forked from github/multus-cni
ac21a96804
gomodule is still in progress to migrate for now, hence multus team decide to keep vendor directory to support build without gomodule.
43 lines
1.5 KiB
Go
43 lines
1.5 KiB
Go
// Copyright 2017 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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// Functions to access/create device major and minor numbers matching the
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// encoding used by the Linux kernel and glibc.
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//
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// The information below is extracted and adapted from bits/sysmacros.h in the
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// glibc sources:
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//
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// dev_t in glibc is 64-bit, with 32-bit major and minor numbers. glibc's
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// default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of the major
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// number and m is a hex digit of the minor number. This is backward compatible
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// with legacy systems where dev_t is 16 bits wide, encoded as MMmm. It is also
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// backward compatible with the Linux kernel, which for some architectures uses
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// 32-bit dev_t, encoded as mmmM MMmm.
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package unix
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// Major returns the major component of a Linux device number.
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func Major(dev uint64) uint32 {
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major := uint32((dev & 0x00000000000fff00) >> 8)
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major |= uint32((dev & 0xfffff00000000000) >> 32)
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return major
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}
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// Minor returns the minor component of a Linux device number.
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func Minor(dev uint64) uint32 {
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minor := uint32((dev & 0x00000000000000ff) >> 0)
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minor |= uint32((dev & 0x00000ffffff00000) >> 12)
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return minor
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}
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// Mkdev returns a Linux device number generated from the given major and minor
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// components.
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func Mkdev(major, minor uint32) uint64 {
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dev := (uint64(major) & 0x00000fff) << 8
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dev |= (uint64(major) & 0xfffff000) << 32
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dev |= (uint64(minor) & 0x000000ff) << 0
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dev |= (uint64(minor) & 0xffffff00) << 12
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return dev
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}
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