Re: Winsock wrappers

[Bruno Haible]

Simon wrote:
> Is there any way for gnulib to detect that a fd was created by gnulib's
> winsock wrappers or the native systems?

Actually these two are different types: gnulib's file descriptors are 'int'
in the small nonnegative range, whereas a SOCKET is actually a HANDLE that
can be passed to ReadFile and WriteFile.

> >>> More or less.  Actually, the flag could be just "use send/recv or
> >>> read/write?" because of what I said above, and that means that it could
> >>> be done without including lib/winsock.c or other similarly unwanted
> >>> baggage into gnutls.
> >> 
> >> Are you saying that read/write on the socket would work under Windows?

Here's a matrix:

                      |  native fd    |   gnulib      | native SOCKET |
                      |               |  wrapped fd   |               |
-----------------------------------------------------------------------
ReadFile, WriteFile   |               |               |      YES      |
-----------------------------------------------------------------------
MSVCRT recv, send     |               |               |      YES      |
-----------------------------------------------------------------------
MSVCRT read, write    |     YES       |     YES       |               |
-----------------------------------------------------------------------

> However, it is rather simple for applications to write these wrappers
> themselves, so I think it is better to document how to do that.

There are only two choices: Either the API takes 'int' file descriptors,
or it takes SOCKET entities. A boolean is perfectly adequate in this
situation, and easier to understand for the user than potential wrapper
functions.

> Then the GnuTLS ABI doesn't depend on how gnulib have implemented sockets
> under Windows.

There was only really one boolean choice in how gnulib supports sockets:
either as SOCKET (in the past) or as 'int' (like on Unix, now).

Bruno