/*******************************
* Wrappers for the SIO routines
******************************/
ssize_t Sio_putl(long v)
{
ssize_t n;
if ((n = sio_putl(v)) < 0)
sio_error("Sio_putl error");
return n;
}
/*
* sigchld_handler - The kernel sends a SIGCHLD to the shell whenever
* a child job terminates (becomes a zombie), or stops because it
* received a SIGSTOP, SIGTSTP, SIGTTIN or SIGTTOU signal. The
* handler reaps all available zombie children, but doesn't wait
* for any other currently running children to terminate.
*/
void sigchld_handler(int sig) {
int status;
pid_t pid;
int olderrno = errno; // store errno in handler
/*
* Reap child with the pid if the child is stopped or terminated
* If a child is terminated normally, delete the child from the job list
* If a child is stopped by a signal, set the job status as stopped
* If a child is terminated by a signal that was not caught, delete the child from the job list
*/
while ((pid = waitpid(-1, &status, WNOHANG|WUNTRACED)) > 0) {
if (WIFEXITED(status)) {
deletejob(job_list, pid); // the child ternimated normally
} else if (WIFSTOPPED(status)) {
/*
* Avoid printf() in handler, use helper function to write the output to stdout
*/
sio_puts("Job [");
sio_putl(pid2jid(pid));
sio_puts("] (");
sio_putl(pid);
sio_puts(") stopped by signal ");
sio_putl(WSTOPSIG(status));
sio_puts("\n");
getjobpid(job_list, pid) -> state = ST; // the child was stopped by a signal
} else if (WIFSIGNALED(status)) { // the child was terminated by a signal that was not caught
/*
* Avoid printf() in handler, use helper function to write the output to stdout
*/
sio_puts("Job [");
sio_putl(pid2jid(pid));
sio_puts("] (");
sio_putl(pid);
sio_puts(") terminated by signal ");
sio_putl(WTERMSIG(status));
sio_puts("\n");
deletejob(job_list, pid);
}
}
errno = olderrno;
return;
}
