fusl/src/select/select.c

#include <sys/select.h>
#include <signal.h>
#include <stdint.h>
#include <errno.h>
#include "syscall.h"
#include "libc.h"

int select(int n,
           fd_set* restrict rfds,
           fd_set* restrict wfds,
           fd_set* restrict efds,
           struct timeval* restrict tv) {
#ifdef SYS_select
  return syscall_cp(SYS_select, n, rfds, wfds, efds, tv);
#else
  syscall_arg_t data[2] = {0, _NSIG / 8};
  struct timespec ts;
  if (tv) {
    if (tv->tv_sec < 0 || tv->tv_usec < 0)
      return __syscall_ret(-EINVAL);
    time_t extra_secs = tv->tv_usec / 1000000;
    ts.tv_nsec = tv->tv_usec % 1000000 * 1000;
    const time_t max_time = (1ULL << 8 * sizeof(time_t) - 1) - 1;
    ts.tv_sec =
        extra_secs > max_time - tv->tv_sec ? max_time : tv->tv_sec + extra_secs;
  }
  return syscall_cp(SYS_pselect6, n, rfds, wfds, efds, tv ? &ts : 0, data);
#endif
}