git.ozlabs.org Git - petitboot/blob - lib/waiter/waiter.c

   1
   2 #include <poll.h>
   3 #include <string.h>
   4 #include <assert.h>
   5
   6 #include <talloc/talloc.h>
   7
   8 #include "waiter.h"
   9
  10 struct waiter {
  11         struct waitset  *set;
  12         int             fd;
  13         int             events;
  14         waiter_cb       callback;
  15         void            *arg;
  16 };
  17
  18 struct waitset {
  19         struct waiter   *waiters;
  20         int             n_waiters;
  21         struct pollfd   *pollfds;
  22         int             n_pollfds;
  23 };
  24
  25 struct waitset *waitset_create(void *ctx)
  26 {
  27         struct waitset *set = talloc_zero(ctx, struct waitset);
  28         return set;
  29 }
  30
  31 void waitset_destroy(struct waitset *set)
  32 {
  33         talloc_free(set);
  34 }
  35
  36 struct waiter *waiter_register(struct waitset *set, int fd, int events,
  37                 waiter_cb callback, void *arg)
  38 {
  39         struct waiter *waiters, *waiter;
  40
  41         waiters = talloc_realloc(set, set->waiters,
  42                         struct waiter, set->n_waiters + 1);
  43
  44         if (!waiters)
  45                 return NULL;
  46
  47         set->n_waiters++;
  48         set->waiters = waiters;
  49
  50         waiter = &set->waiters[set->n_waiters - 1];
  51
  52         waiter->set = set;
  53         waiter->fd = fd;
  54         waiter->events = events;
  55         waiter->callback = callback;
  56         waiter->arg = arg;
  57
  58         return waiter;
  59 }
  60
  61 void waiter_remove(struct waiter *waiter)
  62 {
  63         struct waitset *set = waiter->set;
  64         int i;
  65
  66         i = waiter - set->waiters;
  67         assert(i >= 0 && i < set->n_waiters);
  68
  69         set->n_waiters--;
  70         memmove(&set->waiters[i], &set->waiters[i+1],
  71                 (set->n_waiters - i) * sizeof(set->waiters[0]));
  72
  73         set->waiters = talloc_realloc(set->waiters, set->waiters, struct waiter,
  74                         set->n_waiters);
  75 }
  76
  77 int waiter_poll(struct waitset *set)
  78 {
  79         int i, rc;
  80
  81         if (set->n_waiters != set->n_pollfds) {
  82                 set->pollfds = talloc_realloc(set, set->pollfds,
  83                                 struct pollfd, set->n_waiters);
  84                 set->n_pollfds = set->n_waiters;
  85         }
  86
  87         for (i = 0; i < set->n_waiters; i++) {
  88                 set->pollfds[i].fd = set->waiters[i].fd;
  89                 set->pollfds[i].events = set->waiters[i].events;
  90                 set->pollfds[i].revents = 0;
  91         }
  92
  93         rc = poll(set->pollfds, set->n_waiters, -1);
  94
  95         if (rc <= 0)
  96                 return rc;
  97
  98         for (i = 0; i < set->n_waiters; i++) {
  99                 if (set->pollfds[i].revents) {
 100                         rc = set->waiters[i].callback(set->waiters[i].arg);
 101
 102                         if (rc)
 103                                 waiter_remove(&set->waiters[i]);
 104                 }
 105         }
 106
 107         return 0;
 108 }