| // Copyright 2023 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package toolchain |
| |
| import ( |
| "io/fs" |
| "os" |
| "path/filepath" |
| "strings" |
| "sync" |
| |
| "cmd/go/internal/gover" |
| ) |
| |
| // pathExts is a cached PATHEXT list. |
| var pathExts struct { |
| once sync.Once |
| list []string |
| } |
| |
| func initPathExts() { |
| var exts []string |
| x := os.Getenv(`PATHEXT`) |
| if x != "" { |
| for _, e := range strings.Split(strings.ToLower(x), `;`) { |
| if e == "" { |
| continue |
| } |
| if e[0] != '.' { |
| e = "." + e |
| } |
| exts = append(exts, e) |
| } |
| } else { |
| exts = []string{".com", ".exe", ".bat", ".cmd"} |
| } |
| pathExts.list = exts |
| } |
| |
| // pathDirs returns the directories in the system search path. |
| func pathDirs() []string { |
| return filepath.SplitList(os.Getenv("PATH")) |
| } |
| |
| // pathVersion returns the Go version implemented by the file |
| // described by de and info in directory dir. |
| // The analysis only uses the name itself; it does not run the program. |
| func pathVersion(dir string, de fs.DirEntry, info fs.FileInfo) (string, bool) { |
| pathExts.once.Do(initPathExts) |
| name, _, ok := cutExt(de.Name(), pathExts.list) |
| if !ok { |
| return "", false |
| } |
| v := gover.FromToolchain(name) |
| if v == "" { |
| return "", false |
| } |
| return v, true |
| } |
| |
| // cutExt looks for any of the known extensions at the end of file. |
| // If one is found, cutExt returns the file name with the extension trimmed, |
| // the extension itself, and true to signal that an extension was found. |
| // Otherwise cutExt returns file, "", false. |
| func cutExt(file string, exts []string) (name, ext string, found bool) { |
| i := strings.LastIndex(file, ".") |
| if i < 0 { |
| return file, "", false |
| } |
| for _, x := range exts { |
| if strings.EqualFold(file[i:], x) { |
| return file[:i], file[i:], true |
| } |
| } |
| return file, "", false |
| } |