[PATCH] Use ngx_socket_errno where appropriate.

[Maxim Dounin]

Hello!

On Fri, Jan 31, 2014 at 09:38:08AM +0400, Igor Sysoev wrote:

> On Jan 31, 2014, at 8:35 , Ruslan Ermilov wrote:
> 
> > Hi Piotr,
> > 
> > On Thu, Jan 30, 2014 at 04:16:04PM -0800, Piotr Sikora wrote:
> 
> [ ... ]
> 
> > These seem questionable to me because the ioctl/fcntl calls are
> > known to report back in errno, and they're not wrapped into ngx_foo()
> > calls here.
> > 
> > My own preferences are as follows.
> > 
> > Use "ngx_errno" if we directly call ioctl/fcntl from the UNIX context.
> > I'd even prefer using "errno" here, but that doesn't seem to agree
> > with the current code.  Still, some code uses "errno" here, and that
> > perhaps should be fixed as well.
> > 
> > Use "ngx_socket_errno" for socket-related calls, including wrappers
> > such as ngx_nonblocking() known to apply to exclusively to sockets.
> 
> Yes, ngx_socket_errno should used only for socket-related calls and
> only in cross-plarform parts which can be compiled on no-Unix platform
> (that is on Windows).

The src/os/unix/ currently has lots of ngx_socket_errno uses, e.g. 
os/unix/ngx_recv.c, in ngx_unix_recv():

        n = recv(c->fd, buf, size, 0);

        ...

        err = ngx_socket_errno;

        if (err == NGX_EAGAIN || err == NGX_EINTR) {
            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                           "recv() not ready");
            n = NGX_AGAIN;

        } else {
            n = ngx_connection_error(c, err, "recv() failed");
            break;
        }

And this basically matches similar code in src/os/win32:

    rc = WSARecv(c->fd, wsabuf, 1, &bytes, &flags, NULL, NULL);

    ...

        err = ngx_socket_errno;

        if (err == WSAEWOULDBLOCK) {
            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                           "WSARecv() not ready");
            return NGX_AGAIN;
        }

        n = ngx_connection_error(c, err, "WSARecv() failed");

I don't think we should change this - it's good and easily 
portable to other platforms.  For me it looks like using 
ngx_socket_errno even in non-cross-platform parts is ok and should 
be preferred as long as it's in socket-related code.

-- 
Maxim Dounin
http://nginx.org/