Re: [lwip-users] errno is not set in sockets.c

[address@hidden]

Kieran Mansley wrote:
> On 20 Mar 2012, at 09:53, Mason wrote:
>
> > Looking at sockets.c, the relevant code is:
> >
> > #ifdef ERRNO
> > #ifndef set_errno
> > #define set_errno(err) errno = (err)
> > #endif
> > #else /* ERRNO */
> > #define set_errno(err)
> > #endif /* ERRNO */
> I suspect that it might be something relevant to Windows ports.  I can't see a 
> problem with the change you suggest, but I'd like to understand what this was 
> for in the first place as I'm cautious when it comes to things that require 
> changes to the ports - we need to have a good reason for them.

I don't think it's a Windows port thing: it's not defined in the windows 
port plus it compiles correctly with or without ERRNO being defined. 
It's odd though that it's not defined: I have written code (in 
contrib/apps/socket_examples) that uses 'errno' to assert things (and 
successfully used it for testing nonblocking sockets) but it obviously 
doesn't run without that define... :-/

I do know that I've just added the '#ifndef set_errno' 2 years ago, so 
the '#ifdef ERRNO' was probably the only way to *not* use 'errno' before 
that.

Personally, I think it's correct that we do not change 'errno' without 
explicitly enabling it: we don't want to mess with C library code that 
uses 'errno' by default.

Simon