unix/amd64: add Utimensat call, pass 0 for flags

This CL adds the Utimensat syscall and AT_SYMLINK_NOFOLLOW constant.

This is required for setting the access/modification times on symlinks.

In addition, it updates the UtimesNano function to pass 0 as the flags
parameter, to avoid potentially passing junk.

Change-Id: I280645f3f53173628b1e1986bc7a47bac254fcf8
Reviewed-on: https://go-review.googlesource.com/9379Reviewed-by: Rob Pike <r@golang.org>

unix/syscall_linux.go

@@ -67,13 +67,13 @@ func Utimes(path string, tv []Timeval) (err error) {
 	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
 }
 
-//sys	utimensat(dirfd int, path string, times *[2]Timespec) (err error)
+//sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
 
 func UtimesNano(path string, ts []Timespec) (err error) {
 	if len(ts) != 2 {
 		return EINVAL
 	}
-	err = utimensat(_AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])))
+	err = utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
 	if err != ENOSYS {
 		return err
 	}
@@ -87,6 +87,13 @@ func UtimesNano(path string, ts []Timespec) (err error) {
 	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
 }
 
+func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) (err error) {
+	if len(ts) != 2 {
+		return EINVAL
+	}
+	return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
+}
+
 //sys	futimesat(dirfd int, path *byte, times *[2]Timeval) (err error)
 
 func Futimesat(dirfd int, path string, tv []Timeval) (err error) {

unix/types_linux.go

@@ -385,7 +385,9 @@ type Ustat_t C.struct_ustat
 type EpollEvent C.struct_my_epoll_event
 
 const (
-	_AT_FDCWD = C.AT_FDCWD
+	AT_FDCWD            = C.AT_FDCWD
+	AT_REMOVEDIR        = C.AT_REMOVEDIR
+	AT_SYMLINK_NOFOLLOW = C.AT_SYMLINK_NOFOLLOW
 )
 
 // Terminal handling

unix/zsyscall_linux_386.go

@@ -82,13 +82,13 @@ func utimes(path string, times *[2]Timeval) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func utimensat(dirfd int, path string, times *[2]Timespec) (err error) {
+func utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)
 	if err != nil {
 		return
 	}
-	_, _, e1 := Syscall(SYS_UTIMENSAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(times)))
+	_, _, e1 := Syscall6(SYS_UTIMENSAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(times)), uintptr(flags), 0, 0)
 	use(unsafe.Pointer(_p0))
 	if e1 != 0 {
 		err = errnoErr(e1)

unix/zsyscall_linux_amd64.go

@@ -82,13 +82,13 @@ func utimes(path string, times *[2]Timeval) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func utimensat(dirfd int, path string, times *[2]Timespec) (err error) {
+func utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)
 	if err != nil {
 		return
 	}
-	_, _, e1 := Syscall(SYS_UTIMENSAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(times)))
+	_, _, e1 := Syscall6(SYS_UTIMENSAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(times)), uintptr(flags), 0, 0)
 	use(unsafe.Pointer(_p0))
 	if e1 != 0 {
 		err = errnoErr(e1)

unix/zsyscall_linux_arm.go

@@ -82,13 +82,13 @@ func utimes(path string, times *[2]Timeval) (err error) {
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func utimensat(dirfd int, path string, times *[2]Timespec) (err error) {
+func utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error) {
 	var _p0 *byte
 	_p0, err = BytePtrFromString(path)
 	if err != nil {
 		return
 	}
-	_, _, e1 := Syscall(SYS_UTIMENSAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(times)))
+	_, _, e1 := Syscall6(SYS_UTIMENSAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(unsafe.Pointer(times)), uintptr(flags), 0, 0)
 	use(unsafe.Pointer(_p0))
 	if e1 != 0 {
 		err = errnoErr(e1)

unix/ztypes_linux_386.go

@@ -572,7 +572,9 @@ type EpollEvent struct {
 }
 
 const (
-	_AT_FDCWD = -0x64
+	AT_FDCWD            = -0x64
+	AT_SYMLINK_NOFOLLOW = 0x100
+	AT_REMOVEDIR        = 0x200
 )
 
 type Termios struct {

unix/ztypes_linux_amd64.go

@@ -590,7 +590,9 @@ type EpollEvent struct {
 }
 
 const (
-	_AT_FDCWD = -0x64
+	AT_FDCWD            = -0x64
+	AT_SYMLINK_NOFOLLOW = 0x100
+	AT_REMOVEDIR        = 0x200
 )
 
 type Termios struct {

unix/ztypes_linux_arm.go

@@ -561,7 +561,9 @@ type EpollEvent struct {
 }
 
 const (
-	_AT_FDCWD = -0x64
+	AT_FDCWD            = -0x64
+	AT_SYMLINK_NOFOLLOW = 0x100
+	AT_REMOVEDIR        = 0x200
 )
 
 type Termios struct {