Provide a platform-dependent implementation of CanMaintainSymlinkTime…

…stamps

internal/unpackinfo/lchtimes.go

@@ -8,10 +8,23 @@ import (
 )
 
 // Lchtimes modifies the access and modified timestamps on a target path
-// This capability is only available on Linux and Darwin as of now.
+// This capability is only available on Linux and Darwin as of now. The
+// timestamps within UnpackInfo would have already been rounded by
+// archive/tar so there is no need for subsecond precision.
 func (i UnpackInfo) Lchtimes() error {
 	return unix.Lutimes(i.Path, []unix.Timeval{
 		{Sec: i.OriginalAccessTime.Unix()},
 		{Sec: i.OriginalModTime.Unix()}},
 	)
 }
+
+// CanMaintainSymlinkTimestamps determines whether is is possible to change
+// timestamps on symlinks for the the current platform. For regular files
+// and directories, attempts are made to restore permissions and timestamps
+// after extraction. But for symbolic links, go's cross-platform
+// packages (Chmod and Chtimes) are not capable of changing symlink info
+// because those methods follow the symlinks. However, a platform-dependent option
+// is provided for linux and darwin (see Lchtimes)
+func CanMaintainSymlinkTimestamps() bool {
+	return true
+}

internal/unpackinfo/lchtimes_others.go

@@ -12,3 +12,14 @@ import (
 func (i UnpackInfo) Lchtimes() error {
 	return errors.New("Lchtimes is not supported on this platform")
 }
+
+// CanMaintainSymlinkTimestamps determines whether is is possible to change
+// timestamps on symlinks for the the current platform. For regular files
+// and directories, attempts are made to restore permissions and timestamps
+// after extraction. But for symbolic links, go's cross-platform
+// packages (Chmod and Chtimes) are not capable of changing symlink info
+// because those methods follow the symlinks. However, a platform-dependent option
+// is provided for linux and darwin (see Lchtimes)
+func CanMaintainSymlinkTimestamps() bool {
+	return false
+}

internal/unpackinfo/unpackinfo.go

@@ -7,7 +7,6 @@ import (
 	"io/fs"
 	"os"
 	"path/filepath"
-	"runtime"
 	"strings"
 	"time"
 )
@@ -109,17 +108,6 @@ func (i UnpackInfo) IsRegular() bool {
 	return i.Typeflag == tar.TypeReg || i.Typeflag == tar.TypeRegA
 }
 
-// CanMaintainSymlinkTimestamps determines whether is is possible to change
-// timestamps on symlinks for the the current platform. For regular files
-// and directories, attempts are made to restore permissions and timestamps
-// after extraction. But for symbolic links, go's cross-platform
-// packages (Chmod and Chtimes) are not capable of changing symlink info
-// because those methods follow the symlinks. However, a platform-dependent option
-// is provided for linux and darwin (see Lchtimes)
-func CanMaintainSymlinkTimestamps() bool {
-	return runtime.GOOS == "linux" || runtime.GOOS == "darwin"
-}
-
 // RestoreInfo changes the file mode and timestamps for the given UnpackInfo data
 func (i UnpackInfo) RestoreInfo() error {
 	switch {