///////////////////////////////////////////////////////////////////////////////

// Copyright (c) Lewis Baker

// Licenced under MIT license. See LICENSE.txt for details.

///////////////////////////////////////////////////////////////////////////////

#include <cppcoro/file_read_operation.hpp>

#if CPPCORO_OS_WINNT

# ifndef WIN32_LEAN_AND_MEAN

# define WIN32_LEAN_AND_MEAN

# endif

# include <windows.h>

bool cppcoro::file_read_operation_impl::try_start(

cppcoro::detail::win32_overlapped_operation_base& operation) noexcept

{

const DWORD numberOfBytesToRead =

m_byteCount <= 0xFFFFFFFF ?

static_cast<DWORD>(m_byteCount) : DWORD(0xFFFFFFFF);

DWORD numberOfBytesRead = 0;

BOOL ok = ::ReadFile(

m_fileHandle,

m_buffer,

numberOfBytesToRead,

&numberOfBytesRead,

operation.get_overlapped());

const DWORD errorCode = ok ? ERROR_SUCCESS : ::GetLastError();

if (errorCode != ERROR_IO_PENDING)

{

// Completed synchronously.

//

// We are assuming that the file-handle has been set to the

// mode where synchronous completions do not post a completion

// event to the I/O completion port and thus can return without

// suspending here.

operation.m_errorCode = errorCode;

operation.m_numberOfBytesTransferred = numberOfBytesRead;

return false;

}

return true;

}

void cppcoro::file_read_operation_impl::cancel(

cppcoro::detail::win32_overlapped_operation_base& operation) noexcept

{

(void)::CancelIoEx(m_fileHandle, operation.get_overlapped());

}

#elif CPPCORO_OS_LINUX

bool cppcoro::file_read_operation_impl::try_start(

cppcoro::detail::linux_async_operation_base& operation) noexcept

{

auto seek_res = lseek(m_fd, m_offset, SEEK_SET);

if (seek_res < 0) {

operation.m_res = -errno;

return false;

}

operation.m_completeFunc = [=]() {

int res = read(m_fd, m_buffer, m_byteCount);

operation.m_mq->remove_fd_watch(m_fd);

return res;

};

operation.m_mq->add_fd_watch(m_fd, reinterpret_cast<void*>(&operation), EPOLLIN);

return true;

}

void cppcoro::file_read_operation_impl::cancel(

cppcoro::detail::linux_async_operation_base& operation) noexcept

{

operation.m_mq->remove_fd_watch(m_fd);

}

#endif