kernel_version_freebsd.go

     1  // Copyright 2024 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package unix
     6  
     7  import (
     8  	"sync"
     9  	"syscall"
    10  )
    11  
    12  // KernelVersion returns major and minor kernel version numbers
    13  // parsed from the syscall.Sysctl("kern.osrelease")'s value,
    14  // or (0, 0) if the version can't be obtained or parsed.
    15  func KernelVersion() (major, minor int) {
    16  	release, err := syscall.Sysctl("kern.osrelease")
    17  	if err != nil {
    18  		return 0, 0
    19  	}
    20  
    21  	parseNext := func() (n int) {
    22  		for i, c := range release {
    23  			if c == '.' {
    24  				release = release[i+1:]
    25  				return
    26  			}
    27  			if '0' <= c && c <= '9' {
    28  				n = n*10 + int(c-'0')
    29  			}
    30  		}
    31  		release = ""
    32  		return
    33  	}
    34  
    35  	major = parseNext()
    36  	minor = parseNext()
    37  
    38  	return
    39  }
    40  
    41  // SupportCopyFileRange reports whether the kernel supports the copy_file_range(2).
    42  // This function will examine both the kernel version and the availability of the system call.
    43  var SupportCopyFileRange = sync.OnceValue(func() bool {
    44  	// The copy_file_range() function first appeared in FreeBSD 13.0.
    45  	major, _ := KernelVersion()
    46  	_, err := CopyFileRange(0, nil, 0, nil, 0, 0)
    47  	return major >= 13 && err != syscall.ENOSYS
    48  })
    49
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