diff --git a/3rdparty/cpprestsdk/include/cpprest/filestream.h b/3rdparty/cpprestsdk/include/cpprest/filestream.h
deleted file mode 100644
index 0565a7f3ee8bbf80d714c05a942c6de9b0882cfd..0000000000000000000000000000000000000000
--- a/3rdparty/cpprestsdk/include/cpprest/filestream.h
+++ /dev/null
@@ -1,1132 +0,0 @@
-/***
-* ==++==
-*
-* Copyright (c) Microsoft Corporation. All rights reserved.
-* Licensed under the Apache License, Version 2.0 (the "License");
-* you may not use this file except in compliance with the License.
-* You may obtain a copy of the License at
-* http://www.apache.org/licenses/LICENSE-2.0
-*
-* Unless required by applicable law or agreed to in writing, software
-* distributed under the License is distributed on an "AS IS" BASIS,
-* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-* See the License for the specific language governing permissions and
-* limitations under the License.
-*
-* ==--==
-* =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
-*
-* Asynchronous File streams
-*
-* For the latest on this and related APIs, please see http://casablanca.codeplex.com.
-*
-* =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-****/
-#pragma once
-
-#ifndef _CASA_FILE_STREAMS_H
-#define _CASA_FILE_STREAMS_H
-
-#include "cpprest/details/fileio.h"
-#include "cpprest/astreambuf.h"
-#include "cpprest/streams.h"
-#include <assert.h>
-
-#ifndef _CONCRT_H
-#ifndef _LWRCASE_CNCRRNCY
-#define _LWRCASE_CNCRRNCY
-// Note to reader: we're using lower-case namespace names everywhere, but the 'Concurrency' namespace
-// is capitalized for historical reasons. The alias let's us pretend that style issue doesn't exist.
-namespace Concurrency { }
-namespace concurrency = Concurrency;
-#endif
-#endif
-
-namespace Concurrency { namespace streams
-{
-    // Forward declarations
-    template<typename _CharType> class file_buffer;
-
-namespace details {
-    // This operation queue is NOT thread safe
-    class async_operation_queue
-    {
-        pplx::task<void> m_lastOperation;
-    public:
-        async_operation_queue()
-        {
-            m_lastOperation = pplx::task_from_result();
-        }
-
-        // It only accepts functors that take no argument and return pplx::task<T>
-        // This function may execute op inline, thus it could throw immediately
-        template <typename Func>
-        auto enqueue_operation(Func &&op) -> decltype(op())
-        {
-            decltype(op()) res; // res is task<T> , which always has default constructor
-            if (m_lastOperation.is_done())
-            {
-                res = op(); // Exceptions are expected to be thrown directly without catching
-                if (res.is_done())
-                    return res;
-            }
-            else
-            {
-                res = m_lastOperation.then([=] {
-                    return op(); // It will cause task unwrapping
-                });
-            }
-            m_lastOperation = res.then([&] (decltype(op())) {
-                // This empty task is necessary for keeping the rest of the operations on the list running
-                // even when the previous operation gets error.
-                // Don't observe exception here.
-            });
-            return res;
-        }
-
-        void wait() const
-        {
-            m_lastOperation.wait();
-        }
-    };
-
-
-    /// <summary>
-    /// Private stream buffer implementation for file streams.
-    /// The class itself should not be used in application code, it is used by the stream definitions farther down in the header file.
-    /// </summary>
-    template<typename _CharType>
-    class basic_file_buffer : public details::streambuf_state_manager<_CharType>
-    {
-    public:
-        typedef typename basic_streambuf<_CharType>::traits traits;
-        typedef typename basic_streambuf<_CharType>::int_type int_type;
-        typedef typename basic_streambuf<_CharType>::pos_type pos_type;
-        typedef typename basic_streambuf<_CharType>::off_type off_type;
-
-        virtual ~basic_file_buffer()
-        {
-            if( this->can_read() )
-            {
-                this->_close_read().wait();
-            }
-
-            if (this->can_write())
-            {
-                this->_close_write().wait();
-            }
-        }
-
-    protected:
-
-        /// <summary>
-        /// <c>can_seek</c> is used to determine whether a stream buffer supports seeking.
-        /// </summary>
-        virtual bool can_seek() const { return this->is_open(); }
-
-        /// <summary>
-        /// <c>has_size<c/> is used to determine whether a stream buffer supports size().
-        /// </summary>
-        virtual bool has_size() const { return this->is_open(); }
-
-        virtual utility::size64_t size() const
-        {
-            if (!this->is_open())
-                return 0;
-            return _get_size(m_info, sizeof(_CharType));
-        }
-
-
-        /// <summary>
-        /// Gets the stream buffer size, if one has been set.
-        /// </summary>
-        /// <param name="direction">The direction of buffering (in or out)</param>
-        /// <remarks>An implementation that does not support buffering will always return '0'.</remarks>
-        virtual size_t buffer_size(std::ios_base::openmode direction = std::ios_base::in) const
-        {
-            if ( direction == std::ios_base::in )
-                return m_info->m_buffer_size;
-            else
-                return 0;
-        }
-
-        /// <summary>
-        /// Sets the stream buffer implementation to buffer or not buffer.
-        /// </summary>
-        /// <param name="size">The size to use for internal buffering, 0 if no buffering should be done.</param>
-        /// <param name="direction">The direction of buffering (in or out)</param>
-        /// <remarks>An implementation that does not support buffering will silently ignore calls to this function and it will not have
-        ///          any effect on what is returned by subsequent calls to buffer_size().</remarks>
-        virtual void set_buffer_size(size_t size, std::ios_base::openmode direction = std::ios_base::in)
-        {
-            if ( direction == std::ios_base::out ) return;
-
-            m_info->m_buffer_size = size;
-
-            if ( size == 0 && m_info->m_buffer != nullptr )
-            {
-               delete m_info->m_buffer;
-               m_info->m_buffer = nullptr;
-            }
-        }
-
-        /// <summary>
-        /// For any input stream, <c>in_avail</c> returns the number of characters that are immediately available
-        /// to be consumed without blocking. May be used in conjunction with <cref="::sbumpc method"/> to read data without
-        /// incurring the overhead of using tasks.
-        /// </summary>
-        virtual size_t in_avail() const
-        {
-            pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-            return _in_avail_unprot();
-        }
-
-        size_t _in_avail_unprot() const
-        {
-            if ( !this->is_open() ) return 0;
-
-            if ( m_info->m_buffer == nullptr || m_info->m_buffill == 0 ) return 0;
-            if ( m_info->m_bufoff > m_info->m_rdpos || (m_info->m_bufoff+m_info->m_buffill) < m_info->m_rdpos ) return 0;
-
-            msl::safeint3::SafeInt<size_t> rdpos(m_info->m_rdpos);
-            msl::safeint3::SafeInt<size_t> buffill(m_info->m_buffill);
-            msl::safeint3::SafeInt<size_t> bufpos = rdpos - m_info->m_bufoff;
-
-            return buffill - bufpos;
-        }
-
-        _file_info * _close_stream()
-        {
-            // indicate that we are no longer open
-            auto fileInfo = m_info;
-            m_info = nullptr;
-            return fileInfo;
-        }
-
-        static pplx::task<void> _close_file(_In_ _file_info * fileInfo)
-        {
-            pplx::task_completion_event<void> result_tce;
-            auto callback = new _filestream_callback_close(result_tce);
-
-            if ( !_close_fsb_nolock(&fileInfo, callback) )
-            {
-                delete callback;
-                return pplx::task_from_result();
-            }
-            return pplx::create_task(result_tce);
-        }
-
-        // Workaround GCC compiler bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58972
-        void _invoke_parent_close_read()
-        {
-            streambuf_state_manager<_CharType>::_close_read();
-        }
-
-        pplx::task<void> _close_read()
-        {
-            return m_readOps.enqueue_operation([this]
-            {
-                _invoke_parent_close_read();
-
-                if (this->can_write())
-                {
-                    return pplx::task_from_result();
-                }
-                else
-                {
-                    // Neither heads are open. Close the underlying device
-                    // to indicate that we are no longer open
-                    auto fileInfo = _close_stream();
-
-                    return _close_file(fileInfo);
-                }
-            });
-        }
-
-        pplx::task<void> _close_write()
-        {
-            streambuf_state_manager<_CharType>::_close_write();
-            if (this->can_read())
-            {
-                // Read head is still open. Just flush the write data
-                return flush_internal();
-            }
-            else
-            {
-                // Neither heads are open. Close the underlying device
-
-                // We need to flush all writes if the file was opened for writing.
-                return flush_internal().then([=](pplx::task<void> flushTask) -> pplx::task<void>
-                {
-                    // swallow exception from flush
-                    try
-                    {
-                        flushTask.wait();
-                    }
-                    catch(...)
-                    {
-                    }
-
-                    // indicate that we are no longer open
-                    auto fileInfo = this->_close_stream();
-
-                    return this->_close_file(fileInfo);
-                });
-            }
-        }
-
-        /// <summary>
-        /// Writes a single byte to an output stream.
-        /// </summary>
-        /// <param name="ch">The byte to write</param>
-            /// <returns>A <c>task</c> that holds the value of the byte written. This is EOF if the write operation fails.</returns>
-        virtual pplx::task<int_type> _putc(_CharType ch)
-        {
-            auto result_tce = pplx::task_completion_event<size_t>();
-            auto callback = new _filestream_callback_write<size_t>(m_info, result_tce);
-
-            // Potentially we should consider deprecating this API, it is TERRIBLY inefficient.
-            std::shared_ptr<_CharType> sharedCh;
-            try
-            {
-                sharedCh = std::make_shared<_CharType>(ch);
-            } catch (const std::bad_alloc &)
-            {
-                delete callback;
-                throw;
-            }
-            
-            size_t written = _putn_fsb(m_info, callback, sharedCh.get(), 1, sizeof(_CharType));
-            if (written == sizeof(_CharType))
-            {
-                delete callback;
-                return pplx::task_from_result<int_type>(ch);
-            }
-            
-            return pplx::create_task(result_tce).then([sharedCh](size_t)
-            {
-                return static_cast<int_type>(*sharedCh);
-            });
-        }
-
-        /// <summary>
-        /// Allocates a contiguous memory block and returns it.
-        /// </summary>
-        /// <param name="count">The number of characters to allocate.</param>
-        /// <returns>A pointer to a block to write to, null if the stream buffer implementation does not support alloc/commit.</returns>
-        _CharType* _alloc(size_t)
-        {
-            return nullptr;
-        }
-
-        /// <summary>
-        /// Submits a block already allocated by the stream buffer.
-        /// </summary>
-        /// <param name="ptr">Count of characters to be commited.</param>
-        void _commit(size_t)
-        {
-        }
-
-        /// <summary>
-        /// Gets a pointer to the next already allocated contiguous block of data.
-        /// </summary>
-        /// <param name="ptr">A reference to a pointer variable that will hold the address of the block on success.</param>
-        /// <param name="count">The number of contiguous characters available at the address in 'ptr.'</param>
-        /// <returns><c>true</c> if the operation succeeded, <c>false</c> otherwise.</returns>
-        /// <remarks>
-        /// A return of false does not necessarily indicate that a subsequent read operation would fail, only that
-        /// there is no block to return immediately or that the stream buffer does not support the operation.
-        /// The stream buffer may not de-allocate the block until <see cref="::release method" /> is called.
-        /// If the end of the stream is reached, the function will return <c>true</c>, a null pointer, and a count of zero;
-        /// a subsequent read will not succeed.
-        /// </remarks>
-        virtual bool acquire(_Out_ _CharType*& ptr, _Out_ size_t& count)
-        {
-            ptr = nullptr;
-            count = 0;
-            return false;
-        }
-
-        /// <summary>
-        /// Releases a block of data acquired using <see cref="::acquire method"/>. This frees the stream buffer to de-allocate the
-        /// memory, if it so desires. Move the read position ahead by the count.
-        /// </summary>
-        /// <param name="ptr">A pointer to the block of data to be released.</param>
-        /// <param name="count">The number of characters that were read.</param>
-        virtual void release(_Out_writes_ (count) _CharType *, _In_ size_t count)
-        {
-            (void)(count);
-        }
-
-        /// <summary>
-        /// Writes a number of characters to the stream.
-        /// </summary>
-        /// <param name="ptr">A pointer to the block of data to be written.</param>
-        /// <param name="count">The number of characters to write.</param>
-        /// <returns>A <c>task</c> that holds the number of characters actually written, either 'count' or 0.</returns>
-        virtual pplx::task<size_t> _putn(const _CharType *ptr, size_t count)
-        {
-            auto result_tce = pplx::task_completion_event<size_t>();
-            auto callback = new _filestream_callback_write<size_t>(m_info, result_tce);
-
-            size_t written = _putn_fsb(m_info, callback, ptr, count, sizeof(_CharType));
-
-            if ( written != 0 && written != -1 )
-            {
-                delete callback;
-                written = written/sizeof(_CharType);
-                return pplx::task_from_result<size_t>(written);
-            }
-            return pplx::create_task(result_tce);
-        }
-
-        // Temporarily needed until the deprecated putn is removed.
-        virtual pplx::task<size_t> _putn(const _CharType *ptr, size_t count, bool copy)
-        {
-            if (copy)
-            {
-                auto sharedData = std::make_shared<std::vector<_CharType>>(ptr, ptr + count);
-                return _putn(ptr, count).then([sharedData](size_t size)
-                {
-                    return size;
-                });
-            }
-            else
-            {
-                return _putn(ptr, count);
-            }
-        }
-
-        /// <summary>
-        /// Reads a single byte from the stream and advance the read position.
-        /// </summary>
-            /// <returns>A <c>task</c> that holds the value of the byte read. This is EOF if the read fails.</returns>
-        virtual pplx::task<int_type> _bumpc()
-        {
-            return m_readOps.enqueue_operation([this]()-> pplx::task<int_type> {
-                if ( _in_avail_unprot() > 0 )
-                {
-                    pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-                    // Check again once the lock is held.
-
-                    if ( _in_avail_unprot() > 0 )
-                    {
-                        auto bufoff = m_info->m_rdpos - m_info->m_bufoff;
-                        _CharType ch = m_info->m_buffer[bufoff*sizeof(_CharType)];
-                        m_info->m_rdpos += 1;
-                        return pplx::task_from_result<int_type>(ch);
-                    }
-                }
-
-                auto result_tce = pplx::task_completion_event<int_type>();
-                auto callback = new _filestream_callback_bumpc(m_info, result_tce);
-
-                size_t ch = _getn_fsb(m_info, callback, &callback->m_ch, 1, sizeof(_CharType));
-
-                if ( ch == sizeof(_CharType) )
-                {
-                    pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-                    m_info->m_rdpos += 1;
-                    _CharType ch1 = (_CharType)callback->m_ch;
-                    delete callback;
-                    return pplx::task_from_result<int_type>(ch1);
-                }
-                return pplx::create_task(result_tce);
-            });
-        }
-
-        /// <summary>
-        /// Reads a single byte from the stream and advance the read position.
-        /// </summary>
-        /// <returns>The value of the byte. EOF if the read fails. <see cref="::requires_async method" /> if an asynchronous read is required</returns>
-        /// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>
-        virtual int_type _sbumpc()
-        {
-            m_readOps.wait();
-            if ( m_info->m_atend ) return traits::eof();
-
-            if ( _in_avail_unprot() == 0 ) return traits::requires_async();
-
-            pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-            if ( _in_avail_unprot() == 0 ) return traits::requires_async();
-
-            auto bufoff = m_info->m_rdpos - m_info->m_bufoff;
-            _CharType ch = m_info->m_buffer[bufoff*sizeof(_CharType)];
-            m_info->m_rdpos += 1;
-            return (int_type)ch;
-        }
-
-        pplx::task<int_type> _getcImpl()
-        {
-            if ( _in_avail_unprot() > 0 )
-            {
-                pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-                // Check again once the lock is held.
-
-                if ( _in_avail_unprot() > 0 )
-                {
-                    auto bufoff = m_info->m_rdpos - m_info->m_bufoff;
-                    _CharType ch = m_info->m_buffer[bufoff*sizeof(_CharType)];
-                    return pplx::task_from_result<int_type>(ch);
-                }
-            }
-
-            auto result_tce = pplx::task_completion_event<int_type>();
-            auto callback = new _filestream_callback_getc(m_info, result_tce);
-
-            size_t ch = _getn_fsb(m_info, callback, &callback->m_ch, 1, sizeof(_CharType));
-
-            if ( ch == sizeof(_CharType) )
-            {
-                pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-                _CharType ch1 = (_CharType)callback->m_ch;
-                delete callback;
-                return pplx::task_from_result<int_type>(ch1);
-            }
-            return pplx::create_task(result_tce);
-
-        }
-
-        /// <summary>
-        /// Reads a single byte from the stream without advancing the read position.
-        /// </summary>
-        /// <returns>The value of the byte. EOF if the read fails.</returns>
-        pplx::task<int_type> _getc()
-        {
-            return m_readOps.enqueue_operation([this]()-> pplx::task<int_type> {
-                return _getcImpl();
-            });
-        }
-
-        /// <summary>
-        /// Reads a single byte from the stream without advancing the read position.
-        /// </summary>
-        /// <returns>The value of the byte. EOF if the read fails. <see cref="::requires_async method" /> if an asynchronous read is required</returns>
-        /// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>
-        int_type _sgetc()
-        {
-            m_readOps.wait();
-            if ( m_info->m_atend ) return traits::eof();
-
-            if ( _in_avail_unprot() == 0 ) return traits::requires_async();
-
-            pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-            if ( _in_avail_unprot() == 0 ) return traits::requires_async();
-
-            auto bufoff = m_info->m_rdpos - m_info->m_bufoff;
-            _CharType ch = m_info->m_buffer[bufoff*sizeof(_CharType)];
-            return (int_type)ch;
-        }
-
-        /// <summary>
-        /// Advances the read position, then return the next character without advancing again.
-        /// </summary>
-            /// <returns>A <c>task</c> that holds the value of the byte, which is EOF if the read fails.</returns>
-        virtual pplx::task<int_type> _nextc()
-        {
-            return m_readOps.enqueue_operation([this]()-> pplx::task<int_type> {
-                _seekrdpos_fsb(m_info, m_info->m_rdpos+1, sizeof(_CharType));
-                if ( m_info->m_atend )
-                    return pplx::task_from_result(basic_file_buffer<_CharType>::traits::eof());
-                return this->_getcImpl();
-            });
-        }
-
-        /// <summary>
-        /// Retreats the read position, then return the current character without advancing.
-        /// </summary>
-            /// <returns>A <c>task</c> that holds the value of the byte. The value is EOF if the read fails, <c>requires_async</c> if an asynchronous read is required</returns>
-        virtual pplx::task<int_type> _ungetc()
-        {
-            return m_readOps.enqueue_operation([this]()-> pplx::task<int_type> {
-                if ( m_info->m_rdpos == 0 )
-                    return pplx::task_from_result<int_type>(basic_file_buffer<_CharType>::traits::eof());
-                _seekrdpos_fsb(m_info, m_info->m_rdpos-1, sizeof(_CharType));
-                return this->_getcImpl();
-            });
-        }
-
-        /// <summary>
-        /// Reads up to a given number of characters from the stream.
-        /// </summary>
-        /// <param name="ptr">The address of the target memory area</param>
-        /// <param name="count">The maximum number of characters to read</param>
-            /// <returns>A <c>task</c> that holds the number of characters read. This number is O if the end of the stream is reached, EOF if there is some error.</returns>
-        virtual pplx::task<size_t> _getn(_Out_writes_ (count) _CharType *ptr, _In_ size_t count)
-        {
-            return m_readOps.enqueue_operation([=] ()-> pplx::task<size_t>{
-                if ( m_info->m_atend || count == 0 )
-                    return pplx::task_from_result<size_t>(0);
-
-                if ( _in_avail_unprot() >= count )
-                {
-                    pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-                    // Check again once the lock is held.
-
-                    if ( _in_avail_unprot() >= count )
-                    {
-                        auto bufoff = m_info->m_rdpos - m_info->m_bufoff;
-                        std::memcpy((void *)ptr, this->m_info->m_buffer+bufoff*sizeof(_CharType), count*sizeof(_CharType));
-
-                        m_info->m_rdpos += count;
-                        return pplx::task_from_result<size_t>(count);
-                    }
-                }
-
-                auto result_tce = pplx::task_completion_event<size_t>();
-                auto callback = new _filestream_callback_read(m_info, result_tce);
-
-                size_t read = _getn_fsb(m_info, callback, ptr, count, sizeof(_CharType));
-
-                if ( read != 0 && read != -1)
-                {
-                    delete callback;
-                    pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-                    m_info->m_rdpos += read/sizeof(_CharType);
-                    return pplx::task_from_result<size_t>(read/sizeof(_CharType));
-                }
-                return pplx::create_task(result_tce);
-            });
-        }
-
-        /// <summary>
-        /// Reads up to a given number of characters from the stream.
-        /// </summary>
-        /// <param name="ptr">The address of the target memory area</param>
-        /// <param name="count">The maximum number of characters to read</param>
-        /// <returns>The number of characters read. O if the end of the stream is reached or an asynchronous read is required.</returns>
-        /// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>
-        size_t _sgetn(_Out_writes_ (count) _CharType *ptr, _In_ size_t count)
-        {
-            m_readOps.wait();
-            if ( m_info->m_atend ) return 0;
-
-            if ( count == 0 || in_avail() == 0 ) return 0;
-
-            pplx::extensibility::scoped_recursive_lock_t lck(m_info->m_lock);
-
-            size_t available = _in_avail_unprot();
-            size_t copy = (count < available) ? count : available;
-
-            auto bufoff = m_info->m_rdpos - m_info->m_bufoff;
-            std::memcpy((void *)ptr, this->m_info->m_buffer+bufoff*sizeof(_CharType), copy*sizeof(_CharType));
-
-            m_info->m_rdpos += copy;
-            m_info->m_atend = (copy < count);
-            return copy;
-        }
-
-        /// <summary>
-        /// Copies up to a given number of characters from the stream.
-        /// </summary>
-        /// <param name="ptr">The address of the target memory area</param>
-        /// <param name="count">The maximum number of characters to copy</param>
-        /// <returns>The number of characters copied. O if the end of the stream is reached or an asynchronous read is required.</returns>
-        /// <remarks>This is a synchronous operation, but is guaranteed to never block.</remarks>
-        virtual size_t _scopy(_CharType *, size_t)
-        {
-            return 0;
-        }
-
-        /// <summary>
-        /// Gets the current read or write position in the stream.
-        /// </summary>
-        /// <param name="direction">The I/O direction to seek (see remarks)</param>
-        /// <returns>The current position. EOF if the operation fails.</returns>
-        /// <remarks>Some streams may have separate write and read cursors.
-        ///          For such streams, the direction parameter defines whether to move the read or the write cursor.</remarks>
-        virtual pos_type getpos(std::ios_base::openmode mode) const
-        {
-            return const_cast<basic_file_buffer*>(this)->seekoff(0, std::ios_base::cur, mode);
-        }
-
-        /// <summary>
-        /// Seeks to the given position.
-        /// </summary>
-        /// <param name="pos">The offset from the beginning of the stream</param>
-        /// <param name="direction">The I/O direction to seek (see remarks)</param>
-        /// <returns>The position. EOF if the operation fails.</returns>
-        /// <remarks>Some streams may have separate write and read cursors.
-        ///          For such streams, the direction parameter defines whether to move the read or the write cursor.</remarks>
-        virtual pos_type seekpos(pos_type pos, std::ios_base::openmode mode)
-        {
-            if ( mode == std::ios_base::in )
-            {
-                m_readOps.wait();
-                return (pos_type)_seekrdpos_fsb(m_info, size_t(pos), sizeof(_CharType));
-            }
-            else if ( (m_info->m_mode & std::ios::ios_base::app) == 0 )
-            {
-                return (pos_type)_seekwrpos_fsb(m_info, size_t(pos), sizeof(_CharType));
-            }
-            return (pos_type)Concurrency::streams::char_traits<_CharType>::eof();
-        }
-
-        /// <summary>
-        /// Seeks to a position given by a relative offset.
-        /// </summary>
-        /// <param name="offset">The relative position to seek to</param>
-        /// <param name="way">The starting point (beginning, end, current) for the seek.</param>
-        /// <param name="mode">The I/O direction to seek (see remarks)</param>
-        /// <returns>The position. EOF if the operation fails.</returns>
-        /// <remarks>Some streams may have separate write and read cursors.
-        ///          For such streams, the mode parameter defines whether to move the read or the write cursor.</remarks>
-        virtual pos_type seekoff(off_type offset, std::ios_base::seekdir way, std::ios_base::openmode mode)
-        {
-            if ( mode == std::ios_base::in )
-            {
-                m_readOps.wait();
-                switch ( way )
-                {
-                case std::ios_base::beg:
-                    return (pos_type)_seekrdpos_fsb(m_info, size_t(offset), sizeof(_CharType));
-                case std::ios_base::cur:
-                    return (pos_type)_seekrdpos_fsb(m_info, size_t(m_info->m_rdpos+offset), sizeof(_CharType));
-                case std::ios_base::end:
-                    return (pos_type)_seekrdtoend_fsb(m_info, int64_t(offset), sizeof(_CharType));
-                default:
-                    // Fail on invalid input (_S_ios_seekdir_end)
-                    assert(false);
-                }
-            }
-            else if ( (m_info->m_mode & std::ios::ios_base::app) == 0 )
-            {
-                switch ( way )
-                {
-                case std::ios_base::beg:
-                    return (pos_type)_seekwrpos_fsb(m_info, size_t(offset), sizeof(_CharType));
-                case std::ios_base::cur:
-                    return (pos_type)_seekwrpos_fsb(m_info, size_t(m_info->m_wrpos+offset), sizeof(_CharType));
-                case std::ios_base::end:
-                    return (pos_type)_seekwrpos_fsb(m_info, size_t(-1), sizeof(_CharType));
-                default:
-                    // Fail on invalid input (_S_ios_seekdir_end)
-                    assert(false);
-                }
-            }
-            return (pos_type)traits::eof();
-        }
-
-        /// <summary>
-        /// For output streams, flush any internally buffered data to the underlying medium.
-        /// </summary>
-        virtual pplx::task<bool> _sync()
-        {
-            return flush_internal().then([](){return true;});
-        }
-
-    private:
-        template<typename _CharType1> friend class ::concurrency::streams::file_buffer;
-
-        pplx::task<void> flush_internal()
-        {
-            pplx::task_completion_event<void> result_tce;
-            auto callback = utility::details::make_unique<_filestream_callback_write_b>(m_info, result_tce);
-
-            if ( !_sync_fsb(m_info, callback.get()) )
-            {
-                return pplx::task_from_exception<void>(std::runtime_error("failure to flush stream"));
-            }
-            callback.release();
-            return pplx::create_task(result_tce);
-        }
-
-        basic_file_buffer(_In_ _file_info *info) : streambuf_state_manager<_CharType>(info->m_mode), m_info(info) { }
-
-#if !defined(__cplusplus_winrt)
-        static pplx::task<std::shared_ptr<basic_streambuf<_CharType>>> open(
-            const utility::string_t &_Filename,
-            std::ios_base::openmode _Mode = std::ios_base::out,
-#ifdef _WIN32
-            int _Prot = (int)std::ios_base::_Openprot
-#else
-            int _Prot = 0 // unsupported on Linux, for now
-#endif
-            )
-        {
-            auto result_tce = pplx::task_completion_event<std::shared_ptr<basic_streambuf<_CharType>>>();
-            auto callback = new _filestream_callback_open(result_tce);
-            _open_fsb_str(callback, _Filename.c_str(), _Mode, _Prot);
-            return pplx::create_task(result_tce);
-        }
-
-#else
-        static pplx::task<std::shared_ptr<basic_streambuf<_CharType>>> open(
-            ::Windows::Storage::StorageFile^ file,
-            std::ios_base::openmode _Mode = std::ios_base::out)
-        {
-            auto result_tce = pplx::task_completion_event<std::shared_ptr<basic_streambuf<_CharType>>>();
-            auto callback = new _filestream_callback_open(result_tce);
-            _open_fsb_stf_str(callback, file, _Mode, 0);
-            return pplx::create_task(result_tce);
-        }
-#endif
-
-        class _filestream_callback_open : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_open(const pplx::task_completion_event<std::shared_ptr<basic_streambuf<_CharType>>> &op) : m_op(op) { }
-
-            virtual void on_opened(_In_ _file_info *info)
-            {
-                m_op.set(std::shared_ptr<basic_file_buffer<_CharType>>(new basic_file_buffer<_CharType>(info)));
-                delete this;
-            }
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-        private:
-            pplx::task_completion_event<std::shared_ptr<basic_streambuf<_CharType>>> m_op;
-        };
-
-        class _filestream_callback_close : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_close(const pplx::task_completion_event<void> &op) : m_op(op) { }
-
-            virtual void on_closed()
-            {
-                m_op.set();
-                delete this;
-            }
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-        private:
-            pplx::task_completion_event<void> m_op;
-        };
-
-        template<typename ResultType>
-        class _filestream_callback_write : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_write(_In_ _file_info *info, const pplx::task_completion_event<ResultType> &op) : m_info(info), m_op(op) { }
-
-            virtual void on_completed(size_t result)
-            {
-                m_op.set((ResultType)result / sizeof(_CharType));
-                delete this;
-            }
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-        private:
-            _file_info *m_info;
-            pplx::task_completion_event<ResultType> m_op;
-        };
-
-        class _filestream_callback_write_b : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_write_b(_In_ _file_info *info, const pplx::task_completion_event<void> &op) : m_info(info), m_op(op) { }
-
-            virtual void on_completed(size_t)
-            {
-                m_op.set();
-                delete this;
-            }
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-        private:
-            _file_info *m_info;
-            pplx::task_completion_event<void> m_op;
-        };
-
-
-        class _filestream_callback_read : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_read(_In_ _file_info *info, const pplx::task_completion_event<size_t> &op) : m_info(info), m_op(op) { }
-
-            virtual void on_completed(size_t result)
-            {
-                result = result / sizeof(_CharType);
-                m_info->m_rdpos += result;
-                m_op.set(result);
-                delete this;
-            }
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-        private:
-            _file_info *m_info;
-            pplx::task_completion_event<size_t> m_op;
-        };
-
-        class _filestream_callback_bumpc : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_bumpc(_In_ _file_info *info, const pplx::task_completion_event<int_type> &op) : m_ch(0), m_info(info), m_op(op) { }
-
-            virtual void on_completed(size_t result)
-            {
-                if ( result == sizeof(_CharType) )
-                {
-                    m_info->m_rdpos += 1;
-                    m_op.set(m_ch);
-                }
-                else
-                {
-                    m_op.set(traits::eof());
-                }
-                delete this;
-            }
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-            int_type           m_ch;
-
-        private:
-            _file_info *m_info;
-            pplx::task_completion_event<int_type> m_op;
-        };
-
-        class _filestream_callback_getc : public details::_filestream_callback
-        {
-        public:
-            _filestream_callback_getc(_In_ _file_info *info, const pplx::task_completion_event<int_type> &op) : m_ch(0), m_info(info), m_op(op) { }
-
-            virtual void on_completed(size_t result)
-            {
-                if ( result == sizeof(_CharType) )
-                {
-                    m_op.set(m_ch);
-                }
-                else
-                {
-                    m_op.set(traits::eof());
-                }
-                delete this;
-            }
-
-            int_type           m_ch;
-
-            virtual void on_error(const std::exception_ptr & e)
-            {
-                m_op.set_exception(e);
-                delete this;
-            }
-
-        private:
-            _file_info *m_info;
-            pplx::task_completion_event<int_type> m_op;
-        };
-
-        _file_info *m_info;
-        async_operation_queue m_readOps;
-    };
-
-    } // namespace details
-
-    /// <summary>
-    /// Stream buffer for file streams.
-    /// </summary>
-    /// <typeparam name="_CharType">
-    /// The data type of the basic element of the <c>file_buffer</c>.
-    /// </typeparam>
-    template<typename _CharType>
-    class file_buffer
-    {
-    public:
-#if !defined(__cplusplus_winrt)
-        /// <summary>
-        /// Open a new stream buffer representing the given file.
-        /// </summary>
-        /// <param name="file_name">The name of the file</param>
-        /// <param name="mode">The opening mode of the file</param>
-        /// <param name="prot">The file protection mode</param>
-        /// <returns>A <c>task</c> that returns an opened stream buffer on completion.</returns>
-        static pplx::task<streambuf<_CharType>> open(
-            const utility::string_t &file_name,
-            std::ios_base::openmode mode = std::ios_base::out,
-#ifdef _WIN32
-            int prot = _SH_DENYRD
-#else
-            int prot = 0 // unsupported on Linux
-#endif
-            )
-        {
-            auto bfb = details::basic_file_buffer<_CharType>::open(file_name, mode, prot);
-            return bfb.then([](pplx::task<std::shared_ptr<details::basic_streambuf<_CharType>>> op) -> streambuf<_CharType>
-                {
-                    return streambuf<_CharType>(op.get());
-                });
-        }
-
-#else
-        /// <summary>
-        /// Open a new stream buffer representing the given file.
-        /// </summary>
-        /// <param name="file">The StorageFile instance</param>
-        /// <param name="mode">The opening mode of the file</param>
-        /// <param name="prot">The file protection mode</param>
-        /// <returns>A <c>task</c> that returns an opened stream buffer on completion.</returns>
-        static pplx::task<streambuf<_CharType>> open(
-            ::Windows::Storage::StorageFile^ file,
-            std::ios_base::openmode mode = std::ios_base::out)
-        {
-            auto bfb = details::basic_file_buffer<_CharType>::open(file, mode);
-            return bfb.then([](pplx::task<std::shared_ptr<details::basic_streambuf<_CharType>>> op) -> streambuf<_CharType>
-                {
-                    return streambuf<_CharType>(op.get());
-                });
-        }
-#endif
-    };
-
-
-    /// <summary>
-    /// File stream class containing factory functions for file streams.
-    /// </summary>
-    /// <typeparam name="_CharType">
-    /// The data type of the basic element of the <c>file_stream</c>.
-    /// </typeparam>
-    template<typename _CharType>
-    class file_stream
-    {
-    public:
-
-#if !defined(__cplusplus_winrt)
-        /// <summary>
-        /// Open a new input stream representing the given file.
-        /// The file should already exist on disk, or an exception will be thrown.
-        /// </summary>
-        /// <param name="file_name">The name of the file</param>
-        /// <param name="mode">The opening mode of the file</param>
-        /// <param name="prot">The file protection mode</param>
-        /// <returns>A <c>task</c> that returns an opened input stream on completion.</returns>
-        static pplx::task<streams::basic_istream<_CharType>> open_istream(
-            const utility::string_t &file_name,
-            std::ios_base::openmode mode = std::ios_base::in,
-#ifdef _WIN32
-            int prot = (int) std::ios_base::_Openprot
-#else
-            int prot = 0
-#endif
-            )
-        {
-            mode |= std::ios_base::in;
-            return streams::file_buffer<_CharType>::open(file_name, mode, prot)
-                .then([](streams::streambuf<_CharType> buf) -> basic_istream<_CharType>
-                {
-                    return basic_istream<_CharType>(buf);
-                });
-        }
-
-        /// <summary>
-        /// Open a new ouput stream representing the given file.
-        /// If the file does not exist, it will be create unless the folder or directory
-        /// where it is to be found also does not exist.
-        /// </summary>
-        /// <param name="file_name">The name of the file</param>
-        /// <param name="mode">The opening mode of the file</param>
-        /// <param name="prot">The file protection mode</param>
-        /// <returns>A <c>task</c> that returns an opened output stream on completion.</returns>
-        static pplx::task<streams::basic_ostream<_CharType>> open_ostream(
-            const utility::string_t &file_name,
-            std::ios_base::openmode mode = std::ios_base::out,
-#ifdef _WIN32
-            int prot = (int) std::ios_base::_Openprot
-#else
-            int prot = 0
-#endif
-            )
-        {
-            mode |= std::ios_base::out;
-            return streams::file_buffer<_CharType>::open(file_name, mode, prot)
-                .then([](streams::streambuf<_CharType> buf) -> basic_ostream<_CharType>
-                {
-                    return basic_ostream<_CharType>(buf);
-                });
-        }
-#else
-        /// <summary>
-        /// Open a new input stream representing the given file.
-        /// The file should already exist on disk, or an exception will be thrown.
-        /// </summary>
-        /// <param name="file">The StorageFile reference representing the file</param>
-        /// <param name="mode">The opening mode of the file</param>
-        /// <returns>A <c>task</c> that returns an opened input stream on completion.</returns>
-        static pplx::task<streams::basic_istream<_CharType>> open_istream(
-            ::Windows::Storage::StorageFile^ file,
-            std::ios_base::openmode mode = std::ios_base::in)
-        {
-            mode |= std::ios_base::in;
-            return streams::file_buffer<_CharType>::open(file, mode)
-                .then([](streams::streambuf<_CharType> buf) -> basic_istream<_CharType>
-                {
-                    return basic_istream<_CharType>(buf);
-                });
-        }
-
-        /// <summary>
-        /// Open a new ouput stream representing the given file.
-        /// If the file does not exist, it will be create unless the folder or directory
-        /// where it is to be found also does not exist.
-        /// </summary>
-        /// <param name="file">The StorageFile reference representing the file</param>
-        /// <param name="mode">The opening mode of the file</param>
-        /// <returns>A <c>task</c> that returns an opened output stream on completion.</returns>
-        static pplx::task<streams::basic_ostream<_CharType>> open_ostream(
-            ::Windows::Storage::StorageFile^ file,
-            std::ios_base::openmode mode = std::ios_base::out)
-        {
-            mode |= std::ios_base::out;
-            return streams::file_buffer<_CharType>::open(file, mode)
-                .then([](streams::streambuf<_CharType> buf) -> basic_ostream<_CharType>
-                {
-                    return basic_ostream<_CharType>(buf);
-                });
-        }
-#endif
-    };
-
-    typedef file_stream<uint8_t> fstream;
-}} // namespace concurrency::streams
-
-#endif
-
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