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restic/internal/fs/file_windows.go
Aneesh Nireshwalia 0962917974
Support windows metadata using generic attribs
Add new generic_attributes attribute in Node.
Use the generic attributes to add support for creation time and file attributes like hidden, readonly, encrypted in windows. Handle permission errors for readonly files in windows.
Handle backup and restore of encrypted attributes using windows system calls.
2024-02-22 17:31:20 -07:00

105 lines
2.8 KiB
Go

package fs
import (
"math/rand"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"golang.org/x/sys/windows"
)
// fixpath returns an absolute path on windows, so restic can open long file
// names.
func fixpath(name string) string {
abspath, err := filepath.Abs(name)
if err == nil {
// Check if \\?\UNC\ already exist
if strings.HasPrefix(abspath, `\\?\UNC\`) {
return abspath
}
// Check if \\?\ already exist
if strings.HasPrefix(abspath, `\\?\`) {
return abspath
}
// Check if path starts with \\
if strings.HasPrefix(abspath, `\\`) {
return strings.Replace(abspath, `\\`, `\\?\UNC\`, 1)
}
// Normal path
return `\\?\` + abspath
}
return name
}
// TempFile creates a temporary file which is marked as delete-on-close
func TempFile(dir, prefix string) (f *os.File, err error) {
// slightly modified implementation of os.CreateTemp(dir, prefix) to allow us to add
// the FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_DELETE_ON_CLOSE flags.
// These provide two large benefits:
// FILE_ATTRIBUTE_TEMPORARY tells Windows to keep the file in memory only if possible
// which reduces the amount of unnecessary disk writes.
// FILE_FLAG_DELETE_ON_CLOSE instructs Windows to automatically delete the file once
// all file descriptors are closed.
if dir == "" {
dir = os.TempDir()
}
access := uint32(windows.GENERIC_READ | windows.GENERIC_WRITE)
creation := uint32(windows.CREATE_NEW)
share := uint32(0) // prevent other processes from accessing the file
flags := uint32(windows.FILE_ATTRIBUTE_TEMPORARY | windows.FILE_FLAG_DELETE_ON_CLOSE)
rnd := rand.New(rand.NewSource(time.Now().UnixNano()))
for i := 0; i < 10000; i++ {
randSuffix := strconv.Itoa(int(1e9 + rnd.Intn(1e9)%1e9))[1:]
path := filepath.Join(dir, prefix+randSuffix)
ptr, err := windows.UTF16PtrFromString(path)
if err != nil {
return nil, err
}
h, err := windows.CreateFile(ptr, access, share, nil, creation, flags, 0)
if os.IsExist(err) {
continue
}
return os.NewFile(uintptr(h), path), err
}
// Proper error handling is still to do
return nil, os.ErrExist
}
// Chmod changes the mode of the named file to mode.
func Chmod(name string, mode os.FileMode) error {
return os.Chmod(fixpath(name), mode)
}
// ClearSystem removes the system attribute from the file.
func ClearSystem(path string) error {
return ClearAttribute(path, windows.FILE_ATTRIBUTE_SYSTEM)
}
// ClearAttribute removes the specified attribute from the file.
func ClearAttribute(path string, attribute uint32) error {
ptr, err := windows.UTF16PtrFromString(path)
if err != nil {
return err
}
fileAttributes, err := windows.GetFileAttributes(ptr)
if err != nil {
return err
}
if fileAttributes&attribute != 0 {
// Clear the attribute
fileAttributes &= ^uint32(attribute)
err = windows.SetFileAttributes(ptr, fileAttributes)
if err != nil {
return err
}
}
return nil
}