/*
 *  linux/kernel/exit.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/config.h>
#include <linux/wait.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/resource.h>
#include <linux/mm.h>
#include <linux/tty.h>
#include <linux/malloc.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>

extern void sem_exit (void);
extern void acct_process (long exitcode);
extern void kerneld_exit(void);

int getrusage(struct task_struct *, int, struct rusage *);

static inline void generate(unsigned long sig, struct task_struct * p)
{
        unsigned flags;
        unsigned long mask = 1 << (sig-1);
        struct sigaction * sa = sig + p->sig->action - 1;

        /*
         * Optimize away the signal, if it's a signal that can
         * be handled immediately (ie non-blocked and untraced)
         * and that is ignored (either explicitly or by default)
         */
        spin_lock_irqsave(&p->sig->siglock, flags);
        if (!(mask & p->blocked) && !(p->flags & PF_PTRACED)) {
                /* don't bother with ignored signals (but SIGCHLD is special) */
                if (sa->sa_handler == SIG_IGN && sig != SIGCHLD)
                        goto out;
                /* some signals are ignored by default.. (but SIGCONT already did its deed) */
                if ((sa->sa_handler == SIG_DFL) &&
                    (sig == SIGCONT || sig == SIGCHLD || sig == SIGWINCH || sig == SIGURG))
                        goto out;
        }
        spin_lock(&p->sigmask_lock);
        p->signal |= mask;
        spin_unlock(&p->sigmask_lock);
        if (p->state == TASK_INTERRUPTIBLE && (p->signal & ~p->blocked))
                wake_up_process(p);
out:
        spin_unlock_irqrestore(&p->sig->siglock, flags);
}

/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
 */
void force_sig(unsigned long sig, struct task_struct * p)
{
        sig--;
        if (p->sig) {
                unsigned flags;
                unsigned long mask = 1UL << sig;
                struct sigaction *sa = p->sig->action + sig;

                spin_lock_irqsave(&p->sig->siglock, flags);

                spin_lock(&p->sigmask_lock);
                p->signal |= mask;
                p->blocked &= ~mask;
                spin_unlock(&p->sigmask_lock);

                if (sa->sa_handler == SIG_IGN)
                        sa->sa_handler = SIG_DFL;
                if (p->state == TASK_INTERRUPTIBLE)
                        wake_up_process(p);

                spin_unlock_irqrestore(&p->sig->siglock, flags);
        }
}

int send_sig(unsigned long sig,struct task_struct * p,int priv)
{
        if (!p || sig > 32)
                return -EINVAL;
        if (!priv && ((sig != SIGCONT) || (current->session != p->session)) &&
            (current->euid ^ p->suid) && (current->euid ^ p->uid) &&
            (current->uid ^ p->suid) && (current->uid ^ p->uid) &&
            !suser())
                return -EPERM;

        if (sig && p->sig) {
                unsigned flags;
                spin_lock_irqsave(&p->sigmask_lock, flags);
                if ((sig == SIGKILL) || (sig == SIGCONT)) {
                        if (p->state == TASK_STOPPED)
                                wake_up_process(p);
                        p->exit_code = 0;
                        p->signal &= ~( (1<<(SIGSTOP-1)) | (1<<(SIGTSTP-1)) |
                                        (1<<(SIGTTIN-1)) | (1<<(SIGTTOU-1)) );
                }
                if (sig == SIGSTOP || sig == SIGTSTP || sig == SIGTTIN || sig == SIGTTOU)
                        p->signal &= ~(1<<(SIGCONT-1));
                spin_unlock_irqrestore(&p->sigmask_lock, flags);

                /* Actually generate the signal */
                generate(sig,p);
        }
        return 0;
}

void notify_parent(struct task_struct * tsk, int signal)
{
        struct task_struct * parent = tsk->p_pptr;

        send_sig(signal, parent, 1);
        wake_up_interruptible(&parent->wait_chldexit);
}

static void release(struct task_struct * p)
{
        if (p != current) {
#ifdef __SMP__
                /* FIXME! Cheesy, but kills the window... -DaveM */
                do {
                        barrier();
                } while (p->has_cpu);
                spin_unlock_wait(&scheduler_lock);
#endif
                charge_uid(p, -1);
                nr_tasks--;
                add_free_taskslot(p->tarray_ptr);
                unhash_pid(p);
                REMOVE_LINKS(p);
                release_thread(p);
                current->cmin_flt += p->min_flt + p->cmin_flt;
                current->cmaj_flt += p->maj_flt + p->cmaj_flt;
                current->cnswap += p->nswap + p->cnswap;
                free_task_struct(p);
        } else {
                printk("task releasing itself\n");
        }
}

/*
 * This checks not only the pgrp, but falls back on the pid if no
 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
 * without this...
 */
int session_of_pgrp(int pgrp)
{
        struct task_struct *p;
        int fallback;

        fallback = -1;
        read_lock(&tasklist_lock);
        for_each_task(p) {
                if (p->session <= 0)
                        continue;
                if (p->pgrp == pgrp) {
                        fallback = p->session;
                        break;
                }
                if (p->pid == pgrp)
                        fallback = p->session;
        }
        read_unlock(&tasklist_lock);
        return fallback;
}

/*
 * kill_pg() sends a signal to a process group: this is what the tty
 * control characters do (^C, ^Z etc)
 */
int kill_pg(int pgrp, int sig, int priv)
{
        int retval;

        retval = -EINVAL;
        if (sig >= 0 && sig <= 32 && pgrp > 0) {
                struct task_struct *p;
                int found = 0;

                retval = -ESRCH;
                read_lock(&tasklist_lock);
                for_each_task(p) {
                        if (p->pgrp == pgrp) {
                                int err = send_sig(sig,p,priv);
                                if (err != 0)
                                        retval = err;
                                else
                                        found++;
                        }
                }
                read_unlock(&tasklist_lock);
                if (found)
                        retval = 0;
        }
        return retval;
}

/*
 * kill_sl() sends a signal to the session leader: this is used
 * to send SIGHUP to the controlling process of a terminal when
 * the connection is lost.
 */
int kill_sl(int sess, int sig, int priv)
{
        int retval;

        retval = -EINVAL;
        if (sig >= 0 && sig <= 32 && sess > 0) {
                struct task_struct *p;
                int found = 0;

                retval = -ESRCH;
                read_lock(&tasklist_lock);
                for_each_task(p) {
                        if (p->leader && p->session == sess) {
                                int err = send_sig(sig,p,priv);

                                if (err)
                                        retval = err;
                                else
                                        found++;
                        }
                }
                read_unlock(&tasklist_lock);
                if (found)
                        retval = 0;
        }
        return retval;
}

int kill_proc(int pid, int sig, int priv)
{
        int retval;

        retval = -EINVAL;
        if (sig >= 0 && sig <= 32) {
                struct task_struct *p = find_task_by_pid(pid);
                
                if(p)
                        retval = send_sig(sig, p, priv);
                else
                        retval = -ESRCH;
        }
        return retval;
}

/*
 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
 * is probably wrong.  Should make it like BSD or SYSV.
 */
asmlinkage int sys_kill(int pid,int sig)
{
        if (!pid)
                return kill_pg(current->pgrp,sig,0);

        if (pid == -1) {
                int retval = 0, count = 0;
                struct task_struct * p;

                read_lock(&tasklist_lock);
                for_each_task(p) {
                        if (p->pid > 1 && p != current) {
                                int err;
                                ++count;
                                if ((err = send_sig(sig,p,0)) != -EPERM)
                                        retval = err;
                        }
                }
                read_unlock(&tasklist_lock);
                return count ? retval : -ESRCH;
        }
        if (pid < 0)
                return kill_pg(-pid,sig,0);

        /* Normal kill */
        return kill_proc(pid,sig,0);
}

/*
 * Determine if a process group is "orphaned", according to the POSIX
 * definition in 2.2.2.52.  Orphaned process groups are not to be affected
 * by terminal-generated stop signals.  Newly orphaned process groups are
 * to receive a SIGHUP and a SIGCONT.
 *
 * "I ask you, have you ever known what it is to be an orphan?"
 */
static int will_become_orphaned_pgrp(int pgrp, struct task_struct * ignored_task)
{
        struct task_struct *p;

        read_lock(&tasklist_lock);
        for_each_task(p) {
                if ((p == ignored_task) || (p->pgrp != pgrp) ||
                    (p->state == TASK_ZOMBIE) ||
                    (p->p_pptr->pid == 1))
                        continue;
                if ((p->p_pptr->pgrp != pgrp) &&
                    (p->p_pptr->session == p->session)) {
                        read_unlock(&tasklist_lock);
                        return 0;
                }
        }
        read_unlock(&tasklist_lock);
        return 1;       /* (sighing) "Often!" */
}

int is_orphaned_pgrp(int pgrp)
{
        return will_become_orphaned_pgrp(pgrp, 0);
}

static inline int has_stopped_jobs(int pgrp)
{
        int retval = 0;
        struct task_struct * p;

        read_lock(&tasklist_lock);
        for_each_task(p) {
                if (p->pgrp != pgrp)
                        continue;
                if (p->state != TASK_STOPPED)
                        continue;
                retval = 1;
                break;
        }
        read_unlock(&tasklist_lock);
        return retval;
}

static inline void forget_original_parent(struct task_struct * father)
{
        struct task_struct * p;

        read_lock(&tasklist_lock);
        for_each_task(p) {
                if (p->p_opptr == father) {
                        p->exit_signal = SIGCHLD;
                        p->p_opptr = task[smp_num_cpus] ? : task[0];    /* init */
                }
        }
        read_unlock(&tasklist_lock);
}

static inline void close_files(struct files_struct * files)
{
        int i, j;

        j = 0;
        for (;;) {
                unsigned long set = files->open_fds.fds_bits[j];
                i = j * __NFDBITS;
                j++;
                if (i >= NR_OPEN)
                        break;
                while (set) {
                        if (set & 1) {
                                struct file * file = files->fd[i];
                                if (file) {
                                        files->fd[i] = NULL;
                                        close_fp(file);
                                }
                        }
                        i++;
                        set >>= 1;
                }
        }
}

extern kmem_cache_t *files_cachep;  

static inline void __exit_files(struct task_struct *tsk)
{
        struct files_struct * files = tsk->files;

        if (files) {
                tsk->files = NULL;
                if (!--files->count) {
                        close_files(files);
                        kmem_cache_free(files_cachep, files);
                }
        }
}

void exit_files(struct task_struct *tsk)
{
  __exit_files(tsk);
}

static inline void __exit_fs(struct task_struct *tsk)
{
        struct fs_struct * fs = tsk->fs;

        if (fs) {
                tsk->fs = NULL;
                if (!--fs->count) {
                        dput(fs->root);
                        dput(fs->pwd);
                        kfree(fs);
                }
        }
}

void exit_fs(struct task_struct *tsk)
{
  __exit_fs(tsk);
}

static inline void __exit_sighand(struct task_struct *tsk)
{
        struct signal_struct * sig = tsk->sig;

        if (sig) {
                tsk->sig = NULL;
                if (atomic_dec_and_test(&sig->count))
                        kfree(sig);
        }
}

void exit_sighand(struct task_struct *tsk)
{
        __exit_sighand(tsk);
}

static inline void __exit_mm(struct task_struct * tsk)
{
        struct mm_struct * mm = tsk->mm;

        /* Set us up to use the kernel mm state */
        if (mm != &init_mm) {
                flush_cache_mm(mm);
                flush_tlb_mm(mm);
                destroy_context(mm);
                tsk->mm = &init_mm;
                tsk->swappable = 0;
                SET_PAGE_DIR(tsk, swapper_pg_dir);
                mmput(mm);
        }
}

void exit_mm(struct task_struct *tsk)
{
        __exit_mm(tsk);
}

/*
 * Send signals to all our closest relatives so that they know
 * to properly mourn us..
 */
static void exit_notify(void)
{
        struct task_struct * p;

        forget_original_parent(current);
        /*
         * Check to see if any process groups have become orphaned
         * as a result of our exiting, and if they have any stopped
         * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
         *
         * Case i: Our father is in a different pgrp than we are
         * and we were the only connection outside, so our pgrp
         * is about to become orphaned.
         */
        if ((current->p_pptr->pgrp != current->pgrp) &&
            (current->p_pptr->session == current->session) &&
            will_become_orphaned_pgrp(current->pgrp, current) &&
            has_stopped_jobs(current->pgrp)) {
                kill_pg(current->pgrp,SIGHUP,1);
                kill_pg(current->pgrp,SIGCONT,1);
        }
        /* Let father know we died */
        notify_parent(current, current->exit_signal);

        /*
         * This loop does two things:
         *
         * A.  Make init inherit all the child processes
         * B.  Check to see if any process groups have become orphaned
         *      as a result of our exiting, and if they have any stopped
         *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
         */
        while ((p = current->p_cptr) != NULL) {
                current->p_cptr = p->p_osptr;
                p->p_ysptr = NULL;
                p->flags &= ~(PF_PTRACED|PF_TRACESYS);

                p->p_pptr = p->p_opptr;
                p->p_osptr = p->p_pptr->p_cptr;
                if (p->p_osptr)
                        p->p_osptr->p_ysptr = p;
                p->p_pptr->p_cptr = p;
                if (p->state == TASK_ZOMBIE)
                        notify_parent(p, p->exit_signal);
                /*
                 * process group orphan check
                 * Case ii: Our child is in a different pgrp
                 * than we are, and it was the only connection
                 * outside, so the child pgrp is now orphaned.
                 */
                if ((p->pgrp != current->pgrp) &&
                    (p->session == current->session) &&
                    is_orphaned_pgrp(p->pgrp) &&
                    has_stopped_jobs(p->pgrp)) {
                        kill_pg(p->pgrp,SIGHUP,1);
                        kill_pg(p->pgrp,SIGCONT,1);
                }
        }
        if (current->leader)
                disassociate_ctty(1);
}

NORET_TYPE void do_exit(long code)
{
        if (in_interrupt())
                printk("Aiee, killing interrupt handler\n");
fake_volatile:
        acct_process(code);
        current->flags |= PF_EXITING;
        del_timer(&current->real_timer);
        sem_exit();
        kerneld_exit();
        __exit_mm(current);
#if CONFIG_AP1000
        exit_msc(current);
#endif
        __exit_files(current);
        __exit_fs(current);
        __exit_sighand(current);
        exit_thread();
        current->state = TASK_ZOMBIE;
        current->exit_code = code;
        exit_notify();
#ifdef DEBUG_PROC_TREE
        audit_ptree();
#endif
        if (current->exec_domain && current->exec_domain->module)
                __MOD_DEC_USE_COUNT(current->exec_domain->module);
        if (current->binfmt && current->binfmt->module)
                __MOD_DEC_USE_COUNT(current->binfmt->module);
        schedule();
/*
 * In order to get rid of the "volatile function does return" message
 * I did this little loop that confuses gcc to think do_exit really
 * is volatile. In fact it's schedule() that is volatile in some
 * circumstances: when current->state = ZOMBIE, schedule() never
 * returns.
 *
 * In fact the natural way to do all this is to have the label and the
 * goto right after each other, but I put the fake_volatile label at
 * the start of the function just in case something /really/ bad
 * happens, and the schedule returns. This way we can try again. I'm
 * not paranoid: it's just that everybody is out to get me.
 */
        goto fake_volatile;
}

asmlinkage int sys_exit(int error_code)
{
        lock_kernel();
        do_exit((error_code&0xff)<<8);
        unlock_kernel();
}

asmlinkage int sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struct rusage * ru)
{
        int flag, retval;
        struct wait_queue wait = { current, NULL };
        struct task_struct *p;

        if (stat_addr) {
                if(verify_area(VERIFY_WRITE, stat_addr, sizeof(*stat_addr)))
                        return -EFAULT;
        }
        if (ru) {
                if(verify_area(VERIFY_WRITE, ru, sizeof(*ru)))
                        return -EFAULT;
        }

        if (options & ~(WNOHANG|WUNTRACED|__WCLONE))
                return -EINVAL;

        add_wait_queue(&current->wait_chldexit,&wait);
repeat:
        flag = 0;
        read_lock(&tasklist_lock);
        for (p = current->p_cptr ; p ; p = p->p_osptr) {
                if (pid>0) {
                        if (p->pid != pid)
                                continue;
                } else if (!pid) {
                        if (p->pgrp != current->pgrp)
                                continue;
                } else if (pid != -1) {
                        if (p->pgrp != -pid)
                                continue;
                }
                /* wait for cloned processes iff the __WCLONE flag is set */
                if ((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
                        continue;
                flag = 1;
                switch (p->state) {
                        case TASK_STOPPED:
                                if (!p->exit_code)
                                        continue;
                                if (!(options & WUNTRACED) && !(p->flags & PF_PTRACED))
                                        continue;
                                read_unlock(&tasklist_lock);
                                if (ru != NULL)
                                        getrusage(p, RUSAGE_BOTH, ru);
                                if (stat_addr)
                                        __put_user((p->exit_code << 8) | 0x7f,
                                                   stat_addr);
                                p->exit_code = 0;
                                retval = p->pid;
                                goto end_wait4;
                        case TASK_ZOMBIE:
                                current->times.tms_cutime += p->times.tms_utime + p->times.tms_cutime;
                                current->times.tms_cstime += p->times.tms_stime + p->times.tms_cstime;
                                read_unlock(&tasklist_lock);
                                if (ru != NULL)
                                        getrusage(p, RUSAGE_BOTH, ru);
                                if (stat_addr)
                                        __put_user(p->exit_code, stat_addr);
                                retval = p->pid;
                                if (p->p_opptr != p->p_pptr) {
                                        /* Note this grabs tasklist_lock
                                         * as a writer... (twice!)
                                         */
                                        REMOVE_LINKS(p);
                                        p->p_pptr = p->p_opptr;
                                        SET_LINKS(p);
                                        notify_parent(p, SIGCHLD);
                                } else
                                        release(p);
#ifdef DEBUG_PROC_TREE
                                audit_ptree();
#endif
                                goto end_wait4;
                        default:
                                continue;
                }
        }
        read_unlock(&tasklist_lock);
        if (flag) {
                retval = 0;
                if (options & WNOHANG)
                        goto end_wait4;
                retval = -ERESTARTSYS;
                if (current->signal & ~current->blocked)
                        goto end_wait4;
                current->state=TASK_INTERRUPTIBLE;
                schedule();
                goto repeat;
        }
        retval = -ECHILD;
end_wait4:
        remove_wait_queue(&current->wait_chldexit,&wait);
        return retval;
}

#ifndef __alpha__

/*
 * sys_waitpid() remains for compatibility. waitpid() should be
 * implemented by calling sys_wait4() from libc.a.
 */
asmlinkage int sys_waitpid(pid_t pid,unsigned int * stat_addr, int options)
{
        return sys_wait4(pid, stat_addr, options, NULL);
}

#endif