Any file handle created with FLAG_OVERLAPPED must have
ReadFile()/WriteFile() called with an OVERLAPPED structure.
Failing to do so will give unspecified results, invalid read/write or
corruption.
Without FLAG_OVERLAPPED, it is not possible to read and write
concurrently, even with two seperate threads, created by 2 input and
output gio streams. Also, only with FLAG_OVERLAPPED may an IO
operation be asynchronous and thus be cancellable.
We may want to call ReOpenFile() to make sure the FLAG is set, but
this API is only available since Vista+.
According to MSDN doc, adding the OVERLAPPED argument for IO operation
on handles without FLAG_OVERLAPPED is allowed, and indeed the existing
test still passes.
v2:
- update GetLastError() after _g_win32_overlap_wait_result ()
- split the unrelated ERROR_MORE_DATA handling
https://bugzilla.gnome.org/show_bug.cgi?id=679288
Correspond to GUnixInputStream and GUnixOutputStream. No true async
support though. But that is how the Win32 API is, for files not
explicitly opened for so-called overlapped IO.
The API to create these streams takes Win32 HANDLEs. Not file
descriptors, because file descriptors are specific to the C library
used. The user code and GLib might be using different C libraries.
Also add a test program for the new classes, and a gio-windows-2.0.pc
file.
