3. Checking Pending Signals

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3. Checking Pending Signals

Explain how the sigpending function is used to examine pending signals in a process. Provide an example that checks if SIGINT is pending and prints a message accordingly.

gaurav133232

The sigpending function allows a process to inspect its pending signals. This can be useful for debugging or for applications that need to know which signals have been received while they were blocked. For e.g:-

#include<stdio.h>

#include <stdlib.h>

#include <signal.h>

#include <unistd.h>

void handle_signal(int sig)

{

printf("Caught signal %d\n", sig);

}

int main()

{

struct sigaction sa;

sa.sa_handler = handle_signal;

sa.sa_flags = 0;

sigemptyset(&sa.sa_mask);

// Set up the signal handler for SIGINT

if (sigaction(SIGINT, &sa, NULL) == -1)

{

perror("sigaction");

exit(EXIT_FAILURE);

}

sigset_t mask, oldmask, pending;

// Initialize the signal set to empty

sigemptyset(&mask);

sigaddset(&mask, SIGINT);
// Block SIGINT and save the old signal mask

if (sigprocmask(SIG_BLOCK, &mask, &oldmask) == -1)
{

perror("sigprocmask");

exit(EXIT_FAILURE);

}

printf("SIGINT blocked. Press Ctrl+C...\n");

sleep(5); // SIGINT is blocked during this sleep

// Check for pending signals
if (sigpending(&pending) == -1)

{

perror("sigpending");

exit(EXIT_FAILURE);

}
// Test if SIGINT is pending

if (sigismember(&pending, SIGINT))
{

printf("SIGINT is pending\n");

}

3. Checking Pending Signals

3. Checking Pending Signals

Explain how the sigpending function is used to examine pending signals in a process. Provide an example that checks if SIGINT is pending and prints a message accordingly.

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