libc-top-half/musl/src/select/select.c

   1 #include <sys/select.h>
   2 #include <signal.h>
   3 #include <stdint.h>
   4 #include <errno.h>
   5 #include "syscall.h"
   6
   7 #define IS32BIT(x) !((x)+0x80000000ULL>>32)
   8 #define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
   9
  10 int select(int n, fd_set *restrict rfds, fd_set *restrict wfds, fd_set *restrict efds, struct timeval *restrict tv)
  11 {
  12         time_t s = tv ? tv->tv_sec : 0;
  13         suseconds_t us = tv ? tv->tv_usec : 0;
  14         long ns;
  15         const time_t max_time = (1ULL<<8*sizeof(time_t)-1)-1;
  16
  17         if (s<0 || us<0) return __syscall_ret(-EINVAL);
  18         if (us/1000000 > max_time - s) {
  19                 s = max_time;
  20                 us = 999999;
  21                 ns = 999999999;
  22         } else {
  23                 s += us/1000000;
  24                 us %= 1000000;
  25                 ns = us*1000;
  26         }
  27
  28 #ifdef SYS_pselect6_time64
  29         int r = -ENOSYS;
  30         if (SYS_pselect6 == SYS_pselect6_time64 || !IS32BIT(s))
  31                 r = __syscall_cp(SYS_pselect6_time64, n, rfds, wfds, efds,
  32                         tv ? ((long long[]){s, ns}) : 0,
  33                         ((syscall_arg_t[]){ 0, _NSIG/8 }));
  34         if (SYS_pselect6 == SYS_pselect6_time64 || r!=-ENOSYS)
  35                 return __syscall_ret(r);
  36 #endif
  37 #ifdef SYS_select
  38         return syscall_cp(SYS_select, n, rfds, wfds, efds,
  39                 tv ? ((long[]){s, us}) : 0);
  40 #else
  41         return syscall_cp(SYS_pselect6, n, rfds, wfds, efds,
  42                 tv ? ((long[]){s, ns}) : 0, ((syscall_arg_t[]){ 0, _NSIG/8 }));
  43 #endif
  44 }