[FFmpeg-devel] [PATCH 1/2] ffmpeg: reset tty state correctly

Ganesh Ajjanagadde gajjanag at mit.edu
Mon Jul 27 16:16:04 CEST 2015


On Mon, Jul 27, 2015 at 10:11 AM, wm4 <nfxjfg at googlemail.com> wrote:
> On Mon, 27 Jul 2015 08:30:38 -0400
> Ganesh Ajjanagadde <gajjanag at mit.edu> wrote:
>
>> On Mon, Jul 27, 2015 at 7:35 AM, wm4 <nfxjfg at googlemail.com> wrote:
>> > On Mon, 27 Jul 2015 10:39:16 +0200
>> > Nicolas George <george at nsup.org> wrote:
>> >
>> >
>> >> > +    signal(SIGSEGV, sigterm_handler); /* Segmentation fault (ANSI).     */
>> >> > +    signal(SIGILL , sigterm_handler); /* Invalid instruction (ANSI).    */
>> >> > +    signal(SIGFPE , sigterm_handler); /* Arithmetic error (ANSI).       */
>> >>
>> >> NO!!!
>> >>
>> >> When a crash happens, we want it to happen right there, possibly leave a
>> >> core. We do not want a signal handler to mess up the remains.
>> >
>> > +1
>> >
>> >> >  #ifdef SIGXCPU
>> >> >      signal(SIGXCPU, sigterm_handler);
>> >> >  #endif
>> >
>> > Why?
>>
>> Not sure; note this was not added by me.
>> From Kerrisk's "Linux Programming Interface" book,
>> SIGXCPU is raised when CPU limit is exceeded.
>> It is a Linux thing, relevant when RLIMIT_CPU is set.
>
> You shouldn't just copy paste things you don't understand.

As I mentioned above, this was not part of my patch at all.
Since you asked why, I looked it up out of curiousity and gave
information that I could find.
I felt this would be useful to others on this list as well, and cite a
source for reference.
Therefore, I do not see what the trouble is in posting it to the discussion,
especially since I prefaced it with a "not sure".

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