Fixed bug #633 Description From Michael Stone 2008-09-25 19:27:29 (-) [reply] To determine whether a pid is occupied with the kill(pid, 0) idiom, you have to test #include <signal.h> #include <errno.h> kill(pid, 0) < 0 && errno == ESRCH not just #include <signal.h> kill(pid, 0) < 0 otherwise you get incorrect results when pid is running as a different user (causing kill(pid, 0) to return -1 + EPERM). src/audio/alsa/SDL_alsa_audio.c is certainly affected by this bug in both 1.2.13 and 1.3-trunk. It probably occurs in other places as well.