Re: bug: cygwin-devel v3.0.2-1 socket.h does not #define MSG_EOR per the POSIX standard

[Eliot Moss <moss@cs.umass.edu>]

On 4/24/2019 12:43 PM, Corinna Vinschen wrote:
> On Apr 24 15:47, Brabant, Edward H CTR (USA) wrote:
>> 1. In cygwin-devel v3.0.2-1, <cygwin/socket.h> does not #define
>> MSG_EOR.  In bash, with CWD=/usr/include, the command "find . -name
>> '*.h' -exec grep -Hn MSG_EOR {} \;" does not find any matches.
>>
>> 2. The Open Group man page for <sys/socket.h> contains the following
>> excerpt regarding #define MSG_EOR:
>>
>>       The <sys/socket.h> header shall define the following symbolic
>>       constants with distinct values for use as the valid values for
>>       the msg_flags field in the msghdr structure, or the flags
>>       parameter in recv(), recvfrom(), recvmsg(), send(), sendmsg(), or
>>       sendto() calls:
>> ...
>> MSG_EOR
>> Terminates a record (if supported by the protocol).
>> ...
> 
> MSG_EOR is not supported by underlying WinSock.  There's a similar
> MSG_PARTIAL, but it's defined differently.  It's also unsupported by
> all of the predefined protocols, including UDP.
> 
> Since MSG_EOR isn't implemented in the underlying transport layer,
> there's no way to implement it in userspace.  That's why it's not
> defined in Cygwin's headers.  If you have an idea how to implement
> this in plain userspace, feel free to provide patches.

I don't have a direct interest in this issue, but I do have a wondering.
If Cygwin fails to define an error code -- even if the error cannot
actually happen under Cygwin -- isn't that a problem when trying to
compile imported software?  I wouldn't mind if the code were defined,
and a note included in comments that the error will not actually
occur under Cygwin ...

Is this a reasonable argument in support of including a define of the
error code?

Regards -- Eliot Mos

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