nsz Git - musl/blob - src/aio/aio_suspend.c

   1 #include <aio.h>
   2 #include <errno.h>
   3 #include <time.h>
   4 #include "atomic.h"
   5 #include "libc.h"
   6 #include "pthread_impl.h"
   7
   8 extern volatile int __aio_fut;
   9
  10 int aio_suspend(const struct aiocb *const cbs[], int cnt, const struct timespec *ts)
  11 {
  12         int i, tid = 0, ret, expect = 0;
  13         struct timespec at;
  14         volatile int dummy_fut, *pfut;
  15         int nzcnt = 0;
  16         const struct aiocb *cb = 0;
  17
  18         if (cnt<0) {
  19                 errno = EINVAL;
  20                 return -1;
  21         }
  22
  23         for (i=0; i<cnt; i++) if (cbs[i]) {
  24                 if (aio_error(cbs[i]) != EINPROGRESS) return 0;
  25                 nzcnt++;
  26                 cb = cbs[i];
  27         }
  28
  29         if (ts) {
  30                 clock_gettime(CLOCK_MONOTONIC, &at);
  31                 at.tv_sec += ts->tv_sec;
  32                 if ((at.tv_nsec += ts->tv_nsec) >= 1000000000) {
  33                         at.tv_nsec -= 1000000000;
  34                         at.tv_sec++;
  35                 }
  36         }
  37
  38         for (;;) {
  39                 for (i=0; i<cnt; i++)
  40                         if (cbs[i] && aio_error(cbs[i]) != EINPROGRESS)
  41                                 return 0;
  42
  43                 switch (nzcnt) {
  44                 case 0:
  45                         pfut = &dummy_fut;
  46                         break;
  47                 case 1:
  48                         pfut = (void *)&cb->__err;
  49                         expect = EINPROGRESS | 0x80000000;
  50                         a_cas(pfut, EINPROGRESS, expect);
  51                         break;
  52                 default:
  53                         pfut = &__aio_fut;
  54                         if (!tid) tid = __pthread_self()->tid;
  55                         expect = a_cas(pfut, 0, tid);
  56                         if (!expect) expect = tid;
  57                         /* Need to recheck the predicate before waiting. */
  58                         for (i=0; i<cnt; i++)
  59                                 if (cbs[i] && aio_error(cbs[i]) != EINPROGRESS)
  60                                         return 0;
  61                         break;
  62                 }
  63
  64                 ret = __timedwait(pfut, expect, CLOCK_MONOTONIC, ts?&at:0, 0, 0, 1);
  65
  66                 if (ret) {
  67                         errno = ret==ETIMEDOUT ? EAGAIN : ret;
  68                         return -1;
  69                 }
  70         }
  71 }
  72
  73 LFS64(aio_suspend);