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40 lines
894 B
Go
40 lines
894 B
Go
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build dragonfly || freebsd || linux
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package unix
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import (
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"sync/atomic"
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"syscall"
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"unsafe"
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)
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var getrandomUnsupported int32 // atomic
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// GetRandomFlag is a flag supported by the getrandom system call.
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type GetRandomFlag uintptr
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// GetRandom calls the getrandom system call.
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func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
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if len(p) == 0 {
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return 0, nil
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}
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if atomic.LoadInt32(&getrandomUnsupported) != 0 {
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return 0, syscall.ENOSYS
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}
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r1, _, errno := syscall.Syscall(getrandomTrap,
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uintptr(unsafe.Pointer(&p[0])),
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uintptr(len(p)),
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uintptr(flags))
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if errno != 0 {
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if errno == syscall.ENOSYS {
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atomic.StoreInt32(&getrandomUnsupported, 1)
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}
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return 0, errno
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}
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return int(r1), nil
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}
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