i86/elks/elkscmd/rc/wait.c

   1 #include <errno.h>
   2 #include <setjmp.h>
   3 #include "rc.h"
   4 #include "jbwrap.h"
   5
   6 bool forked = FALSE;
   7
   8 static int rc_wait(int *);
   9
  10 typedef struct Pid Pid;
  11
  12 static struct Pid {
  13         int pid, stat;
  14         bool alive;
  15         Pid *n;
  16 } *plist = NULL;
  17
  18 extern int rc_fork() {
  19         Pid *new;
  20         int pid = fork();
  21         switch (pid) {
  22         case -1:
  23                 uerror("fork");
  24                 rc_error(NULL);
  25                 /* NOTREACHED */
  26         case 0:
  27                 forked = TRUE;
  28                 sigchk();
  29                 return 0;
  30         default:
  31                 new = enew(Pid);
  32                 new->pid = pid;
  33                 new->alive = TRUE;
  34                 new->n = plist;
  35                 plist = new;
  36                 return pid;
  37         }
  38 }
  39
  40 extern int rc_wait4(int pid, int *stat, bool nointr) {
  41         Pid *r, *prev;
  42         int ret;
  43         /* first look for a child which may already have exited */
  44 again:  for (r = plist, prev = NULL; r != NULL; prev = r, r = r->n)
  45                 if (r->pid == pid)
  46                         break;
  47         if (r == NULL) {
  48                 errno = ECHILD; /* no children */
  49                 uerror("wait");
  50                 *stat = 0x100; /* exit(1) */
  51                 return -1;
  52         }
  53         if (r->alive) {
  54                 while (pid != (ret = rc_wait(stat))) {
  55                         Pid *q;
  56                         if (ret < 0) {
  57                                 if (nointr)
  58                                         goto again;
  59                                 return ret;
  60                         }
  61                         for (q = plist; q != NULL; q = q->n)
  62                                 if (q->pid == ret) {
  63                                         q->alive = FALSE;
  64                                         q->stat = *stat;
  65                                         break;
  66                                 }
  67                 }
  68         } else
  69                 *stat = r->stat;
  70         if (prev == NULL)
  71                 plist = r->n; /* remove element from head of list */
  72         else
  73                 prev->n = r->n;
  74         efree(r);
  75         return pid;
  76 }
  77
  78 extern List *sgetapids() {
  79         List *r;
  80         Pid *p;
  81         for (r = NULL, p = plist; p != NULL; p = p->n) {
  82                 List *q;
  83                 if (!p->alive)
  84                         continue;
  85                 q = nnew(List);
  86                 q->w = nprint("%d", p->pid);
  87                 q->m = NULL;
  88                 q->n = r;
  89                 r = q;
  90         }
  91         return r;
  92 }
  93
  94 extern void waitforall() {
  95         int stat;
  96         while (plist != NULL) {
  97                 int pid = rc_wait4(plist->pid, &stat, FALSE);
  98                 if (pid > 0)
  99                         setstatus(pid, stat);
 100                 else
 101                         set(FALSE);
 102                 sigchk();
 103         }
 104 }
 105
 106 /*
 107    rc_wait: a wait() wrapper that interfaces wait() w/rc signals.
 108    Note that the signal queue is not checked in this fn; someone
 109    may want to resume the wait() without delivering any signals.
 110 */
 111
 112 static int rc_wait(int *stat) {
 113         int r;
 114         interrupt_happened = FALSE;
 115         if (!setjmp(slowbuf.j)) {
 116                 slow = TRUE;
 117                 if (!interrupt_happened)
 118                         r = wait(stat);
 119                 else
 120                         r = -1;
 121         } else
 122                 r = -1;
 123         slow = FALSE;
 124         return r;
 125 }