svn commit: r278737 - head/usr.sbin/flowctl

[Gleb Smirnoff]

  Bruce,

On Sat, Feb 14, 2015 at 08:46:58PM +1100, Bruce Evans wrote:
B> Using VLAs and also the C99 feature of declarations anwhere, and extensions
B> like __aligned(), we can almost implement a full alloca() using the fixed
B> version of this change:
B> 
B> /*
B>   * XXX need extended statement-expression so that __buf doesn't go out
B>   * of scope after the right brace.
B>   */
B> #define	my_alloca(n) __extension__ ({
B>  	/* XXX need unique name. */				\
B>  	char __buf[__roundup2((n), MUMBLE)] __aligned(MUMBLE);	\
B>  								\
B>  	(void *)__buf;						\
B> })

I like this idea. But would this exact code work? The life of
__buf is limited by the code block, and we exit the block
immediately. Wouldn't the allocation be overwritten if we
enter any function or block later?

-- 
Totus tuus, Glebius.