// Copyright 2020 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 cache
import (
"fmt"
"path/filepath"
"syscall"
)
func init() {
checkPathValid = windowsCheckPathValid
}
func windowsCheckPathValid(path string) error {
// Back in the day, Windows used to have short and long filenames, and
// it still supports those APIs. GetLongPathName gets the real case for a
// path, so we can use it here. Inspired by
// http://stackoverflow.com/q/2113822.
// Short paths can be longer than long paths, and unicode, so be generous.
buflen := 4 * len(path)
namep, err := syscall.UTF16PtrFromString(path)
if err != nil {
return err
}
short := make([]uint16, buflen)
n, err := syscall.GetShortPathName(namep, &short[0], uint32(len(short)*2)) // buflen is in bytes.
if err != nil {
return err
}
if int(n) > len(short)*2 {
return fmt.Errorf("short buffer too short: %v vs %v*2", n, len(short))
}
long := make([]uint16, buflen)
n, err = syscall.GetLongPathName(&short[0], &long[0], uint32(len(long)*2))
if err != nil {
return err
}
if int(n) > len(long)*2 {
return fmt.Errorf("long buffer too short: %v vs %v*2", n, len(long))
}
longstr := syscall.UTF16ToString(long)
isRoot := func(p string) bool {
return p[len(p)-1] == filepath.Separator
}
for got, want := path, longstr; !isRoot(got) && !isRoot(want); got, want = filepath.Dir(got), filepath.Dir(want) {
if g, w := filepath.Base(got), filepath.Base(want); g != w {
return fmt.Errorf("invalid path %q: component %q is listed by Windows as %q", path, g, w)
}
}
return nil
}