[release-branch.go1] syscall: revert API changes in Windows Win32finddata fix.

««« backport 7a7a91c3da32
syscall: revert API changes in Windows Win32finddata fix.

Preserve old API by using correct struct in system call
and then copying the results, as we did for SetsockoptLinger.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6307065

»»»

api/next.txt

@@ -419,36 +419,10 @@ pkg syscall (darwin-amd64-cgo), type Termios struct, Pad_cgo_0 [4]byte
 pkg syscall (windows-386), const CREATE_NEW_PROCESS_GROUP ideal-int
 pkg syscall (windows-386), const CTRL_BREAK_EVENT ideal-int
 pkg syscall (windows-386), const CTRL_C_EVENT ideal-int
-pkg syscall (windows-386), func FindFirstFile1(*uint16, *Win32finddata1) (Handle, error)
-pkg syscall (windows-386), func FindNextFile1(Handle, *Win32finddata1) error
 pkg syscall (windows-386), func GetCurrentProcessId() uint32
 pkg syscall (windows-386), type SysProcAttr struct, CreationFlags uint32
-pkg syscall (windows-386), type Win32finddata1 struct
-pkg syscall (windows-386), type Win32finddata1 struct, AlternateFileName [14]uint16
-pkg syscall (windows-386), type Win32finddata1 struct, CreationTime Filetime
-pkg syscall (windows-386), type Win32finddata1 struct, FileAttributes uint32
-pkg syscall (windows-386), type Win32finddata1 struct, FileName [MAX_PATH]uint16
-pkg syscall (windows-386), type Win32finddata1 struct, FileSizeHigh uint32
-pkg syscall (windows-386), type Win32finddata1 struct, FileSizeLow uint32
-pkg syscall (windows-386), type Win32finddata1 struct, LastAccessTime Filetime
-pkg syscall (windows-386), type Win32finddata1 struct, LastWriteTime Filetime
-pkg syscall (windows-386), type Win32finddata1 struct, Reserved0 uint32
-pkg syscall (windows-386), type Win32finddata1 struct, Reserved1 uint32
 pkg syscall (windows-amd64), const CREATE_NEW_PROCESS_GROUP ideal-int
 pkg syscall (windows-amd64), const CTRL_BREAK_EVENT ideal-int
 pkg syscall (windows-amd64), const CTRL_C_EVENT ideal-int
-pkg syscall (windows-amd64), func FindFirstFile1(*uint16, *Win32finddata1) (Handle, error)
-pkg syscall (windows-amd64), func FindNextFile1(Handle, *Win32finddata1) error
 pkg syscall (windows-amd64), func GetCurrentProcessId() uint32
 pkg syscall (windows-amd64), type SysProcAttr struct, CreationFlags uint32
-pkg syscall (windows-amd64), type Win32finddata1 struct
-pkg syscall (windows-amd64), type Win32finddata1 struct, AlternateFileName [14]uint16
-pkg syscall (windows-amd64), type Win32finddata1 struct, CreationTime Filetime
-pkg syscall (windows-amd64), type Win32finddata1 struct, FileAttributes uint32
-pkg syscall (windows-amd64), type Win32finddata1 struct, FileName [MAX_PATH]uint16
-pkg syscall (windows-amd64), type Win32finddata1 struct, FileSizeHigh uint32
-pkg syscall (windows-amd64), type Win32finddata1 struct, FileSizeLow uint32
-pkg syscall (windows-amd64), type Win32finddata1 struct, LastAccessTime Filetime
-pkg syscall (windows-amd64), type Win32finddata1 struct, LastWriteTime Filetime
-pkg syscall (windows-amd64), type Win32finddata1 struct, Reserved0 uint32
-pkg syscall (windows-amd64), type Win32finddata1 struct, Reserved1 uint32

src/pkg/os/file_windows.go

@@ -50,7 +50,7 @@ func NewFile(fd uintptr, name string) *File {
 
 // Auxiliary information if the File describes a directory
 type dirInfo struct {
-	data     syscall.Win32finddata1
+	data     syscall.Win32finddata
 	needdata bool
 	path     string
 }
@@ -76,7 +76,7 @@ func openFile(name string, flag int, perm FileMode) (file *File, err error) {
 
 func openDir(name string) (file *File, err error) {
 	d := new(dirInfo)
-	r, e := syscall.FindFirstFile1(syscall.StringToUTF16Ptr(name+`\*`), &d.data)
+	r, e := syscall.FindFirstFile(syscall.StringToUTF16Ptr(name+`\*`), &d.data)
 	if e != nil {
 		return nil, &PathError{"open", name, e}
 	}
@@ -159,7 +159,7 @@ func (file *File) readdir(n int) (fi []FileInfo, err error) {
 	d := &file.dirinfo.data
 	for n != 0 {
 		if file.dirinfo.needdata {
-			e := syscall.FindNextFile1(syscall.Handle(file.fd), d)
+			e := syscall.FindNextFile(syscall.Handle(file.fd), d)
 			if e != nil {
 				if e == syscall.ERROR_NO_MORE_FILES {
 					break

src/pkg/syscall/syscall_windows.go

@@ -7,7 +7,6 @@
 package syscall
 
 import (
-	errorspkg "errors"
 	"unicode/utf16"
 	"unsafe"
 )
@@ -130,8 +129,8 @@ func NewCallback(fn interface{}) uintptr
 //sys	SetFilePointer(handle Handle, lowoffset int32, highoffsetptr *int32, whence uint32) (newlowoffset uint32, err error) [failretval==0xffffffff]
 //sys	CloseHandle(handle Handle) (err error)
 //sys	GetStdHandle(stdhandle int) (handle Handle, err error) [failretval==InvalidHandle]
-//sys	FindFirstFile1(name *uint16, data *Win32finddata1) (handle Handle, err error) [failretval==InvalidHandle] = FindFirstFileW
-//sys	FindNextFile1(handle Handle, data *Win32finddata1) (err error) = FindNextFileW
+//sys	findFirstFile1(name *uint16, data *win32finddata1) (handle Handle, err error) [failretval==InvalidHandle] = FindFirstFileW
+//sys	findNextFile1(handle Handle, data *win32finddata1) (err error) = FindNextFileW
 //sys	FindClose(handle Handle) (err error)
 //sys	GetFileInformationByHandle(handle Handle, data *ByHandleFileInformation) (err error)
 //sys	GetCurrentDirectory(buflen uint32, buf *uint16) (n uint32, err error) = GetCurrentDirectoryW
@@ -688,11 +687,29 @@ func SetsockoptIPv6Mreq(fd Handle, level, opt int, mreq *IPv6Mreq) (err error) {
 func Getpid() (pid int) { return int(GetCurrentProcessId()) }
 
 func FindFirstFile(name *uint16, data *Win32finddata) (handle Handle, err error) {
-	return InvalidHandle, errorspkg.New("FindFirstFile is broken, use FindFirstFile1 instead")
+	// NOTE(rsc): The Win32finddata struct is wrong for the system call:
+	// the two paths are each one uint16 short. Use the correct struct,
+	// a win32finddata1, and then copy the results out.
+	// There is no loss of expressivity here, because the final
+	// uint16, if it is used, is supposed to be a NUL, and Go doesn't need that.
+	// For Go 1.1, we might avoid the allocation of win32finddata1 here
+	// by adding a final Bug [2]uint16 field to the struct and then
+	// adjusting the fields in the result directly.
+	var data1 win32finddata1
+	handle, err = findFirstFile1(name, &data1)
+	if err == nil {
+		copyFindData(data, &data1)
+	}
+	return
 }
 
 func FindNextFile(handle Handle, data *Win32finddata) (err error) {
-	return errorspkg.New("FindNextFile is broken, use FindNextFile1 instead")
+	var data1 win32finddata1
+	err = findNextFile1(handle, &data1)
+	if err == nil {
+		copyFindData(data, &data1)
+	}
+	return
 }
 
 // TODO(brainman): fix all needed for os

src/pkg/syscall/zsyscall_windows_386.go

@@ -309,7 +309,7 @@ func GetStdHandle(stdhandle int) (handle Handle, err error) {
 	return
 }
 
-func FindFirstFile1(name *uint16, data *Win32finddata1) (handle Handle, err error) {
+func findFirstFile1(name *uint16, data *win32finddata1) (handle Handle, err error) {
 	r0, _, e1 := Syscall(procFindFirstFileW.Addr(), 2, uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(data)), 0)
 	handle = Handle(r0)
 	if handle == InvalidHandle {
@@ -322,7 +322,7 @@ func FindFirstFile1(name *uint16, data *Win32finddata1) (handle Handle, err erro
 	return
 }
 
-func FindNextFile1(handle Handle, data *Win32finddata1) (err error) {
+func findNextFile1(handle Handle, data *win32finddata1) (err error) {
 	r1, _, e1 := Syscall(procFindNextFileW.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(data)), 0)
 	if int(r1) == 0 {
 		if e1 != 0 {

src/pkg/syscall/zsyscall_windows_amd64.go

@@ -309,7 +309,7 @@ func GetStdHandle(stdhandle int) (handle Handle, err error) {
 	return
 }
 
-func FindFirstFile1(name *uint16, data *Win32finddata1) (handle Handle, err error) {
+func findFirstFile1(name *uint16, data *win32finddata1) (handle Handle, err error) {
 	r0, _, e1 := Syscall(procFindFirstFileW.Addr(), 2, uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(data)), 0)
 	handle = Handle(r0)
 	if handle == InvalidHandle {
@@ -322,7 +322,7 @@ func FindFirstFile1(name *uint16, data *Win32finddata1) (handle Handle, err erro
 	return
 }
 
-func FindNextFile1(handle Handle, data *Win32finddata1) (err error) {
+func findNextFile1(handle Handle, data *win32finddata1) (err error) {
 	r1, _, e1 := Syscall(procFindNextFileW.Addr(), 2, uintptr(handle), uintptr(unsafe.Pointer(data)), 0)
 	if int(r1) == 0 {
 		if e1 != 0 {

src/pkg/syscall/ztypes_windows.go

@@ -334,9 +334,6 @@ func NsecToFiletime(nsec int64) (ft Filetime) {
 	return ft
 }
 
-// Win32finddata is an incorrect struct definition, preserved for
-// backwards compatibility. Use Win32finddata1 and the
-// FindFirstFile1 and FindNextFile1 functions instead.
 type Win32finddata struct {
 	FileAttributes    uint32
 	CreationTime      Filetime
@@ -350,7 +347,9 @@ type Win32finddata struct {
 	AlternateFileName [13]uint16
 }
 
-type Win32finddata1 struct {
+// This is the actual system call structure.
+// Win32finddata is what we committed to in Go 1.
+type win32finddata1 struct {
 	FileAttributes    uint32
 	CreationTime      Filetime
 	LastAccessTime    Filetime
@@ -363,6 +362,23 @@ type Win32finddata1 struct {
 	AlternateFileName [14]uint16
 }
 
+func copyFindData(dst *Win32finddata, src *win32finddata1) {
+	dst.FileAttributes = src.FileAttributes
+	dst.CreationTime = src.CreationTime
+	dst.LastAccessTime = src.LastAccessTime
+	dst.LastWriteTime = src.LastWriteTime
+	dst.FileSizeHigh = src.FileSizeHigh
+	dst.FileSizeLow = src.FileSizeLow
+	dst.Reserved0 = src.Reserved0
+	dst.Reserved1 = src.Reserved1
+
+	// The src is 1 element shorter than dst. Zero that last one.
+	copy(dst.FileName[:], src.FileName[:])
+	dst.FileName[len(dst.FileName)-1] = 0
+	copy(dst.AlternateFileName[:], src.AlternateFileName[:])
+	src.AlternateFileName[len(dst.AlternateFileName)-1] = 0
+}
+
 type ByHandleFileInformation struct {
 	FileAttributes     uint32
 	CreationTime       Filetime