Help: Unwinding the C++ stack...throw, longjmp & threads

[Joe Buck]

> >Making try, catch, and throw available in C would be a nice GNU
> >extension,
...
Josh writes:
> If this extension would allow exceptions to be thrown from
> Unix signal handlers, that would be a very cool feature
> for even non-threaded programs.

It wouldn't, since we don't support that in C++ either.  The problem
is that signals can happen anywhere.  Consider

   char * buf = 0;
   try {
	buf = malloc(buf_size);
   }
   catch (SIGNAL) {
	if (buf)
		free(buf);
   }

This code has a race and a leak, and there's no way to write it correctly,
because the signal could come after malloc has allocated memory but before
buf is assigned.

I suppose there could be a mechanism to queue signals and throw exceptions
at "safe" points.