kernel/exit.c

/* */
This source file includes following definitions.
release
send_sig
kill_session
sys_kill
tell_father
do_exit
sys_exit
sys_waitpid
   1 /*
   2  *  linux/kernel/exit.c
   3  *
   4  *  (C) 1991  Linus Torvalds
   5  */
   6 
   7 #include <errno.h>
   8 #include <signal.h>
   9 #include <sys/wait.h>
  10 
  11 #include <linux/sched.h>
  12 #include <linux/kernel.h>
  13 #include <linux/tty.h>
  14 #include <asm/segment.h>
  15 
  16 int sys_pause(void);
  17 int sys_close(int fd);
  18 
  19 void release(struct task_struct * p)
     /*  */
  20 {
  21         int i;
  22 
  23         if (!p)
  24                 return;
  25         for (i=1 ; i<NR_TASKS ; i++)
  26                 if (task[i]==p) {
  27                         task[i]=NULL;
  28                         free_page((long)p);
  29                         schedule();
  30                         return;
  31                 }
  32         panic("trying to release non-existent task");
  33 }
  34 
  35 static inline int send_sig(long sig,struct task_struct * p,int priv)
     /*  */
  36 {
  37         if (!p || sig<1 || sig>32)
  38                 return -EINVAL;
  39         if (priv || (current->euid==p->euid) || suser())
  40                 p->signal |= (1<<(sig-1));
  41         else
  42                 return -EPERM;
  43         return 0;
  44 }
  45 
  46 static void kill_session(void)
     /*  */
  47 {
  48         struct task_struct **p = NR_TASKS + task;
  49         
  50         while (--p > &FIRST_TASK) {
  51                 if (*p && (*p)->session == current->session)
  52                         (*p)->signal |= 1<<(SIGHUP-1);
  53         }
  54 }
  55 
  56 /*
  57  * XXX need to check permissions needed to send signals to process
  58  * groups, etc. etc.  kill() permissions semantics are tricky!
  59  */
  60 int sys_kill(int pid,int sig)
     /*  */
  61 {
  62         struct task_struct **p = NR_TASKS + task;
  63         int err, retval = 0;
  64 
  65         if (!pid) while (--p > &FIRST_TASK) {
  66                 if (*p && (*p)->pgrp == current->pid) 
  67                         if (err=send_sig(sig,*p,1))
  68                                 retval = err;
  69         } else if (pid>0) while (--p > &FIRST_TASK) {
  70                 if (*p && (*p)->pid == pid) 
  71                         if (err=send_sig(sig,*p,0))
  72                                 retval = err;
  73         } else if (pid == -1) while (--p > &FIRST_TASK)
  74                 if (err = send_sig(sig,*p,0))
  75                         retval = err;
  76         else while (--p > &FIRST_TASK)
  77                 if (*p && (*p)->pgrp == -pid)
  78                         if (err = send_sig(sig,*p,0))
  79                                 retval = err;
  80         return retval;
  81 }
  82 
  83 static void tell_father(int pid)
     /*  */
  84 {
  85         int i;
  86 
  87         if (pid)
  88                 for (i=0;i<NR_TASKS;i++) {
  89                         if (!task[i])
  90                                 continue;
  91                         if (task[i]->pid != pid)
  92                                 continue;
  93                         task[i]->signal |= (1<<(SIGCHLD-1));
  94                         return;
  95                 }
  96 /* if we don't find any fathers, we just release ourselves */
  97         release(current);
  98 }
  99 
 100 int do_exit(long code)
     /*  */
 101 {
 102         int i;
 103 
 104         free_page_tables(get_base(current->ldt[1]),get_limit(0x0f));
 105         free_page_tables(get_base(current->ldt[2]),get_limit(0x17));
 106         for (i=0 ; i<NR_TASKS ; i++)
 107                 if (task[i] && task[i]->father == current->pid)
 108                         task[i]->father = 0;
 109         for (i=0 ; i<NR_OPEN ; i++)
 110                 if (current->filp[i])
 111                         sys_close(i);
 112         iput(current->pwd);
 113         current->pwd=NULL;
 114         iput(current->root);
 115         current->root=NULL;
 116         if (current->leader && current->tty >= 0)
 117                 tty_table[current->tty].pgrp = 0;
 118         if (last_task_used_math == current)
 119                 last_task_used_math = NULL;
 120         if (current->leader)
 121                 kill_session();
 122         current->state = TASK_ZOMBIE;
 123         current->exit_code = code;
 124         tell_father(current->father);
 125         schedule();
 126         return (-1);    /* just to suppress warnings */
 127 }
 128 
 129 int sys_exit(int error_code)
     /*  */
 130 {
 131         return do_exit((error_code&0xff)<<8);
 132 }
 133 
 134 int sys_waitpid(pid_t pid,unsigned long * stat_addr, int options)
     /*  */
 135 {
 136         int flag;
 137         struct task_struct ** p;
 138 
 139         verify_area(stat_addr,4);
 140 repeat:
 141         flag=0;
 142         for(p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
 143                 if (!*p || *p == current)
 144                         continue;
 145                 if ((*p)->father != current->pid)
 146                         continue;
 147                 if (pid>0) {
 148                         if ((*p)->pid != pid)
 149                                 continue;
 150                 } else if (!pid) {
 151                         if ((*p)->pgrp != current->pgrp)
 152                                 continue;
 153                 } else if (pid != -1) {
 154                         if ((*p)->pgrp != -pid)
 155                                 continue;
 156                 }
 157                 switch ((*p)->state) {
 158                         case TASK_STOPPED:
 159                                 if (!(options & WUNTRACED))
 160                                         continue;
 161                                 put_fs_long(0x7f,stat_addr);
 162                                 return (*p)->pid;
 163                         case TASK_ZOMBIE:
 164                                 current->cutime += (*p)->utime;
 165                                 current->cstime += (*p)->stime;
 166                                 flag = (*p)->pid;
 167                                 put_fs_long((*p)->exit_code,stat_addr);
 168                                 release(*p);
 169                                 return flag;
 170                         default:
 171                                 flag=1;
 172                                 continue;
 173                 }
 174         }
 175         if (flag) {
 176                 if (options & WNOHANG)
 177                         return 0;
 178                 current->state=TASK_INTERRUPTIBLE;
 179                 schedule();
 180                 if (!(current->signal &= ~(1<<(SIGCHLD-1))))
 181                         goto repeat;
 182                 else
 183                         return -EINTR;
 184         }
 185         return -ECHILD;
 186 }
 187 
 188
/* */
root/kernel/exit.c

DEFINITIONS
