fs: implement Atime for Windows

Taken from moby/buildkit@0b5a315

Co-authored-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

fs/stat_atim.go → fs/stat_unix.go

@@ -20,10 +20,36 @@
 package fs
 
 import (
+	"fmt"
+	"io/fs"
 	"syscall"
 	"time"
 )
 
+func Atime(st fs.FileInfo) (time.Time, error) {
+	stSys, ok := st.Sys().(*syscall.Stat_t)
+	if !ok {
+		return time.Time{}, fmt.Errorf("expected st.Sys() to be *syscall.Stat_t, got %T", st.Sys())
+	}
+	return StatATimeAsTime(stSys), nil
+}
+
+func Ctime(st fs.FileInfo) (time.Time, error) {
+	stSys, ok := st.Sys().(*syscall.Stat_t)
+	if !ok {
+		return time.Time{}, fmt.Errorf("expected st.Sys() to be *syscall.Stat_t, got %T", st.Sys())
+	}
+	return time.Unix(stSys.Atim.Unix()), nil
+}
+
+func Mtime(st fs.FileInfo) (time.Time, error) {
+	stSys, ok := st.Sys().(*syscall.Stat_t)
+	if !ok {
+		return time.Time{}, fmt.Errorf("expected st.Sys() to be *syscall.Stat_t, got %T", st.Sys())
+	}
+	return time.Unix(stSys.Mtim.Unix()), nil
+}
+
 // StatAtime returns the Atim
 func StatAtime(st *syscall.Stat_t) syscall.Timespec {
 	return st.Atim

fs/stat_windows.go

@@ -0,0 +1,33 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package fs
+
+import (
+	"fmt"
+	"io/fs"
+	"syscall"
+	"time"
+)
+
+func Atime(st fs.FileInfo) (time.Time, error) {
+	stSys, ok := st.Sys().(*syscall.Win32FileAttributeData)
+	if !ok {
+		return time.Time{}, fmt.Errorf("expected st.Sys() to be *syscall.Win32FileAttributeData, got %T", st.Sys())
+	}
+	// ref: https://github.com/golang/go/blob/go1.19.2/src/os/types_windows.go#L230
+	return time.Unix(0, stSys.LastAccessTime.Nanoseconds()), nil
+}