DockerCLI/vendor/github.com/Microsoft/hcsshim/internal/safefile/safeopen.go

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package safefile
import (
"errors"
"io"
"os"
"path/filepath"
"strings"
"syscall"
"unicode/utf16"
"unsafe"
"github.com/Microsoft/hcsshim/internal/longpath"
winio "github.com/Microsoft/go-winio"
)
//go:generate go run $GOROOT\src\syscall\mksyscall_windows.go -output zsyscall_windows.go safeopen.go
//sys ntCreateFile(handle *uintptr, accessMask uint32, oa *objectAttributes, iosb *ioStatusBlock, allocationSize *uint64, fileAttributes uint32, shareAccess uint32, createDisposition uint32, createOptions uint32, eaBuffer *byte, eaLength uint32) (status uint32) = ntdll.NtCreateFile
//sys ntSetInformationFile(handle uintptr, iosb *ioStatusBlock, information uintptr, length uint32, class uint32) (status uint32) = ntdll.NtSetInformationFile
//sys rtlNtStatusToDosError(status uint32) (winerr error) = ntdll.RtlNtStatusToDosErrorNoTeb
//sys localAlloc(flags uint32, size int) (ptr uintptr) = kernel32.LocalAlloc
//sys localFree(ptr uintptr) = kernel32.LocalFree
type ioStatusBlock struct {
Status, Information uintptr
}
type objectAttributes struct {
Length uintptr
RootDirectory uintptr
ObjectName uintptr
Attributes uintptr
SecurityDescriptor uintptr
SecurityQoS uintptr
}
type unicodeString struct {
Length uint16
MaximumLength uint16
Buffer uintptr
}
type fileLinkInformation struct {
ReplaceIfExists bool
RootDirectory uintptr
FileNameLength uint32
FileName [1]uint16
}
type fileDispositionInformationEx struct {
Flags uintptr
}
const (
_FileLinkInformation = 11
_FileDispositionInformationEx = 64
FILE_READ_ATTRIBUTES = 0x0080
FILE_WRITE_ATTRIBUTES = 0x0100
DELETE = 0x10000
FILE_OPEN = 1
FILE_CREATE = 2
FILE_DIRECTORY_FILE = 0x00000001
FILE_SYNCHRONOUS_IO_NONALERT = 0x00000020
FILE_DELETE_ON_CLOSE = 0x00001000
FILE_OPEN_FOR_BACKUP_INTENT = 0x00004000
FILE_OPEN_REPARSE_POINT = 0x00200000
FILE_DISPOSITION_DELETE = 0x00000001
_OBJ_DONT_REPARSE = 0x1000
_STATUS_REPARSE_POINT_ENCOUNTERED = 0xC000050B
)
func OpenRoot(path string) (*os.File, error) {
longpath, err := longpath.LongAbs(path)
if err != nil {
return nil, err
}
return winio.OpenForBackup(longpath, syscall.GENERIC_READ, syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE, syscall.OPEN_EXISTING)
}
func ntRelativePath(path string) ([]uint16, error) {
path = filepath.Clean(path)
if strings.Contains(":", path) {
// Since alternate data streams must follow the file they
// are attached to, finding one here (out of order) is invalid.
return nil, errors.New("path contains invalid character `:`")
}
fspath := filepath.FromSlash(path)
if len(fspath) > 0 && fspath[0] == '\\' {
return nil, errors.New("expected relative path")
}
path16 := utf16.Encode(([]rune)(fspath))
if len(path16) > 32767 {
return nil, syscall.ENAMETOOLONG
}
return path16, nil
}
// openRelativeInternal opens a relative path from the given root, failing if
// any of the intermediate path components are reparse points.
func openRelativeInternal(path string, root *os.File, accessMask uint32, shareFlags uint32, createDisposition uint32, flags uint32) (*os.File, error) {
var (
h uintptr
iosb ioStatusBlock
oa objectAttributes
)
path16, err := ntRelativePath(path)
if err != nil {
return nil, err
}
if root == nil || root.Fd() == 0 {
return nil, errors.New("missing root directory")
}
upathBuffer := localAlloc(0, int(unsafe.Sizeof(unicodeString{}))+len(path16)*2)
defer localFree(upathBuffer)
upath := (*unicodeString)(unsafe.Pointer(upathBuffer))
upath.Length = uint16(len(path16) * 2)
upath.MaximumLength = upath.Length
upath.Buffer = upathBuffer + unsafe.Sizeof(*upath)
copy((*[32768]uint16)(unsafe.Pointer(upath.Buffer))[:], path16)
oa.Length = unsafe.Sizeof(oa)
oa.ObjectName = upathBuffer
oa.RootDirectory = uintptr(root.Fd())
oa.Attributes = _OBJ_DONT_REPARSE
status := ntCreateFile(
&h,
accessMask|syscall.SYNCHRONIZE,
&oa,
&iosb,
nil,
0,
shareFlags,
createDisposition,
FILE_OPEN_FOR_BACKUP_INTENT|FILE_SYNCHRONOUS_IO_NONALERT|flags,
nil,
0,
)
if status != 0 {
return nil, rtlNtStatusToDosError(status)
}
fullPath, err := longpath.LongAbs(filepath.Join(root.Name(), path))
if err != nil {
syscall.Close(syscall.Handle(h))
return nil, err
}
return os.NewFile(h, fullPath), nil
}
// OpenRelative opens a relative path from the given root, failing if
// any of the intermediate path components are reparse points.
func OpenRelative(path string, root *os.File, accessMask uint32, shareFlags uint32, createDisposition uint32, flags uint32) (*os.File, error) {
f, err := openRelativeInternal(path, root, accessMask, shareFlags, createDisposition, flags)
if err != nil {
err = &os.PathError{Op: "open", Path: filepath.Join(root.Name(), path), Err: err}
}
return f, err
}
// LinkRelative creates a hard link from oldname to newname (relative to oldroot
// and newroot), failing if any of the intermediate path components are reparse
// points.
func LinkRelative(oldname string, oldroot *os.File, newname string, newroot *os.File) error {
// Open the old file.
oldf, err := openRelativeInternal(
oldname,
oldroot,
syscall.FILE_WRITE_ATTRIBUTES,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
FILE_OPEN,
0,
)
if err != nil {
return &os.LinkError{Op: "link", Old: filepath.Join(oldroot.Name(), oldname), New: filepath.Join(newroot.Name(), newname), Err: err}
}
defer oldf.Close()
// Open the parent of the new file.
var parent *os.File
parentPath := filepath.Dir(newname)
if parentPath != "." {
parent, err = openRelativeInternal(
parentPath,
newroot,
syscall.GENERIC_READ,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
FILE_OPEN,
FILE_DIRECTORY_FILE)
if err != nil {
return &os.LinkError{Op: "link", Old: oldf.Name(), New: filepath.Join(newroot.Name(), newname), Err: err}
}
defer parent.Close()
fi, err := winio.GetFileBasicInfo(parent)
if err != nil {
return err
}
if (fi.FileAttributes & syscall.FILE_ATTRIBUTE_REPARSE_POINT) != 0 {
return &os.LinkError{Op: "link", Old: oldf.Name(), New: filepath.Join(newroot.Name(), newname), Err: rtlNtStatusToDosError(_STATUS_REPARSE_POINT_ENCOUNTERED)}
}
} else {
parent = newroot
}
// Issue an NT call to create the link. This will be safe because NT will
// not open any more directories to create the link, so it cannot walk any
// more reparse points.
newbase := filepath.Base(newname)
newbase16, err := ntRelativePath(newbase)
if err != nil {
return err
}
size := int(unsafe.Offsetof(fileLinkInformation{}.FileName)) + len(newbase16)*2
linkinfoBuffer := localAlloc(0, size)
defer localFree(linkinfoBuffer)
linkinfo := (*fileLinkInformation)(unsafe.Pointer(linkinfoBuffer))
linkinfo.RootDirectory = parent.Fd()
linkinfo.FileNameLength = uint32(len(newbase16) * 2)
copy((*[32768]uint16)(unsafe.Pointer(&linkinfo.FileName[0]))[:], newbase16)
var iosb ioStatusBlock
status := ntSetInformationFile(
oldf.Fd(),
&iosb,
linkinfoBuffer,
uint32(size),
_FileLinkInformation,
)
if status != 0 {
return &os.LinkError{Op: "link", Old: oldf.Name(), New: filepath.Join(parent.Name(), newbase), Err: rtlNtStatusToDosError(status)}
}
return nil
}
// deleteOnClose marks a file to be deleted when the handle is closed.
func deleteOnClose(f *os.File) error {
disposition := fileDispositionInformationEx{Flags: FILE_DISPOSITION_DELETE}
var iosb ioStatusBlock
status := ntSetInformationFile(
f.Fd(),
&iosb,
uintptr(unsafe.Pointer(&disposition)),
uint32(unsafe.Sizeof(disposition)),
_FileDispositionInformationEx,
)
if status != 0 {
return rtlNtStatusToDosError(status)
}
return nil
}
// clearReadOnly clears the readonly attribute on a file.
func clearReadOnly(f *os.File) error {
bi, err := winio.GetFileBasicInfo(f)
if err != nil {
return err
}
if bi.FileAttributes&syscall.FILE_ATTRIBUTE_READONLY == 0 {
return nil
}
sbi := winio.FileBasicInfo{
FileAttributes: bi.FileAttributes &^ syscall.FILE_ATTRIBUTE_READONLY,
}
if sbi.FileAttributes == 0 {
sbi.FileAttributes = syscall.FILE_ATTRIBUTE_NORMAL
}
return winio.SetFileBasicInfo(f, &sbi)
}
// RemoveRelative removes a file or directory relative to a root, failing if any
// intermediate path components are reparse points.
func RemoveRelative(path string, root *os.File) error {
f, err := openRelativeInternal(
path,
root,
FILE_READ_ATTRIBUTES|FILE_WRITE_ATTRIBUTES|DELETE,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
FILE_OPEN,
FILE_OPEN_REPARSE_POINT)
if err == nil {
defer f.Close()
err = deleteOnClose(f)
if err == syscall.ERROR_ACCESS_DENIED {
// Maybe the file is marked readonly. Clear the bit and retry.
clearReadOnly(f)
err = deleteOnClose(f)
}
}
if err != nil {
return &os.PathError{Op: "remove", Path: filepath.Join(root.Name(), path), Err: err}
}
return nil
}
// RemoveAllRelative removes a directory tree relative to a root, failing if any
// intermediate path components are reparse points.
func RemoveAllRelative(path string, root *os.File) error {
fi, err := LstatRelative(path, root)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
fileAttributes := fi.Sys().(*syscall.Win32FileAttributeData).FileAttributes
if fileAttributes&syscall.FILE_ATTRIBUTE_DIRECTORY == 0 || fileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT != 0 {
// If this is a reparse point, it can't have children. Simple remove will do.
err := RemoveRelative(path, root)
if err == nil || os.IsNotExist(err) {
return nil
}
return err
}
// It is necessary to use os.Open as Readdirnames does not work with
// OpenRelative. This is safe because the above lstatrelative fails
// if the target is outside the root, and we know this is not a
// symlink from the above FILE_ATTRIBUTE_REPARSE_POINT check.
fd, err := os.Open(filepath.Join(root.Name(), path))
if err != nil {
if os.IsNotExist(err) {
// Race. It was deleted between the Lstat and Open.
// Return nil per RemoveAll's docs.
return nil
}
return err
}
// Remove contents & return first error.
for {
names, err1 := fd.Readdirnames(100)
for _, name := range names {
err1 := RemoveAllRelative(path+string(os.PathSeparator)+name, root)
if err == nil {
err = err1
}
}
if err1 == io.EOF {
break
}
// If Readdirnames returned an error, use it.
if err == nil {
err = err1
}
if len(names) == 0 {
break
}
}
fd.Close()
// Remove directory.
err1 := RemoveRelative(path, root)
if err1 == nil || os.IsNotExist(err1) {
return nil
}
if err == nil {
err = err1
}
return err
}
// MkdirRelative creates a directory relative to a root, failing if any
// intermediate path components are reparse points.
func MkdirRelative(path string, root *os.File) error {
f, err := openRelativeInternal(
path,
root,
0,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
FILE_CREATE,
FILE_DIRECTORY_FILE)
if err == nil {
f.Close()
} else {
err = &os.PathError{Op: "mkdir", Path: filepath.Join(root.Name(), path), Err: err}
}
return err
}
// LstatRelative performs a stat operation on a file relative to a root, failing
// if any intermediate path components are reparse points.
func LstatRelative(path string, root *os.File) (os.FileInfo, error) {
f, err := openRelativeInternal(
path,
root,
FILE_READ_ATTRIBUTES,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
FILE_OPEN,
FILE_OPEN_REPARSE_POINT)
if err != nil {
return nil, &os.PathError{Op: "stat", Path: filepath.Join(root.Name(), path), Err: err}
}
defer f.Close()
return f.Stat()
}
// EnsureNotReparsePointRelative validates that a given file (relative to a
// root) and all intermediate path components are not a reparse points.
func EnsureNotReparsePointRelative(path string, root *os.File) error {
// Perform an open with OBJ_DONT_REPARSE but without specifying FILE_OPEN_REPARSE_POINT.
f, err := OpenRelative(
path,
root,
0,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE|syscall.FILE_SHARE_DELETE,
FILE_OPEN,
0)
if err != nil {
return err
}
f.Close()
return nil
}