SIGINT - how to delete files after sigint has been send to interrupt the process

[baxy]

Hi, i have a simple question. I have a program that makes a directory (temporary) and in it some files that are necessary for computation while program is running. Now suppose a user decides to interrupt the program at some stage. what happens is that the program stops but my folder and files remain.

Q: How to override SIGINT command so that before the the execution stops the folder is deleted ?

thank you

baxy

[Salem]

signal(2): ANSI C signal handling - Linux man page

You also need this
"Async-signal-safe functions"
signal(7) - Linux manual page

You can call unlink() to remove files with a known name, and rmdir() to remove the whole directory once it is empty.

[baxy]

Thank you for kicking me in the right direction

However I have another related question

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>

void sig_stop(int signo){
  if (signo == SIGINT){
    printf("You are done:  SIGINT\n");
    exit(0);
	}
}

int main(){
	int i=0;
  if (signal(SIGINT, sig_stop) == SIG_ERR)
  printf("\nerror SIGINT\n");

  while(i<10){ 
    i++;
    printf("i:%d\n",i);
    sleep(1);
}
  return 0;
}

So the above code is catching the SIGINT, and i know that the function prototipe for interrupt "= sig_end(int sig)" but is there a way to pass more arguments ?? so that i can do something before i exit() the program ??

PS

I want to avoid any global variables if possible. If not, then the solution is straightforward ...

[Salem]

The only parameter you get in a signal handler is the signal number.
So if you want more data, it has to be global.

You also need to make sure that any data you set up is consistent at all times (as much as possible anyway).
So for example, your list of filenames to be deleted should be in something like

// 50 files, max path length is 300
char filesToDelete[50][300] = { { 0 } };

Yes it wastes some space, but it's a lot safer than some fancy scheme involving malloc and lots of pointers which would be very hard to make signal-safe.


When you're in a signal handler, you're in a kind of "limbo" state.
You can only use a certain set of functions (see the link previously posted), and you shouldn't spend an excessive amount of time doing work.

You can't call printf() for example, as per your post (you have to use write() if you want to write a message), and you should use _exit() rather than exit() if you want to bail out of a program inside the signal handler.

[baxy]

Thank you, i think i get it now , thanks !