nfs/internal/nfsfs/mknod_freebsd.go

// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
// SPDX-License-Identifier: MIT

//go:build freebsd

package nfsfs

import "syscall"

// mknod creates a device node. It needs the superuser on FreeBSD, and a
// failure of permission is reported as such rather than as an io error.
// The kind is picked before the single call: a second mknod over an
// existing node fails EEXIST and leaves the wrong kind behind.
func mknod(path string, spec CreateSpec, perm uint32) error {
	dev := makedev(spec.Major, spec.Minor)
	kind := uint32(syscall.S_IFCHR)
	if spec.Kind == KindBlk {
		kind = syscall.S_IFBLK
	}
	return syscall.Mknod(path, perm|kind, dev)
}

// makedev assembles a device number the way the kernel expects it: the
// encoding of makedev in sys/sys/types.h, where the low byte of the
// major number sits at bits eight to fifteen with the rest of it above
// the thirty-second bit, and the minor number keeps its low byte at bit
// zero with the byte at bits eight to fifteen lifted above the
// thirty-second bit.
func makedev(major, minor uint32) uint64 {
	return uint64(major&0xffffff00)<<32 | uint64(major&0xff)<<8 |
		uint64(minor&0xff00)<<24 | uint64(minor&0xffff00ff)
}