49 lines
1.3 KiB
Go
49 lines
1.3 KiB
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 linux
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// +build linux
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package unix
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import "unsafe"
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// Helpers for dealing with ifreq since it contains a union and thus requires a
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// lot of unsafe.Pointer casts to use properly.
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// newIfreq creates an ifreq with the input network interface name after
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// validating the name does not exceed IFNAMSIZ-1 (trailing NULL required)
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// bytes.
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func newIfreq(name string) (*ifreq, error) {
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// Leave room for terminating NULL byte.
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if len(name) >= IFNAMSIZ {
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return nil, EINVAL
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}
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var ifr ifreq
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copy(ifr.Ifrn[:], name)
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return &ifr, nil
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}
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// An ifreqData is an ifreq but with a typed unsafe.Pointer field for data in
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// the union. This is required in order to comply with the unsafe.Pointer rules
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// since the "pointer-ness" of data would not be preserved if it were cast into
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// the byte array of a raw ifreq.
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type ifreqData struct {
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name [IFNAMSIZ]byte
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data unsafe.Pointer
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// Pad to the same size as ifreq.
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_ [len(ifreq{}.Ifru) - SizeofPtr]byte
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}
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// SetData produces an ifreqData with the pointer p set for ioctls which require
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// arbitrary pointer data.
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func (ifr ifreq) SetData(p unsafe.Pointer) ifreqData {
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return ifreqData{
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name: ifr.Ifrn,
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data: p,
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}
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}
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