kernel.go

// MIT License
//
// Copyright (c) 2023 Paweł Gaczyński
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package giouring

import (
	"fmt"

	"golang.org/x/sys/unix"
)

type KernelVersion struct {
	Kernel int
	Major  int
	Minor  int
	Flavor string
}

const (
	firstNumberOfParts  = 2
	secondNumberOfParts = 1
)

func parseKernelVersion(kernelVersionStr string) (*KernelVersion, error) {
	var (
		kernel, major, minor, parsed int
		flavor, partial              string
	)

	parsed, _ = fmt.Sscanf(kernelVersionStr, "%d.%d%s", &kernel, &major, &partial)
	if parsed < firstNumberOfParts {
		return nil, fmt.Errorf("cannot parse kernel version: %s", kernelVersionStr)
	}

	parsed, _ = fmt.Sscanf(partial, ".%d%s", &minor, &flavor)
	if parsed < secondNumberOfParts {
		flavor = partial
	}

	return &KernelVersion{
		Kernel: kernel,
		Major:  major,
		Minor:  minor,
		Flavor: flavor,
	}, nil
}

func GetKernelVersion() (*KernelVersion, error) {
	uts := &unix.Utsname{}

	if err := unix.Uname(uts); err != nil {
		return nil, err
	}

	return parseKernelVersion(unix.ByteSliceToString(uts.Release[:]))
}

func CompareKernelVersion(a, b KernelVersion) int {
	if a.Kernel > b.Kernel {
		return 1
	} else if a.Kernel < b.Kernel {
		return -1
	}

	if a.Major > b.Major {
		return 1
	} else if a.Major < b.Major {
		return -1
	}

	if a.Minor > b.Minor {
		return 1
	} else if a.Minor < b.Minor {
		return -1
	}

	return 0
}

func CheckKernelVersion(k, major, minor int) (bool, error) {
	var (
		v   *KernelVersion
		err error
	)
	if v, err = GetKernelVersion(); err != nil {
		return false, err
	}
	if CompareKernelVersion(*v, KernelVersion{Kernel: k, Major: major, Minor: minor}) < 0 {
		return false, nil
	}

	return true, nil
}