mirror of git://gcc.gnu.org/git/gcc.git
50 lines
1.2 KiB
Go
50 lines
1.2 KiB
Go
// Copyright 2014 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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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 randomUnsupported 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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const (
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// GRND_NONBLOCK means return EAGAIN rather than blocking.
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GRND_NONBLOCK GetRandomFlag = 0x0001
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// GRND_RANDOM means use the /dev/random pool instead of /dev/urandom.
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GRND_RANDOM GetRandomFlag = 0x0002
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)
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// GetRandom calls the Linux getrandom system call.
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// See https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c6e9d6f38894798696f23c8084ca7edbf16ee895
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func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
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if randomTrap == 0 {
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return 0, syscall.ENOSYS
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}
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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(&randomUnsupported) != 0 {
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return 0, syscall.ENOSYS
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}
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r1, _, errno := syscall.Syscall(randomTrap,
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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(&randomUnsupported, 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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