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Bug 633 - Incorrect use of the kill($pid, 0) idiom.
Summary: Incorrect use of the kill($pid, 0) idiom.
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: audio (show other bugs)
Version: HG 2.0
Hardware: x86 Linux
: P2 normal
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL: http://dev.laptop.org/ticket/8307
Keywords:
Depends on:
Blocks:
 
Reported: 2008-09-25 19:27 UTC by Michael Stone
Modified: 2009-02-16 21:18 UTC (History)
0 users

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Description Michael Stone 2008-09-25 19:27:29 UTC 
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.
Comment 1 Sam Lantinga 2009-02-16 21:18:19 UTC 
Thanks, this is fixed in revision 4433.