根据它的运行时间运行func（）

Question

i wrote some code that monitors a directory DIR with inotify() and when a file gets moved in DIR i get a .txt output of that file(its an nfcapd file with flows of my network interface). This happens every 5 minutes.

After that, i used Snort's DPX starter kit, with which you can extend Snort by writing your own preprocessor. This preprocessor,like all the others, is just a function that's executed every time a new packet is available. My problem is that i want, when a new file gets exported from my previous code(so every 5 minutes), to read that file inside the preprocessor's function.

So, is there any way of getting the time and executing only if it's the desired time?

if (time is 15:36){
    func(output.txt);}

i'm writing in c.

Thanks

Answer 1

You can do something like the following:

#include <time.h>
...

time_t t = time(NULL); //obtain current time in seconds
struct tm broken_time;
localtime_r(&t, &broken_time); // split time into fields

if(broken_time.tm_hour == 15 && broken_time.tm_min == 36) { //perform the check
    func(output.txt);
}

Answer 2

Since you're using inotify , I'm assuming your environment supports POSIX signals.

You can use alarm() to raise a signal after a predetermined amount of time has passed and have the appropriate signal handler do whatever work you need to do. It would avoid what I think is going to end up being a very ugly infinite loop in your code.

So, in your case, the function handling SIGALRM would not need to worry what time it was, it would know that a predetermined amount of time has passed by the fact that it was entered. However, you'll need to provide some context that function can access to know what to do, kind of hard to suggest how without seeing your code.

I'm not entirely sure you're going down the right path with this, but using alarm() would probably be the sanest approach given what you described.