I'm assuming this doesn't already happen, i've not seen it before, the newest gcc I use is 4.3.2 Would it be possible to add a warning to gcc C when code in an signal handler (alarm) uses non thread safe calls. My documentation for linux is old enough it has zero warning other than a possible interaction between alarm() and sleep(). I've found the information I need in the signal man page from an updated debian, but this is largely news to me :-( I filed this report: http://sourceware.org/bugzilla/show_bug.cgi?id=13845 Gcc's own documentation is incomplete on the subject The example here risks not just printing incorrect values but stopping completely waiting in a futex forever. http://www.gnu.org/software/libc/manual/html_node/Non_002datomic-Example.html#Non_002datomic-Example No warning here http://www.gnu.org/software/libc/manual/html_node/Setting-an-Alarm.html Typical alarm example, also not safe http://www.ccplusplus.com/2011/10/alarm-function-example-in-c.html http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04 "unspecified" is a very vague warning. Its sometimes acceptable for something to give the wrong answer for its output but its never acceptable for a process to stall and never resume. If this kind of thing is the outcome then gcc needs to babysit me more :-) Thanks, Jon
