lib/file: use builtin MkdirAll with go1.22 instead of our own custom version for windows

Starting with go1.22 the standard os.MkdirAll has improved its handling of volume names,
and as part of that it now stops recursing into parent directory if it is a volume name
(see: cd589c8a73).
This is similar to what was our main change and reason for creating a custom version. When
building with go1.22 or newer we can therefore stop using our custom version, with the
advantage that we automatically get current and future relevant improvements from golang.
To support building with go1.21 the existing custom version is still kept, and therefore
also our wrapper function file.MkdirAll - but it now just calls os.MkdirAll with go1.22
or newer on Windows.

See #5401, #6420 and acf1e2df84 for details about the
creation of our custom version of MkdirAll.

lib/file/mkdir_other.go

@@ -1,10 +1,10 @@
-//go:build !windows
+//go:build !windows || go1.22
 
 package file
 
 import "os"
 
-// MkdirAll just calls os.MkdirAll on non-Windows.
+// MkdirAll just calls os.MkdirAll on non-Windows and with go1.22 or newer on Windows
 func MkdirAll(path string, perm os.FileMode) error {
 	return os.MkdirAll(path, perm)
 }

lib/file/mkdir_windows.go

@@ -1,4 +1,4 @@
-//go:build windows
+//go:build windows && !go1.22
 
 package file
 

lib/file/mkdir_windows_go122_test.go

@@ -0,0 +1,122 @@
+//go:build windows && go1.22
+
+package file
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func checkMkdirAll(t *testing.T, path string, valid bool, errormsgs ...string) {
+	if valid {
+		assert.NoError(t, os.MkdirAll(path, 0777))
+	} else {
+		err := os.MkdirAll(path, 0777)
+		assert.Error(t, err)
+		ok := false
+		for _, msg := range errormsgs {
+			if err.Error() == msg {
+				ok = true
+			}
+		}
+		assert.True(t, ok, fmt.Sprintf("Error message '%v' didn't match any of %v", err, errormsgs))
+	}
+}
+
+func checkMkdirAllSubdirs(t *testing.T, path string, valid bool, errormsgs ...string) {
+	checkMkdirAll(t, path, valid, errormsgs...)
+	checkMkdirAll(t, path+`\`, valid, errormsgs...)
+	checkMkdirAll(t, path+`\parent`, valid, errormsgs...)
+	checkMkdirAll(t, path+`\parent\`, valid, errormsgs...)
+	checkMkdirAll(t, path+`\parent\child`, valid, errormsgs...)
+	checkMkdirAll(t, path+`\parent\child\`, valid, errormsgs...)
+}
+
+// Testing paths on existing drive
+func TestMkdirAllOnDrive(t *testing.T) {
+	path := t.TempDir()
+
+	dir, err := os.Stat(path)
+	require.NoError(t, err)
+	require.True(t, dir.IsDir())
+
+	drive := filepath.VolumeName(path)
+
+	checkMkdirAll(t, drive, true, "")
+	checkMkdirAll(t, drive+`\`, true, "")
+	checkMkdirAll(t, `\\?\`+drive, false, fmt.Sprintf(`mkdir \\?\%s: Access is denied.`, drive)) // This isn't actually a valid Windows path, it worked under go1.21.3 but fails under go1.21.4 and newer
+	checkMkdirAll(t, `\\?\`+drive+`\`, true, "")
+	checkMkdirAllSubdirs(t, path, true, "")
+	checkMkdirAllSubdirs(t, `\\?\`+path, true, "")
+}
+
+// Testing paths on unused drive
+// This covers the cases that we wanted to improve with our own custom version
+// of golang's os.MkdirAll, introduced in PR #5401. Before go1.22 the original
+// os.MkdirAll would recurse extended-length paths down to the "\\?" prefix and
+// return the noninformative error:
+// "mkdir \\?: The filename, directory name, or volume label syntax is incorrect."
+// Our version stopped the recursion at drive's root directory, and reported,
+// before go1.21.4:
+// "mkdir \\?\A:\: The system cannot find the path specified."
+// or, starting with go1.21.4:
+// "mkdir \\?\A:: The system cannot find the path specified."
+// See https://github.com/rclone/rclone/pull/5401.
+// Starting with go1.22 golang's os.MkdirAll have similar improvements that made
+// our custom version no longer necessary.
+func TestMkdirAllOnUnusedDrive(t *testing.T) {
+	letter := FindUnusedDriveLetter()
+	require.NotEqual(t, letter, 0)
+	drive := string(letter) + ":"
+	checkMkdirAll(t, drive, false, fmt.Sprintf(`mkdir %s: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\`, false, fmt.Sprintf(`mkdir %s\: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent`, false, fmt.Sprintf(`mkdir %s\parent: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent\`, false, fmt.Sprintf(`mkdir %s\parent\: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent\child`, false, fmt.Sprintf(`mkdir %s\parent: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent\child\`, false, fmt.Sprintf(`mkdir %s\parent: The system cannot find the path specified.`, drive))
+
+	drive = `\\?\` + drive
+	checkMkdirAll(t, drive, false, fmt.Sprintf(`mkdir %s: The system cannot find the file specified.`, drive))
+	checkMkdirAll(t, drive+`\`, false, fmt.Sprintf(`mkdir %s\: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent`, false, fmt.Sprintf(`mkdir %s\parent: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent\`, false, fmt.Sprintf(`mkdir %s\parent\: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent\child`, false, fmt.Sprintf(`mkdir %s\parent: The system cannot find the path specified.`, drive))
+	checkMkdirAll(t, drive+`\parent\child\`, false, fmt.Sprintf(`mkdir %s\parent: The system cannot find the path specified.`, drive))
+}
+
+// Testing paths on unknown network host
+// This covers more cases that we wanted to improve in our custom version of
+// golang's os.MkdirAll, extending that explained in TestMkdirAllOnUnusedDrive.
+// With our first fix, stopping it from recursing extended-length paths down to
+// the "\\?" prefix, it would now stop at `\\?\UNC`, because that is what
+// filepath.VolumeName returns (which is wrong, that is not a volume name!),
+// and still return a noninformative error:
+// "mkdir \\?\UNC\\: The filename, directory name, or volume label syntax is incorrect."
+// Our version stopped the recursion at level before this, and reports:
+// "mkdir \\?\UNC\0.0.0.0: The specified path is invalid."
+// See https://github.com/rclone/rclone/pull/6420.
+// Starting with go1.22 golang's os.MkdirAll have similar improvements that made
+// our custom version no longer necessary.
+func TestMkdirAllOnUnusedNetworkHost(t *testing.T) {
+	sharePath := `\\0.0.0.0\share`
+	checkMkdirAll(t, sharePath, false, fmt.Sprintf(`mkdir %s: The format of the specified network name is invalid.`, sharePath))
+	checkMkdirAll(t, sharePath+`\`, false, fmt.Sprintf(`mkdir %s\: The format of the specified network name is invalid.`, sharePath))
+	checkMkdirAll(t, sharePath+`\parent`, false, fmt.Sprintf(`mkdir %s\parent: The format of the specified network name is invalid.`, sharePath))
+	checkMkdirAll(t, sharePath+`\parent\`, false, fmt.Sprintf(`mkdir %s\parent\: The format of the specified network name is invalid.`, sharePath))
+	checkMkdirAll(t, sharePath+`\parent\child`, false, fmt.Sprintf(`mkdir %s\parent: The format of the specified network name is invalid.`, sharePath))
+	checkMkdirAll(t, sharePath+`\parent\child\`, false, fmt.Sprintf(`mkdir %s\parent: The format of the specified network name is invalid.`, sharePath))
+
+	serverPath := `\\?\UNC\0.0.0.0`
+	sharePath = serverPath + `\share`
+	checkMkdirAll(t, sharePath, false, fmt.Sprintf(`mkdir %s: The specified path is invalid.`, serverPath))
+	checkMkdirAll(t, sharePath+`\`, false, fmt.Sprintf(`mkdir %s: The specified path is invalid.`, serverPath))
+	checkMkdirAll(t, sharePath+`\parent`, false, fmt.Sprintf(`mkdir %s: The specified path is invalid.`, serverPath))
+	checkMkdirAll(t, sharePath+`\parent\`, false, fmt.Sprintf(`mkdir %s: The specified path is invalid.`, serverPath))
+	checkMkdirAll(t, sharePath+`\parent\child`, false, fmt.Sprintf(`mkdir %s: The specified path is invalid.`, serverPath))
+	checkMkdirAll(t, sharePath+`\parent\child\`, false, fmt.Sprintf(`mkdir %s: The specified path is invalid.`, serverPath))
+}

lib/file/mkdir_windows_test.go

@@ -1,4 +1,4 @@
-//go:build windows
+//go:build windows && !go1.22
 
 package file