Separate linux and darwin because unix.Timeval differs

internal/unpackinfo/lchtimes.go → internal/unpackinfo/lchtimes_darwin.go

@@ -1,5 +1,5 @@
-//go:build darwin || linux
-// +build darwin linux
+//go:build darwin
+// +build darwin
 
 package unpackinfo
 

internal/unpackinfo/lchtimes_linux.go

@@ -0,0 +1,30 @@
+//go:build linux
+// +build linux
+
+package unpackinfo
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// Lchtimes modifies the access and modified timestamps on a target path
+// 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(), Usec: i.OriginalAccessTime.UnixMicro() % 1000},
+		{Sec: i.OriginalModTime.Unix(), Usec: i.OriginalModTime.UnixMicro() % 1000}},
+	)
+}
+
+// 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
+}