golang.org/x/oauth2@v0.18.0/google/externalaccount/header.go (about)

     1  // Copyright 2023 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 externalaccount
     6  
     7  import (
     8  	"runtime"
     9  	"strings"
    10  	"unicode"
    11  )
    12  
    13  var (
    14  	// version is a package internal global variable for testing purposes.
    15  	version = runtime.Version
    16  )
    17  
    18  // versionUnknown is only used when the runtime version cannot be determined.
    19  const versionUnknown = "UNKNOWN"
    20  
    21  // goVersion returns a Go runtime version derived from the runtime environment
    22  // that is modified to be suitable for reporting in a header, meaning it has no
    23  // whitespace. If it is unable to determine the Go runtime version, it returns
    24  // versionUnknown.
    25  func goVersion() string {
    26  	const develPrefix = "devel +"
    27  
    28  	s := version()
    29  	if strings.HasPrefix(s, develPrefix) {
    30  		s = s[len(develPrefix):]
    31  		if p := strings.IndexFunc(s, unicode.IsSpace); p >= 0 {
    32  			s = s[:p]
    33  		}
    34  		return s
    35  	} else if p := strings.IndexFunc(s, unicode.IsSpace); p >= 0 {
    36  		s = s[:p]
    37  	}
    38  
    39  	notSemverRune := func(r rune) bool {
    40  		return !strings.ContainsRune("0123456789.", r)
    41  	}
    42  
    43  	if strings.HasPrefix(s, "go1") {
    44  		s = s[2:]
    45  		var prerelease string
    46  		if p := strings.IndexFunc(s, notSemverRune); p >= 0 {
    47  			s, prerelease = s[:p], s[p:]
    48  		}
    49  		if strings.HasSuffix(s, ".") {
    50  			s += "0"
    51  		} else if strings.Count(s, ".") < 2 {
    52  			s += ".0"
    53  		}
    54  		if prerelease != "" {
    55  			// Some release candidates already have a dash in them.
    56  			if !strings.HasPrefix(prerelease, "-") {
    57  				prerelease = "-" + prerelease
    58  			}
    59  			s += prerelease
    60  		}
    61  		return s
    62  	}
    63  	return "UNKNOWN"
    64  }