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

On 4/25/19 10:28 AM, Brian Inglis wrote:

>> - add a define for MSG_EOR to a non-zero value that is bitwise distinct
>> from other required MSG_ values
>> - return EOPNOTSUPP on attempts to use the flag in
>> send()/sendmsg()/sendto() (POSIX permits that failure for protocols that
>> don't support it - and none of Cygwin's protocols support it)

>> although I personally thought POSIX was clear enough that MSG_EOR is
>> required to be defined, even if only so that it can trigger send()
>> errors showing that it is unsupported.
> Would it be allowed and valid to #define MSG_EOR 0 to simplify lack of support?

No, because that implies that EVERY send() call is requesting MSG_EOR
and that it never fails.  Defining it to a distinct non-zero value makes
it possible to report EOPNOTSUPP.

Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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