getrandom_solaris.mx raw

   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  	"unsafe"
  11  )
  12  
  13  //go:cgo_import_dynamic libc_getrandom getrandom "libc.so"
  14  
  15  //go:linkname procGetrandom libc_getrandom
  16  
  17  var procGetrandom uintptr
  18  
  19  var getrandomUnsupported atomic.Bool
  20  
  21  // GetRandomFlag is a flag supported by the getrandom system call.
  22  type GetRandomFlag uintptr
  23  
  24  const (
  25  	// GRND_NONBLOCK means return EAGAIN rather than blocking.
  26  	GRND_NONBLOCK GetRandomFlag = 0x0001
  27  
  28  	// GRND_RANDOM means use the /dev/random pool instead of /dev/urandom.
  29  	GRND_RANDOM GetRandomFlag = 0x0002
  30  )
  31  
  32  // GetRandom calls the getrandom system call.
  33  func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
  34  	if len(p) == 0 {
  35  		return 0, nil
  36  	}
  37  	if getrandomUnsupported.Load() {
  38  		return 0, syscall.ENOSYS
  39  	}
  40  	r1, _, errno := syscall6(uintptr(unsafe.Pointer(&procGetrandom)),
  41  		3,
  42  		uintptr(unsafe.Pointer(&p[0])),
  43  		uintptr(len(p)),
  44  		uintptr(flags),
  45  		0, 0, 0)
  46  	if errno != 0 {
  47  		if errno == syscall.ENOSYS {
  48  			getrandomUnsupported.Store(true)
  49  		}
  50  		return 0, errno
  51  	}
  52  	return int(r1), nil
  53  }
  54