code review 6905057: os: Improve the accuracy of os.Chtimes

src/pkg/syscall/syscall_bsd.go

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // +build darwin freebsd netbsd openbsd
 
 // BSD system call wrappers shared by *BSD based systems
 // including OS X (Darwin) and FreeBSD.  Like the other
 // syscall_*.go files it is compiled as Go code but also
 // used as input to mksyscall which parses the //sys
@@ skipping 591 matching lines @@
 }
 
 //sys   utimes(path string, timeval *[2]Timeval) (err error)
 func Utimes(path string, tv []Timeval) (err error) {
         if len(tv) != 2 {
                 return EINVAL
         }
         return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
 }
 
+func UtimesNano(path string, ts []Timespec) error {
+        // TODO: The BSDs can do utimensat with SYS_UTIMENSAT but it
+        // isn't supported by darwin so this uses utimes instead
+        if len(ts) != 2 {
+                return EINVAL
+        }
+        // Not as efficient as it could be because Timespec and
+        // Timeval have different types in the different OSes
+        tv := [2]Timeval{
+                NsecToTimeval(TimespecToNsec(ts[0])),
+                NsecToTimeval(TimespecToNsec(ts[1])),
+        }
+        return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
+}
+
 //sys   futimes(fd int, timeval *[2]Timeval) (err error)
 func Futimes(fd int, tv []Timeval) (err error) {
         if len(tv) != 2 {
                 return EINVAL
         }
         return futimes(fd, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
 }
 
 //sys   fcntl(fd int, cmd int, arg int) (val int, err error)
 
@@ skipping 11 matching lines @@
         munmap: munmap,
 }
 
 func Mmap(fd int, offset int64, length int, prot int, flags int) (data []byte, err error) {
         return mapper.Mmap(fd, offset, length, prot, flags)
 }
 
 func Munmap(b []byte) (err error) {
         return mapper.Munmap(b)
 }