Re: About signal handler install info

2011-12-01 Thread rahul dev 
See sigaction.

--- On Thu, 1/12/11, naveen yadav  wrote:

> From: naveen yadav 
> Subject: About signal handler install info
> To: Kernelnewbies@kernelnewbies.org, kernelnewb...@nl.linux.org
> Date: Thursday, 1 December, 2011, 3:33 PM
> Dear All,
> 
> I want to know is there any method/API  to know
> whether there is
> previous signal handler for specific signal no.
> 
> Example:
> 
> In below case  we install 3 handler. So my question is
> if before
> calling signal (SIGUSR1, handler2); is there any way i can
> get info
> that there is "handler1" already install with SIGUSR1.
> 
>         signal (SIGUSR1, handler1);
>         signal (SIGUSR1, handler2);
>         signal (SIGUSR1, handler3);
> 
> #include 
> #include 
> #include 
> #include 
> 
> void *func ();
> 
> void handler1 ()
> {
>         printf ("\nIn handler 1\n");
> }
> 
> void handler2 ()
> {
>         printf ("\nIn handler 2\n");
> }
> 
> void handler3 ()
> { printf ("\nIn handler 3\n"); }
> int main ()
> {
>         int err=-1;
>         pthread_t t1,t2;
> 
> 
>         signal (SIGUSR1, handler1);
>         sleep(5);
>         signal (SIGUSR1, handler2);
>         sleep(5);
>         signal (SIGUSR1, handler3);
>         sleep(5);
>         pthread_create (&t1, NULL,
> &func, NULL);
> 
>         sleep(20);
> 
>         return 0;
> }
> 
> void *func()
> {
>         while (1) usleep(10);
> }
> 
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> 

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About signal handler install info

2011-12-01 Thread naveen yadav 
Dear All,

I want to know is there any method/API  to know whether there is
previous signal handler for specific signal no.

Example:

In below case  we install 3 handler. So my question is if before
calling signal (SIGUSR1, handler2); is there any way i can get info
that there is "handler1" already install with SIGUSR1.

signal (SIGUSR1, handler1);
signal (SIGUSR1, handler2);
signal (SIGUSR1, handler3);

#include 
#include 
#include 
#include 

void *func ();

void handler1 ()
{
printf ("\nIn handler 1\n");
}

void handler2 ()
{
printf ("\nIn handler 2\n");
}

void handler3 ()
{ printf ("\nIn handler 3\n"); }
int main ()
{
int err=-1;
pthread_t t1,t2;


signal (SIGUSR1, handler1);
sleep(5);
signal (SIGUSR1, handler2);
sleep(5);
signal (SIGUSR1, handler3);
sleep(5);
pthread_create (&t1, NULL, &func, NULL);

sleep(20);

return 0;
}

void *func()
{
while (1) usleep(10);
}

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