gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/pkg/hostos/hostos.go (about)

     1  // Copyright 2022 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package hostos contains utility functions for getting information about the host OS.
    16  package hostos
    17  
    18  import (
    19  	"fmt"
    20  	"regexp"
    21  	"strings"
    22  	"sync"
    23  
    24  	"golang.org/x/mod/semver"
    25  	"golang.org/x/sys/unix"
    26  )
    27  
    28  // Version represents a semantic version of the form "%d.%d[.%d]".
    29  type Version struct {
    30  	version string
    31  }
    32  
    33  // AtLeast returns whether vr is at least version major.minor.
    34  func (vr Version) AtLeast(major, minor int) bool {
    35  	return semver.Compare(vr.version, fmt.Sprintf("v%d.%d", major, minor)) >= 0
    36  }
    37  
    38  // LessThan returns whether vr is less than version major.minor.
    39  func (vr Version) LessThan(major, minor int) bool {
    40  	return !vr.AtLeast(major, minor)
    41  }
    42  
    43  // String implements fmt.Stringer.
    44  func (vr Version) String() string {
    45  	if vr.version == "" {
    46  		return "unknown"
    47  	}
    48  	// Omit the "v" prefix required by semver.
    49  	return vr.version[1:]
    50  }
    51  
    52  // These values are effectively local to KernelVersion, but kept here so as to
    53  // work with sync.Once.
    54  var (
    55  	semVersion Version
    56  	unameErr   error
    57  	once       sync.Once
    58  )
    59  
    60  // KernelVersion returns the version of the kernel using uname().
    61  func KernelVersion() (Version, error) {
    62  	once.Do(func() {
    63  		var utsname unix.Utsname
    64  		if err := unix.Uname(&utsname); err != nil {
    65  			unameErr = err
    66  			return
    67  		}
    68  
    69  		var sb strings.Builder
    70  		for _, b := range utsname.Release {
    71  			if b == 0 {
    72  				break
    73  			}
    74  			sb.WriteByte(byte(b))
    75  		}
    76  
    77  		versionRegexp := regexp.MustCompile(`[0-9]+\.[0-9]+(\.[0-9]+)?`)
    78  		version := "v" + string(versionRegexp.Find([]byte(sb.String())))
    79  		if !semver.IsValid(version) {
    80  			unameErr = fmt.Errorf("invalid version found in release %q", sb.String())
    81  			return
    82  		}
    83  		semVersion.version = version
    84  	})
    85  
    86  	return semVersion, unameErr
    87  }