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server_3.c 5.39 KiB
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#include <iostream>
#include <csignal>
#include <cstdlib>
#include <unistd.h>
#include <cstring>
#include <unistd.h> 
#include <ctime>
#include <sys/wait.h>


volatile bool running = true;

void print_in_exit() {
    std::cout << "Message during exit" << std::endl;
}

void handle_signal(int signal_number) {
    std::cout << "Received signal: " << signal_number << std::endl;
    std::cout << "Stopping the program" << std::endl;
    running = false;
}

void print_process_info(const char* process_type) {
    std::cout <<process_type << " | id: " << getpid() << std::endl;
    std::cout <<process_type << " | father id: " << getppid() << std::endl;
    std::cout <<process_type << " | groupd id: " << getpgrp() << std::endl;
    std::cout << rand() % 100 << std::endl;
}


int main(){
    std::cout << "started" << std::endl;
    if (atexit(print_in_exit) != 0) {
        perror("Fail in exit");
        exit(EXIT_FAILURE);
    }

    struct sigaction sa;
    sa.sa_handler = handle_signal;
    sa.sa_flags = 0;
    sigemptyset(&sa.sa_mask);

    if (sigaction(SIGINT, &sa, nullptr) == -1) {
        perror("Fail in exit");
        exit(EXIT_FAILURE);
    }

    if (sigaction(SIGTERM, &sa, nullptr) == -1) {
        perror("Fail in exit");
        exit(EXIT_FAILURE);
    }

    pid_t pid = fork();
    if (pid == 0) {
        while (running) {
            print_process_info("Child");
            sleep(1);
        }
    } else {
        while (running) {
            print_process_info("Parent");
            sleep(1);
            int status;
            pid_t result = waitpid(pid, &status, WNOHANG);
            if (result == pid) {
                std::cout << "child dead, father stopping" << std::endl;
                running = false;
            }
        }
    }

    std::cout << "finished" << std::endl;

    return EXIT_SUCCESS;
}

/*
Ouput:
Parent | id: 26677
Parent | father id: 16628
Parent | groupd id: 26677
23
Child | id: 26678
Child | father id: 26677
Child | groupd id: 26677
23
Parent | id: 26677
Parent | father id: 16628
Parent | groupd id: 26677
67
Child | id: 26678
Child | father id: 26677
Child | groupd id: 26677
67
Parent | id: 26677
Parent | father id: 16628
Parent | groupd id: 26677
35
Child | id: 26678
Child | father id: 26677
Child | groupd id: 26677
35
Parent | id: 26677
Parent | father id: 16628
Parent | groupd id: 26677
29
Child | id: 26678
Child | father id: 26677
Child | groupd id: 26677
29
Parent | id: 26677
Parent | father id: 16628
Parent | groupd id: 26677
2
Child | id: 26678
Child | father id: 26677
Child | groupd id: 26677
2
^CReceived signal: 2
Received signal: 2
Stopping the program
Stopping the program
finished
finished
Message during exit
Message during exit

They have the same group id, and they both stop cin CTR+C because they belong to the same group,
 and this singal is sent to all the process in the group


==============================================================================================================


   PPID     PID    PGID     SID TTY        TPGID STAT   UID   TIME COMMAND
   2344   16628   16628   16628 pts/1      28184 Ss     911   0:02 /bin/zsh -i
   2344   21290   21290   21290 pts/2      28302 Ss     911   0:00 /bin/zsh -i
  16628   28184   28184   16628 pts/1      28184 S+     911   0:00 ./a.out
  28184   28185   28184   16628 pts/1      28184 S+     911   0:00 ./a.out
  21290   28302   28302   21290 pts/2      28302 R+     911   0:00 ps aj

output:
58
Parent | id: 28184
Parent | father id: 16628
Parent | groupd id: 28184
58
Child | id: 28185
Child | father id: 28184
Child | groupd id: 28184

after killing the son:
36
Child | id: 28185
Parent | id: 28184
Child | father id: 28184
Child | groupd id: 28184
Parent | father id: 16628
5
Parent | groupd id: 28184
5
Child | id: 28185
Parent | id: 28184
Child | father id: 28184
Parent | father id: 16628
Child | groupd id: 28184
Parent | groupd id: 28184
46
46
Received signal: 15
Stopping the program
finished
Message during exit
Parent | id: 28184
Parent | father id: 16628
Parent | groupd id: 28184
29


AND

   PPID     PID    PGID     SID TTY        TPGID STAT   UID   TIME COMMAND
   2344   16628   16628   16628 pts/1      28184 Ss     911   0:02 /bin/zsh -i
   2344   21290   21290   21290 pts/2      28984 Ss     911   0:00 /bin/zsh -i
  16628   28184   28184   16628 pts/1      28184 S+     911   0:00 ./a.out
  28184   28185   28184   16628 pts/1      28184 Z+     911   0:00 [a.out] <defunct>
  21290   28984   28984   21290 pts/2      28984 R+     911   0:00 ps aj


the child continous there, but has a <defunct>

after killing first the parent:

   PPID     PID    PGID     SID TTY        TPGID STAT   UID   TIME COMMAND
   2344   16628   16628   16628 pts/1      16628 Ss+    911   0:02 /bin/zsh -i
   2344   21290   21290   21290 pts/2      30012 Ss     911   0:01 /bin/zsh -i
      1   29861   29860   16628 pts/1      16628 S      911   0:00 ./a.out
  21290   30012   30012   21290 pts/2      30012 R+     911   0:00 ps aj

the child continous to be running

If first I kill the child and then the father, both of them will desapear


After killing first the child:
Child | groupd id: 31529
29
Received signal: 15
Stopping the program
finished
Message during exit
child dead, father stopping
finished
Message during exit