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Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/dev_linux.go | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/dev_linux.go b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/dev_linux.go new file mode 100644 index 0000000..d165d6f --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/dev_linux.go @@ -0,0 +1,42 @@ +// Copyright 2017 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Functions to access/create device major and minor numbers matching the +// encoding used by the Linux kernel and glibc. +// +// The information below is extracted and adapted from bits/sysmacros.h in the +// glibc sources: +// +// dev_t in glibc is 64-bit, with 32-bit major and minor numbers. glibc's +// default encoding is MMMM Mmmm mmmM MMmm, where M is a hex digit of the major +// number and m is a hex digit of the minor number. This is backward compatible +// with legacy systems where dev_t is 16 bits wide, encoded as MMmm. It is also +// backward compatible with the Linux kernel, which for some architectures uses +// 32-bit dev_t, encoded as mmmM MMmm. + +package unix + +// Major returns the major component of a Linux device number. +func Major(dev uint64) uint32 { + major := uint32((dev & 0x00000000000fff00) >> 8) + major |= uint32((dev & 0xfffff00000000000) >> 32) + return major +} + +// Minor returns the minor component of a Linux device number. +func Minor(dev uint64) uint32 { + minor := uint32((dev & 0x00000000000000ff) >> 0) + minor |= uint32((dev & 0x00000ffffff00000) >> 12) + return minor +} + +// Mkdev returns a Linux device number generated from the given major and minor +// components. +func Mkdev(major, minor uint32) uint64 { + dev := (uint64(major) & 0x00000fff) << 8 + dev |= (uint64(major) & 0xfffff000) << 32 + dev |= (uint64(minor) & 0x000000ff) << 0 + dev |= (uint64(minor) & 0xffffff00) << 12 + return dev +} |