libgo/go/internal/syscall/unix/getrandom_solaris.go

   1 // Copyright 2021 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package unix
   6
   7 import (
   8         "sync/atomic"
   9         "syscall"
  10 )
  11
  12 //extern getrandom
  13 func libc_getrandom(*byte, uintptr, uint32) uintptr
  14
  15 var getrandomUnsupported int32 // atomic
  16
  17 // GetRandomFlag is a flag supported by the getrandom system call.
  18 type GetRandomFlag uintptr
  19
  20 const (
  21         // GRND_NONBLOCK means return EAGAIN rather than blocking.
  22         GRND_NONBLOCK GetRandomFlag = 0x0001
  23
  24         // GRND_RANDOM means use the /dev/random pool instead of /dev/urandom.
  25         GRND_RANDOM GetRandomFlag = 0x0002
  26 )
  27
  28 // GetRandom calls the getrandom system call.
  29 func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
  30         if len(p) == 0 {
  31                 return 0, nil
  32         }
  33         if atomic.LoadInt32(&getrandomUnsupported) != 0 {
  34                 return 0, syscall.ENOSYS
  35         }
  36         syscall.Entersyscall()
  37         r1 := libc_getrandom(&p[0], uintptr(len(p)), uint32(flags))
  38         syscall.Exitsyscall()
  39         if r1 == 0 {
  40                 errno := syscall.GetErrno()
  41                 if errno == syscall.ENOSYS {
  42                         atomic.StoreInt32(&getrandomUnsupported, 1)
  43                 }
  44                 return 0, errno
  45         }
  46         return int(r1), nil
  47 }