1 files changed, 3 insertions, 197 deletions
diff --git a/src/path/filepath/path_windows.go b/src/path/filepath/path_windows.go
index 6adb7d4bc4..d53f87f1ac 100644
--- a/src/path/filepath/path_windows.go
+++ b/src/path/filepath/path_windows.go
@@ -1,179 +1,11 @@
-// Copyright 2010 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 filepath
 
 import (
-	"internal/safefilepath"
 	"os"
 	"strings"
 	"syscall"
 )
 
-func isSlash(c uint8) bool {
-	return c == '\\' || c == '/'
-}
-
-func toUpper(c byte) byte {
-	if 'a' <= c && c <= 'z' {
-		return c - ('a' - 'A')
-	}
-	return c
-}
-
-func isLocal(path string) bool {
-	if path == "" {
-		return false
-	}
-	if isSlash(path[0]) {
-		// Path rooted in the current drive.
-		return false
-	}
-	if strings.IndexByte(path, ':') >= 0 {
-		// Colons are only valid when marking a drive letter ("C:foo").
-		// Rejecting any path with a colon is conservative but safe.
-		return false
-	}
-	hasDots := false // contains . or .. path elements
-	for p := path; p != ""; {
-		var part string
-		part, p, _ = cutPath(p)
-		if part == "." || part == ".." {
-			hasDots = true
-		}
-		if safefilepath.IsReservedName(part) {
-			return false
-		}
-	}
-	if hasDots {
-		path = Clean(path)
-	}
-	if path == ".." || strings.HasPrefix(path, `..\`) {
-		return false
-	}
-	return true
-}
-
-// IsAbs reports whether the path is absolute.
-func IsAbs(path string) (b bool) {
-	l := volumeNameLen(path)
-	if l == 0 {
-		return false
-	}
-	// If the volume name starts with a double slash, this is an absolute path.
-	if isSlash(path[0]) && isSlash(path[1]) {
-		return true
-	}
-	path = path[l:]
-	if path == "" {
-		return false
-	}
-	return isSlash(path[0])
-}
-
-// volumeNameLen returns length of the leading volume name on Windows.
-// It returns 0 elsewhere.
-//
-// See:
-// https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats
-// https://googleprojectzero.blogspot.com/2016/02/the-definitive-guide-on-win32-to-nt.html
-func volumeNameLen(path string) int {
-	switch {
-	case len(path) >= 2 && path[1] == ':':
-		// Path starts with a drive letter.
-		//
-		// Not all Windows functions necessarily enforce the requirement that
-		// drive letters be in the set A-Z, and we don't try to here.
-		//
-		// We don't handle the case of a path starting with a non-ASCII character,
-		// in which case the "drive letter" might be multiple bytes long.
-		return 2
-
-	case len(path) == 0 || !isSlash(path[0]):
-		// Path does not have a volume component.
-		return 0
-
-	case pathHasPrefixFold(path, `\\.\UNC`):
-		// We're going to treat the UNC host and share as part of the volume
-		// prefix for historical reasons, but this isn't really principled;
-		// Windows's own GetFullPathName will happily remove the first
-		// component of the path in this space, converting
-		// \\.\unc\a\b\..\c into \\.\unc\a\c.
-		return uncLen(path, len(`\\.\UNC\`))
-
-	case pathHasPrefixFold(path, `\\.`) ||
-		pathHasPrefixFold(path, `\\?`) || pathHasPrefixFold(path, `\??`):
-		// Path starts with \\.\, and is a Local Device path; or
-		// path starts with \\?\ or \??\ and is a Root Local Device path.
-		//
-		// We treat the next component after the \\.\ prefix as
-		// part of the volume name, which means Clean(`\\?\c:\`)
-		// won't remove the trailing \. (See #64028.)
-		if len(path) == 3 {
-			return 3 // exactly \\.
-		}
-		_, rest, ok := cutPath(path[4:])
-		if !ok {
-			return len(path)
-		}
-		return len(path) - len(rest) - 1
-
-	case len(path) >= 2 && isSlash(path[1]):
-		// Path starts with \\, and is a UNC path.
-		return uncLen(path, 2)
-	}
-	return 0
-}
-
-// pathHasPrefixFold tests whether the path s begins with prefix,
-// ignoring case and treating all path separators as equivalent.
-// If s is longer than prefix, then s[len(prefix)] must be a path separator.
-func pathHasPrefixFold(s, prefix string) bool {
-	if len(s) < len(prefix) {
-		return false
-	}
-	for i := 0; i < len(prefix); i++ {
-		if isSlash(prefix[i]) {
-			if !isSlash(s[i]) {
-				return false
-			}
-		} else if toUpper(prefix[i]) != toUpper(s[i]) {
-			return false
-		}
-	}
-	if len(s) > len(prefix) && !isSlash(s[len(prefix)]) {
-		return false
-	}
-	return true
-}
-
-// uncLen returns the length of the volume prefix of a UNC path.
-// prefixLen is the prefix prior to the start of the UNC host;
-// for example, for "//host/share", the prefixLen is len("//")==2.
-func uncLen(path string, prefixLen int) int {
-	count := 0
-	for i := prefixLen; i < len(path); i++ {
-		if isSlash(path[i]) {
-			count++
-			if count == 2 {
-				return i
-			}
-		}
-	}
-	return len(path)
-}
-
-// cutPath slices path around the first path separator.
-func cutPath(path string) (before, after string, found bool) {
-	for i := range path {
-		if isSlash(path[i]) {
-			return path[:i], path[i+1:], true
-		}
-	}
-	return path, "", false
-}
-
 // HasPrefix exists for historical compatibility and should not be used.
 //
 // Deprecated: HasPrefix does not respect path boundaries and
@@ -237,7 +69,7 @@ func join(elem []string) string {
 		switch {
 		case b.Len() == 0:
 			// Add the first non-empty path element unchanged.
-		case isSlash(lastChar):
+		case os.IsPathSeparator(lastChar):
 			// If the path ends in a slash, strip any leading slashes from the next
 			// path element to avoid creating a UNC path (any path starting with "\\")
 			// from non-UNC elements.
@@ -245,13 +77,13 @@ func join(elem []string) string {
 			// The correct behavior for Join when the first element is an incomplete UNC
 			// path (for example, "\\") is underspecified. We currently join subsequent
 			// elements so Join("\\", "host", "share") produces "\\host\share".
-			for len(e) > 0 && isSlash(e[0]) {
+			for len(e) > 0 && os.IsPathSeparator(e[0]) {
 				e = e[1:]
 			}
 			// If the path is \ and the next path element is ??,
 			// add an extra .\ to create \.\?? rather than \??\
 			// (a Root Local Device path).
-			if b.Len() == 1 && pathHasPrefixFold(e, "??") {
+			if b.Len() == 1 && strings.HasPrefix(e, "??") && (len(e) == len("??") || os.IsPathSeparator(e[2])) {
 				b.WriteString(`.\`)
 			}
 		case lastChar == ':':
@@ -280,29 +112,3 @@ func join(elem []string) string {
 func sameWord(a, b string) bool {
 	return strings.EqualFold(a, b)
 }
-
-// postClean adjusts the results of Clean to avoid turning a relative path
-// into an absolute or rooted one.
-func postClean(out *lazybuf) {
-	if out.volLen != 0 || out.buf == nil {
-		return
-	}
-	// If a ':' appears in the path element at the start of a path,
-	// insert a .\ at the beginning to avoid converting relative paths
-	// like a/../c: into c:.
-	for _, c := range out.buf {
-		if os.IsPathSeparator(c) {
-			break
-		}
-		if c == ':' {
-			out.prepend('.', Separator)
-			return
-		}
-	}
-	// If a path begins with \??\, insert a \. at the beginning
-	// to avoid converting paths like \a\..\??\c:\x into \??\c:\x
-	// (equivalent to c:\x).
-	if len(out.buf) >= 3 && os.IsPathSeparator(out.buf[0]) && out.buf[1] == '?' && out.buf[2] == '?' {
-		out.prepend(Separator, '.')
-	}
-}