Variable-length messages.

[Dave Jones]

>From article <LJZ.88Oct20131114%fxgrp.fx.com at ames.arc.nasa.gov>, by ljz%fxgrp.fx.com at ames.arc.nasa.gov (Lloyd Zusman):
> We have a difference of opinion at our site as to what is the most
> desirable way to handle variable-length messages in C.

...

> One group of us here says it's OK to handle this case as follows:
> 
> 	struct message {
> 		int msgType;		/* msg type code */
> 		int msgLength;		/* length of msg body */
> 		char msgBody[1];	/* variable length msg body */
> 	};
> 

This looks unsafe to me.  That one-char-long "msgBody" can be
packed into the structure at any of a number of different places,
depending on the compiler's alignment strategy.

The "msgBody" is not a one-char-long arrary. In general, it's not nice
to fool Mother Nature.




One thing you might consider is using Sun's public domain "XDR".
I think you can get it from anonymous ftp somewhere around the net.
It's got some defects, but it *is* already written, and it *is*
free.  Check it out.