[Boost-bugs] [Boost C++ Libraries] #12383: boost::asio fails to read more than 65536 bytes from file asyncronously

Subject: [Boost-bugs] [Boost C++ Libraries] #12383: boost::asio fails to read more than 65536 bytes from file asyncronously
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-08-09 07:10:22

#12383: boost::asio fails to read more than 65536 bytes from file asyncronously
------------------------------+----------------------------
 Reporter:  AStepanjuk@…      |      Owner:  chris_kohlhoff
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  asio
  Version:  Boost 1.61.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+----------------------------
 When more than `65536` bytes are read into a buffer from a file using
 `boost::asio::windows::stream_handle` asynchronously, then buffer contains
 the wrong data after reading is completed.

 Starting from `65537`th byte the buffer contains the the data from the
 very beginning of the file, rather than the expected data.

 Here is a code example, which reproduces the issue:

 {{{
 auto handle = ::CreateFile(L"BigFile.xml", GENERIC_READ, FILE_SHARE_READ,
 nullptr, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, nullptr);
 boost::asio::io_service ios;

 boost::asio::windows::stream_handle streamHandle(ios, handle);

 const auto to_read_bytes = 100000;
 char buffer[to_read_bytes];

 boost::asio::async_read(streamHandle, boost::asio::buffer(buffer,
 to_read_bytes), [](auto &ec, auto read) {
         std::cout << "Bytes read: " << read << std::endl;
 });

 ios.run();

 auto bufferBegin = std::string(buffer, 38);
 auto bufferCorrupted = std::string(buffer + 65536, 38);   // <- it
 contains bytes from the beginning of the file

 std::cout << "offset 0: " << bufferBegin << std::endl;
 std::cout << "offset 65536: " << bufferCorrupted << std::endl;

 ::CloseHandle(handle);
 }}}

 That code produces an output:

     > `Bytes read: 100000` [[br]]
     > `offset 0: <?xml version="1.0" encoding="UTF-8"?>`  [[br]]
     > `offset 65536: <?xml version="1.0" encoding="UTF-8"?>` [[br]]

 The source file is a valid XML file, which is bigger than 65536 bytes in
 size.

 This is reproducible with boost 1.61 + VS2015. Also that issue was in
 boost 1.55 + VS2010.  [[br]]
 Operating systems are: Windows 7 and Windows Server 2008R2.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/12383>
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