I believe this is in reference to the following quote: http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03 http://pubs.opengro

I believe this is in reference to the following quote: http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03 http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2... The relevant quote is: the behavior is undefined if the signal handler refers to any object other than errno with static storage duration other than by assigning a value to an object declared as volatile sig_atomic_t, or if the signal handler calls any function defined in this standard other than one of the functions listed in the following table.