[Mono-list] LCC and CIL

Michael Poole poole@troilus.org
12 Mar 2002 17:25:29 -0500


"Dominic Cooney" <dominic@dcooney.com> writes:

> I guess I need to brush up on my C! gcc allows this:
> 
> #include <setjmp.h>
> 
> jmp_buf env_buf;
> 
> int funcA()
> {
> 	int v = setjmp(env_buf);
> 	printf("setjmp returned %d\n", v);
> 	return v;
> }
> 
> int main()
> {
> 	if (!funcA())
> 		longjmp(env_buf, 1);
> }
> 
> gcc's executable works correctly, and I thought the program was legal.
> MSVC++ accepts it and prints "setjmp returned 0, setjmp returned 1" but
> then crashes.

What is "works correctly"?  I don't have an ANSI/ISO C spec handy, but
http://www.opengroup.org/onlinepubs/007908799/xsh/longjmp.html (the
longjmp() specification from SuSv2) says that the behavior of
longjmp(env_buf, ...) is undefined if the corresponding
setjmp(env_buf) was called from a function that has returned.  This is
the case in the above code.

-- Michael Poole