Re: [9fans] how to avoid a memset() optimization

["Douglas A. Gwyn" <DAGwyn@null.net>]

Tomas wrote:
> I've been fantasizing about having some sort of atreturn()
> functionality similar to atexit() to use in error handling (as
> soon as a file is opened, do an atreturn() and specify that that
> fd should be closed upon a "return -1;" but not otherwise, for
> example).
> Has anyone else been thinking in that direction? Does anyone have
> references to mailing list/usenet discussions or papers about
> such a feature?

Back in the Good Old Days (tm), we had what we called "completion
routines".  In an I/O service call one could optionally include a
pointer to a completion routine, which the OS would invoke after
the operation was complete.  (Of course the service call returned
immediately without waiting for the operation to complete.)

In C you could invent an API implemented as macros that would do
more or less what you indicated; there would have to be a label
near the end of the function.  It's not obvious that this buys
you very much, unlike general exception handling which spans
multiple function depth.