os: add Chtimes function

R=rsc, r
CC=golang-dev
https://golang.org/cl/1103041

diff --git a/src/pkg/os/file.go b/src/pkg/os/file.go
index ccecf67edaeaf792773ac507eb827c2cc5e2b25a..3196406d6089eba61753488e1a457752fb0bafca 100644 (file)
--- a/src/pkg/os/file.go
+++ b/src/pkg/os/file.go
@@ -407,3 +407,19 @@ func (f *File) Truncate(size int64) Error {
        }
        return nil
 }
+
+// Chtimes changes the access and modification times of the named
+// file, similar to the Unix utime() or utimes() functions.
+//
+// The argument times are in nanoseconds, although the underlying
+// filesystem may truncate or round the values to a more
+// coarse time unit.
+func Chtimes(name string, atime_ns int64, mtime_ns int64) Error {
+       var utimes [2]syscall.Timeval
+       utimes[0] = syscall.NsecToTimeval(atime_ns)
+       utimes[1] = syscall.NsecToTimeval(mtime_ns)
+       if e := syscall.Utimes(name, &utimes); e != 0 {
+               return &PathError{"chtimes", name, Errno(e)}
+       }
+       return nil
+}

diff --git a/src/pkg/os/os_test.go b/src/pkg/os/os_test.go
index 5fb599265ea7921a182f968d68e07c344f1a952f..b2332f0c8f8e3b483e1813f5bb2b5d138c31ef15 100644 (file)
--- a/src/pkg/os/os_test.go
+++ b/src/pkg/os/os_test.go
@@ -483,6 +483,48 @@ func TestTruncate(t *testing.T) {
        Remove(Path)
 }
 
+func TestChtimes(t *testing.T) {
+       MkdirAll("_obj", 0777)
+       const Path = "_obj/_TestChtimes_"
+       fd, err := Open(Path, O_WRONLY|O_CREAT, 0666)
+       if err != nil {
+               t.Fatalf("create %s: %s", Path, err)
+       }
+       fd.Write([]byte("hello, world\n"))
+       fd.Close()
+
+       preStat, err := Stat(Path)
+       if err != nil {
+               t.Fatalf("Stat %s: %s", Path, err)
+       }
+
+       // Move access and modification time back a second
+       const OneSecond = 1e9 // in nanoseconds
+       err = Chtimes(Path, preStat.Atime_ns-OneSecond, preStat.Mtime_ns-OneSecond)
+       if err != nil {
+               t.Fatalf("Chtimes %s: %s", Path, err)
+       }
+
+       postStat, err := Stat(Path)
+       if err != nil {
+               t.Fatalf("second Stat %s: %s", Path, err)
+       }
+
+       if postStat.Atime_ns >= preStat.Atime_ns {
+               t.Errorf("Atime_ns didn't go backwards; was=%d, after=%d",
+                       preStat.Atime_ns,
+                       postStat.Atime_ns)
+       }
+
+       if postStat.Mtime_ns >= preStat.Mtime_ns {
+               t.Errorf("Mtime_ns didn't go backwards; was=%d, after=%d",
+                       preStat.Mtime_ns,
+                       postStat.Mtime_ns)
+       }
+
+       Remove(Path)
+}
+
 func TestChdirAndGetwd(t *testing.T) {
        fd, err := Open(".", O_RDONLY, 0)
        if err != nil {