H */
    112