--- /dev/null
+// Copyright 2018 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 get
+
+import (
+ "fmt"
+ "strings"
+ "unicode"
+ "unicode/utf8"
+)
+
+// The following functions are copied verbatim from cmd/go/internal/module/module.go.
+//
+// TODO(bcmills): After the call site for this function is backported,
+// consolidate this back down to a single copy.
+
+// CheckImportPath checks that an import path is valid.
+func CheckImportPath(path string) error {
+ if err := checkPath(path, false); err != nil {
+ return fmt.Errorf("malformed import path %q: %v", path, err)
+ }
+ return nil
+}
+
+// checkPath checks that a general path is valid.
+// It returns an error describing why but not mentioning path.
+// Because these checks apply to both module paths and import paths,
+// the caller is expected to add the "malformed ___ path %q: " prefix.
+// fileName indicates whether the final element of the path is a file name
+// (as opposed to a directory name).
+func checkPath(path string, fileName bool) error {
+ if !utf8.ValidString(path) {
+ return fmt.Errorf("invalid UTF-8")
+ }
+ if path == "" {
+ return fmt.Errorf("empty string")
+ }
+ if strings.Contains(path, "..") {
+ return fmt.Errorf("double dot")
+ }
+ if strings.Contains(path, "//") {
+ return fmt.Errorf("double slash")
+ }
+ if path[len(path)-1] == '/' {
+ return fmt.Errorf("trailing slash")
+ }
+ elemStart := 0
+ for i, r := range path {
+ if r == '/' {
+ if err := checkElem(path[elemStart:i], fileName); err != nil {
+ return err
+ }
+ elemStart = i + 1
+ }
+ }
+ if err := checkElem(path[elemStart:], fileName); err != nil {
+ return err
+ }
+ return nil
+}
+
+// checkElem checks whether an individual path element is valid.
+// fileName indicates whether the element is a file name (not a directory name).
+func checkElem(elem string, fileName bool) error {
+ if elem == "" {
+ return fmt.Errorf("empty path element")
+ }
+ if strings.Count(elem, ".") == len(elem) {
+ return fmt.Errorf("invalid path element %q", elem)
+ }
+ if elem[0] == '.' && !fileName {
+ return fmt.Errorf("leading dot in path element")
+ }
+ if elem[len(elem)-1] == '.' {
+ return fmt.Errorf("trailing dot in path element")
+ }
+ charOK := pathOK
+ if fileName {
+ charOK = fileNameOK
+ }
+ for _, r := range elem {
+ if !charOK(r) {
+ return fmt.Errorf("invalid char %q", r)
+ }
+ }
+
+ // Windows disallows a bunch of path elements, sadly.
+ // See https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file
+ short := elem
+ if i := strings.Index(short, "."); i >= 0 {
+ short = short[:i]
+ }
+ for _, bad := range badWindowsNames {
+ if strings.EqualFold(bad, short) {
+ return fmt.Errorf("disallowed path element %q", elem)
+ }
+ }
+ return nil
+}
+
+// pathOK reports whether r can appear in an import path element.
+// Paths can be ASCII letters, ASCII digits, and limited ASCII punctuation: + - . _ and ~.
+// This matches what "go get" has historically recognized in import paths.
+// TODO(rsc): We would like to allow Unicode letters, but that requires additional
+// care in the safe encoding (see note below).
+func pathOK(r rune) bool {
+ if r < utf8.RuneSelf {
+ return r == '+' || r == '-' || r == '.' || r == '_' || r == '~' ||
+ '0' <= r && r <= '9' ||
+ 'A' <= r && r <= 'Z' ||
+ 'a' <= r && r <= 'z'
+ }
+ return false
+}
+
+// fileNameOK reports whether r can appear in a file name.
+// For now we allow all Unicode letters but otherwise limit to pathOK plus a few more punctuation characters.
+// If we expand the set of allowed characters here, we have to
+// work harder at detecting potential case-folding and normalization collisions.
+// See note about "safe encoding" below.
+func fileNameOK(r rune) bool {
+ if r < utf8.RuneSelf {
+ // Entire set of ASCII punctuation, from which we remove characters:
+ // ! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~
+ // We disallow some shell special characters: " ' * < > ? ` |
+ // (Note that some of those are disallowed by the Windows file system as well.)
+ // We also disallow path separators / : and \ (fileNameOK is only called on path element characters).
+ // We allow spaces (U+0020) in file names.
+ const allowed = "!#$%&()+,-.=@[]^_{}~ "
+ if '0' <= r && r <= '9' || 'A' <= r && r <= 'Z' || 'a' <= r && r <= 'z' {
+ return true
+ }
+ for i := 0; i < len(allowed); i++ {
+ if rune(allowed[i]) == r {
+ return true
+ }
+ }
+ return false
+ }
+ // It may be OK to add more ASCII punctuation here, but only carefully.
+ // For example Windows disallows < > \, and macOS disallows :, so we must not allow those.
+ return unicode.IsLetter(r)
+}
+
+// badWindowsNames are the reserved file path elements on Windows.
+// See https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file
+var badWindowsNames = []string{
+ "CON",
+ "PRN",
+ "AUX",
+ "NUL",
+ "COM1",
+ "COM2",
+ "COM3",
+ "COM4",
+ "COM5",
+ "COM6",
+ "COM7",
+ "COM8",
+ "COM9",
+ "LPT1",
+ "LPT2",
+ "LPT3",
+ "LPT4",
+ "LPT5",
+ "LPT6",
+ "LPT7",
+ "LPT8",
+ "LPT9",
+}