unix: check Fchmodat flags parameter on Linux

Currently Linux' fchmodat(2) syscall implementation doesn't support the
flags parameter (though it might in future versions [1]). Fchmodat in
x/sys/unix takes the parameter and (wrongly) passes it on to the syscall
which will ignore it.

According to the POSIX.1-2008 manual page [2], AT_SYMLINK_NOFOLLOW is
the only valid value for the flags parameter and EOPNOTSUPP should be
returned in case changing the mode of a symbolic link is not supported
by the underlying system.  EINVAL should be returned for any other value
of the flags parameter.

  [1] https://patchwork.kernel.org/patch/9596301/
  [2] http://pubs.opengroup.org/onlinepubs/9699919799/functions/chmod.html

Change the Fchmodat implementation accordingly and also add the
corresponding test.

Fixes golang/go#20130

Change-Id: I62e677e6674d3702eaf388af0ac3d7e623a35c24
Reviewed-on: https://go-review.googlesource.com/46474
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Tobias Klauser
2017-06-23 14:22:15 +00:00
committed by Ian Lance Taylor
parent fb4cac33e3
commit c23410a886
13 changed files with 205 additions and 166 deletions
+15 -15
View File
@@ -14,6 +14,21 @@ var _ syscall.Errno
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func fchmodat(dirfd int, path string, mode uint32) (err error) {
var _p0 *byte
_p0, err = BytePtrFromString(path)
if err != nil {
return
}
_, _, e1 := Syscall(SYS_FCHMODAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode))
if e1 != 0 {
err = errnoErr(e1)
}
return
}
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func ioctl(fd int, req uint, arg uintptr) (err error) {
_, _, e1 := Syscall(SYS_IOCTL, uintptr(fd), uintptr(req), uintptr(arg))
if e1 != 0 {
@@ -574,21 +589,6 @@ func Fchmod(fd int, mode uint32) (err error) {
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
var _p0 *byte
_p0, err = BytePtrFromString(path)
if err != nil {
return
}
_, _, e1 := Syscall6(SYS_FCHMODAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode), uintptr(flags), 0, 0)
if e1 != 0 {
err = errnoErr(e1)
}
return
}
// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
func Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error) {
var _p0 *byte
_p0, err = BytePtrFromString(path)