Re: [RFT] Wrap winsock functions for improved compatibility

[Bruno Haible]

Hi Paolo,

This is exciting! By using _open_osfhandle you are ensuring that there
are no collisions between native file handles and socket-related file handles.
Great!

A few comments, though:

- > It needs to be tested on Windows (mingw and cygwin)

  The patch is supposed to change nothing on Cygwin, right? Cygwin has
  perfectly fine POSIX socket support already.

- The transformation of WSAGetLastError() values to errno values is a nice
  trick, but the mapping e -> e - 10000 will not work out because of some
  clashes. Looking at mingw's <errno.h> and <winsock2.h> the first ones are
  ok but not the later ones:

#define EINTR           4       /* Interrupted function call */
#define WSAEINTR        (WSABASEERR+4)
ok

#define EBADF           9       /* Bad file descriptor */
#define WSAEBADF        (WSABASEERR+9)
ok

#define EACCES          13      /* Permission denied */
#define WSAEACCES       (WSABASEERR+13)
ok

#define EFAULT          14      /* Bad address */
#define WSAEFAULT       (WSABASEERR+14)
ok

#define EINVAL          22      /* Invalid argument */
#define WSAEINVAL       (WSABASEERR+22)
ok

#define EMFILE          24      /* Too many open files */
#define WSAEMFILE       (WSABASEERR+24)
ok

#define WSAEWOULDBLOCK  (WSABASEERR+35)
ok

#define EDEADLOCK       36      /* Resource deadlock avoided (non-Cyg) */
#define WSAEINPROGRESS  (WSABASEERR+36) /* deprecated on WinSock2 */ 
clash

#define WSAEALREADY     (WSABASEERR+37)

#define ENAMETOOLONG    38      /* Filename too long (91 in Cyg?) */
#define WSAENOTSOCK     (WSABASEERR+38)
clash

#define ENOLCK          39      /* No locks available (46 in Cyg?) */
#define WSAEDESTADDRREQ (WSABASEERR+39)
clash

#define ENOSYS          40      /* Function not implemented (88 in Cyg?) */
#define WSAEMSGSIZE     (WSABASEERR+40)
clash

#define ENOTEMPTY       41      /* Directory not empty (90 in Cyg?) */
#define WSAEPROTOTYPE   (WSABASEERR+41)
clash

#define EILSEQ          42      /* Illegal byte sequence */
#define WSAENOPROTOOPT  (WSABASEERR+42)
clash

  I would propose to leave the higher WSA* values as is, though a
  mapping   e -> (e < 10025 ? e - 10000 : e)

- It would be good to extend the gnulib <errno.h>, <string.h>, <stdio.h>,
  strerror, perror replacements to handle these values (when the sys_socket
  module is in use). (errno values are supposed to be all defined in <errno.h>,
  strerror is supposed to be declared in <string.h>, and perror is supposed
  to be declared in <stdio.h>.)

- Can we call the replacement functions "rpl_getsockopt" etc. please, not
  "win_getsockopt"? To make it clear that it's the gnulib replacement, and
  because the prefix "win" is subtle brainwashing.

- What about the need to call WSAInit()? Is it still needed at all?

- The doc should document that while most fd-based POSIX functions are
  correctly replaced, things like
     int fd = connect (...);
     FILE *fp = fdopen (fd, "w");
  will not work - because the fwrite() function will call write(), not send(),
  under the hood.

Bruno