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 }
65