parse.go

     1  // Copyright 2022 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 cpu
     6  
     7  import "strconv"
     8  
     9  // parseRelease parses a dot-separated version number from the prefix
    10  // of rel. It returns ok=true only if at least the major and minor
    11  // components were successfully parsed; the patch component is
    12  // best-effort. Trailing vendor or build suffixes such as
    13  // "-generic", "+", "_hi3535", or "-rc1" are ignored.
    14  //
    15  // This is a copy of the Go runtime's parseRelease from
    16  // https://golang.org/cl/209597, updated in https://golang.org/cl/781800.
    17  func parseRelease(rel string) (major, minor, patch int, ok bool) {
    18  	// next consumes a run of decimal digits from the front of rel,
    19  	// returning the parsed value. If the digits are followed by a
    20  	// '.', it is consumed and more is set so the caller knows to
    21  	// parse another component; otherwise scanning terminates and
    22  	// the rest of rel is discarded.
    23  	next := func() (n int, more, ok bool) {
    24  		i := 0
    25  		for i < len(rel) && rel[i] >= '0' && rel[i] <= '9' {
    26  			i++
    27  		}
    28  		if i == 0 {
    29  			return 0, false, false
    30  		}
    31  		n, err := strconv.Atoi(rel[:i])
    32  		if err != nil {
    33  			return 0, false, false
    34  		}
    35  		if i < len(rel) && rel[i] == '.' {
    36  			rel = rel[i+1:]
    37  			return n, true, true
    38  		}
    39  		rel = ""
    40  		return n, false, true
    41  	}
    42  
    43  	var more bool
    44  	if major, more, ok = next(); !ok || !more {
    45  		return 0, 0, 0, false
    46  	}
    47  	if minor, more, ok = next(); !ok {
    48  		return 0, 0, 0, false
    49  	}
    50  	if !more {
    51  		return major, minor, 0, true
    52  	}
    53  	patch, _, _ = next()
    54  	return major, minor, patch, true
    55  }
    56
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