os: use GetFileAttributesEx to implement Stat on windows

Fixes #2129.

R=rsc
CC=golang-dev
https://golang.org/cl/4934049

src/pkg/os/file_posix.go

@@ -21,39 +21,6 @@ func epipecheck(file *File, e int) {
 	}
 }
 
-// Stat returns a FileInfo structure describing the named file and an error, if any.
-// If name names a valid symbolic link, the returned FileInfo describes
-// the file pointed at by the link and has fi.FollowedSymlink set to true.
-// If name names an invalid symbolic link, the returned FileInfo describes
-// the link itself and has fi.FollowedSymlink set to false.
-func Stat(name string) (fi *FileInfo, err Error) {
-	var lstat, stat syscall.Stat_t
-	e := syscall.Lstat(name, &lstat)
-	if iserror(e) {
-		return nil, &PathError{"stat", name, Errno(e)}
-	}
-	statp := &lstat
-	if lstat.Mode&syscall.S_IFMT == syscall.S_IFLNK {
-		e := syscall.Stat(name, &stat)
-		if !iserror(e) {
-			statp = &stat
-		}
-	}
-	return fileInfoFromStat(name, new(FileInfo), &lstat, statp), nil
-}
-
-// Lstat returns the FileInfo structure describing the named file and an
-// error, if any.  If the file is a symbolic link, the returned FileInfo
-// describes the symbolic link.  Lstat makes no attempt to follow the link.
-func Lstat(name string) (fi *FileInfo, err Error) {
-	var stat syscall.Stat_t
-	e := syscall.Lstat(name, &stat)
-	if iserror(e) {
-		return nil, &PathError{"lstat", name, Errno(e)}
-	}
-	return fileInfoFromStat(name, new(FileInfo), &stat, &stat), nil
-}
-
 // Remove removes the named file or directory.
 func Remove(name string) Error {
 	// System call interface forces us to know

src/pkg/os/file_unix.go

@@ -94,6 +94,39 @@ func (file *File) Stat() (fi *FileInfo, err Error) {
 	return fileInfoFromStat(file.name, new(FileInfo), &stat, &stat), nil
 }
 
+// Stat returns a FileInfo structure describing the named file and an error, if any.
+// If name names a valid symbolic link, the returned FileInfo describes
+// the file pointed at by the link and has fi.FollowedSymlink set to true.
+// If name names an invalid symbolic link, the returned FileInfo describes
+// the link itself and has fi.FollowedSymlink set to false.
+func Stat(name string) (fi *FileInfo, err Error) {
+	var lstat, stat syscall.Stat_t
+	e := syscall.Lstat(name, &lstat)
+	if iserror(e) {
+		return nil, &PathError{"stat", name, Errno(e)}
+	}
+	statp := &lstat
+	if lstat.Mode&syscall.S_IFMT == syscall.S_IFLNK {
+		e := syscall.Stat(name, &stat)
+		if !iserror(e) {
+			statp = &stat
+		}
+	}
+	return fileInfoFromStat(name, new(FileInfo), &lstat, statp), nil
+}
+
+// Lstat returns the FileInfo structure describing the named file and an
+// error, if any.  If the file is a symbolic link, the returned FileInfo
+// describes the symbolic link.  Lstat makes no attempt to follow the link.
+func Lstat(name string) (fi *FileInfo, err Error) {
+	var stat syscall.Stat_t
+	e := syscall.Lstat(name, &stat)
+	if iserror(e) {
+		return nil, &PathError{"lstat", name, Errno(e)}
+	}
+	return fileInfoFromStat(name, new(FileInfo), &stat, &stat), nil
+}
+
 // Readdir reads the contents of the directory associated with file and
 // returns an array of up to n FileInfo structures, as would be returned
 // by Lstat, in directory order. Subsequent calls on the same file will yield

src/pkg/os/file_windows.go

@@ -39,8 +39,8 @@ func NewFile(fd syscall.Handle, name string) *File {
 
 // Auxiliary information if the File describes a directory
 type dirInfo struct {
-	stat         syscall.Stat_t
+	data     syscall.Win32finddata
-	usefirststat bool
+	needdata bool
 }
 
 const DevNull = "NUL"
@@ -64,12 +64,11 @@ func openFile(name string, flag int, perm uint32) (file *File, err Error) {
 
 func openDir(name string) (file *File, err Error) {
 	d := new(dirInfo)
-	r, e := syscall.FindFirstFile(syscall.StringToUTF16Ptr(name+"\\*"), &d.stat.Windata)
+	r, e := syscall.FindFirstFile(syscall.StringToUTF16Ptr(name+`\*`), &d.data)
 	if e != 0 {
 		return nil, &PathError{"open", name, Errno(e)}
 	}
 	f := NewFile(r, name)
-	d.usefirststat = true
 	f.dirinfo = d
 	return f, nil
 }
@@ -128,28 +127,6 @@ func (file *File) Close() Error {
 	return err
 }
 
-func (file *File) statFile(name string) (fi *FileInfo, err Error) {
-	var stat syscall.ByHandleFileInformation
-	e := syscall.GetFileInformationByHandle(syscall.Handle(file.fd), &stat)
-	if e != 0 {
-		return nil, &PathError{"stat", file.name, Errno(e)}
-	}
-	return fileInfoFromByHandleInfo(new(FileInfo), file.name, &stat), nil
-}
-
-// Stat returns the FileInfo structure describing file.
-// It returns the FileInfo and an error, if any.
-func (file *File) Stat() (fi *FileInfo, err Error) {
-	if file == nil || file.fd < 0 {
-		return nil, EINVAL
-	}
-	if file.isdir() {
-		// I don't know any better way to do that for directory
-		return Stat(file.name)
-	}
-	return file.statFile(file.name)
-}
-
 // Readdir reads the contents of the directory associated with file and
 // returns an array of up to n FileInfo structures, as would be returned
 // by Lstat, in directory order. Subsequent calls on the same file will yield
@@ -172,7 +149,6 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 	if !file.isdir() {
 		return nil, &PathError{"Readdir", file.name, ENOTDIR}
 	}
-	di := file.dirinfo
 	wantAll := n <= 0
 	size := n
 	if wantAll {
@@ -180,11 +156,10 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 		size = 100
 	}
 	fi = make([]FileInfo, 0, size) // Empty with room to grow.
+	d := &file.dirinfo.data
 	for n != 0 {
-		if di.usefirststat {
+		if file.dirinfo.needdata {
-			di.usefirststat = false
+			e := syscall.FindNextFile(syscall.Handle(file.fd), d)
-		} else {
-			e := syscall.FindNextFile(syscall.Handle(file.fd), &di.stat.Windata)
 			if e != 0 {
 				if e == syscall.ERROR_NO_MORE_FILES {
 					break
@@ -198,7 +173,8 @@ func (file *File) Readdir(n int) (fi []FileInfo, err Error) {
 			}
 		}
 		var f FileInfo
-		fileInfoFromWin32finddata(&f, &di.stat.Windata)
+		setFileInfo(&f, string(syscall.UTF16ToString(d.FileName[0:])), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
+		file.dirinfo.needdata = true
 		if f.Name == "." || f.Name == ".." { // Useless names
 			continue
 		}

src/pkg/os/stat_windows.go

@@ -4,24 +4,76 @@
 
 package os
 
-import "syscall"
+import (
+	"unsafe"
+	"syscall"
+)
 
-func fileInfoFromStat(name string, fi *FileInfo, lstat, stat *syscall.Stat_t) *FileInfo {
+// Stat returns the FileInfo structure describing file.
-	return fileInfoFromWin32finddata(fi, &stat.Windata)
+// It returns the FileInfo and an error, if any.
+func (file *File) Stat() (fi *FileInfo, err Error) {
+	if file == nil || file.fd < 0 {
+		return nil, EINVAL
+	}
+	if file.isdir() {
+		// I don't know any better way to do that for directory
+		return Stat(file.name)
+	}
+	var d syscall.ByHandleFileInformation
+	e := syscall.GetFileInformationByHandle(syscall.Handle(file.fd), &d)
+	if e != 0 {
+		return nil, &PathError{"GetFileInformationByHandle", file.name, Errno(e)}
+	}
+	return setFileInfo(new(FileInfo), basename(file.name), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime), nil
 }
 
-func fileInfoFromWin32finddata(fi *FileInfo, d *syscall.Win32finddata) *FileInfo {
+// Stat returns a FileInfo structure describing the named file and an error, if any.
-	return setFileInfo(fi, string(syscall.UTF16ToString(d.FileName[0:])), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
+// If name names a valid symbolic link, the returned FileInfo describes
+// the file pointed at by the link and has fi.FollowedSymlink set to true.
+// If name names an invalid symbolic link, the returned FileInfo describes
+// the link itself and has fi.FollowedSymlink set to false.
+func Stat(name string) (fi *FileInfo, err Error) {
+	if len(name) == 0 {
+		return nil, &PathError{"Stat", name, Errno(syscall.ERROR_PATH_NOT_FOUND)}
+	}
+	var d syscall.Win32FileAttributeData
+	e := syscall.GetFileAttributesEx(syscall.StringToUTF16Ptr(name), syscall.GetFileExInfoStandard, (*byte)(unsafe.Pointer(&d)))
+	if e != 0 {
+		return nil, &PathError{"GetFileAttributesEx", name, Errno(e)}
+	}
+	return setFileInfo(new(FileInfo), basename(name), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime), nil
 }
 
-func fileInfoFromByHandleInfo(fi *FileInfo, name string, d *syscall.ByHandleFileInformation) *FileInfo {
+// Lstat returns the FileInfo structure describing the named file and an
-	for i := len(name) - 1; i >= 0; i-- {
+// error, if any.  If the file is a symbolic link, the returned FileInfo
+// describes the symbolic link.  Lstat makes no attempt to follow the link.
+func Lstat(name string) (fi *FileInfo, err Error) {
+	// No links on Windows
+	return Stat(name)
+}
+
+// basename removes trailing slashes and the leading
+// directory name and drive letter from path name.
+func basename(name string) string {
+	// Remove drive letter
+	if len(name) == 2 && name[1] == ':' {
+		name = "."
+	} else if len(name) > 2 && name[1] == ':' {
+		name = name[2:]
+	}
+	i := len(name) - 1
+	// Remove trailing slashes
+	for ; i > 0 && (name[i] == '/' || name[i] == '\\'); i-- {
+		name = name[:i]
+	}
+	// Remove leading directory name
+	for i--; i >= 0; i-- {
 		if name[i] == '/' || name[i] == '\\' {
 			name = name[i+1:]
 			break
 		}
 	}
-	return setFileInfo(fi, name, d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
+	return name
 }
 
 func setFileInfo(fi *FileInfo, name string, fa, sizehi, sizelo uint32, ctime, atime, wtime syscall.Filetime) *FileInfo {

src/pkg/syscall/syscall_windows.go

@@ -207,6 +207,7 @@ func NewCallback(fn interface{}) uintptr
 //sys	SetFileTime(handle Handle, ctime *Filetime, atime *Filetime, wtime *Filetime) (errno int)
 //sys	GetFileAttributes(name *uint16) (attrs uint32, errno int) [failretval==INVALID_FILE_ATTRIBUTES] = kernel32.GetFileAttributesW
 //sys	SetFileAttributes(name *uint16, attrs uint32) (errno int) = kernel32.SetFileAttributesW
+//sys	GetFileAttributesEx(name *uint16, level uint32, info *byte) (errno int) = kernel32.GetFileAttributesExW
 //sys	GetCommandLine() (cmd *uint16) = kernel32.GetCommandLineW
 //sys	CommandLineToArgv(cmd *uint16, argc *int32) (argv *[8192]*[8192]uint16, errno int) [failretval==nil] = shell32.CommandLineToArgvW
 //sys	LocalFree(hmem Handle) (handle Handle, errno int) [failretval!=0]
@@ -354,39 +355,6 @@ func getStdHandle(h int) (fd Handle) {
 	return r
 }
 
-func Stat(path string, stat *Stat_t) (errno int) {
-	if len(path) == 0 {
-		return ERROR_PATH_NOT_FOUND
-	}
-	// Remove trailing slash.
-	if path[len(path)-1] == '/' || path[len(path)-1] == '\\' {
-		// Check if we're given root directory ("\" or "c:\").
-		if len(path) == 1 || (len(path) == 3 && path[1] == ':') {
-			// TODO(brainman): Perhaps should fetch other fields, not just FileAttributes.
-			stat.Windata = Win32finddata{}
-			a, e := GetFileAttributes(StringToUTF16Ptr(path))
-			if e != 0 {
-				return e
-			}
-			stat.Windata.FileAttributes = a
-			return 0
-		}
-		path = path[:len(path)-1]
-	}
-	h, e := FindFirstFile(StringToUTF16Ptr(path), &stat.Windata)
-	if e != 0 {
-		return e
-	}
-	defer FindClose(h)
-	stat.Mode = 0
-	return 0
-}
-
-func Lstat(path string, stat *Stat_t) (errno int) {
-	// no links on windows, just call Stat
-	return Stat(path, stat)
-}
-
 const ImplementsGetwd = true
 
 func Getwd() (wd string, errno int) {

src/pkg/syscall/zsyscall_windows_386.go

@@ -66,6 +66,7 @@ var (
 	procSetFileTime                = modkernel32.NewProc("SetFileTime")
 	procGetFileAttributesW         = modkernel32.NewProc("GetFileAttributesW")
 	procSetFileAttributesW         = modkernel32.NewProc("SetFileAttributesW")
+	procGetFileAttributesExW       = modkernel32.NewProc("GetFileAttributesExW")
 	procGetCommandLineW            = modkernel32.NewProc("GetCommandLineW")
 	procCommandLineToArgvW         = modshell32.NewProc("CommandLineToArgvW")
 	procLocalFree                  = modkernel32.NewProc("LocalFree")
@@ -142,7 +143,8 @@ func FreeLibrary(handle Handle) (errno int) {
 }
 
 func GetProcAddress(module Handle, procname string) (proc uintptr, errno int) {
-	proc, _, e1 := Syscall(procGetProcAddress.Addr(), 2, uintptr(module), uintptr(unsafe.Pointer(StringBytePtr(procname))), 0)
+	r0, _, e1 := Syscall(procGetProcAddress.Addr(), 2, uintptr(module), uintptr(unsafe.Pointer(StringBytePtr(procname))), 0)
+	proc = uintptr(r0)
 	if proc == 0 {
 		if e1 != 0 {
 			errno = int(e1)
@@ -847,6 +849,20 @@ func SetFileAttributes(name *uint16, attrs uint32) (errno int) {
 	return
 }
 
+func GetFileAttributesEx(name *uint16, level uint32, info *byte) (errno int) {
+	r1, _, e1 := Syscall(procGetFileAttributesExW.Addr(), 3, uintptr(unsafe.Pointer(name)), uintptr(level), uintptr(unsafe.Pointer(info)))
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func GetCommandLine() (cmd *uint16) {
 	r0, _, _ := Syscall(procGetCommandLineW.Addr(), 0, 0, 0, 0)
 	cmd = (*uint16)(unsafe.Pointer(r0))

src/pkg/syscall/zsyscall_windows_amd64.go

@@ -66,6 +66,7 @@ var (
 	procSetFileTime                = modkernel32.NewProc("SetFileTime")
 	procGetFileAttributesW         = modkernel32.NewProc("GetFileAttributesW")
 	procSetFileAttributesW         = modkernel32.NewProc("SetFileAttributesW")
+	procGetFileAttributesExW       = modkernel32.NewProc("GetFileAttributesExW")
 	procGetCommandLineW            = modkernel32.NewProc("GetCommandLineW")
 	procCommandLineToArgvW         = modshell32.NewProc("CommandLineToArgvW")
 	procLocalFree                  = modkernel32.NewProc("LocalFree")
@@ -142,7 +143,8 @@ func FreeLibrary(handle Handle) (errno int) {
 }
 
 func GetProcAddress(module Handle, procname string) (proc uintptr, errno int) {
-	proc, _, e1 := Syscall(procGetProcAddress.Addr(), 2, uintptr(module), uintptr(unsafe.Pointer(StringBytePtr(procname))), 0)
+	r0, _, e1 := Syscall(procGetProcAddress.Addr(), 2, uintptr(module), uintptr(unsafe.Pointer(StringBytePtr(procname))), 0)
+	proc = uintptr(r0)
 	if proc == 0 {
 		if e1 != 0 {
 			errno = int(e1)
@@ -847,6 +849,20 @@ func SetFileAttributes(name *uint16, attrs uint32) (errno int) {
 	return
 }
 
+func GetFileAttributesEx(name *uint16, level uint32, info *byte) (errno int) {
+	r1, _, e1 := Syscall(procGetFileAttributesExW.Addr(), 3, uintptr(unsafe.Pointer(name)), uintptr(level), uintptr(unsafe.Pointer(info)))
+	if int(r1) == 0 {
+		if e1 != 0 {
+			errno = int(e1)
+		} else {
+			errno = EINVAL
+		}
+	} else {
+		errno = 0
+	}
+	return
+}
+
 func GetCommandLine() (cmd *uint16) {
 	r0, _, _ := Syscall(procGetCommandLineW.Addr(), 0, 0, 0, 0)
 	cmd = (*uint16)(unsafe.Pointer(r0))

src/pkg/syscall/ztypes_windows.go

@@ -244,6 +244,20 @@ type ByHandleFileInformation struct {
 	FileIndexLow       uint32
 }
 
+const (
+	GetFileExInfoStandard = 0
+	GetFileExMaxInfoLevel = 1
+)
+
+type Win32FileAttributeData struct {
+	FileAttributes uint32
+	CreationTime   Filetime
+	LastAccessTime Filetime
+	LastWriteTime  Filetime
+	FileSizeHigh   uint32
+	FileSizeLow    uint32
+}
+
 // ShowWindow constants
 const (
 	// winuser.h
@@ -291,12 +305,6 @@ type ProcessInformation struct {
 	ThreadId  uint32
 }
 
-// Invented values to support what package os expects.
-type Stat_t struct {
-	Windata Win32finddata
-	Mode    uint32
-}
-
 type Systemtime struct {
 	Year         uint16
 	Month        uint16