/**
* @brief Yields the processor.
*/
PUBLIC void yield(void)
{
struct process *p; /* Working process. */
struct process *next; /* Next process to run. */
/* Re-schedule process for execution. */
if (curr_proc->state == PROC_RUNNING)
sched(curr_proc);
/* Remember this process. */
last_proc = curr_proc;
/* Check alarm. */
for (p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip invalid processes. */
if (!IS_VALID(p))
continue;
/* Alarm has expired. */
if ((p->alarm) && (p->alarm < ticks))
p->alarm = 0, sndsig(p, SIGALRM);
}
/* Choose a process to run next. */
next = IDLE;
for (p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip non-ready process. */
if (p->state != PROC_READY)
continue;
/*
* Process with higher
* waiting time found.
*/
if (p->counter > next->counter)
{
next->counter++;
next = p;
}
/*
* Increment waiting
* time of process.
*/
else
p->counter++;
}
/* Switch to next process. */
next->priority = PRIO_USER;
next->state = PROC_RUNNING;
next->counter = PROC_QUANTUM;
switch_to(next);
}
/**
* @brief Sends a signal to process group.
*
* @details Sends the signal @p sig to the process group of the currently active
* TTY device.
*
* @param sig Signal to be sent.
*/
PRIVATE void tty_signal(int sig)
{
for (struct process *p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip invalid processes. */
if (!IS_VALID(p))
continue;
if (active->pgrp == p->pgrp)
sndsig(p, sig);
}
}
/**
* @brief Stops the current running process.
*/
PUBLIC void stop(void)
{
curr_proc->state = PROC_STOPPED;
sndsig(curr_proc->father, SIGCHLD);
yield();
}
/*
* Sends a signal to a process or a process group.
*/
PUBLIC int sys_kill(pid_t pid, int sig)
{
int err;
struct process *p;
/* Invalid signal. */
if ((sig < 0) || (sig > NR_SIGNALS - 1))
return (-EINVAL);
err = -ESRCH;
/* Send signal to process. */
if (pid > 0)
{
/* Search for process. */
for (p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip invalid processes. */
if (!IS_VALID(p))
continue;
/* Found. */
if (pid == p->pid)
{
err = -EPERM;
if (AUTHORIZED(curr_proc, p, sig))
{
err = 0;
sndsig(p, sig);
}
}
}
}
/* Send signal to process group. */
else if (pid == 0)
{
/* Search for processes. */
for (p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip invalid processes. */
if (!IS_VALID(p))
continue;
/* Found. */
if (curr_proc->pgrp == p->pgrp)
{
err = -EPERM;
if (AUTHORIZED(curr_proc, p, sig))
{
err = 0;
sndsig(p, sig);
}
}
}
}
/* Send signal to all processes. */
else if (pid == -1)
{
err = -EPERM;
/* Search for processes. */
for (p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip invalid processes. */
if (!IS_VALID(p))
continue;
if (AUTHORIZED(curr_proc, p, sig))
{
err = 0;
sndsig(p, sig);
}
}
}
/* Send signal to absolute proces group. */
else
{
/* Search for processes. */
for (p = FIRST_PROC; p <= LAST_PROC; p++)
{
/* Skip invalid processes. */
if (!IS_VALID(p))
continue;
/* Found. */
if (p->pgrp->pid == -pid)
{
err = -EPERM;
if (AUTHORIZED(curr_proc, p, sig))
{
err = 0;
sndsig(p, sig);
}
}
}
}
return (err);
}