[zeromq-dev] patch: non-blocking tcp accept
sustrik at fastmq.com
Tue Apr 28 12:53:14 CEST 2009
>> The one thing I'm unsure of is EAGAIN/EWOULDBLOCK distinction. It seems
>> that both Linux and Win32 assign the same numeric value to both errors.
>> I am not sure of other platforms.
>> POSIX says:
>> Resource unavailable, try again (may be the same value as
>> Operation would block (may be the same value as [EAGAIN]).
>> Pretty confusing...
> from /usr/include/errno.h on AIX 5.3 ...
> /* non-blocking and interrupt i/o */
> * AIX returns EAGAIN where 4.3BSD used EWOULDBLOCK;
> * but, the standards insist on unique errno values for each errno.
> * A unique value is reserved for users that want to code case
> * statements for systems that return either EAGAIN or EWOULDBLOCK.
> #if _XOPEN_SOURCE_EXTENDED==1
> #define EWOULDBLOCK EAGAIN /* Operation would block */
> #else /* _XOPEN_SOURCE_EXTENDED */
> #define EWOULDBLOCK 54
> #endif /* _XOPEN_SOURCE_EXTENDED */
> Might help de-confuse?
Oh my. It's even worse then I've expected :) The actual values may
change depending on macros defined.
I've checked Solaris in the meantime - same value for both errors.
Anyway, it seems that checking for both errors everywhere we are
checking for one of the two at the moment would yield a sane result.
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