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发信人: GyeaonWoo (柏林恋人), 信区: Linux
标  题: Linus's Linux--kernel/exit.c
发信站: 荔园晨风BBS站 (Mon Aug 25 20:38:53 2003), 站内信件

#include <errno.h>
#include <signal.h>
#include <sys/wait.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/tty.h>
#include <asm/segment.h>

int sys_pause(void);
int sys_close(int fd);

void release(struct task_struct * p)
{
        int i;

        if (!p)
                return;
        for (i=1 ; i<NR_TASKS ; i++)
                if (task[i]==p) {
                        task[i]=NULL;
                        free_page((long)p);
                        schedule();
                        return;
                }
        panic("trying to release non-existent task");
}

static inline void send_sig(long sig,struct task_struct * p,int priv)
{
        if (!p || sig<1 || sig>32)
                return;
        if (priv ||
                current->uid==p->uid ||
                current->euid==p->uid ||
                current->uid==p->euid ||
                current->euid==p->euid)
                p->signal |= (1<<(sig-1));
}

void do_kill(long pid,long sig,int priv)
{
        struct task_struct **p = NR_TASKS + task;

        if (!pid) while (--p > &FIRST_TASK) {
                if (*p && (*p)->pgrp == current->pid)
                        send_sig(sig,*p,priv);
        } else if (pid>0) while (--p > &FIRST_TASK) {
                if (*p && (*p)->pid == pid)
                        send_sig(sig,*p,priv);
        } else if (pid == -1) while (--p > &FIRST_TASK)
                send_sig(sig,*p,priv);
        else while (--p > &FIRST_TASK)
                if (*p && (*p)->pgrp == -pid)
                        send_sig(sig,*p,priv);
}

int sys_kill(int pid,int sig)
{
        do_kill(pid,sig,!(current->uid || current->euid));
        return 0;
}

int do_exit(long code)
{
        int i;

        free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
        free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
        for (i=0 ; i<NR_TASKS ; i++)
                if (task[i] && task[i]->father == current->pid)
                        task[i]->father = 0;
        for (i=0 ; i<NR_OPEN ; i++)
                if (current->filp[i])
                        sys_close(i);
        iput(current->pwd);
        current->pwd=NULL;
        iput(current->root);
        current->root=NULL;
        if (current->leader && current->tty >= 0)
                tty_table[current->tty].pgrp = 0;
        if (last_task_used_math == current)
                last_task_used_math = NULL;
        if (current->father) {
                current->state = TASK_ZOMBIE;
                do_kill(current->father,SIGCHLD,1);
                current->exit_code = code;
        } else
                release(current);
        schedule();
        return (-1);    /* just to suppress warnings */
}

int sys_exit(int error_code)
{
        return do_exit((error_code&0xff)<<8);
}

int sys_waitpid(pid_t pid,int * stat_addr, int options)
{
        int flag=0;
        struct task_struct ** p;

        verify_area(stat_addr,4);
repeat:
        for(p = &LAST_TASK ; p > &FIRST_TASK ; --p)
                if (*p && *p != current &&
                   (pid==-1 || (*p)->pid==pid ||
                   (pid==0 && (*p)->pgrp==current->pgrp) ||
                   (pid<0 && (*p)->pgrp==-pid)))
                        if ((*p)->father == current->pid) {
                                flag=1;
                                if ((*p)->state==TASK_ZOMBIE) {
                                        put_fs_long((*p)->exit_code,
                                                (unsigned long *) stat_addr);
                                        current->cutime += (*p)->utime;
                                        current->cstime += (*p)->stime;
                                        flag = (*p)->pid;
                                        release(*p);
                                        return flag;
                                }
                        }
        if (flag) {
                if (options & WNOHANG)
                        return 0;
                sys_pause();
                if (!(current->signal &= ~(1<<(SIGCHLD-1))))
                        goto repeat;
                else
                        return -EINTR;
        }
        return -ECHILD;
}

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