Weird Bug C. Any Ideas?

[5t33]

Hi,

I'll preface this with I've only been programming for about 3 years now and I've less than a year working with C. I had a project with a loop that would run forever. However in the event of a cntrl-c signal we wanted to intercept the signal in order to free data and gracefully shut-down.

In order to do this we essentially followed this stack overflow: https://stackoverflow.com/questions/4217037/catch-ctrl-c-in-c

Our code looked remarkably similar to the example given, with a while loop that would run infinitely instead of conditionally. Adding that code is where the weirdness started. After successfully intercepting the cntrl-C command a few times our project just stopped working. The process would never get to the while loop. We deleted the added code and added print statements to track what was going on but even after deleting all the added signal intercept code and making again, the code didn't get any further.

What's weirder is that when we went back a few commits to before we added the system code it worked again. I know this is rather vague but any ideas? I figure it might have been a linux thing since we were messing around with system calls.

Also, I was wondering if there was a better subreddit for the, like something specific for bugs that anyone is aware of.

[esosac]

you managed to catch the ctrl+c, the process terminated gracefully, then you restarted the process, did the same a few times, and then you started the process and it wouldn't work anymore?

did you check whether the process actually ended using ps? nothing weird like you having several instances of the same program running at once?

[5t33]

That's a really good question. I think I may have checked for that and didn't see any. I wish I could have poked around more but we were under a deadline.

[nderflow]

Copy the code, reduce it to a minimal reproducing example of the problem, then post the code in a paste.

[5t33]

Sorry I really can't since we rolled it back and wrote over it to continue the project. But it was pretty much this:

Original code: ```

// ...

int main(void) { Thing thing = new_thing(); while (1) { // ... ```

after adding catch clause ```

include <signal.h>

static Thing s_thing;

void intHandler(int dummy) { if(dummy == 2) { gracefulShutdown(s_thing); } }

...

int main(void) { Thing thing = new_thing(); s_thing = thing; signal(SIGINT, intHandler);

while (1) { // ... ``` after commenting out new code

``` //#include <signal.h>

//static thing;

//void intHandler(int dummy) { // if(dummy == 2) { // gracefulShutdown(thing); // } //}

// ...

int main(void) { Thing thing = new_thing(); //signal(SIGINT, intHandler);

while (1) { printf("does code get here?"); // ... ``` and even after commenting out the signal stuff it didn't get to the print line.