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minio/pkg/x/os/stat_windows.go

268 lines
8.0 KiB

// +build windows
/*
* Minio Cloud Storage, (C) 2017 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// FIXME: Once we have a go version released with the
// following fix https://go-review.googlesource.com/#/c/41834/.
// We should actively purge this block.
// Copyright 2009 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 os implements extended safe functions
// for stdlib "os".
package os
import (
os1 "os"
"path/filepath"
"syscall"
"time"
)
const errSharingViolation syscall.Errno = 32
// fixLongPath returns the extended-length (\\?\-prefixed) form of
// path when needed, in order to avoid the default 260 character file
// path limit imposed by Windows. If path is not easily converted to
// the extended-length form (for example, if path is a relative path
// or contains .. elements), or is short enough, fixLongPath returns
// path unmodified.
//
// See https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath
func fixLongPath(path string) string {
// Do nothing (and don't allocate) if the path is "short".
// Empirically (at least on the Windows Server 2013 builder),
// the kernel is arbitrarily okay with < 248 bytes. That
// matches what the docs above say:
// "When using an API to create a directory, the specified
// path cannot be so long that you cannot append an 8.3 file
// name (that is, the directory name cannot exceed MAX_PATH
// minus 12)." Since MAX_PATH is 260, 260 - 12 = 248.
//
// The MSDN docs appear to say that a normal path that is 248 bytes long
// will work; empirically the path must be less then 248 bytes long.
if len(path) < 248 {
// Don't fix. (This is how Go 1.7 and earlier worked,
// not automatically generating the \\?\ form)
return path
}
// The extended form begins with \\?\, as in
// \\?\c:\windows\foo.txt or \\?\UNC\server\share\foo.txt.
// The extended form disables evaluation of . and .. path
// elements and disables the interpretation of / as equivalent
// to \. The conversion here rewrites / to \ and elides
// . elements as well as trailing or duplicate separators. For
// simplicity it avoids the conversion entirely for relative
// paths or paths containing .. elements. For now,
// \\server\share paths are not converted to
// \\?\UNC\server\share paths because the rules for doing so
// are less well-specified.
if len(path) >= 2 && path[:2] == `\\` {
// Don't canonicalize UNC paths.
return path
}
if !filepath.IsAbs(path) {
// Relative path
return path
}
const prefix = `\\?`
pathbuf := make([]byte, len(prefix)+len(path)+len(`\`))
copy(pathbuf, prefix)
n := len(path)
r, w := 0, len(prefix)
for r < n {
switch {
case os1.IsPathSeparator(path[r]):
// empty block
r++
case path[r] == '.' && (r+1 == n || os1.IsPathSeparator(path[r+1])):
// /./
r++
case r+1 < n && path[r] == '.' && path[r+1] == '.' && (r+2 == n || os1.IsPathSeparator(path[r+2])):
// /../ is currently unhandled
return path
default:
pathbuf[w] = '\\'
w++
for ; r < n && !os1.IsPathSeparator(path[r]); r++ {
pathbuf[w] = path[r]
w++
}
}
}
// A drive's root directory needs a trailing \
if w == len(`\\?\c:`) {
pathbuf[w] = '\\'
w++
}
return string(pathbuf[:w])
}
// Stat returns a FileInfo structure describing the
// named file. If there is an error, it will be of type
// *PathError.
func Stat(name string) (os1.FileInfo, error) {
if len(name) == 0 {
return nil, &os1.PathError{
Op: "Stat",
Path: name,
Err: syscall.Errno(syscall.ERROR_PATH_NOT_FOUND),
}
}
if name == os1.DevNull {
return &devNullStat, nil
}
namep, err := syscall.UTF16PtrFromString(fixLongPath(name))
if err != nil {
return nil, &os1.PathError{Op: "Stat", Path: name, Err: err}
}
// Use Windows I/O manager to dereference the symbolic link, as per
// https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/
h, err := syscall.CreateFile(namep, 0, 0, nil,
syscall.OPEN_EXISTING, syscall.FILE_FLAG_BACKUP_SEMANTICS, 0)
if err != nil {
if err == errSharingViolation {
// try FindFirstFile now that CreateFile failed
return statWithFindFirstFile(name, namep)
}
return nil, &os1.PathError{Op: "CreateFile", Path: name, Err: err}
}
defer syscall.CloseHandle(h)
var d syscall.ByHandleFileInformation
if err = syscall.GetFileInformationByHandle(h, &d); err != nil {
return nil, &os1.PathError{
Op: "GetFileInformationByHandle",
Path: name,
Err: err,
}
}
return &fileStat{
name: filepath.Base(name),
sys: syscall.Win32FileAttributeData{
FileAttributes: d.FileAttributes,
CreationTime: d.CreationTime,
LastAccessTime: d.LastAccessTime,
LastWriteTime: d.LastWriteTime,
FileSizeHigh: d.FileSizeHigh,
FileSizeLow: d.FileSizeLow,
},
vol: d.VolumeSerialNumber,
idxhi: d.FileIndexHigh,
idxlo: d.FileIndexLow,
// fileStat.path is used by os1.SameFile to decide, if it needs
// to fetch vol, idxhi and idxlo. But these are already set,
// so set fileStat.path to "" to prevent os1.SameFile doing it again.
// Also do not set fileStat.filetype, because it is only used for
// console and stdin/stdout. But you cannot call os1.Stat for these.
}, nil
}
// statWithFindFirstFile is used by Stat to handle special case of stating
// c:\pagefile.sys. We might discovered other files need similar treatment.
func statWithFindFirstFile(name string, namep *uint16) (os1.FileInfo, error) {
var fd syscall.Win32finddata
h, err := syscall.FindFirstFile(namep, &fd)
if err != nil {
return nil, &os1.PathError{Op: "FindFirstFile", Path: name, Err: err}
}
syscall.FindClose(h)
fullpath := name
if !filepath.IsAbs(fullpath) {
fullpath, err = syscall.FullPath(fullpath)
if err != nil {
return nil, &os1.PathError{Op: "FullPath", Path: name, Err: err}
}
}
return &fileStat{
name: filepath.Base(name),
path: fullpath,
sys: syscall.Win32FileAttributeData{
FileAttributes: fd.FileAttributes,
CreationTime: fd.CreationTime,
LastAccessTime: fd.LastAccessTime,
LastWriteTime: fd.LastWriteTime,
FileSizeHigh: fd.FileSizeHigh,
FileSizeLow: fd.FileSizeLow,
},
}, nil
}
// A fileStat is the implementation of os1.FileInfo returned by stat.
type fileStat struct {
name string
sys syscall.Win32FileAttributeData
filetype uint32 // what syscall.GetFileType returns
path string
vol uint32
idxhi uint32
idxlo uint32
}
func (fs *fileStat) Name() string { return fs.name }
func (fs *fileStat) IsDir() bool { return fs.Mode().IsDir() }
func (fs *fileStat) Size() int64 {
return int64(fs.sys.FileSizeHigh)<<32 + int64(fs.sys.FileSizeLow)
}
// devNullStat is fileStat structure describing DevNull file ("NUL").
var devNullStat = fileStat{
name: os1.DevNull,
vol: 0,
idxhi: 0,
idxlo: 0,
}
func (fs *fileStat) Mode() (m os1.FileMode) {
if fs == &devNullStat {
return os1.ModeDevice | os1.ModeCharDevice | 0666
}
if fs.sys.FileAttributes&syscall.FILE_ATTRIBUTE_READONLY != 0 {
m |= 0444
} else {
m |= 0666
}
if fs.sys.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT != 0 {
return m | os1.ModeSymlink
}
if fs.sys.FileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY != 0 {
m |= os1.ModeDir | 0111
}
switch fs.filetype {
case syscall.FILE_TYPE_PIPE:
m |= os1.ModeNamedPipe
case syscall.FILE_TYPE_CHAR:
m |= os1.ModeCharDevice
}
return m
}
func (fs *fileStat) ModTime() time.Time {
return time.Unix(0, fs.sys.LastWriteTime.Nanoseconds())
}
// Sys returns syscall.Win32FileAttributeData for file fs.
func (fs *fileStat) Sys() interface{} { return &fs.sys }