Update golang to 1.21.6

1 files changed, 115 insertions, 73 deletions

diff --git a/contrib/go/_std_1.21/src/path/filepath/path_windows.go b/contrib/go/_std_1.21/src/path/filepath/path_windows.go
index 4dca9e0f55..eacab0e5ce 100644
--- a/contrib/go/_std_1.21/src/path/filepath/path_windows.go
+++ b/contrib/go/_std_1.21/src/path/filepath/path_windows.go
@@ -5,6 +5,8 @@
 package filepath
 
 import (
+	"internal/safefilepath"
+	"os"
 	"strings"
 	"syscall"
 )
@@ -20,34 +22,6 @@ func toUpper(c byte) byte {
 	return c
 }
 
-// isReservedName reports if name is a Windows reserved device name or a console handle.
-// It does not detect names with an extension, which are also reserved on some Windows versions.
-//
-// For details, search for PRN in
-// https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file.
-func isReservedName(name string) bool {
-	if 3 <= len(name) && len(name) <= 4 {
-		switch string([]byte{toUpper(name[0]), toUpper(name[1]), toUpper(name[2])}) {
-		case "CON", "PRN", "AUX", "NUL":
-			return len(name) == 3
-		case "COM", "LPT":
-			return len(name) == 4 && '1' <= name[3] && name[3] <= '9'
-		}
-	}
-	// Passing CONIN$ or CONOUT$ to CreateFile opens a console handle.
-	// https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea#consoles
-	//
-	// While CONIN$ and CONOUT$ aren't documented as being files,
-	// they behave the same as CON. For example, ./CONIN$ also opens the console input.
-	if len(name) == 6 && name[5] == '$' && strings.EqualFold(name, "CONIN$") {
-		return true
-	}
-	if len(name) == 7 && name[6] == '$' && strings.EqualFold(name, "CONOUT$") {
-		return true
-	}
-	return false
-}
-
 func isLocal(path string) bool {
 	if path == "" {
 		return false
@@ -68,25 +42,8 @@ func isLocal(path string) bool {
 		if part == "." || part == ".." {
 			hasDots = true
 		}
-		// Trim the extension and look for a reserved name.
-		base, _, hasExt := strings.Cut(part, ".")
-		if isReservedName(base) {
-			if !hasExt {
-				return false
-			}
-			// The path element is a reserved name with an extension. Some Windows
-			// versions consider this a reserved name, while others do not. Use
-			// FullPath to see if the name is reserved.
-			//
-			// FullPath will convert references to reserved device names to their
-			// canonical form: \\.\${DEVICE_NAME}
-			//
-			// FullPath does not perform this conversion for paths which contain
-			// a reserved device name anywhere other than in the last element,
-			// so check the part rather than the full path.
-			if p, _ := syscall.FullPath(part); len(p) >= 4 && p[:4] == `\\.\` {
-				return false
-			}
+		if safefilepath.IsReservedName(part) {
+			return false
 		}
 	}
 	if hasDots {
@@ -118,40 +75,93 @@ func IsAbs(path string) (b bool) {
 // 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
+// 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 {
-	if len(path) < 2 {
-		return 0
-	}
-	// with drive letter
-	c := path[0]
-	if path[1] == ':' && ('a' <= c && c <= 'z' || 'A' <= c && c <= 'Z') {
+	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
-	}
-	// UNC and DOS device paths start with two slashes.
-	if !isSlash(path[0]) || !isSlash(path[1]) {
+
+	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)
 	}
-	rest := path[2:]
-	p1, rest, _ := cutPath(rest)
-	p2, rest, ok := cutPath(rest)
-	if !ok {
-		return len(path)
+	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
 	}
-	if p1 != "." && p1 != "?" {
-		// This is a UNC path: \\${HOST}\${SHARE}\
-		return len(path) - len(rest) - 1
+	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
+		}
 	}
-	// This is a DOS device path.
-	if len(p2) == 3 && toUpper(p2[0]) == 'U' && toUpper(p2[1]) == 'N' && toUpper(p2[2]) == 'C' {
-		// This is a DOS device path that links to a UNC: \\.\UNC\${HOST}\${SHARE}\
-		_, rest, _ = cutPath(rest)  // host
-		_, rest, ok = cutPath(rest) // share
-		if !ok {
-			return len(path)
+	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) - len(rest) - 1
+	return len(path)
 }
 
 // cutPath slices path around the first path separator.
@@ -238,6 +248,12 @@ func join(elem []string) string {
 			for len(e) > 0 && isSlash(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, "??") {
+				b.WriteString(`.\`)
+			}
 		case lastChar == ':':
 			// If the path ends in a colon, keep the path relative to the current directory
 			// on a drive and don't add a separator. Preserve leading slashes in the next
@@ -304,3 +320,29 @@ func isUNC(path string) bool {
 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, '.')
+	}
+}