I am learning about signals and wrote a simple programs that plays with them.
So i am inputting a number then using fork i create a process.The parent process is supposed to send the number as a signal to the child process,then the child_signal handler is supposed to send back the number squared as a signal.
This is the code.
#include <iostream>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>
#include <errno.h>
using namespace std;
void child_handler(int sig_num){
cout<<"Child recieved a signal"<<endl;
pid_t ppid = getppid();
if(kill(ppid,sig_num*sig_num) == -1){
cout<<"Childs signal handler failed to send a signal "<<endl;
}
cout<<"Sent a sgnal to the parent"<<endl;
return;
}
void parent_handler(int sig_num){
cout<<"Parent recieved a signal "<<endl;
cout<<sig_num<<endl;
return;
}
int main(){
int n;
cin>>n;
pid_t pid = fork();
if(pid != 0){
struct sigaction sa2;
memset(&sa2,0,sizeof(sa2));
sa2.sa_handler = parent_handler;
if(sigaction(n,&sa2,NULL) == -1){
cout<<"Parents sigaction failed "<<endl;
}
if(kill(pid,n) == -1){
cout<<"Kill failed "<<endl;
}
cout<<"Sent a signal to the child"<<endl;
waitpid(pid,0,0);
}
else{
struct sigaction sa1;
memset(&sa1,0,sizeof(sa1));
sa1.sa_handler = child_handler;
if(sigaction(n,&sa1,NULL) == -1){
cout<<"Childs sigaction failed eerno:"<<errno<<endl;
}
sleep(20);
return 0;
}
return 0;
}
The output is this.
Sent a signal to the child.
And it doesn't say anything about sigaction.
