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os: use CreateFile for Stat of symlinks

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Stat uses Windows FindFirstFile + CreateFile to gather symlink
information - FindFirstFile determines if file is a symlink,
and then CreateFile follows symlink to capture target details.

Lstat only uses FindFirstFile.

This CL replaces current approach with just a call to CreateFile.
Lstat uses FILE_FLAG_OPEN_REPARSE_POINT flag, that instructs
CreateFile not to follow symlink. Other than that both Stat and
Lstat look the same now. New code is simpler.

CreateFile + GetFileInformationByHandle (unlike FindFirstFile)
does not report reparse tag of a file. I tried to ignore reparse
tag altogether. And it works for symlinks and mount points.
Unfortunately (see https://github.com/moby/moby/issues/37026),
files on deduped disk volumes are reported with
FILE_ATTRIBUTE_REPARSE_POINT attribute set and reparse tag set
to IO_REPARSE_TAG_DEDUP. So, if we ignore reparse tag, Lstat
interprets deduped volume files as symlinks. That is incorrect.
So I had to add GetFileInformationByHandleEx call to gather
reparse tag after calling CreateFile and GetFileInformationByHandle.

Fixes #27225
Fixes #27515

Change-Id: If60233bcf18836c147597cc17450d82f3f88c623
Reviewed-on: https://go-review.googlesource.com/c/143578
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Kirill Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Alex Brainman 2018-10-20 16:30:57 +11:00
parent d154ef60a0
commit f10815898c
6 changed files with 127 additions and 123 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/internal/syscall/windows/mksyscall.go
View File

@ -4,4 +4,4 @@
package windows
//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go syscall_windows.go security_windows.go psapi_windows.go
//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go syscall_windows.go security_windows.go psapi_windows.go symlink_windows.go

25
src/internal/syscall/windows/symlink_windows.go
View File

@ -11,4 +11,29 @@ const (
// symlink support for CreateSymbolicLink() starting with Windows 10 (1703, v10.0.14972)
SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE = 0x2
// FileInformationClass values
FileBasicInfo = 0 // FILE_BASIC_INFO
FileStandardInfo = 1 // FILE_STANDARD_INFO
FileNameInfo = 2 // FILE_NAME_INFO
FileStreamInfo = 7 // FILE_STREAM_INFO
FileCompressionInfo = 8 // FILE_COMPRESSION_INFO
FileAttributeTagInfo = 9 // FILE_ATTRIBUTE_TAG_INFO
FileIdBothDirectoryInfo = 0xa // FILE_ID_BOTH_DIR_INFO
FileIdBothDirectoryRestartInfo = 0xb // FILE_ID_BOTH_DIR_INFO
FileRemoteProtocolInfo = 0xd // FILE_REMOTE_PROTOCOL_INFO
FileFullDirectoryInfo = 0xe // FILE_FULL_DIR_INFO
FileFullDirectoryRestartInfo = 0xf // FILE_FULL_DIR_INFO
FileStorageInfo = 0x10 // FILE_STORAGE_INFO
FileAlignmentInfo = 0x11 // FILE_ALIGNMENT_INFO
FileIdInfo = 0x12 // FILE_ID_INFO
FileIdExtdDirectoryInfo = 0x13 // FILE_ID_EXTD_DIR_INFO
FileIdExtdDirectoryRestartInfo = 0x14 // FILE_ID_EXTD_DIR_INFO
)
type FILE_ATTRIBUTE_TAG_INFO struct {
FileAttributes uint32
ReparseTag uint32
}
//sys GetFileInformationByHandleEx(handle syscall.Handle, class uint32, info *byte, bufsize uint32) (err error)

57
src/internal/syscall/windows/zsyscall_windows.go
View File

@ -44,28 +44,29 @@ var (
moduserenv = syscall.NewLazyDLL(sysdll.Add("userenv.dll"))
modpsapi = syscall.NewLazyDLL(sysdll.Add("psapi.dll"))
procGetAdaptersAddresses = modiphlpapi.NewProc("GetAdaptersAddresses")
procGetComputerNameExW = modkernel32.NewProc("GetComputerNameExW")
procMoveFileExW = modkernel32.NewProc("MoveFileExW")
procGetModuleFileNameW = modkernel32.NewProc("GetModuleFileNameW")
procWSASocketW = modws2_32.NewProc("WSASocketW")
procGetACP = modkernel32.NewProc("GetACP")
procGetConsoleCP = modkernel32.NewProc("GetConsoleCP")
procMultiByteToWideChar = modkernel32.NewProc("MultiByteToWideChar")
procGetCurrentThread = modkernel32.NewProc("GetCurrentThread")
procNetShareAdd = modnetapi32.NewProc("NetShareAdd")
procNetShareDel = modnetapi32.NewProc("NetShareDel")
procGetFinalPathNameByHandleW = modkernel32.NewProc("GetFinalPathNameByHandleW")
procImpersonateSelf = modadvapi32.NewProc("ImpersonateSelf")
procRevertToSelf = modadvapi32.NewProc("RevertToSelf")
procOpenThreadToken = modadvapi32.NewProc("OpenThreadToken")
procLookupPrivilegeValueW = modadvapi32.NewProc("LookupPrivilegeValueW")
procAdjustTokenPrivileges = modadvapi32.NewProc("AdjustTokenPrivileges")
procDuplicateTokenEx = modadvapi32.NewProc("DuplicateTokenEx")
procSetTokenInformation = modadvapi32.NewProc("SetTokenInformation")
procGetProfilesDirectoryW = moduserenv.NewProc("GetProfilesDirectoryW")
procNetUserGetLocalGroups = modnetapi32.NewProc("NetUserGetLocalGroups")
procGetProcessMemoryInfo = modpsapi.NewProc("GetProcessMemoryInfo")
procGetAdaptersAddresses = modiphlpapi.NewProc("GetAdaptersAddresses")
procGetComputerNameExW = modkernel32.NewProc("GetComputerNameExW")
procMoveFileExW = modkernel32.NewProc("MoveFileExW")
procGetModuleFileNameW = modkernel32.NewProc("GetModuleFileNameW")
procWSASocketW = modws2_32.NewProc("WSASocketW")
procGetACP = modkernel32.NewProc("GetACP")
procGetConsoleCP = modkernel32.NewProc("GetConsoleCP")
procMultiByteToWideChar = modkernel32.NewProc("MultiByteToWideChar")
procGetCurrentThread = modkernel32.NewProc("GetCurrentThread")
procNetShareAdd = modnetapi32.NewProc("NetShareAdd")
procNetShareDel = modnetapi32.NewProc("NetShareDel")
procGetFinalPathNameByHandleW = modkernel32.NewProc("GetFinalPathNameByHandleW")
procImpersonateSelf = modadvapi32.NewProc("ImpersonateSelf")
procRevertToSelf = modadvapi32.NewProc("RevertToSelf")
procOpenThreadToken = modadvapi32.NewProc("OpenThreadToken")
procLookupPrivilegeValueW = modadvapi32.NewProc("LookupPrivilegeValueW")
procAdjustTokenPrivileges = modadvapi32.NewProc("AdjustTokenPrivileges")
procDuplicateTokenEx = modadvapi32.NewProc("DuplicateTokenEx")
procSetTokenInformation = modadvapi32.NewProc("SetTokenInformation")
procGetProfilesDirectoryW = moduserenv.NewProc("GetProfilesDirectoryW")
procNetUserGetLocalGroups = modnetapi32.NewProc("NetUserGetLocalGroups")
procGetProcessMemoryInfo = modpsapi.NewProc("GetProcessMemoryInfo")
procGetFileInformationByHandleEx = modkernel32.NewProc("GetFileInformationByHandleEx")
)
func GetAdaptersAddresses(family uint32, flags uint32, reserved uintptr, adapterAddresses *IpAdapterAddresses, sizePointer *uint32) (errcode error) {
@ -321,3 +322,15 @@ func GetProcessMemoryInfo(handle syscall.Handle, memCounters *PROCESS_MEMORY_COU
}
return
}
func GetFileInformationByHandleEx(handle syscall.Handle, class uint32, info *byte, bufsize uint32) (err error) {
r1, _, e1 := syscall.Syscall6(procGetFileInformationByHandleEx.Addr(), 4, uintptr(handle), uintptr(class), uintptr(unsafe.Pointer(info)), uintptr(bufsize), 0, 0)
if r1 == 0 {
if e1 != 0 {
err = errnoErr(e1)
} else {
err = syscall.EINVAL
}
}
return
}

10
src/os/stat_test.go
View File

@ -250,10 +250,6 @@ func TestFileAndSymlinkStats(t *testing.T) {
// see issue 27225 for details
func TestSymlinkWithTrailingSlash(t *testing.T) {
if runtime.GOOS == "windows" {
t.Skip("skipping on windows; issue 27225")
}
testenv.MustHaveSymlink(t)
tmpdir, err := ioutil.TempDir("", "TestSymlinkWithTrailingSlash")
@ -274,7 +270,11 @@ func TestSymlinkWithTrailingSlash(t *testing.T) {
}
dirlinkWithSlash := dirlink + string(os.PathSeparator)
testDirStats(t, dirlinkWithSlash)
if runtime.GOOS == "windows" {
testSymlinkStats(t, dirlinkWithSlash, true)
} else {
testDirStats(t, dirlinkWithSlash)
}
fi1, err := os.Stat(dir)
if err != nil {

87
src/os/stat_windows.go
View File

@ -5,7 +5,9 @@
package os
import (
"internal/syscall/windows"
"syscall"
"unsafe"
)
// isNulName returns true if name is NUL file name.
@ -58,33 +60,59 @@ func (file *File) Stat() (FileInfo, error) {
return fs, err
}
// statNolog implements Stat for Windows.
func statNolog(name string) (FileInfo, error) {
// stat implements both Stat and Lstat of a file.
func stat(funcname, name string, createFileAttrs uint32) (FileInfo, error) {
if len(name) == 0 {
return nil, &PathError{"Stat", name, syscall.Errno(syscall.ERROR_PATH_NOT_FOUND)}
return nil, &PathError{funcname, name, syscall.Errno(syscall.ERROR_PATH_NOT_FOUND)}
}
if isNulName(name) {
return &devNullStat, nil
}
namep, err := syscall.UTF16PtrFromString(fixLongPath(name))
if err != nil {
return nil, &PathError{"Stat", name, err}
return nil, &PathError{funcname, name, err}
}
fs, err := newFileStatFromGetFileAttributesExOrFindFirstFile(name, namep)
if err != nil {
return nil, err
}
if !fs.isSymlink() {
err = fs.updatePathAndName(name)
if err != nil {
return nil, err
// Try GetFileAttributesEx first, because it is faster than CreateFile.
// See https://golang.org/issues/19922#issuecomment-300031421 for details.
var fa syscall.Win32FileAttributeData
err = syscall.GetFileAttributesEx(namep, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
if err == nil && fa.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
// Not a symlink.
fs := &fileStat{
path: name,
FileAttributes: fa.FileAttributes,
CreationTime: fa.CreationTime,
LastAccessTime: fa.LastAccessTime,
LastWriteTime: fa.LastWriteTime,
FileSizeHigh: fa.FileSizeHigh,
FileSizeLow: fa.FileSizeLow,
}
// Gather full path to be used by os.SameFile later.
if !isAbs(fs.path) {
fs.path, err = syscall.FullPath(fs.path)
if err != nil {
return nil, &PathError{"FullPath", name, err}
}
}
fs.name = basename(name)
return fs, nil
}
// Use Windows I/O manager to dereference the symbolic link, as per
// https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/
// GetFileAttributesEx fails with ERROR_SHARING_VIOLATION error for
// files, like c:\pagefile.sys. Use FindFirstFile for such files.
if err == windows.ERROR_SHARING_VIOLATION {
var fd syscall.Win32finddata
sh, err := syscall.FindFirstFile(namep, &fd)
if err != nil {
return nil, &PathError{"FindFirstFile", name, err}
}
syscall.FindClose(sh)
return newFileStatFromWin32finddata(&fd), nil
}
// Finally use CreateFile.
h, err := syscall.CreateFile(namep, 0, 0, nil,
syscall.OPEN_EXISTING, syscall.FILE_FLAG_BACKUP_SEMANTICS, 0)
syscall.OPEN_EXISTING, createFileAttrs, 0)
if err != nil {
return nil, &PathError{"CreateFile", name, err}
}
@ -93,25 +121,16 @@ func statNolog(name string) (FileInfo, error) {
return newFileStatFromGetFileInformationByHandle(name, h)
}
// statNolog implements Stat for Windows.
func statNolog(name string) (FileInfo, error) {
return stat("Stat", name, syscall.FILE_FLAG_BACKUP_SEMANTICS)
}
// lstatNolog implements Lstat for Windows.
func lstatNolog(name string) (FileInfo, error) {
if len(name) == 0 {
return nil, &PathError{"Lstat", name, syscall.Errno(syscall.ERROR_PATH_NOT_FOUND)}
}
if isNulName(name) {
return &devNullStat, nil
}
namep, err := syscall.UTF16PtrFromString(fixLongPath(name))
if err != nil {
return nil, &PathError{"Lstat", name, err}
}
fs, err := newFileStatFromGetFileAttributesExOrFindFirstFile(name, namep)
if err != nil {
return nil, err
}
err = fs.updatePathAndName(name)
if err != nil {
return nil, err
}
return fs, nil
attrs := uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS)
// Use FILE_FLAG_OPEN_REPARSE_POINT, otherwise CreateFile will follow symlink.
// See https://docs.microsoft.com/en-us/windows/desktop/FileIO/symbolic-link-effects-on-file-systems-functions#createfile-and-createfiletransacted
attrs |= syscall.FILE_FLAG_OPEN_REPARSE_POINT
return stat("Lstat", name, attrs)
}

69
src/os/types_windows.go
View File

@ -47,6 +47,13 @@ func newFileStatFromGetFileInformationByHandle(path string, h syscall.Handle) (f
if err != nil {
return nil, &PathError{"GetFileInformationByHandle", path, err}
}
var ti windows.FILE_ATTRIBUTE_TAG_INFO
err = windows.GetFileInformationByHandleEx(h, windows.FileAttributeTagInfo, (*byte)(unsafe.Pointer(&ti)), uint32(unsafe.Sizeof(ti)))
if err != nil {
return nil, &PathError{"GetFileInformationByHandleEx", path, err}
}
return &fileStat{
name: basename(path),
FileAttributes: d.FileAttributes,
@ -58,6 +65,7 @@ func newFileStatFromGetFileInformationByHandle(path string, h syscall.Handle) (f
vol: d.VolumeSerialNumber,
idxhi: d.FileIndexHigh,
idxlo: d.FileIndexLow,
Reserved0: ti.ReparseTag,
// fileStat.path is used by os.SameFile to decide if it needs
// to fetch vol, idxhi and idxlo. But these are already set,
// so set fileStat.path to "" to prevent os.SameFile doing it again.
@ -78,67 +86,6 @@ func newFileStatFromWin32finddata(d *syscall.Win32finddata) *fileStat {
}
}
// newFileStatFromGetFileAttributesExOrFindFirstFile calls GetFileAttributesEx
// and FindFirstFile to gather all required information about the provided file path pathp.
func newFileStatFromGetFileAttributesExOrFindFirstFile(path string, pathp *uint16) (*fileStat, error) {
// As suggested by Microsoft, use GetFileAttributes() to acquire the file information,
// and if it's a reparse point use FindFirstFile() to get the tag:
// https://msdn.microsoft.com/en-us/library/windows/desktop/aa363940(v=vs.85).aspx
// Notice that always calling FindFirstFile can create performance problems
// (https://golang.org/issues/19922#issuecomment-300031421)
var fa syscall.Win32FileAttributeData
err := syscall.GetFileAttributesEx(pathp, syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&fa)))
if err == nil && fa.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT == 0 {
// Not a symlink.
return &fileStat{
FileAttributes: fa.FileAttributes,
CreationTime: fa.CreationTime,
LastAccessTime: fa.LastAccessTime,
LastWriteTime: fa.LastWriteTime,
FileSizeHigh: fa.FileSizeHigh,
FileSizeLow: fa.FileSizeLow,
}, nil
}
// GetFileAttributesEx returns ERROR_INVALID_NAME if called
// for invalid file name like "*.txt". Do not attempt to call
// FindFirstFile with "*.txt", because FindFirstFile will
// succeed. So just return ERROR_INVALID_NAME instead.
// see https://golang.org/issue/24999 for details.
if errno, _ := err.(syscall.Errno); errno == windows.ERROR_INVALID_NAME {
return nil, &PathError{"GetFileAttributesEx", path, err}
}
// We might have symlink here. But some directories also have
// FileAttributes FILE_ATTRIBUTE_REPARSE_POINT bit set.
// For example, OneDrive directory is like that
// (see golang.org/issue/22579 for details).
// So use FindFirstFile instead to distinguish directories like
// OneDrive from real symlinks (see instructions described at
// https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/
// and in particular bits about using both FileAttributes and
// Reserved0 fields).
var fd syscall.Win32finddata
sh, err := syscall.FindFirstFile(pathp, &fd)
if err != nil {
return nil, &PathError{"FindFirstFile", path, err}
}
syscall.FindClose(sh)
return newFileStatFromWin32finddata(&fd), nil
}
func (fs *fileStat) updatePathAndName(name string) error {
fs.path = name
if !isAbs(fs.path) {
var err error
fs.path, err = syscall.FullPath(fs.path)
if err != nil {
return &PathError{"FullPath", name, err}
}
}
fs.name = basename(name)
return nil
}
func (fs *fileStat) isSymlink() bool {
// Use instructions described at
// https://blogs.msdn.microsoft.com/oldnewthing/20100212-00/?p=14963/