Problem with Socket under Linux...

John M McIntosh johnmci at
Wed Apr 24 21:55:08 UTC 2002

>>  (Andreas, you must be in Germany right? Normally the list is
>>  pretty dead when I am awake... :-))
>You're right ;-)
>>  > > Then... you do not in fact signal the semaphore when there is
>>  > > no data - right? (I don't really know what your last line before
>>  > > "return 0" does, is that the "arming" stuff? Hey, btw, the Unix
>>  > > version returns -1 if the socket is not valid, not 0...)
>>  >
>>  > Which is right. It means that the socket is broke, thus returning an
>>  > error code (-1) instead of telling the client that there's simply no
>>  > data available is the right thing to do.
>>  Good.
>Bad ... I just looked at the plugin side of it and it turns out that the
>code for receiveDataAvailable _cannot_ return an error code. The return
>code is converted into a boolean and any non-zero return value will be
>interpreted as "true". There ya go. Gotta check my own code now.
>   - Andreas

Beware of returning -1 from these calls. I think some older code once 
returned -1 as the result of wanting to see how much data was 
available. The Smalltalk code then said, oh, not zero, lets allocate 
a new bytearray of -1 in length...

It's fuzzy to remember which call that was, but at the time it caused 
of course a new primitive failure walkback.
John M. McIntosh <johnmci at> 1-800-477-2659
Corporate Smalltalk Consulting Ltd.

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