BOOL My_ReadFileScatter()
{
HANDLE hFile=NULL;
FILE_SEGMENT_ELEMENT aSegmentArray[50];
DWORD nNumberOfBytesToRead=NULL;
LPDWORD lpReserved=NULL;
LPOVERLAPPED lpOverlapped=NULL;
BOOL returnVal_Real = NULL;
BOOL returnVal_Intercepted = NULL;
DWORD error_Real = 0;
DWORD error_Intercepted = 0;
disableInterception();
returnVal_Real = ReadFileScatter (hFile,aSegmentArray,nNumberOfBytesToRead,lpReserved,lpOverlapped);
error_Real = GetLastError();
enableInterception();
returnVal_Intercepted = ReadFileScatter (hFile,aSegmentArray,nNumberOfBytesToRead,lpReserved,lpOverlapped);
error_Intercepted = GetLastError();
return ((returnVal_Real == returnVal_Intercepted) && (error_Real == error_Intercepted));
}
size_type file::readv(size_type file_offset, iovec_t const* bufs, int num_bufs, error_code& ec)
{
TORRENT_ASSERT((m_open_mode & rw_mask) == read_only || (m_open_mode & rw_mask) == read_write);
TORRENT_ASSERT(bufs);
TORRENT_ASSERT(num_bufs > 0);
TORRENT_ASSERT(is_open());
#if defined TORRENT_WINDOWS || defined TORRENT_LINUX || defined TORRENT_DEBUG
// make sure m_page_size is initialized
init_file();
#endif
#ifdef TORRENT_DEBUG
if (m_open_mode & no_buffer)
{
bool eof = false;
int size = 0;
// when opened in no_buffer mode, the file_offset must
// be aligned to pos_alignment()
TORRENT_ASSERT((file_offset & (pos_alignment()-1)) == 0);
for (file::iovec_t const* i = bufs, *end(bufs + num_bufs); i < end; ++i)
{
TORRENT_ASSERT((uintptr_t(i->iov_base) & (buf_alignment()-1)) == 0);
// every buffer must be a multiple of the page size
// except for the last one
TORRENT_ASSERT((i->iov_len & (size_alignment()-1)) == 0 || i == end-1);
if ((i->iov_len & (size_alignment()-1)) != 0) eof = true;
size += i->iov_len;
}
error_code code;
if (eof) TORRENT_ASSERT(file_offset + size >= get_size(code));
}
#endif
#ifdef TORRENT_WINDOWS
DWORD ret = 0;
// since the ReadFileScatter requires the file to be opened
// with no buffering, and no buffering requires page aligned
// buffers, open the file in non-buffered mode in case the
// buffer is not aligned. Most of the times the buffer should
// be aligned though
if ((m_open_mode & no_buffer) == 0)
{
// this means the buffer base or the buffer size is not aligned
// to the page size. Use a regular file for this operation.
LARGE_INTEGER offs;
offs.QuadPart = file_offset;
if (SetFilePointerEx(m_file_handle, offs, &offs, FILE_BEGIN) == FALSE)
{
ec = error_code(GetLastError(), get_system_category());
return -1;
}
for (file::iovec_t const* i = bufs, *end(bufs + num_bufs); i < end; ++i)
{
DWORD intermediate = 0;
if (ReadFile(m_file_handle, (char*)i->iov_base
, (DWORD)i->iov_len, &intermediate, 0) == FALSE)
{
ec = error_code(GetLastError(), get_system_category());
return -1;
}
ret += intermediate;
}
return ret;
}
int size = bufs_size(bufs, num_bufs);
// number of pages for the read. round up
int num_pages = (size + m_page_size - 1) / m_page_size;
// allocate array of FILE_SEGMENT_ELEMENT for ReadFileScatter
FILE_SEGMENT_ELEMENT* segment_array = TORRENT_ALLOCA(FILE_SEGMENT_ELEMENT, num_pages + 1);
FILE_SEGMENT_ELEMENT* cur_seg = segment_array;
for (file::iovec_t const* i = bufs, *end(bufs + num_bufs); i < end; ++i)
{
for (int k = 0; k < i->iov_len; k += m_page_size)
{
cur_seg->Buffer = PtrToPtr64((((char*)i->iov_base) + k));
++cur_seg;
}
}
// terminate the array
cur_seg->Buffer = 0;
OVERLAPPED ol;
ol.Internal = 0;
ol.InternalHigh = 0;
ol.OffsetHigh = file_offset >> 32;
ol.Offset = file_offset & 0xffffffff;
ol.hEvent = CreateEvent(0, true, false, 0);
ret += size;
size = num_pages * m_page_size;
if (ReadFileScatter(m_file_handle, segment_array, size, 0, &ol) == 0)
{
DWORD last_error = GetLastError();
if (last_error != ERROR_IO_PENDING)
{
TORRENT_ASSERT(GetLastError() != ERROR_BAD_ARGUMENTS);
ec = error_code(GetLastError(), get_system_category());
CloseHandle(ol.hEvent);
return -1;
}
if (GetOverlappedResult(m_file_handle, &ol, &ret, true) == 0)
{
ec = error_code(GetLastError(), get_system_category());
CloseHandle(ol.hEvent);
return -1;
}
}
CloseHandle(ol.hEvent);
return ret;
#else // TORRENT_WINDOWS
size_type ret = lseek(m_fd, file_offset, SEEK_SET);
if (ret < 0)
{
ec = error_code(errno, get_posix_category());
return -1;
}
#if TORRENT_USE_READV
#ifdef TORRENT_LINUX
bool aligned = false;
int size = 0;
// if we're not opened in no-buffer mode, we don't need alignment
if ((m_open_mode & no_buffer) == 0) aligned = true;
if (!aligned)
{
size = bufs_size(bufs, num_bufs);
if ((size & (size_alignment()-1)) == 0) aligned = true;
}
if (aligned)
#endif // TORRENT_LINUX
{
ret = ::readv(m_fd, bufs, num_bufs);
if (ret < 0)
{
ec = error_code(errno, get_posix_category());
return -1;
}
return ret;
}
#ifdef TORRENT_LINUX
file::iovec_t* temp_bufs = TORRENT_ALLOCA(file::iovec_t, num_bufs);
memcpy(temp_bufs, bufs, sizeof(file::iovec_t) * num_bufs);
iovec_t& last = temp_bufs[num_bufs-1];
last.iov_len = (last.iov_len & ~(size_alignment()-1)) + m_page_size;
ret = ::readv(m_fd, temp_bufs, num_bufs);
if (ret < 0)
{
ec = error_code(errno, get_posix_category());
return -1;
}
return (std::min)(ret, size_type(size));
#endif // TORRENT_LINUX
#else // TORRENT_USE_READV
ret = 0;
for (file::iovec_t const* i = bufs, *end(bufs + num_bufs); i < end; ++i)
{
int tmp = read(m_fd, i->iov_base, i->iov_len);
if (tmp < 0)
{
ec = error_code(errno, get_posix_category());
return -1;
}
ret += tmp;
if (tmp < i->iov_len) break;
}
return ret;
#endif // TORRENT_USE_READV
#endif // TORRENT_WINDOWS
}
