What exactly SIG_DFL do?

Question

What exactly SIG_DFL (defaut handler for signals) does? I'm interested in debugging SIGTSTP. It misbehaves slightly under weird conditions. I have suspicion it is doing something strange if one the threads is in the TASK_ININTERRUPTBLE state.

Where is SIG_DFL source code? Libc?

Thanks.

Employed Russian · Accepted Answer · 2022-03-19T03:58:03.717

29

What exactly SIG_DFL (defaut handler for signals) do?

It does exactly what one would expect: informs the kernel that there is no user signal handler for the given signal, and that the kernel should take default action for it (the action itself may be to ignore the signal, to terminate the program (with or without core dump), etc. depending on the signal).

Where is SIG_DFL source code? Libc?

There is usually a #define SIG_DLF -1 in /usr/include/signal.h, but the decision on what to do is in the kernel.

edited Mar 19 '22 at 03:58

answered Nov 29 '15 at 00:14

Employed Russian

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So it is in the kernel... I think this explains all my struggle. Thank you. – George Shuklin Dec 01 '15 at 10:59
@Employed Russian The link is broken :-( , could you update it？Thanks. :-) – Li-Guangda Mar 19 '22 at 02:40
@LGD Updated the link. – Employed Russian Mar 19 '22 at 03:58

What exactly SIG_DFL do?

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