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257 lines
6.5 KiB
Go
257 lines
6.5 KiB
Go
package usn
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import (
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"b612.me/win32api"
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"golang.org/x/sys/windows"
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"os"
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"sync"
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"syscall"
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"time"
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)
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const DevNull = "NUL"
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// A fileStat is the implementation of FileInfo returned by Stat and Lstat.
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type FileStat struct {
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name string
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// from ByHandleFileInformation, Win32FileAttributeData and Win32finddata
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FileAttributes uint32
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CreationTime syscall.Filetime
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LastAccessTime syscall.Filetime
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LastWriteTime syscall.Filetime
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FileSizeHigh uint32
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FileSizeLow uint32
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// from Win32finddata
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Reserved0 uint32
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// what syscall.GetFileType returns
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filetype uint32
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// used to implement SameFile
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sync.Mutex
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path string
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vol uint32
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idxhi uint32
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idxlo uint32
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appendNameToPath bool
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}
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// newFileStatFromWin32finddata copies all required information
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// from syscall.Win32finddata d into the newly created fileStat.
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func newFileStatFromInformation(d *syscall.ByHandleFileInformation, name string, path string) FileStat {
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return FileStat{
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name: name,
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path: path,
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FileAttributes: d.FileAttributes,
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CreationTime: d.CreationTime,
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LastAccessTime: d.LastAccessTime,
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LastWriteTime: d.LastWriteTime,
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FileSizeHigh: d.FileSizeHigh,
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FileSizeLow: d.FileSizeLow,
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}
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}
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func (fs *FileStat) Name() string {
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return fs.name
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}
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func (fs *FileStat) IsDir() bool {
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return fs.FileAttributes&win32api.FILE_ATTRIBUTE_DIRECTORY != 0
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}
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func (fs *FileStat) isSymlink() bool {
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// Use instructions described at
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// https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/
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// to recognize whether it's a symlink.
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if fs.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
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return false
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}
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return fs.Reserved0 == syscall.IO_REPARSE_TAG_SYMLINK ||
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fs.Reserved0 == windows.IO_REPARSE_TAG_MOUNT_POINT
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}
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func (fs *FileStat) Size() int64 {
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return int64(fs.FileSizeHigh)<<32 + int64(fs.FileSizeLow)
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}
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func (fs *FileStat) Mode() (m os.FileMode) {
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if fs == &devNullStat {
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return os.ModeDevice | os.ModeCharDevice | 0666
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}
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if fs.FileAttributes&syscall.FILE_ATTRIBUTE_READONLY != 0 {
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m |= 0444
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} else {
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m |= 0666
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}
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if fs.isSymlink() {
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return m | os.ModeSymlink
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}
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if fs.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
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m |= os.ModeDir | 0111
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}
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switch fs.filetype {
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case syscall.FILE_TYPE_PIPE:
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m |= os.ModeNamedPipe
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case syscall.FILE_TYPE_CHAR:
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m |= os.ModeDevice | os.ModeCharDevice
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}
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return m
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}
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func (fs *FileStat) ModTime() time.Time {
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return time.Unix(0, fs.LastWriteTime.Nanoseconds())
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}
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// Sys returns syscall.Win32FileAttributeData for file fs.
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func (fs *FileStat) Sys() interface{} {
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return &syscall.Win32FileAttributeData{
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FileAttributes: fs.FileAttributes,
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CreationTime: fs.CreationTime,
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LastAccessTime: fs.LastAccessTime,
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LastWriteTime: fs.LastWriteTime,
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FileSizeHigh: fs.FileSizeHigh,
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FileSizeLow: fs.FileSizeLow,
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}
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}
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// saveInfoFromPath saves full path of the file to be used by os.SameFile later,
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// and set name from path.
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// devNullStat is fileStat structure describing DevNull file ("NUL").
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var devNullStat = FileStat{
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name: DevNull,
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// hopefully this will work for SameFile
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vol: 0,
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idxhi: 0,
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idxlo: 0,
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}
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func fixLongPath(path string) string {
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// Do nothing (and don't allocate) if the path is "short".
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// Empirically (at least on the Windows Server 2013 builder),
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// the kernel is arbitrarily okay with < 248 bytes. That
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// matches what the docs above say:
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// "When using an API to create a directory, the specified
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// path cannot be so long that you cannot append an 8.3 file
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// name (that is, the directory name cannot exceed MAX_PATH
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// minus 12)." Since MAX_PATH is 260, 260 - 12 = 248.
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//
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// The MSDN docs appear to say that a normal path that is 248 bytes long
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// will work; empirically the path must be less then 248 bytes long.
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if len(path) < 248 {
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// Don't fix. (This is how Go 1.7 and earlier worked,
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// not automatically generating the \\?\ form)
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return path
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}
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// The extended form begins with \\?\, as in
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// \\?\c:\windows\foo.txt or \\?\UNC\server\share\foo.txt.
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// The extended form disables evaluation of . and .. path
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// elements and disables the interpretation of / as equivalent
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// to \. The conversion here rewrites / to \ and elides
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// . elements as well as trailing or duplicate separators. For
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// simplicity it avoids the conversion entirely for relative
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// paths or paths containing .. elements. For now,
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// \\server\share paths are not converted to
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// \\?\UNC\server\share paths because the rules for doing so
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// are less well-specified.
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if len(path) >= 2 && path[:2] == `\\` {
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// Don't canonicalize UNC paths.
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return path
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}
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if !isAbs(path) {
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// Relative path
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return path
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}
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const prefix = `\\?`
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pathbuf := make([]byte, len(prefix)+len(path)+len(`\`))
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copy(pathbuf, prefix)
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n := len(path)
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r, w := 0, len(prefix)
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for r < n {
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switch {
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case IsPathSeparator(path[r]):
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// empty block
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r++
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case path[r] == '.' && (r+1 == n || IsPathSeparator(path[r+1])):
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// /./
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r++
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case r+1 < n && path[r] == '.' && path[r+1] == '.' && (r+2 == n || IsPathSeparator(path[r+2])):
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// /../ is currently unhandled
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return path
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default:
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pathbuf[w] = '\\'
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w++
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for ; r < n && !IsPathSeparator(path[r]); r++ {
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pathbuf[w] = path[r]
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w++
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}
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}
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}
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// A drive's root directory needs a trailing \
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if w == len(`\\?\c:`) {
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pathbuf[w] = '\\'
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w++
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}
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return string(pathbuf[:w])
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}
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func IsPathSeparator(c uint8) bool {
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// NOTE: Windows accept / as path separator.
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return c == '\\' || c == '/'
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}
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func isAbs(path string) (b bool) {
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v := volumeName(path)
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if v == "" {
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return false
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}
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path = path[len(v):]
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if path == "" {
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return false
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}
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return IsPathSeparator(path[0])
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}
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func volumeName(path string) (v string) {
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if len(path) < 2 {
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return ""
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}
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// with drive letter
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c := path[0]
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if path[1] == ':' &&
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('0' <= c && c <= '9' || 'a' <= c && c <= 'z' ||
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'A' <= c && c <= 'Z') {
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return path[:2]
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}
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// is it UNC
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if l := len(path); l >= 5 && IsPathSeparator(path[0]) && IsPathSeparator(path[1]) &&
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!IsPathSeparator(path[2]) && path[2] != '.' {
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// first, leading `\\` and next shouldn't be `\`. its server name.
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for n := 3; n < l-1; n++ {
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// second, next '\' shouldn't be repeated.
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if IsPathSeparator(path[n]) {
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n++
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// third, following something characters. its share name.
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if !IsPathSeparator(path[n]) {
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if path[n] == '.' {
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break
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}
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for ; n < l; n++ {
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if IsPathSeparator(path[n]) {
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break
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}
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}
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return path[:n]
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}
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break
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}
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}
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}
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return ""
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}
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